Germanium Dioxide

Correction for 'Preparation of hexagonal GeO 2 particles with particle size and crystallinity controlled by peptides, silk and silk-peptide chimeras' by Estefania Boix et al., Dalton Trans., 2014, 43, 16902-16910. The following acknowledgment was inadvertently omitted from the paper. We gratefully acknowledge receipt of an EPSRC research grant (EP/E048439/1) 'A novel approach to nanoscale materials assembly using bioengineered spider silk fusion proteins: a generic approach' for the aspects of research on the silk chimeras presented in this article.

The structure of the network forming glass GeO 2 is investigated by making the first application of the method of in situ neutron diffraction with isotope substitution at pressures increasing from ambient to 8 GPa. Of the various models, the experimental results are in quantitative agreement only with molecular dynamics simulations made using interaction potentials that include dipole-polarisation effects. When the reduced density ρ/ρ 0 1.16, where ρ 0 is the value at ambient pressure, network collapse proceeds via an interplay between the predominance of distorted square pyramidal GeO 5 units versus octahedral GeO 6 units as they replace tetrahedral GeO 4 units. This replacement necessitates the formation of threefold coordinated oxygen atoms and leads to an increase with density in the number of small rings, where a preference is shown for 6-fold rings when ρ/ρ 0 = 1 and 4-fold rings when ρ/ρ 0 = 1.64.

El objetivo del trabajo fue evaluar el empleo de microesferas de sílice mesoporosa MCM-41 como soporte del carvacrol para el desarrollo de pinturas antifúngicas de base agua. Las MCM-41 se sintetizaron mediante la técnica de Liu et al., fundada en el uso de ligandos de silicatos como precursores inorgánicos hidrolíticos y tensioactivos como especies porógenas. La carga del carvacrol en MCM-41 se realizó por impregnación y posterior adsorción de vapor en un vial herméticamente cerrado incubado a 40 º C durante 24 horas. Se formularon y prepararon pinturas base acuosa en las que se incorporó como aditivo, 2% p/p, microesferas impregnadas con carvacrol (Pintura A), una pintura con microesferas sin impregnar (Pintura B), una pintura con carvacrol 2% p/p en forma libre (Pintura C) y otra pintura control sin microesferas y sin carvacrol (Pintura D). Se pintaron paneles de yeso y se realizaron ensayos de bioresistencia de la película seca frente al hongo Aspergillus sp. Al finalizar el ensayo se realizó una inspección visual y observaciones mediante microscopia electrónica de barrido (MEB). Los resultados mostraron que los paneles con la Pintura C y D se encontraban cubiertos con crecimiento fúngico. El porcentaje de cobertura fue alrededor de un 30 a 70% para la pintura C y un porcentaje mayor a 70% para la pintura D. Las pinturas A y B no presentaron crecimiento a simple vista. Las observaciones en MEB mostraron diferencias entre estas dos últimas, exponiendo crecimiento en el caso de la Pintura B. Estos resultados indican que la incorporación de las microesferas de por sí tienen un efecto biocida, debido muy probablemente al tensioactivo utilizado para su síntesis. A su vez, las micrografías MEB revelan que la impregnación del carvacrol en la sílice mejora aún más el efecto biocida de las microesferas. Este estudio demuestra que las microesferas de sílica mesoporosa MCM-41 podrían ser una alternativa como soporte para la carga del carvacrol en pinturas con actividad antifúngica.

The local structure of germanium dioxide, in its crystalline (quartzlike and rutilelike) and amorphous (a-GeO 2) solid phases, has been investigated by means of x-ray absorption spectroscopy (XAS). The short-range distance and angular distributions have been determined by modeling the experimental spectra with multiple-scattering contributions associated with selected n-body atomic configurations. Even for a-GeO 2 , the experimental x-ray absorption signal ends up being significantly affected by the intra-tetrahedral (O-Ge-O) and inter-tetrahedral (Ge-O-Ge) angle distributions. Results from the present XAS structural refinements, including experimental determination of the local bond-angle distributions, are compared with previous experiments and molecular dynamics simulations.

