Advanced Ceramics

This presentation examines MoSi₂ heating elements and their pivotal role in the sintering of advanced ceramics and powder metallurgy components. It highlights their high-temperature efficiency, oxidation resistance, and long service life, enabling uniform heating, energy-efficient operations, and superior densification of high-performance materials.

A combined experimental-numerical method was used to investigate the role of microstructure on the fracture of advanced ceramics. In particular, the effect of grain size and matrix content were examined. Two dimensional representative finite volume (FV) microstructures were created using Voronoi tessellation to synthetically represent the microstructure of a two phase ceramic composite. It is shown, by comparing with real micrographs, that the method captures the features of real microstructures in terms of grain size distribution, grain aspect ratio and the distribution of second phase agglomerations. Simulation results indicate the computed elastic parameters are within the Hashin-Shtrikman bounds and also agree well with the Eshelby-Mori-Tanaka method. It is found that the underlying microstructure significantly affects the local stress and strain distributions in these advanced ceramics.

Lanthanum strontium cobalt ferrite (LSCF) is an appreciable cathode material for solid oxide fuel cells (SOFCs), and it has been widely investigated, owing to its excellent thermal and chemical stability. However, its poor oxygen reduction reaction (ORR) activity, particularly at a temperature of ⩽ 800 °C, causes setbacks in achieving a peak power density of > 1.0 W·cm−2, limiting its application in the commercialization of SOFCs. To improve the ORR of LSCF, doping strategies have been found useful. Herein, the porous tantalum-doped LSCF materials (La0.6Sr0.4Co0.4Fe0.57Ta0.03O3 (LSCFT-0), La0.6Sr0.4Co0.4Fe0.54Ta0.06O3, and La0.6Sr0.4Co0.4Fe0.5Ta0.1O3) are prepared via camphor-assisted solid-state reaction (CSSR). The LSCFT-0 material exhibits promising ORR with area-specific resistance (ASR) of 1.260, 0.580, 0.260, 0.100, and 0.06 Ω·cm2 at 600, 650, 700, 750, and 800 C, respectively. The performance is about 2 times higher than that of undoped La0.6Sr0.4Co0.4Fe0.6O3 with the ASR ...

Conversion of inorganic-organic frameworks (ceramic precursors and ceramic-polymer mixtures) into solid mass ceramic structures based on photopolymerization process is currently receiving plentiful attention in the field of additive manufacturing (3D printing). Various techniques (e.g., stereolithography, digital light processing, and two-photon polymerization) that are compatible with this strategy have so far been widely investigated. This is due to their cost-viability, flexibility, and ability to design and manufacture complex geometric structures. Different platforms related to these techniques have been developed too, in order to meet up with modern technology demand. Most relevant to this review are the challenges faced by the researchers in using these 3D printing techniques for the fabrication of ceramic structures. These challenges often range from shape shrinkage, mass loss, poor densification, cracking, weak mechanical performance to undesirable surface roughness of the ...

Inkjet printing is a promising alternative for the fabrication of thin film components for solid oxide fuel cells (SOFCs) due to its contactless, mask free, and controllable printing process. In order to obtain satisfying electrolyte thin layer structures in anode-supported SOFCs, the preparation of suitable electrolyte ceramic inks is a key. At present, such a kind of 8 mol% Y2O3-stabilized ZrO2 (8YSZ) electrolyte ceramic ink with long-term stability and high solid loading (> 15 wt%) seems rare for precise inkjet printing, and a number of characterization and performance aspects of the inks, such as homogeneity, viscosity, and printability, should be studied. In this study, 8YSZ ceramic inks of varied compositions were developed for inkjet printing of SOFC ceramic electrolyte layers. The dispersing effect of two types of dispersants, i.e., polyacrylic acid ammonium (PAANH4) and polyacrylic acid (PAA), were compared. The results show that ultrasonic dispersion treatment can help ...

of applications due to its exceptional piezoelectric properties, chemical stability, and mechanical flexibility [1, 2]. This semi-crystalline polymer features a complex molecular structure, characterized by five distinct crystalline phases. Each phase corresponds to specific chain conformations: the β-phase adopts an all-trans (TTT) planar zigzag configuration, the α-and δ-phases exhibit a trans-gauche-transgauche (TGTG) arrangement, while the γ-and ε-phases display a T 3 GT 3 G conformation [3, 4]. In capacitive applications, optimizing the β-phase is crucial due to its superior piezoelectric response [d 33 ~ 34 pC/N] [5, 6]. This is attributed to the all-trans conformation of parallel dipoles (the difluoro methylene group,-CF2), which creates an imbalance in the distribution of negatively charged fluorine ions, resulting in an electric dipole and, consequently, a piezoelectric effect. As a result, significant research efforts have been directed toward enhancing the β-phase content in PVDF and its copolymers for technological applications,

The melt-quenching method has been employed to fabricate 30B 2 O 3-(70-x)CdO-xV 2 O 5 ; x = 0, 1, 2, 3, and 5 mol% glasses. The physical, optical, mechanical, and dielectric properties of the prepared glasses were measured. Structural FTIR spectra and their related deconvolution process showed distinct absorption bands, from which some parameters especially, the N 4 ratio, could be determined by calculating the area under peaks. The successive addition of V 2 O 5 up to 2 mol% at the expense of CdO in the glass network led to an increase in density from 4.27 to 4.69 g/cm 3 for the prepared glasses while adding more V 2 O 5 led to a decrease in density. The molar volume showed the same trend that occurred in the density, but in an opposite direction, as it decreased by increasing V 2 O 5 content till the 2 mol% samples, then increased. The optical energy gap values (Eg) were calculated and were found to decrease from 2.95 to 1.35 eV with increasing levels of V 2 O 5. With varying V 2 O 5 concentrations, the mechanical characteristics of cadmium borate glasses increased up to 2%, declined at 3%, and then improved once again at mol%. The maximum microhardness, fracture toughness, and Young's modulus were 624.12 HV, 2.87 MPa.m 0.5 , and 63.71 GPa for samples contained 2 mol% V 2 O 5 which improved about 14.91, 32.26, and 21.84% compared to unreinforced glass sample. In addition, adding V 2 O 5 and increasing the frequency had a positive effect on the electrical conductivity with the real and imaginary dielectric constant, and tan δ is the opposite. The electrical conductivity and tan δ of glass containing high V 2 O 5 at a frequency of 20 MHz were 1.45 × 10⁻ 2 S/cm and 0.0619, respectively, at a frequency of 20 mΩ.

