Michael Johnscher

CaTMg2 and CaTCd2 (T = Rh, Pd, Pt) with YPd2Si-type structure

The intermetallic calcium compounds CaTMg2 and CaTCd2 (T =Rh, Pd, Pt) were obtained by high-frequency melting of the elements in sealed niobium ampoules or through reactions in muffle furnaces. The polycrystalline samples were characterized by powder X-ray diffraction. They crystallize with a site occupancy variant of YPd2Si, a ternary ordered version of Fe3C. The structures of CaPdMg2 and CaPdCd2 were refined from single-crystal diffractometer data: Pnma, a=792.2(2), b=803.4(2), c=572.0(1) pm, wR2=0.0663, 1621 F2 values, 24 variables for Ca0:94PdMg2:06 and a=794.6(2), b=809.5(3), c=554.7(2) pm, wR2=0.0301, 819 F2 values, 23 variables for CaPdCd2. A small range of homogeneity was observed for Ca1-xPdMg2+x. The magnesium and cadmium atoms build up three-dimensional tetrahedral substructures (306 - 327 pm Mg-Mg and 307 - 317 pm Cd-Cd) that resemble hexagonal diamond, lonsdaleite. Together with the palladium atoms one obtains three-dimensional, covalently bonded [PdMg2] and [PdCd2] networks which leave cages for the calcium atoms. The latter are bonded to these networks via shorter Ca-Pd contacts (298 - 319 pm in Ca0:94PdMg2:06 and 295 - 312 pm in CaPdCd2). The course of the interatomic distances is in line with calculated overlap populations. The CaPdMg2, SrPdMg2 and CaRhIn2 structures are all derived from a CaIn2-related subcell by an ordered filling of transition metal atoms into trigonal prisms. This leads to different herringbone patterns for the networks of puckered and elongated hexagons of magnesium and indium atoms. Graphical Abstract CaTMg2 and CaTCd2 (T =Rh, Pd, Pt) with YPd2Si-type Structure

MgCuAl2-type Intermetallics REPdCd2(RE = Ce, Pr, Nd, Sm)

The cadmium-rich intermetallic compounds REPdCd2 (RE=Ce, Pr, Nd, Sm) were obtained by high-frequency melting of the elements in sealed niobium ampoules and subsequent annealing in muffle furnaces. The REPdCd2 phases crystallize with the orthorhombic MgCuAl2-type structure, space group Cmcm. The structure of NdPdCd2 was refined from single-crystal X-ray diffractometer data: a=421.9(3), b=995.4(7), c=834.5(6) pm, wR=0.0286, 451 structure factors, 16 variables. The palladium and cadmium atoms build up a three-dimensional [PdCd2] network (281 - 283 pm Pd-Cd; 298 - 335 pm Cd-Cd) in which the neodymium atoms fill cavities. They are connected to the [PdCd2] network via shorter Nd-Pd bonds of 286 pm. Graphical Abstract MgCuAl2-type Intermetallics REPdCd2(RE = Ce, Pr, Nd, Sm)

Magnetic properties of RE10TCd3 (RE = Ho, Er, Tm, Lu; T = Fe, Co, Ni, Ru) and 57Fe Mössbauer spectroscopic data of Y10FeCd3

Abstract Fourteen X-ray-pure intermetallic compounds RE10TCd3 (RE = Ho, Er, Tm, Lu; T = Fe, Co, Ni, Ru) and Y10FeCd3 were obtained through high-frequency melting of the elements in sealed niobium tubes and subsequent annealing in a muffle furnace. They adopt the Er10FeCd3 structure, a ternary ordered version of the Co2Al5 type. Temperature-dependent magnetic susceptibility measurements show Pauli paramagnetism for the lutetium compounds Lu10FeCd3, Lu10CoCd3, and Lu10RuCd3. The RE10TCd3 phases with holmium, erbium, and thulium show Curie–Weiss paramagnetism and the experimental magnetic moments match with the free ion values of RE3+. All these compounds order antiferromagnetically. The highest Néel temperature was observed for the holmium compounds, e.g. 46.5 K for Ho10RuCd3. Some of the RE10TCd3 phases show field-induced spin reorientations. A 57Fe Mössbauer spectrum of Y10FeCd3 confirms the single crystallographic iron site.

Ternary aurides RE4Mg3Au10 (RE=Y, Nd, Sm, Gd–Dy) and their silver analogues

Abstract The ternary aurides RE4Mg3Au10 (RE=Y, Nd, Sm, Gd–Dy) and their silver analogues were synthesized by induction melting of the elements in sealed niobium tubes. These intermetallic phases were characterized by powder X-ray diffraction. They crystallize with the Ca4In3Au10-type structure, which, from a geometrical point of view, is a ternary ordered version of Zr7Ni10 with the rare earth and magnesium atoms ordering on the four crystallographically independent zirconium sites. The structures of crystals from three differently prepared gadolinium samples were refined from single-crystal X-ray diffractometer data: Cmca, a=1366.69(3), b=998.07(4), c=1005.54(3) pm, wR2=0.0332, 1234 F2 values, 46 variables for Gd4.43Mg2.57Au10, a=1378.7(1), b=1005.3(1), c=1011.2(1) pm, wR2=0.0409, 1255 F2 values, 48 variables for Gd5.50Mg1.50Au10, and a=1350.2(5), b=995.5(1), c=1009.3(1) pm, wR2=0.0478, 1075 F2 values, 48 variables for Gd5.61Mg1.39Au10. All crystals show substantial Mg/Gd mixing on two sites. The gold atoms form a pronounced two-dimensional substructure with Au–Au distances of 278 to 297 pm in Gd4.43Mg2.57Au10. These gold blocks are condensed via magnesium atoms (278–315 pm Mg–Au). The gadolinium atoms fill larger cavities within the three-dimensional networks. The magnesium vs. gadolinium site preference is a consequence of the different coordination numbers of the cation sites. All phases show homogeneity ranges RE4+xMg3–xAg10 and RE4+xMg3–xAu10. The influence of the synthesis conditions is briefly discussed.