In this study, germanium nanowire junctionless (GeNW-JL) metal-oxide-semiconductor-field-effect-transistors (MOSFETs) exhibited enhanced electrical performance with low source/drain (S/D) contact resistance under the influence of Ar plasma treatment on the contact regions. We found that the transformation of the surface oxide states by Ar plasma treatment affected the S/D contact resistance. With Ar plasma treatment, the germanium dioxide on the GeNW surface was effectively removed and increased oxygen vacancies were formed in the suboxide on the GeNW, whose germaniumenrichment surface was obtained to form a germanide contact at low temperature. After a rapid thermal annealing process, Nigermanide contacts were formed on the Ar-plasma-treated GeNW surface. Ni-germanide contact resistance was improved by more than an order of magnitude compared to that of the other devices without Ni-germanide contact. Moreover, the peak field effect mobility value of the GeNW-JL MOSFETs was dramatically improved from 15 cm 2 /(V s) to 550 cm 2 /(V s), and the I on/off ratio was enhanced from 1 × 10 to 3 × 10 3 due to Ar plasma treatment. The Ar plasma treatment process is essential for forming uniform Ni-germanide-contacts with reduced time and low temperature. It is also crucial for increasing mass productivity and lowering the thermal budget without sacrificing the performance of GeNW-JL MOSFETs.

The local structure of germanium dioxide, in its crystalline (quartzlike and rutilelike) and amorphous (a-GeO 2) solid phases, has been investigated by means of x-ray absorption spectroscopy (XAS). The short-range distance and angular distributions have been determined by modeling the experimental spectra with multiple-scattering contributions associated with selected n-body atomic configurations. Even for a-GeO 2 , the experimental x-ray absorption signal ends up being significantly affected by the intra-tetrahedral (O-Ge-O) and inter-tetrahedral (Ge-O-Ge) angle distributions. Results from the present XAS structural refinements, including experimental determination of the local bond-angle distributions, are compared with previous experiments and molecular dynamics simulations.

The structures of novel bismuth-lead-silver glasses and glass ceramics doped with neodymium ions were studied by X-ray diffraction (XRD) and FTIR spectroscopy. FTIR spectroscopy data show that BiO 3 , BiO 6 , PbO 3 and PbO 4 are the most important structural units in the studied systems. These data also made it possible to obtain essential information concerning the arrangement of the structural units in the studied glasses and glass ceramics. XRD diffraction shows the presence of Bi 2 O 3 and PbO 1.44 crystalline phases for the samples heat treated at 600°C for 20 h.

The samples SBS20, SBS25 and SBS30 are prepared by traditional melt quenching method. The XRD pattern of prepared samples confirms the glassy nature and a broad peak at 2θ=28 0. The Raman spectra indicate that addition of SrF 2 into the glass matrix leads to loosening of network. It will create more non-bridging oxygen in the samples. The Absorption spectra shows two peaks at 466 nm and 499 nm due to Bi 2+ in different environments. The absorption edge shifted to lower wavelength with lower content of Bi 2 O 3 due to the less amount of Bi 3+ ion in the glass matrix. Optical band gap increases from 2.84eV to 2.86eV with increasing the SrF 2 content leads to loosening of network. Emission spectra consist of three peaks at 435 nm, 510 nm and 630 nm, blue region is arising from Bi 3+ and other two are from Bi 2+. 20SBS and 25SBS show white light whereas 30SBS shows yellowish green in CIE diagram. The color purity and correlated color temperature are also calculated.

Germanium-based glasses containing heavy metal oxides (Sb2O3) have been investigated. These materials are good candidates for near infrared (IR) applications due to their mid-wave IR cut-off wavelengths (5 ≈ 7 mum). Among inorganic glasses, sulfide materials exhibit the largest third-order optical nonlinear susceptibility and good IR transparency but suffer from low thermal-mechanical stability and photo-induced degradation upon exposure to near-bandgap radiation. The preparation of oxysulfide materials for optical applications offers a unique trade off between the superb chemical stability of the oxide and the attractive optical properties of sulfide. In this presentation we describe a new chemical route for the preparation of oxysulfide glasses for optical applications. The evidence of glass network structural modification is confirmed using infrared and Raman spectroscopy. Film deposition based on sputtering techniques compatible with synthesis of such materials has been performe...