Since the 1960s, a new class of Si-based advanced ceramics called polymer-derived ceramics (PDCs) has been widely reported because of their unique capabilities to produce various ceramic materials (e.g., ceramic fibers, ceramic matrix composites, foams, films, and coatings) and their versatile applications. Particularly, due to their promising structural and functional properties for energy conversion and storage, the applications of PDCs in these fields have attracted much attention in recent years. This review highlights the recent progress in the PDC field with the focus on energy conversion and storage applications. Firstly, a brief introduction of the Si-based polymer-derived ceramics in terms of synthesis, processing, and microstructure characterization is provided, followed by a summary of PDCs used in energy conversion systems (mainly in gas turbine engines), including fundamentals and material issues, ceramic matrix composites, ceramic fibers, thermal and environmental barr...

In the research field of energy storage dielectrics, the "responsivity" parameter, defined as the recyclable/recoverable energy density per unit electric field, has become critically important for a comprehensive evaluation of the energy storage capability of a dielectric. In this work, high recyclable energy density and responsivity, i.e., W rec = 161.1 J•cm -3 and ξ = 373.8 J•(kV•m 2 ) -1 , have been simultaneously achieved in a prototype perovskite dielectric, BaTiO 3 , which is integrated on Si at 500 ℃ in the form of a submicron thick film. This ferroelectric film features a multi-scale polar structure consisting of ferroelectric grains with different orientations and inner-grain ferroelastic domains. A LaNiO 3 buffer layer is used to induce a {001} textured, columnar nanograin microstructure, while an elevated deposition temperature promotes lateral growth of the nanograins (in-plane diameter increases from ~10-20 nm at lower temperatures to ~30 nm). These preferably oriented and periodically regulated nanograins have resulted in a small remnant polarization and a delayed polarization saturation in the film's P-E behavior, leading to a high recyclable energy density. Meanwhile, an improved polarizability/dielectric constant of the BaTiO 3 film has produced a much larger maximum polarization than those deposited at lower temperatures at the same electric field, leading to a record-breaking responsivity for this simple perovskite.

Achieving an excellent energy storage performance, together with high cycling reliability, is desirable for expanding technological applications of ferroelectric dielectrics. However, in well-crystallized ferroelectric materials, the concomitant high polarizability and low polarizationsaturation field have led to a square-shaped polarization-electric field loop, fatally impairing both recoverable energy density (W rec ) and efficiency (η). Nanocrystalline ferroelectric films with a macroscopically amorphous structure have shown an improved W rec and η, but their much lower polarizability demands an extremely high electric field to achieve such performances, which is undesirable from an economic viewpoint. Here, we propose a strategy to boost the energy storage performances and stability of ferroelectric capacitors simultaneously by constructing a tri-layer film in which a well-crystallized ferroelectric layer was sandwiched by two pseudo-linear dielectric layers with a dominant amorphous structure. In sol-gel-derived BaTiO 3 /(Pb,La,Ca)TiO 3 /BaTiO 3 (BTO/ PLCT/BTO) tri-layer films, we show that the above design is realized via rapid thermal annealing which fully crystallized the middle PLCT layer while left the top/bottom BTO cap layers in a poor crystallization status. This sandwiched structure is endowed with an enhanced maximum polarization while a small remnant one and a much-delayed polarization saturation, which corresponds to large W rec ≈ 80 J/cm 3 and high η ≈ 86%. Furthermore, the film showed an outstanding cycling stability: its W rec and η remain essentially unchanged after 10 9 electric cycles (W/W < 4%, η/η < 2%). These † Jinpeng Liu and Ying Wang contributed equally to this work.

To meet the expectation set by Moore's law on transistors, the search for thickness-scalable high dielectric constant (k) gate layers has become an emergent research frontier. Previous investigations have failed to solve the "polarizability-scalability-insulation robustness" trilemma. In this work, we show that this trilemma can be solved by using a gate layer of a high k ferroelectric oxide in its superparaelectric (SPE) state. In the SPE, its polar order becomes local and is dispersed in an amorphous matrix with a crystalline size down to a few nanometers, leading to an excellent dimensional scalability and a good field-stability of the k value. As an example, a stable high k value (37±3) is shown in ultrathin SPE films of (Ba 0.95 ,Sr 0.05 )(Zr 0.2 ,Ti 0.8 )O 3 deposited on LaNiO 3 -buffered Pt/Ti/SiO 2 /(100)Si down to a 4 nm thickness, leading to a small equivalent oxide thickness of ~0.46 nm. The aforementioned characteristic microstructure endows the SPE film a high breakdown strength (~10.5 MV•cm -1 for the 4 nm film), and hence ensures a low leakage current for the operation of the complementary metal oxide semiconductor (CMOS) gate. Lastly, a high electrical fatigue resistance is displayed by the SPE films. These results reveal a great potential of superparaelectric materials as gate dielectrics in the next-generation microelectronics.