Ternary aurides RE4Mg3Au10 (RE = La, Ce, Pr) and RE4Cd3Au10 (RE = Y, La–Nd, Sm, Gd–Dy) – ordering variants of the Zr7Ni10 type

Abstract The intermetallic gold compounds RE4Mg3Au10 (RE = La, Ce, Pr) and RE4Cd3Au10 (RE = Y, La–Nd, Sm, Gd–Dy) were obtained from the elements through high-frequency melting in sealed niobium tubes and subsequent annealing in a muffle furnace. The new aurides crystallize with the Ca4In3Au10-type structure. They were characterized through Guinier powder patterns. The structures of Pr4.46Cd2.54Au10 and Tb4.38Cd2.62Au10 were refined from single crystal X-ray diffractometer data: Cmce, a = 1396.73(6), b = 1009.38(3), c = 1019.51(3) pm, wR2 = 0.0423, 1281 F2 values, 47 variables for Pr4.46Cd2.54Au10 and a = 1362.68(3), b = 995.52(4), c = 1003.79(3) pm, wR2 = 0.0381, 1594 F2 values, F2 47 variables for Tb4.38Cd2.62Au10. The 8e sites of both crystals show substantial Cd/Pr respectively Cd/Tb mixing, indicating small homogeneity ranges for all RE4+xMg3–xAu10 and RE4+xCd3–xAu10 aurides. The gold atoms in these aurides form a pronounced two-dimensional substructure (275–327 pm Au–Au in Pr4.46Cd2.54Au10) which encages the Mg1/Cd1 (coordination number 8) and RE2 (coordination number 11) atoms. These blocks are separated by the Mg2/Cd2 and RE1 atoms with an intergrowth of Mg2/Cd2@Au8 and RE1@Au10 polyhedra. Temperature dependent magnetic susceptibility and specific heat measurements of Tb4Cd3Au10 have shown antiferromagnetic ordering at a Néel temperature of 12(1) K.

The equiatomic intermetallics REPtCd (RE = La, Ce, Pr, Nd, Eu) and magnetic properties of CeAuCd

Abstract The cadmium intermetallics REPtCd (RE = La, Ce, Pr, Nd, Eu) and CeAuCd were synthesized by induction-melting of the elements in sealed niobium ampoules followed by annealing in muffle furnaces. The samples were characterized by powder X-ray diffraction. The structures of CePtCd (ZrNiAl type, P6¯2m,

Ca2Pd2Cd with W2B2Co-type Structure

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Magnesium and cadmium in covalently bonded networks: synthesis and structure of AETMg and AETCd (AE = Ca, Sr; T = Pd, Ag, Pt, Au) with TiNiSi type structure and the solid solution Yb2–xPtMgx

a = 763.8(6), c = 409.1(4) pm, wR2 = 0.0195, 298 F2 values, 14 variables) and EuPtCd (TiNiSi type, Pnma, a = 741.3(2), b = 436.4(1), c = 858.0(4) pm, wR2 = 0.0385, 440 F2 values, 20 variables) were refined from single-crystal data. The REPtCd structures exhibit three-dimensional networks of corner- and edge-sharing Cd@Pt2/6Pt2/3 and Cd@Pt4/4 tetrahedra, which leave cages for the rare earth atoms. Temperature-dependent magnetic susceptibility data of CeAuCd reveal a paramagnetic to antiferromagnetic phase transition at TN = 3.7(5) K.

Copper-rich Intermetallic Compounds RECu9Cd2(RE = La, Ce, Pr, Nd) with YNi9In2-type Structure

Ca2Pd2Cd was synthesized by high-frequency melting of the elements in a sealed niobium ampoule. Its structure was refined from single-crystal X-ray diffractometer data: W2B2Co type, Immm, a=444.58(6), b=590.25(6), c=863.07(10) pm, wR2=0.0252, 305 structure factors, 13 variables. The palladium and cadmium atoms build up twodimensional [Pd2Cd] networks which consist of Pd4Cd2 hexagons and Pd2Cd2 rectangles with 272.7 pm Pd-Pd and 273.2 pm Pd-Cd. The calcium atoms are coordinated by one Pd4Cd2 and one Pd2Cd2 unit. The structure of Ca2Pd2Cd is compared to that of Ce2Pd2Cd with its tetragonal Mo2B2Fe type. Graphical Abstract Ca2Pd2Cd with W2B2Co-type Structure

Magnetic properties and tuneable magnetocaloric effect with large temperature span in GdCd1−xRux solid solutions

Abstract The equiatomic intermetallic compounds AETMg and AETCd (AE = Ca, Sr; T = Pd, Ag, Pt, Au) and the whole solid solution Yb2-xPtMgx were synthesized from the elements in sealed niobium tubes in a high-frequency or a muffle furnace. All samples were characterized on the basis of their powder X-ray diffraction patterns. The structures of SrAuCd, CaPdCd, CaPtCd, CaPdMg, SrPtMg, CaAg1.017Mg0.983, SrAg1.032Mg0.968, and Yb1.792PtMg0.208 were refined on the basis of single-crystal X-ray diffractometer data. Some of the crystals showed small homogeneity ranges. All compounds crystallize with the orthorhombic TiNiSi type structure, space group Pnma. The crystal chemistry is briefly discussed and variations in chemical bonding as a result of the electronegativity of the transition metal are described.