In the presented work, two kinds of germanium oxide glass with different compositions, namely GeO2 and GeO2–Al2O3–Bi2O3, were investigated. After controlled crystallization of a glassy sample, the emission in the NIR-range was determined (1165 nm with excitation at 470 nm). To better understanding the kinetics of the glass crystallization, the activation energy was also determined by applying the Kissinger method. The obtained results show that in the case of GeO2–Al2O3–Bi2O3, activation energy value was 400 and 477 kJ/mol, which means that such values are significantly larger than for pure GeO2 (254 kJ/mol). The investigations also show that two phases crystallized in the complex glass matrix: the mullite-like phase and germanium oxide.

Zinc bismuth silicate glasses with compositions 40 2. . 60 − 2 3 (= 0,5,10,15,20,25,30,35, 40) were prepared using standard melt-quench techniques and zinc solubility limits were estimated using X-ray diffraction techniques in the bismuth silicate glass scheme. Density was measured using the principle of Archimedes; the molar volume and density decreased with a rise in ZnO in the samples. The temperature of the glass transition () was determined using differential calorimetry scanning (DSC) and is expected to raise with a rise in ZnO content. Raman and FTIR spectra were registered at room temperature and Raman and FTIR analysis demonstrates that in all glass compositions there are asymmetric and symmetric extended vibrations of Si-O bonds in 4 tetrahedral units and with reduction in Bi 2 O 3 , the input of symmetric vibrations starts to dominate resulting in enhanced compactness of the glass composition.

This paper reports the elastic properties and structure of GeO 2 PbOBi 2 O 3 ternary bulk glasses which were successfully prepared by melt quenching technique. The study was performed by ultrasonic measurements and Fourier transform infra red (FTIR) spectroscopy. Increasing values of density, ultrasonic velocity and elastic moduli were observed due to substitution of bismuth to lead atoms with fixed composition of GeO 2 . Also, FTIR spectrum showed different profiles between samples with higher content of lead or bismuth. In Pb-rich samples all of the components contributed in the structure as network former; however, in Bi-rich samples lead and bismuth showed modifier behavior and the structure was depolymerized by adding of bismuth content.

Heavy metal oxide glasses, containing bismuth and/or lead in their glass structure are new alternatives for rare eart (RE) doped hosts. Hence, the study of the structure of these vitreous systems is of great interest for science and technology. In this research work, GeO 2 -PbO-Bi 2 O 3 glass host doped with Er 3+ /Yb 3+ ions was synthesized by a conventional melt quenching method. The Fourier transform infrared (FTIR) results showed that PbO and Bi 2 O 3 participate with PbO 4 tetragonal pyramids and strongly distort BiO 6 octahedral units in the glass network, which subsequently act as modifiers in glass structure. These results also confirmed the existence of both four and six coordination of germanium oxide in glass matrix.

This paper reports the elastic properties and structure of GeO 2 PbOBi 2 O 3 ternary bulk glasses which were successfully prepared by melt quenching technique. The study was performed by ultrasonic measurements and Fourier transform infra red (FTIR) spectroscopy. Increasing values of density, ultrasonic velocity and elastic moduli were observed due to substitution of bismuth to lead atoms with fixed composition of GeO 2 . Also, FTIR spectrum showed different profiles between samples with higher content of lead or bismuth. In Pb-rich samples all of the components contributed in the structure as network former; however, in Bi-rich samples lead and bismuth showed modifier behavior and the structure was depolymerized by adding of bismuth content.

The broadband luminescence covering 1.2-1.6 lm was observed from bismuth and aluminum co-doped germanium oxide glasses pumped by 808 nm laser at room temperature. The spectroscopic properties of GeO 2 :Bi,Al glasses strongly depend on the glass compositions and the pumping sources. To a certain extent, the Al 3+ ions play as dispersing reagent for the infrared-emission centers in the GeO 2 :Bi,Al glasses. The broad infrared luminescence with a full width at half maximum larger than 200 nm and a lifetime longer than 200 ls possesses these glasses with the potential applications in broadly tunable laser sources and ultra-broadband fiber amplifiers in optical communication field.