The engineering, various factors, and mechanism responsible for emission and high intensity of ZnO luminescence are well developed. Only a few researchers investigate the role of oxygen vacancy on the luminescence properties of doped ZnO. The objective of this research is to synthesize the ZnO fine particle with tailored oxygen vacancy by doping with 5 at.% of divalent and trivalent dopants, i.e., magnesium (ZnO:Mg 2+ ), calcium (ZnO:Ca 2+ ), gadolinium (ZnO:Gd 3+ ), and lanthanum (ZnO:La 3+ ) using spray pyrolysis method. The samples prepared at 700 °C with 5 l/min carrier gas flow characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL) spectroscopy. The oxygen vacancy was successfully tuned by introducing various doping into ZnO fine particles. It is found that the oxygen vacancy responsible for the increase of DLE intensity (I DLE ) on the deconvoluted of PL spectra. When the ZnO fine particle doped with trivalent ions (Gd 3+ , La 3+ ), the contribution of NBE intensity (I NBE ) is higher than I DLE . Important phenomena also observed when the excitation wavelength was tuned. The contribution of I DLE and I NBE changes, lead to control the luminescence properties.

Lead-free (1x)Na 0.5 Bi 0.5 TiO 3 -xSrTiO 3 (NBT-STx; x = 0.05, 0.10, 0.15 and 0.20) ceramics were prepared using a hightemperature solid-state reaction method. X-ray diffraction patterns indicated that the ceramics were a cubic structure with space group Pm3m at room temperature. The average grain sizes slightly decreased with the increasing SrTiO 3 content observed by scanning electron microscope. The dielectric properties and complex impedance spectra were used to analyze the electrical behavior of the ceramics as a function of frequency at different temperature. The results showed that with the increase of x, the dielectric constant increased, however, the temperature of the dielectric maximum (T m ) and depolarization temperature (T d ) decreased. The modified Curie-Weiss law was used to describe the diffuseness behavior of the ceramics. The relaxation activation energy was estimated to be 2.32-2.73 eV through Arrhenius fitting, which indicated that the oxygen vacancy concentration in the samples was low.

Ba 0.85 Ca 0.15 Zr 0.10 Ti 0.90 O 3 (BCZT) lead-free ceramics demonstrated excellent dielectric, ferroelectric, and piezoelectric properties at the morphotropic phase boundary (MPB). So far, to study the effect of morphological changes on dielectric and ferroelectric properties in lead-free BCZT ceramics, researchers have mostly focused on the influence of spherical grain shape change. In this study, BCZT ceramics with rod-like grains and aspect ratio of about 10 were synthesized by surfactant-assisted solvothermal route. X-ray diffraction (XRD) and selected area electron diffraction (SAED) performed at room temperature confirm the crystallization of pure perovskite with tetragonal symmetry. Scanning electron microscopy (SEM) image showed that BCZT ceramics have kept the 1D rod-like grains with an average aspect ratio of about 4. Rod-like BCZT ceramics exhibit enhanced dielectric ferroelectric (ε r = 11,906, tanδ = 0.014, P r = 6.01 µC/cm², and E c = 2.46 kV/cm), and electrocaloric properties (ΔT = 0.492 K and  = 0.289 (Kmm)/kV at 17 kV/cm) with respect to spherical BCZT ceramics. Therefore, rod-like BCZT lead-free ceramics have good potential to be used in solid-state refrigeration technology. Keywords: lead-free Ba 0.85 Ca 0.15 Zr 0.10 Ti 0.90 O 3 (BCZT); rod-like Ba 0.85 Ca 0.15 Zr 0.10 Ti 0.90 O 3 (BCZT); dielectric; ferroelectric; electrocaloric effect

Ba0.85Ca0.15Zr0.10Ti0.90O3 (BCZT) lead-free ceramics demonstrated excellent dielectric, ferroelectric, and piezoelectric properties at the morphotropic phase boundary (MPB). So far, to study the effect of morphological changes on dielectric and ferroelectric properties in lead-free BCZT ceramics, researchers have mostly focused on the influence of spherical grain shape change. In this study, BCZT ceramics with rod-like grains and aspect ratio of about 10 were synthesized by surfactant-assisted solvothermal route. X-ray diffraction (XRD) and selected area electron diffraction (SAED) performed at room temperature confirm the crystallization of pure perovskite with tetragonal symmetry. Scanning electron microscopy (SEM) image showed that BCZT ceramics have kept the 1D rod-like grains with an average aspect ratio of about 4. Rod-like BCZT ceramics exhibit enhanced dielectric ferroelectric (ɛr = 11,906, tanδ = 0.014, Pr = 6.01 μgC/cm2, and Ec = 2.46 kV/cm), and electrocaloric properties ...

A thorough understanding of the technology process parameters' is needed because of the final material structure and its dependence on the parameters. This paper describes determination of technology parameters directional solidification process and their influence on CMSX-3 nickel based superalloy structure of casting. A technológiai folyamatok paramétereinek ismerete szükséges a végső anyagszerkezet és ezen paraméterek közti összefüggések feltárása szempontjából. A dolgozat az irányított kristályosítás technológiai paramétereinek meghatározását vázolja és bemutatja a technológia paramétereinek hatását a kialakuló CMSX-3 jelölésű nikkel alapú szuperötvözet-öntvény szövetszerkezetére. Köszönetemet fejezem ki Žitňanský professzornak és Maroš Martinkovič docensnek az irányított kristályosítással összefüggő projektek során megvalósult sikeres együttműködésért.

In this study, the latest developments in 3D printing of porous glasses are discussed. Current challenges in 3D printing of porous-based microfluidic devices mostly include the printing resolution which is correlated with the processing time, post treating, and developing tailored materials for porous glasses. Although the latter issue has been resolved to some extent recently, the former has remained a challenge. Currently, the smallest 3D printed feature in a microfluidic structure is 200µm while higher resolutions are required in some applications. On the other hand, previous reports have shown intensive printing time for higher resolutions. To achieve an optimal compromise, further investigations and technological advancements in the printing technology should be carried out. An extrusion-based 3D printing system "G3DP2" developed by MIT researchers enables the printing of porous glasses by controlling the heating and cooling cycles. The other important challenge is related to the printable glass materials. Recently, newly developed materials such as ceramic-based resins and "Glassomer" that contains fine glass powders in a plastic binder matrix, has enabled the fabrication of porous glasses by resin 3D printing systems.

