TWO NEW MAGNETIC CUBIC COMPOUNDS: Pr3Pt23Si11 AND Nd3Pt23Si11

Journal of Alloys and Compounds, 2012

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Physical Review B, 1992

We report on the magnetic and electronic properties of NpSi3, NpGa3, and NpIn3, which crystallize in the cubic AuCu3 crystallographic structure (space group Pm 3m). Studies by Mossbauer as well as ac and dc magnetization techniques are presented. From the Mossbauer isomer-shift data we argue that the Np ion in NpX3 is close to the formal 3+ (I4) charge state. The magnetic moment of the Np in NpSi3 is totally suppressed, whereas in NpGa3 a localized (narrow band) moment (1.Spy) is established. However, in NpIn3 at 4 K, a modulated magnetic moment [(0-1. 5}pe] is observed. Comparing the magnetic behavior of the NpX3 family (X= Si, Al, Ga, Ge, Sn, and In), we find an impressive variation of the magnetic properties, from temperature-independent paramagnetism, localized and modulated ordered moments, to the formation of a concentrated Kondo lattice. Hybridization of 5 f electrons with ligand electrons appears to play a crucial role in establishing these magnetic properties. However, a consistent theoretical picture cannot be drawn at present.

The results of the magnetization studies on Pr 5 Ge 3 and Tb 5 Ge 3 single crystals are reported. Single crystals of Pr 5 Ge 3 and Tb 5 Ge 3 compounds were successfully grown by Czochralski method. These compounds crystallize in a Mn 5 Si 3 -type hexagonal structure with space group P6 3 / mcm. Ferromagnetic correlations set in at around 36 K in Pr 5 Ge 3 in the ab plane followed by an antiferromagnetic transition at 13 K. Along the c axis the magnetization shows a ferromagnetic transition around 13 K with an overall ferrimagnetic behavior. At 2 K, the magnetic isotherm of the compound along the ͓0001͔ direction is typical for a ferromagnet, while a field-induced ferromagneticlike response is observed along the ͓1010͔ direction. The hexagonal ab plane or ͓1010͔ direction was found to be the easy axis of magnetization. Tb 5 Ge 3 orders antiferromagnetically at 85 K with a hexagonal ab plane as the easy axis of magnetization. The compound shows a field-induced ferromagnetic behavior in its magnetic isotherm at 2 K.

Crystal Growth & Design, 2018

Single crystals of the ternary Pr 3 Co 2+x Ge 7 and Ln 3 Co 2+x Ge 7−y Sn y (Ln = Pr, Nd, Sm) adopting a disordered version of the La 3 Co 2 Sn 7 structure type have been prepared via flux-growth methods and characterized by single crystal X-ray diffraction. The structure consists of two lanthanide crystallographic sites with one occupying a cuboctahedral coordination environment and a second in a trigonal prismatic environment. The structure can also be described as an intergrowth of AuCu 3 and CeNiSi 2 structure types, and the stability of the germanide analogues requires Sn incorporation and Co site preferences. Magnetic properties of the Pr 3 Co 2+x Ge 7−y Sn y series are highlighted with the Sn-substituted Pr 3 Co 2.514(5) Ge 6.66(7) Sn 0.360(2) orders magnetically near 5.8 K, while the germanide Pr 3 Co 2.3376(5) Ge 7.056(7) exhibits magnetic transitions at 5.3 and 9.3 K, arising from the magnetic sublattices with field-dependent magnetization revealing three metamagnetic transitions at 0.46, 0.80, and 2.1 T.

Physica B: Condensed Matter

A series of Co-substituted compounds with nominal stoichiometries Nd 1Àx Y x Fe 27.7Ày Co y Ti 1.3 (x ¼ 0.3-2.1, y ¼ 3,6) and Nd 1.5 Y 1.5 Fe 27.7Ày Co y Ti 1.3 (y ¼ 3,6,9,11) were prepared and their structures were analyzed with powder X-ray diffraction (XRD) and neutron diffraction (ND). All samples are found to crystallize mainly in the R 3 (Fe,Ti) 29-type structure with monoclinic symmetry (space group A2/m). The lattice parameters a, b and c and the unit cell volume V decrease monotonically with the increase of Y or Co content. The Curie temperature T c and the saturation magnetization M s are both found to increase with increasing Co content. The results of Rietveld refinements of the neutron diffraction data show that the stabilizing Ti atoms are distributed over the Fe2, Fe3 and Fe6 sites, while the Co atoms mainly occupy those Fe sites not shared with Ti atoms, particularly Fe8 and Fe11 sites.