Germanium-based glasses containing heavy metal oxides (Sb2O3) have been investigated. These materials are good candidates for near infrared (IR) applications due to their mid-wave IR cut-off wavelengths (5 ≈ 7 mum). Among inorganic glasses, sulfide materials exhibit the largest third-order optical nonlinear susceptibility and good IR transparency but suffer from low thermal-mechanical stability and photo-induced degradation upon exposure to near-bandgap radiation. The preparation of oxysulfide materials for optical applications offers a unique trade off between the superb chemical stability of the oxide and the attractive optical properties of sulfide. In this presentation we describe a new chemical route for the preparation of oxysulfide glasses for optical applications. The evidence of glass network structural modification is confirmed using infrared and Raman spectroscopy. Film deposition based on sputtering techniques compatible with synthesis of such materials has been performe...

Heavy metal oxide glasses, containing bismuth and/or lead in their glass structure are new alternatives for rare eart (RE) doped hosts. Hence, the study of the structure of these vitreous systems is of great interest for science and technology. In this research work, GeO 2 -PbO-Bi 2 O 3 glass host doped with Er 3+ /Yb 3+ ions was synthesized by a conventional melt quenching method. The Fourier transform infrared (FTIR) results showed that PbO and Bi 2 O 3 participate with PbO 4 tetragonal pyramids and strongly distort BiO 6 octahedral units in the glass network, which subsequently act as modifiers in glass structure. These results also confirmed the existence of both four and six coordination of germanium oxide in glass matrix.

The performance of Tie.3 W O . 7 and Nb thin films as diffusion barriers for Au was investigated by Rutherford backscattering spectrometry (RBS) and Auger electron spectroscopy (AES). The films were sputter deposited in Ar:N2 (70:30 vol%) or pure Ar on amorphous Si0 2 . They were annealed in air at temperatures ranging from 250·C up to 750·C for several hours. In-depth profiles revealed an onset of oxidation ofthe barriers at 520 ·C for and 600 ·C TiW. Barrier oxidation and extensive diffusion could be correlated. DlStlOct dlffusiOn behaViOr as a function of temperature was established between TiW and Nb. A Nb multilayer structure was found to provide the best reliability as the barrier and as the adhesion layer.

Reaction order in Bi-doped oxide glasses depends on the optical basicity of the glass host. Red and NIR photoluminescence (PL) bands result from Bi 2+ and Bi n clusters, respectively. Very similar centers are present in Bi-and Pb-doped oxide and chalcogenide glasses. Bi-implanted and Bi melt-doped chalcogenide glasses display new PL bands, indicating that new Bi centers are formed. Bi-related PL bands have been observed in glasses with very similar compositions to those in which carrier-type reversal has been observed, indicating that these phenomena are related to the same Bi centers, which we suggest are interstitial Bi 2+ and Bi clusters.

We are investigating the use oflaw energy ions ( < 1 keY) in low temperature thin film growth techniques, ion beam deposition (IBD) and combined ion and molecular deposition (CIMD). In IBD, a thin film is directly grown from a low energy ion beam as the only source of material, while in CIMD, low temperature growth of thin films is achieved by depositing materials simultaneously from a low energy ion beam and one or several molecular beams. A simple model of the IBD process has been developed and accounts for atomic collisions and thermal diffusion during thin film growth. Computer simulation of IBD of Si on Si have been conducted as a function of ion energy to support more quantitatively this physical description orIED. The results show that the IBD growth mechanism is mediated by the fast diffusing interstitials and establish a low energy limit to achieve epitaxial growth by IBD that depends on the point defect diffusivities. The defect generation has to be confined in the subsurface region in order to favor interstitial recombination with the surface, leading to net thin film growth, and vacancy annihilation to prevent amorphization. The effect of point defect diffusivities on the lED growth process is also investigated. It is found that a model including fast moving interstitials can account for various experimental observations specific to IBD.