Co 2+ doped TiO 2 nanocrystals were synthetized by a hydrothermal treatment procedure applied to precursor dispersion of titania nanotubes and Co 2+ ions. Mixture of polygonal and prolate spheroid-like nanocrystals was obtained. The results of X-ray diffraction (XRD) analysis showed that resulted nanocrystals retain anatase crystal phase for both dopant concentrations (1.69 and 2.5 at%), but the crystal lattice parameters were affected. Reflection spectra revealed altered optical properties compared to bare TiO 2 . Room temperature ferromagnetic ordering with saturation magnetic moment in the range of 0.001-0.002 B /Co  was observed for both measured films made of Co 2+ doped TiO 2 nanocrystals.

Since the 1960s, a new class of Si-based advanced ceramics called polymer-derived ceramics (PDCs) has been widely reported because of their unique capabilities to produce various ceramic materials (e.g., ceramic fibers, ceramic matrix composites, foams, films, and coatings) and their versatile applications. Particularly, due to their promising structural and functional properties for energy conversion and storage, the applications of PDCs in these fields have attracted much attention in recent years. This review highlights the recent progress in the PDC field with the focus on energy conversion and storage applications. Firstly, a brief introduction of the Si-based polymer-derived ceramics in terms of synthesis, processing, and microstructure characterization is provided, followed by a summary of PDCs used in energy conversion systems (mainly in gas turbine engines), including fundamentals and material issues, ceramic matrix composites, ceramic fibers, thermal and environmental barr...

High-density (with a relative density of up to 98.8%) ultra-high-temperature ceramic materials (UHTCs) based on the ZrB 2-TaC-SiC system were obtained by hot pressing for 15 min at 2000°C 30 MPa of pressure in an argon atmosphere. Phase composition, lattice parameters, microstructure, flexural strength, Vickers hardness and crack resistance were studied. The maximum values of strength, hardness and crack resistance were 440 MPa, 20.3 GPa and 5.3 MPa•m 1/2 , respectively. The effect of the ZrB 2 /TaC ratio on the lattice constants and the mechanical properties of the material is established.

This research paper presents a comprehensive study on modeling the failure behavior of advanced ceramics by integrating phenomenological and physics-based approaches. The proposed methodology utilizes the bivariate Weibull distribution to capture the complex failure mechanisms in advanced ceramics, considering the impact of Subcritical Crack Growth (SCG). Approximate Bayesian Computation (ABC) is employed for parameter estimation, leveraging Metropolis-Hastings (MH) and Hamiltonian Monte Carlo (HMC) algorithms to enhance computational efficiency. The study validates the proposed models against a physics-based Batdorf theory approach using NASA's CARES/Life. Results demonstrate the robustness of the ABC MH and ABC HMC models, highlighting the capability of statistical approach to predict failure dynamics in advanced ceramics under varying conditions. This research contributes to a deeper understanding of advanced ceramic failure mechanisms, paving the way for further advancements in material science and engineering applications of ceramics.

Despite the unique advantages of natural fibers as a reinforcement in polymer composites, they have high natural variability in their mechanical properties, resulting in significant uncertainties in the properties of natural fiber composites. This study aims to propose a multilevel framework based on the Approximate Bayesian Computation (ABC) to analyze the uncertainty of fitting the Weibull distribution to the strength data of date palm fibers. Two computationally efficient algorithms of the ABC, namely the Metropolis-Hasting as a family of Markov Chain Monte Carlo and the Sequential Monte Carlo (SMC), are employed for estimating the highest density interval of the fitting parameters of the modified 3-parameter Weibull distribution, and their performances are evaluated. Moreover, appropriate probability distributions that best fit the estimated parameters are determined based on the goodness of fit to describe their characteristics. It is found that the SMC algorithm leads to a higher scatter in the posterior predictive distribution of the fitting parameters. The results suggest that the uncertainty of the fitting parameters should be considered to have a reliable model for the probability of natural fiber failure.

Endothelium-dependent vasodilation is thought to be mediated primarily by the NO/cGMP signalling pathway whereas cAMP-elevating vasodilators are considered to act independent of the endothelial cell layer. However, recent functional data suggest that cAMP-elevating vasodilators such as β-receptor agonists, adenosine or forskolin may also be endothelium-dependent. Here we used functional and biochemical assays to analyze endothelium-dependent, cGMP-and cAMP-mediated signalling in rat aorta. Acetylcholine and sodium nitroprusside (SNP) induced a concentration-dependent relaxation of phenylephrine precontracted aorta. This response was reflected by the phosphorylation of the vasodilator-stimulated phosphoprotein (VASP), a validated substrate of cGMP-and cAMP-dependent protein kinases (cGK, cAK), on Ser 157 and Ser 239 . As expected, the effects of acetylcholine were endothelium-dependent. However, relaxation induced by the β-receptor agonist isoproterenol was also almost completely impaired after endothelial denudation. At the biochemical level, acetylcholine-and isoproterenol-evoked cGK and cAK activation, respectively, as measured by VASP Ser 239 and Ser 157 phosphorylation, was strongly diminished. Furthermore, the effects of isoproterenol were repressed by eNOS inhibition when endothelium was present. We also observed that the relaxing and biochemical effects of forskolin were at least partially endothelium-dependent. We conclude that cAMP-elevating vasodilators, i.e. isoproterenol and to a lesser extent also forskolin, induce vasodilation and concomitant cyclic nucleotide protein kinase activation in the vessel wall in an endothelium-dependent way.

Gd-doped ZnO samples prepared using the solid-phase reaction technique were investigated for their structural, optical, and dielectric properties. The presence of a hexagonal wurtzite phase was confirmed by XRD spectra, with the crystallite size distribution of 42.85, 45.38, and 47.13 nm. The grains showed an almost spherical shape, as revealed by FE-SEM images. The bonding behaviors of stretching modes such as O-H, O=C=O, and Zn-O were confirmed by FT-IR spectra. The optical energy gap gradually decreased (3.17, 3.18, and 3.20 eV, respectively), as confirmed by the optical absorption spectra. The PL spectra of all samples showed near-band emission, blue-shift emission, and green-shift emission peaks. The Gddoped ZnO samples have a high dielectric, making them suitable as a coolant and insulator for transformers and charge storage devices. As the Gd concentration increases, the mobility and resistivity increase, according to Hall effect data.