Journal of Alloys and Compounds

In this study, we have expanded our previous work on the Gd2(Co3-xSix) system to form the family of R2(T3-xSix) compounds with a wide range of the rare earth metals (Pr, Nd, Sm, Gd, Tb, Dy, Ho and Er) by variation of the composition and, where necessary, the transition element (Co and Ni). We report the crystallographic and the magnetic properties of this La2Ni3-type series. The R2Co3-xSix compounds with R= Pr, Nd, Sm and Gd, undergo ferro-or ferrimagnetic transitions at TC ranging from 64 K (Nd) to 338 K (Gd) and the R2Ni3-xSix phases with R = Gd-Er display ferromagnetic order below TC from 96 K (Gd) to 7 K (Er).

Physica B: Condensed Matter, 2002

The structural and magnetic properties of (Nd 1Àx Tb x) 3 Fe 27.31 Ti 1.69 compounds have been investigated by means of X-ray diffraction and magnetic measurements. It is found that all compounds with x ¼ 021:0 retain the Nd 3 (Fe,Ti) 29type of structure and space group A 2/m. Substitution of Tb for Nd leads to a decrease of the lattice constants and the unit-cell volume, reflecting the lanthanide contraction. With increasing Tb content, the Curie temperature T C increases slightly, while the saturation magnetization M s decreases monotonically. The latter can be described in terms of a simple dilution model. At room temperature, the easy magnetization direction of the (Nd 1Àx Tb x) 3 Fe 27.31 Ti 1.69 compounds depends on the Tb content x and changes from the [4 0 À2] direction for x ¼ 0 to the [0 4 0] direction for x ¼ 1:0: As the temperature decreases, a spin-reorientation transition is observed at 233 K in the compound Nd 3 Fe 27.31 Ti 1.69 , whereas no spin reorientation is observed in the compounds in which Tb has been substituted for Nd. The anisotropy field B a at room temperature increases with increasing Tb content from 3.0 T for x ¼ 0 to 5.2 T for x ¼ 1:0: At low temperatures, a first-order magnetization process (FOMP) (of type-II) is observed in Tb 3 Fe 27.31 Ti 1.69. The critical field B cr of the FOMP decreases monotonically with increasing temperature.

Inorganic Chemistry, 2009

synthesized in dry DMF through the metathesis reactions of [(18-crown-6)K] 3 Fe(CN) 6 with LnX 3 (DMF) n (X = Cl or NO 3 ). Anhydrous DMF solutions of LnX 3 (DMF) n were prepared at room temperature from LnCl 3 or LnX 3 3 nH 2 O under a dynamic vacuum. All compounds were characterized by IR, X-ray powder diffraction (except for 10), and single crystal X-ray diffraction (except for 2, 7, 10). Infrared spectra reveal that a monotonic, linear relationship exists between the ionic radius of the lanthanide and the ν μ-CN stretching frequency of 1-10, 12-15 while 11 deviates slightly from the ionic radius relationship. X-ray powder diffraction data are in agreement with powder patterns calculated from single crystal X-ray diffraction results, a useful alternative for bulk sample confirmation when elemental analysis data are difficult to obtain. Eight-coordinate Ln(III) metal centers are observed for all structures. trans-cyanide units of [Fe(CN) 6 ] 3formed isocyanide linkages to Ln(III) resulting in one-dimensional polymeric chains. Structures of compounds 1-9 and 11 are isomorphous, crystallizing in the space group C2/c. Structures of compounds 12-15 are also isomorphous, crystallizing in the space group P2/n. One unique polymeric chain exists in the structures of 1-9 and 11 while two unique polymeric chains exist in structures of 12-15. One of the polymeric chains of 12-15 is similar to that observed for 1-9, 11 while the other is more distorted and has a shorter Ln-Fe distance. Magnetic susceptibility measurements for compounds 3-6, 8, 11 were performed on polycrystalline samples of the compounds.

J. Alloys Compd. 367(1-2) pp. 255-261 (2004)

Starting with the Nd3(Fe,Ti)29 stoichiometry [Tb3(Fe1-xCox)27.4V1.6 and Dy3(Fe1-xCox)27.8V1.2; x= 0.6, 0.8, 1.0] two novel series of R-Fe-Co-V intermetallic compounds with a disordered variant of the hexagonal Th2Ni17-type structure were formed. The cell parameters decrease and the Curie temperature increases with increasing Co content. XRD patterns of magnetically aligned powder samples revealed the presence of planar magnetic anisotropy. Keywords: R-TM intermetallics (A); Magnetically ordered materials (A); Powder metallurgy (B); X-ray and γ-ray spectroscopy (D); Magnetic measurements (D)

Physica Status Solidi (a), 1974