We are investigating the use oflaw energy ions ( < 1 keY) in low temperature thin film growth techniques, ion beam deposition (IBD) and combined ion and molecular deposition (CIMD). In IBD, a thin film is directly grown from a low energy ion beam as the only source of material, while in CIMD, low temperature growth of thin films is achieved by depositing materials simultaneously from a low energy ion beam and one or several molecular beams. A simple model of the IBD process has been developed and accounts for atomic collisions and thermal diffusion during thin film growth. Computer simulation of IBD of Si on Si have been conducted as a function of ion energy to support more quantitatively this physical description orIED. The results show that the IBD growth mechanism is mediated by the fast diffusing interstitials and establish a low energy limit to achieve epitaxial growth by IBD that depends on the point defect diffusivities. The defect generation has to be confined in the subsurface region in order to favor interstitial recombination with the surface, leading to net thin film growth, and vacancy annihilation to prevent amorphization. The effect of point defect diffusivities on the lED growth process is also investigated. It is found that a model including fast moving interstitials can account for various experimental observations specific to IBD.

We are investigating the use oflaw energy ions ( < 1 keY) in low temperature thin film growth techniques, ion beam deposition (IBD) and combined ion and molecular deposition (CIMD). In IBD, a thin film is directly grown from a low energy ion beam as the only source of material, while in CIMD, low temperature growth of thin films is achieved by depositing materials simultaneously from a low energy ion beam and one or several molecular beams. A simple model of the IBD process has been developed and accounts for atomic collisions and thermal diffusion during thin film growth. Computer simulation of IBD of Si on Si have been conducted as a function of ion energy to support more quantitatively this physical description orIED. The results show that the IBD growth mechanism is mediated by the fast diffusing interstitials and establish a low energy limit to achieve epitaxial growth by IBD that depends on the point defect diffusivities. The defect generation has to be confined in the subsurface region in order to favor interstitial recombination with the surface, leading to net thin film growth, and vacancy annihilation to prevent amorphization. The effect of point defect diffusivities on the lED growth process is also investigated. It is found that a model including fast moving interstitials can account for various experimental observations specific to IBD.

We are investigating the use oflaw energy ions ( < 1 keY) in low temperature thin film growth techniques, ion beam deposition (IBD) and combined ion and molecular deposition (CIMD). In IBD, a thin film is directly grown from a low energy ion beam as the only source of material, while in CIMD, low temperature growth of thin films is achieved by depositing materials simultaneously from a low energy ion beam and one or several molecular beams. A simple model of the IBD process has been developed and accounts for atomic collisions and thermal diffusion during thin film growth. Computer simulation of IBD of Si on Si have been conducted as a function of ion energy to support more quantitatively this physical description orIED. The results show that the IBD growth mechanism is mediated by the fast diffusing interstitials and establish a low energy limit to achieve epitaxial growth by IBD that depends on the point defect diffusivities. The defect generation has to be confined in the subsurface region in order to favor interstitial recombination with the surface, leading to net thin film growth, and vacancy annihilation to prevent amorphization. The effect of point defect diffusivities on the lED growth process is also investigated. It is found that a model including fast moving interstitials can account for various experimental observations specific to IBD.

We are investigating the use of low energy ions ( < 1 keV) in low temperature thin film growth techniques, ion beam deposition (IBD) and combined ion and molecular deposition (CIMD). In IBD, a thin film is directly grown from a low energy ion beam as the only source of material, while in CIMD, low temperature growth of thin films is achieved by depositing materials simultaneously from a low energy ion beam and one or several molecular beams. A simple model of the IBD process has been developed and accounts for atomic collisions and thermal diffusion during thin film growth. Computer simulation of IBD of Si on Si have been conducted as a function ofion energy to support more quantitatively this physical description of IBD. The results show that the IBD growth mechanism is mediated by the fast diffusing interstitials and establish a low energy limit to achieve epitaxial growth by IBD that depends on the point defect diffusivities. The defect generation has to be confined in the subsurface region in order to favor interstitial recombination with the surface, leading to net thin film growth, and vacancy annihilation to prevent amorphization. The effect of point defect diffusivities on the lED growth process is alsoinvestigated. It is found that a model including fast moving interstitials can account for various experimental observations specific to IBD.