A Borsod-Bos 2004 Kft. mechanikusan és termikusan aktivált hulladék alapanyagok felhasználásával saját fejlesztésű, de a piacon ma is elérhető statikai tulajdonságokkal bíró betonelemek gyártástechnológiáját fejlesztette ki kutatás-fejlesztési projektje keretében. A projektben felhasznált erőműi pernye- és salak, bányameddő, perlit és hulladék beton alapanyagokat nagy teljesítményű őrléssel aktiváltuk, majd a különböző részecskeméretű frakciókat beton töltőanyagként teszteltük. Annak érdekében, hogy elérjük azt a nyomószilárdságot, amit hagyományos úton cementkötéssel elérhetünk egy C25-C30-C35 betonterméknél, a mechanikai kezelést egy termikus aktiválással egészítettük ki, melynek során elértük, hogy a betontermékek kevesebb cement felhasználásával is megfelelő nyomószilárdsággal voltak jellemezhetőek. A mechanikai előkezelés után egyes adalék anyagainkat betonipari tulajdonság javító szerekkel is aktiváltuk, és vizsgáltuk ezek hatását a késztermékekre. Az öntési kísérleteket a Borsod-Bos 2004 Kft. Igriciben lévő telephelyén végeztük, a nyomószilárdság méréshez készített próbakockákon kívül térkövek és zsalukövek formájában.

Background: With regard to the ceramic hip joint implant, given the concerns in ceramic about the alumina brittleness and zirconia instability, is there any alternative material solution for the orthopedic implant? Beyond the metastable oxide ceramics, along the echelon of advanced technical ceramics, looking at the non-oxide ceramic, the silicon nitride could be an excellent candidate for the joint implant's application. The purpose of this study is to investigate the safety, effectiveness and to demonstrate the potential of this silicon nitride hip implant. Methods: According to the related ISO (International Organization for Standardization) standards, a series of in vitro (nine) & in vivo (five) tests, which had been accomplished for the aforementioned aim. Especially, the total hip replacement in pigs had been achieved, as per the authors' knowledge, this is the first time to apply the THA (Total Hip Arthroplasty) in the big animal. Results: Refer to the ISO 6474-2, in comparison with the current monopolized German product, this silicon nitride ceramic hip implant has high strength, high hardness, excellent fracture toughness, lower density, better wear resistance, good biocompatibility, inherent stability, corrosion resistance and bioactivity, bone integration capability. Conclusions: This silicon nitride ceramic will be an admirable alternative solution with superior comprehensive property that can withstand the toughest conditions in the most demanding applications like in orthopedic and beyond.

Hydrothermal synthesis is one a chemical method with high potential for obtaining nanostructured materials with controlled properties for energy harvesting applications. The main advantage of the hydrothermal processes is the ability to control nucleation and growth in complex systems containing a large number of components and dopants, without affecting the structural and morphological homogeneity. This is leading to some important technological and environmental advantages such as: one step process for direct production of crystalline ceramic powders, low energy consumption, products with much higher homogeneity than classical solid state processing, versatility in producing oxides, non-oxides and hybrid materials with different morphologies, possibility to be up-scaled to pilot and production levels. These features are proved for some selected nanomaterials with high impact in energy harvesting technologies: yttria doped zirconia nanomaterials for solid oxide fuel cells, lead zir...

High-frequency soft magnetic ferrite ceramics are desired in miniaturized and efficient power electronics but remain extremely challenging to deploy on account of the power loss (P cv ) at megahertz frequencies. Here, we prepared NiCuZn ferrite with superior high-frequency properties by V 2 O 5 and Bi 2 O 3 synergistic doping, which proves to be a potent pathway to reduce P cv of the ferrite at megahertz frequencies. The sample doped with 800 ppm V 2 O 5 and 800 ppm Bi 2 O 3 yielded the most optimized magnetic properties with a P cv of 113 kW/m 3 (10 MHz, 5 mT, 25 ℃), an initial permeability (μ i ) of 89, and a saturation induction (B s ) of 340 mT, which is at the forefront of the reported results. These outstanding properties are closely related to the notable grain boundary structure, which features a new type of nano-Bi 2 Fe 4 O 9 phase around ferrite grains and a Ca/Si/V/O amorphous layer. Our results indicate great strides in correlating the grain boundary structure with multiple-ion doping and set the scene for the developing high-frequency soft magnet ferrites.

High-frequency soft magnetic ferrite ceramics are desired in miniaturized and efficient power electronics but remain extremely challenging to deploy on account of the power loss (Pcv) at megahertz frequencies. Here, we prepared NiCuZn ferrite with superior high-frequency properties by V2O5 and Bi2O3 synergistic doping, which proves to be a potent pathway to reduce Pcv of the ferrite at megahertz frequencies. The sample doped with 800 ppm V2O5 and 800 ppm Bi2O3 yielded the most optimized magnetic properties with a Pcv of 113 kW/m3 (10 MHz, 5 mT, 25 °C), an initial permeability (μi) of 89, and a saturation induction (Bs) of 340 mT, which is at the forefront of the reported results. These outstanding properties are closely related to the notable grain boundary structure, which features a new type of nano-Bi2Fe4O9 phase around ferrite grains and a Ca/Si/V/O amorphous layer. Our results indicate great strides in correlating the grain boundary structure with multiple-ion doping and set th...

Nb-doped SrFeO 3-δ (SFO) is used as a cathode in proton-conducting solid oxide fuel cells (H-SOFCs). Firstprinciples calculations show that the SrFe 0.9 Nb 0.1 O 3-δ (SFNO) cathode has a lower energy barrier in the cathode reaction for H-SOFCs than the Nb-free SrFeO 3-δ cathode. Subsequent experimental studies show that Nb doping substantially enhances the performance of the SrFeO 3-δ cathode. Then, oxygen vacancies (V O ) were introduced into SFNO using the microwave sintering method, further improving the performance of the SFNO cathode. The mechanism behind the performance improvement owing to V O was revealed using first-principles calculations, with further optimization of the SFNO cathode achieved by developing a suitable wet chemical synthesis route to prepare nanosized SFNO materials. This method significantly reduces the grain size of SFNO compared with the conventional solid-state reaction method, although the solid-state reaction method is generally used for preparing Nb-containing oxides. As a result of defect engineering and synthesis approaches, the SFNO cathode achieved an attractive fuel cell performance, attaining an output of 1764 mW•cm -2 at 700 °C and operating for more than 200 h. The manipulation of Nb-doped SrFeO 3-δ can be seen as a "one stone, two birds" strategy, enhancing cathode performance while retaining good stability, thus providing an interesting approach for constructing high-performance cathodes for H-SOFCs.

Keramia reszecskek kemiai nikkelezese tobblepcss folyamat. Felulettisztitas, feluletaktivalas, feluletbevonas, melyek mindegyike fontos lehet a vegeredmeny szempontjabol. De hogyan modosul a retegkepzdes, milyen lesz a bevonat, ha a felulettisztitast vagy akar feluletaktivalast reszben vagy egeszeben elhagyjuk. Kutatomunkank soran ezekre a kerdesekre kerestuk a valaszt, es aluminium-oxid illetve sziliciumkarbid szemcseken elvegzett kiserleti eredmenyeinket es az ezekbl levonhato kovetkezteteseinket jelen cikkunkben foglaltuk ossze. Abstract The electroless nickel plating of ceramic particles are a multi-step process. Each step that is surface cleaning, surface activation and surface coating, is important from the view-point of the end-product. But how the deposit formation is modified, what the coating will be, if the surface cleaning or the surface activation are left partially or fully from the technology. In our research work these queries would be answered. The results of the re...

A szív- és érrendszeri betegségek az Európai Unióban a halálesetek majdnem felét okozzák. Az életmód, a környezet valamint az egészségügy döntően meghatározzák e betegségek alakulását. Tekintve, hogy az említett megbetegedések esetében nagy segítséget jelent a sztentbeültetés, az ezzel kapcsolatos kutató-fejlesztő tevékenység rendkívül fontos. Munkánkban elhunytakból eltávolított sztenteken végzünk roncsolásmentes anyagvizsgálatokat optikai, elektronés konfokális mikroszkóppal a törések, felületi hibák feltárása és a sztentek típusainak beazonosítása céljából. A vizsgálatok eredményeként megállapítható, hogy az elhunytakból eltávolított sztenteken megfigyelhető jelentős deformációt a sztentek az explantáció során szenvedték el. Az eleketronmikroszkópos vizsgálatok segítségével egyértelműen eldönthetővé vált a bevonatok jelenéte vagy hiánya

Silicon nanostructures can improve the bending strength of wafers, but often trap particle contaminates. A double-sided surface nanostructure with a morphology controlled via wet chemical etching is used to both improve the mechanical strength and reduce surface reflection. Compared with a conventional polished silicon wafer, the bending strength was increased by 3.4 times and the surface reflection was reduced to 1%, and so can provide a promising solution for photovoltaic applications. The optically unused side of the wafer was protected by a thin silicon layer that prevented the entrapment of particles that might cause glitches in subsequent fabrication processes, all the while maintaining the enhancement in strength. The particle test confirmed that incorporating protection layer intacts the particle count with polished silicon sample.

Honeycomb structures have found numerous applications as structural and biomedical materials due to their favourable properties such as low weight, high stiffness, and porosity. Application of additive manufacturing and 3D printing techniques allows for manufacturing of honeycombs with arbitrary shape and wall thickness, opening the way for optimizing the mechanical and physical properties for specific applications. In this study, the mechanical properties of honeycomb structures with a new geometry, called octagonal honeycomb, were investigated using analytical, numerical, and experimental approaches. An additive manufacturing technique, namely fused deposition modelling, was used to fabricate the honeycomb from polylactic acid (PLA). The honeycombs structures were then mechanically tested under compression and the mechanical properties of the structures were determined. In addition, the Euler-Bernoulli and Timoshenko beam theories were used for deriving analytical relationships for elastic modulus, yield stress, Poisson's ratio, and buckling stress of this new design of honeycomb structures. Finite element models were also created to analyse the mechanical behaviour of the honeycombs computationally. The analytical solutions obtained using Timoshenko beam theory were close to computational results in terms of elastic modulus, Poisson's ratio and yield stress, especially for relative densities smaller than 25%. The analytical solutions based on the Timoshenko analytical solution and the computational results were in good agreement with experimental observations. Finally, the elastic properties of the proposed honeycomb structure were compared to those of other honeycomb structures such as square, triangular, hexagonal, mixed, diamond, and Kagome. The octagonal honeycomb showed yield stress and elastic modulus values very close to those of regular hexagonal honeycombs and lower than the other considered honeycombs.

Honeycombs resemble the structure of a number of natural and biological materials such as cancellous bone, wood, and cork. Thick honeycomb could be also used for energy absorption applications. Moreover, studying the mechanical behavior of honeycombs under in-plane loading could help understanding the mechanical behavior of more complex 3D tessellated structures such as porous biomaterials. In this paper, we study the mechanical behavior of thick honeycombs made using additive manufacturing techniques that allow for fabrication of honeycombs with arbitrary and precisely controlled thickness. Thick honeycombs with different wall thicknesses were produced from polylactic acid (PLA) using fused deposition modelling, i.e., an additive manufacturing technique. The samples were mechanically tested in-plane under compression to determine their mechanical properties. We also obtained exact analytical solutions for the stiffness matrix of thick hexagonal honeycombs using both Euler-Bernoulli and Timoshenko beam theories. The stiffness matrix was then used to derive analytical relationships that describe the elastic modulus, yield stress, and Poisson's ratio of thick honeycombs. Finite element models were also built for computational analysis of the mechanical behavior of thick honeycombs under compression. The mechanical properties obtained using our analytical relationships were compared with experimental observations and computational results as well as with analytical solutions available in the literature. It was found that the analytical solutions presented here are in good agreement with experimental and computational results even for very thick honeycombs, whereas the analytical solutions available in the literature show a large deviation from experimental observation, computational results, and our analytical solutions.