Ternary system of lead-bismuth-borate glasses has been fabricated in three different compositions (PbO)x% -(Bi 2 O 3 )(50-x)% -(B 2 O 3 )50% with x = 5, 15 and 25 using the melt quench technique. The D.C. electrical transport mechanism has been discussed both in the low and high field regions. The coefficients of barrier lowering are calculated based on the Schottky and Poole-Frenkel conduction mechanisms. The refractive index and the high frequency dielectric constants for the prepared glass compositions are evaluated using the optical techniques. The observed decrease in the current level with the increase of the PbO contents is explained. The high field transport in these glasses is explained in terms of the Jonscher's modified model of the Poole-Frenkel phenomenon.

The goal of this study is to investigate the effect of carbon incorporation upon thermal oxidation of Si1−x Ge x alloys and its role on strain compensation in Si1−x Ge x alloys. Si1−x Ge x and Si1−x−y Ge x C y alloys on Si(100) are grown by combined ion and molecular beam deposition and are then oxidized at 1000 °C in a dry oxygen ambient for two h. The thickness and the composition of all samples before and after oxidation are measured by Rutherford backscattering spectrometry (RBS) combined with ion channeling at 2.0 MeV and carbon nuclear resonance analysis at 4.3 MeV using 4He++ ions. In agreement with previously reported results of dry oxidation on Si1−x Ge x thin films, 2.0 MeV RBS analysis shows that a layer of SiO2 is formed on the top surface of both Si1−x Ge x and Si1−x−y Ge x C y thin films, while Ge segregates towards the top surface and at the SiO2/Si1−x Ge x and SiO2/Si1−x−y Ge x C y interfaces. However, it is observed for the first time that dry oxidation rates of Si1−x Ge x thin films decrease with increasing Ge fraction x for x≳0.20 and with increasing minimum yield. Ion channeling analysis and strain measurements indicate that the incorporation of C rather than the amount of C itself affects the dry oxidation mechanism because of its strong influence on film strain and crystalline quality. These results are discussed in conjunction with observations by secondary ion mass spectrometry, high resolution transmission electron microscopy, Fourier transform infrared spectrometry, and tapping mode atomic force microscopy.

Heavy metal oxide glasses, containing bismuth and/or lead in their glass structure are new alternatives for rare eart (RE) doped hosts. Hence, the study of the structure of these vitreous systems is of great interest for science and technology. In this research work, GeO2-PbO-Bi2O3 glass host doped with Er3+/Yb3+ ions was synthesized by a conventional melt quenching method. The Fourier transform infrared (FTIR) results showed that PbO and Bi2O3 participate with PbO4 tetragonal pyramids and strongly distort BiO6 octahedral units in the glass network, which subsequently act as modifiers in glass structure. These results also confirmed the existence of both four and six coordination of germanium oxide in glass matrix.

This paper reports the elastic properties and structure of GeO 2PbOBi 2O 3 ternary bulk glasses which were successfully prepared by melt quenching technique. The study was performed by ultrasonic measurements and Fourier transform infra red (FTIR) spectroscopy. Increasing values of density, ultrasonic velocity and elastic moduli were observed due to substitution of bismuth to lead atoms with fixed composition of GeO 2. Also, FTIR spectrum showed different profiles between samples with higher content of lead or bismuth. In Pb-rich samples all of the components contributed in the structure as network former; however, in Bi-rich samples lead and bismuth showed modifier behavior and the structure was depolymerized by adding of bismuth content.

Glasses with composition (85−x)Bi2O3–xZnO–15B2O3 with 15 ≤ x ≤ 40 have been prepared by conventional melt quench technique. Systematic variation in density and molar volume in these glasses indicates the effect of Bi2O3 on the glass structure. The parameters glass transition temperature (Tg), change in the transition temperature (ΔTg) and specific heat capacity difference (ΔCp) in the glass transition range were measured. The values of optical band gap and theoretical optical basicity are also reported. Raman and infrared studies have been employed on these glasses in order to obtain information regarding the competitive role of Bi2O3 in the formation of glass network.