In this work, a titanium boron carbonitride advanced ceramic was successfully synthesised by a solid-gas mechanochemical reaction in a planetary ball mill from a mixture of elemental Ti, B, and C under nitrogen atmosphere. This material, with a general formula of Ti(BCN), exhibits a face-centred cubic structure (NaCl type) that is analogous to Ti(CN). This phase was gradually formed with sufficient milling time as a result of diffusional processes, which were permitted by the reduction of the energy in the system caused by the decrease in the spinning rate of the planetary ball mill. In contrast, under more energetic milling conditions, a mechanically induced selfsustaining reaction (MSR) took place, leading to the formation of a TiB 2 -Ti(CN) ceramic composite. The microstructural characterisation revealed that Ti(BCN) was composed of ceramic particles constituted of misoriented nanocrystalline domains. B, C and N were optimally distributed in the Ti(BCN) phase. The TiB 2 -Ti(CN) ceramic composite was composed of micrometric and nanometric particles homogeneously distributed. Additionally, the nitrogen content obtained for Ti(BCN) was higher than for the Ti(CN) phase in the composite material.

In the present study, we report a fabrication of dual-mode carbon coated gadolinia C@Gd 2 O 3 particles by a facile hydrothermal synthesis method without using any organic solvents. The prepared C@Gd 2 O 3 particles have a core-shell structure and a narrow size distribution in the range of 261±27 nm. The fluorescent properties of the prepared C@Gd 2 O 3 particles were accessed by a room-temperature photoluminescence study, while the longitudinal relaxivity (r 1 ) was examined by using a clinical 1.5 T MRI scanner. A murine fibroblast L-929 cell line was used to examine the cytotoxicity and capability of the prepared C@Gd 2 O 3 particles for the fluorescent labeling. The obtained results show that the prepared C@Gd 2 O 3 particles could be used as a dual-mode contrast agent for magnetic resonance and fluorescence imaging.

The ferromagnetically coupled cobalt ion is observed to create a magnetocrystalline anisotropy in the PrNi 5-x Co x structure above a critical composition of x = 2. The competition of the anisotropy energies between Co and Pr sublattices gives rise to a spin reorientation (SR) phenomenon in PrNi 5-x Co x compounds at a low temperature (∼150 K) which is then followed by a magnetic transition at a higher temperature. Co-doping has a strong influence on the Curie temperature, changing it from ∼60 K (x = 1.95) to ∼537 K (x = 3). The magnetic entropy change is associated with SR as well as a magnetic transition, and correspondingly a large full width at half maximum (δT FWHM ) is obtained for this series of compounds. For example, the PrNi 2.85 Co 2.15 compound presents δT FWHM = 166 K at a 1 T field. This series therefore has an appreciable relative cooling power, which makes this material a suitable magnetic refrigerant over a large temperature span.

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Li 4 Ti 5 O 12 /C composite anode materials have been prepared by solid-state reactions using lithiumor titanium-containing reagents (lithium lactate, acetate, and acetylacetonate or titanium oxyacetylacetonate) not only as precursors for the synthesis of lithium titanate but also as carbon sources. In addition, two surfactants, Pluronic 123 (P123) and cetyltrimethylammonium bromide, have been used as carbon sources. The composites have been characterized by X-ray diffraction, scanning electron microscopy, and Raman spectroscopy, and their electrochemical properties have been studied. The results demonstrate that the best electrochemical performance is offered by the materials prepared using P123. In particular, the discharge capacity of the Li 4 Ti 5 O 12 /C material prepared using TiO 2 /P123 and lithium lactate is 119 and 44 mAh/g at current densities of 200 and 3200 mA/g, respectively. The materials prepared using lithium and titanium acetylacetonates have high carbon content and undergo more severe degradation during cycling at high current densities.

Orthopaedic-implant-related infections are challenging for clinicians: despite progresses in surgical procedures, the mortality rate of patients experiencing periprosthetic joint infections still ranges from 10 to 18%. Generally, infection starts when planktonic bacteria arising from surgery escape immunological surveillance adhering onto implant surface. Bacterial adhesion depends mainly on material's intrinsic surface features depending on its chemical and physical properties. This study compares materials used for bearings of total hip arthroplasty, advanced ceramics (alumina and zirconia-platelet toughened alumina composites), metals (cobalt-chromium-molybdenum alloy) and polymers (highly cross-linked polyethylene), in terms of wettability and protein adsorption. Materials were infected with Staphylococcus aureus and Staphylococcus epidermidis biofilm for 24 or 48 h. Bacterial adhesion properties were evaluated by means of biofilm viability, morphology, and thickness, in a worst-case surface roughness condition. Thanks to selective protein adsorption, bioceramics reduced bacterial adhesion and subsequent biofilm formation more effectively in comparison with metal and polymer surfaces.

A new silicon nitride precursor: TICZ is presented. Salient features are: No Si-C bonds, which tend to increase carbon content Readily decomposed (propene leaving group, ring opening reaction) Scalable synthesis (confirmed) Sufficiently volatile and stable Deposition parameters can be controlled to produce SiN or SIC:N

In this paper, a simple and cheap method to prepare porous ZnO by using zinc nitrate, ethanol and triethanolamine (TEA) is reported. The as-prepared sample consisted of nano and micro pores. The sample was calcined at 300 ℃, 400 ℃ and 500 ℃ with different heating rates. At 500 ℃, the nano pores disappeared but the sample maintained its micro porosity. Field emission scanning electron microscopy (FE-SEM) pictures confirmed that the size and growth of ZnO nanoparticles depended on the heating conditions. The infrared (IR) absorption peak of Zn-O stretching vibration positioned at 457 cm 1 was split into two peaks centered at 518 cm 1 and 682 cm 1 with the change of morphology. These results confirmed that Fourier transform infrared (FT-IR) spectrum was sensitive to variations in particle size, shape and morphology. The photoluminescence (PL) spectrum of porous ZnO contained five emission peaks at 397 nm, 437 nm, 466 nm, 492 nm and 527 nm. Emission intensity enhanced monotonously with increase of temperature and the change was rapid between temperatures of 300 ℃ and 500 ℃. This was due to the elimination of organic species and improvement in the crystallanity of the sample at 500 ℃.

Alle rechten voorbehouden. Niets uit deze uitgave mag worden vermenigvuldigd en/of openbaar gemaakt worden door middel van druk, fotokopie, microfilm, elektronisch of op welke andere wijze ook zonder voorafgaande schriftelijke toestemming van de uitgever. All rights reserved. No part of the publication may be reproduced in any form by print, photoprint, microfilm, electronic or any other means without written permission from the publisher. PREFACE Mam, Nicholas en Julia, Fish, Geert, Bommeke en Moeke. Pap, bedankt voor alle wijze raad, en om ervoor te zorgen dat ik mij altijd thuis voel in Asse, wanneer ik ook op bezoek kom. Ge hebt mij geleerd hoe belangrijk het is om altijd bescheiden te blijven en met de voeten op de grond te staan, en getoond hoe waardevol het is om iets te doen waar ge voldoening uithaalt. Mam, bedankt voor alle warmte en zorgzaamheid. Uw vriendelijkheid, empathie en tolerantie hebben mij geïnspireerd om deze waarden hoog in het vaandel te dragen, bij mezelf en anderen. Spijtig dat dat ook niet gelukt is met uw ordelijkheid en georganiseerd zijn, maar ik hoop dat ge dat niet te erg vindt ;). Bedankt Smeyers, Fish en Mathildeke, voor de clowneske vertoningen, voor de diep filosofische discussies over solitaire wezens, voor Mexico, voor jullie gezichten, voor de autoritjes waar ik jullie nooit genoeg voor bedank en voor al het plezier dat we samen maken, in Asse, aan zee, in Leuven, in Italia, waar dan ook. Nicholas & Jules, ik heb ongelooflijk veel geluk dat ik kan zeggen dat jullie niet gewoon broer en zus zijn, maar echte vrienden. En Julia nog eens merci voor het nalezen van twee pagina's van mijn tekst hé, dat moet expliciet vermeld worden. Een grootse verwezenlijking. Ik ga dit nog twintig keer opnieuw schrijven, en ik zal er nooit tevreden over zijn, maar ooit zal ik mijn definitieve tekst moeten 2D-printen, dus hier eindigt het. Ik hoop dat jullie er iets aan gehad hebben, al is het maar een fractie van wat ik heb gehad aan jullie. Ah ja en veel leesplezier he. Ge gaat toch niet enkel mijn dankwoord lezen zeker?!?

Bioactivity and biodegradability are among the key indices used to identify an ideal material for use as an implant in bone regeneration. Sr-doped bioactive glasses and ceramics have attracted a lot of research attention because they induce hydroxyapatite (HA) formation and stimulate high cellular responses. In the system K2O-CaO-SiO2-SrO-P2O5, a bioactive glass-ceramic was synthesized as the aim of the current investigation wherein the traditional Na2O component was replaced by K2O to prevent the formation of Na2Ca2Si3O9 crystals upon devitrification. As a less expensive alternative to alkoxysilane silica precursors, sodium metasilicate was used to prepare the glass-ceramic utilizing the solution precipitation method. The diffraction pattern of the sintered glass revealed the formation of different strontium and silicate-based crystalline phases. The glass was tested for in vitro bioactivity in simulated body fluid (SBF) for a maximum of 14 days, and the results showed that the glass changed from crystalline to amorphous phases while promoting the development of HA on the sample surface. The Sr-bioactive glass-ceramic prepared herein via a simple process shows potential as a candidate material in bone grafting and can be upscaled for commercial production.

Enhancing the solar-physical conversion efficacy ability of the nanomaterials is an essential for real-time
implementation. We report the enhanced solar-physical efficiency of the BiFeO3 nanospheres via Gd3+ doping
and Au nanoparticles decoration. Initially, we have obtained the Bi1-xGdxFeO3 nanospheres were attained via a
simple solvothermal technique and then citrate reduction of Au was conducted. Obtained perovskite BiFeO
systems were studied for the Gd3+ doping, crystalline phase and elemental purity using the XRD and XPS
techniques. Transmission electron microscope had revealed the ~400 nm sized BiFeO3 nanospheres. Optical
absorption spectrum revealed the enhanced visible photon absorption occurring in BiFeO3 for both Gd3+ doping and Au decoration. The bandgap values of pristine, 1%, 3% and 5% Gd3+ doped in BiFeO3 are 2.2 eV, 2.19 eV, 2.17 eV and 2.12 eV, respectively. Conducted  photoluminescence revealed the dual electron trapping occurring
in BiFeO3 via Gd3+ ions and Au nanoparticles. LED light assisted 72% of piezo-photocatalytic degradation efficiency of Tetracycline is achieved with Bi0 95Fe0 05O3/Au, whereas the photo catalytic is only 65% and piezo catalytic efficiency is 58%. In recyclable studies the Bi0.95Gd0.05FeO3/Au had shown the consistent piezophotocatalytic
efficiency for 3 reaction cycles. Further, fabricated DSSC studies revealed that near 30 % enhanced solar photovoltaic efficiency for Bi0 95Fe0 05O3/Au (η = 6.5%) solar cells on par to the pristine BiFeO3
(η = 5.02%).