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Novel ternary intermetallic phase Ce2RuGe was synthesized via arc-melting of the constituents and subsequent annealing at 700°С. Its crystal structure was determined from the powder X-ray diffraction data collected at room temperature. The compound crystallizes in the orthorhombic structure of a new type: space group Pmmn (No. 59), lattice parameters: a = 4.38235(5) A, b = 4.31818(5) A, c = 9.91496(15) A, Z = 2, Pearson symbol oP8. In the fully ordered unit cell of Ce2RuGe, there are two crystallographic positions for Ce atoms, single site with Ru atoms, and single site with Ge atoms, each with the multiplicity of two. The crystal structure is built of infinite zigzag-like chains of the Ru and Ge atoms, propagating along the [010] direction. The essential feature is a very short interatomic distance between the Ce1 atoms and the Ru atoms being equal to 2.226(2) A, while the Ce2–Ru distance is of regular length. This structural property gives rise to distinctive physical behavior of the compound that exhibits the coexistence of valence fluctuations associated with unstable 4f shell of the Ce1 ions and a long-range magnetic ordering that emerges in the Ce2 ions sublattice. As revealed by means of magnetization, heat capacity and electrical resistivity measurements, Ce2RuGe orders antiferromagnetically at TN = 12.0(1) K, and becomes ferromagnetic below TC = 8.5(3) K.

We have studied phase equilibria in the silicon-rich part of the Yb–Pt–Si system. To this end, 22 alloys were prepared by a standard arc-melting process in an argon atmosphere and annealed at a temperature of 850°C. Physicochemical characterization of the samples included electron microscopy, X-ray microanalysis, X-ray diffraction, and differential thermal analysis. We have confirmed the existence of four previously known intermetallic compounds: YbPtSi, YbPt2Si2, Yb3Pt4Si6, and Yb2Pt3Si5. In addition, three new phases have been identified: YbPtSi2, Yb33Pt17Si50, and Yb11Pt33Si56. The structure type of the YbPtSi2 compound has been determined. We present statistical crystallographic data for the ternary phases and describe phase equilibria in the region studied in the 850°C isothermal section of the Yb–Pt–Si phase diagram.

Novel Ce-rich phases Ce 4 RuAl and Ce 23 Ru 7+ x Al 4- x (0 ≤ x ≤ 2.97) were found in the systematic investigation of the ternary Ce-Ru-Al system. Both compounds were investigated by scanning electron microscopy, EDX spectroscopy and X-ray diffraction methods. The Ce 4 RuAl compound crystallizes with a cubic structure of a Gd 4 RhIn type with lattice parameter a = 13.7709(8) A (sp. gr. F -43 m , Z = 16). Its crystal structure was determined from single crystal X-ray data (R F = 0.0241 for 741 independent reflections). The Ce 23 Ru 7+ x Al 4- x structure was established by X-ray powder diffraction. This compound belongs to Pr 23 Ir 7 Mg 4 structure type, space group P 6 3 mc . Cell parameters of Ce 23 Ru 7+ x Al 4- x at x = 0.4 are: a = 9.8137(4) A, c = 22.2010(13) A. In both compounds Ce 4 RuAl and Ce 23 Ru 7+ x Al 4- x some of the Ce-Ru distances are short, equal to 2.630 A and 2.562 A, respectively. Crystal chemistry of these intermetallics is characterized by packing of non-linear layers in which the Ru-centered trigonal [Ce 6 ] prisms are connected via common vertices and edges, - similar to packing in the related Ce 7 Ru 3 and La 15 Rh 5 Cd 2 compounds.

The crystal structure of the novel Al-rich intermetallic phase Ce4Pt9Al13 was determined from single-crystal X-ray diffraction data and confirmed by powder X-ray diffraction. The compound crystallizes with its own structure type, which is a “site exchange” variant of the Ho4Ir13Ge9-type (Pearson symbol oP52, space group Pmmn, No. 59, Z = 2, lattice parameters: a = 4.1826(1) A, b = 11.4424(3) A, c = 19.8475(5) A, V = 949.88(7) A3). The magnetic properties of Ce4Pt9Al13 were determined in the temperature range 1.72–400 K. Down to the lowest temperatures studied, the compound shows a Curie-Weiss paramagnetic behavior with strong crystalline electric field contribution observed below about 200 K. The electrical conductivity in Ce4Pt9Al13 has metallic character, and at low temperatures it is governed by an interplay of strong crystal field and Kondo interactions.

The formation of a ternary cerium germanide Ce4Rh4Ge3 was established. The crystal structure of this novel compound was determined by mean of single crystal and powder X-ray diffraction techniques to be of the monoclinic Nd4Rh4Ge3-type (space group C2/c, No.15, Pearson symbol mS44, Z = 4) with the lattice parameters: a = 21.027(6) A, b = 5.7248(16) A, c = 7.999(3) A, β = 110.39(3) deg. The low-temperature physical properties of Ce4Rh4Ge3 were studied by means of magnetic susceptibility, magnetization, heat capacity, electrical resistivity and magnetoresistance measurements. The compound was found to order ferromagnetically at TC = 4.2(2) K. Its physical behavior in the paramagnetic state was found to be governed by interplay of crystalline electric field effect and Kondo interactions, with possible contribution due to valence fluctuations associated with one of the two inequivalent cerium atoms located in the crystallographic unit cell of Ce4Rh4Ge3.

Ternary intermetallic alloys Ce 2 Rh 3+x Ge 1-x (0 ≤ x ≤ 0.33) have been found to crystallize in a rhombohedral structure of the Mg 2 Ni 3 Si-type (space group R -3 m ). With varying the stoichiometry, the lattice parameters significantly vary from a = 5.5887(2) A, c = 11.9557(5) A (hexagonal setting) for x = 0 to a = 5.5127(2) A, c = 12.2790(5) A for x = 0.33, while the unit cell volume remains nearly unchanged. By means of magnetic susceptibility, heat capacity and electrical resistivity measurements, the Ce 2 Rh 3+x Ge 1-x alloys have been shown to be intermediate valence systems with highly unstable 4 f shell of Ce ions. Notably, the ferromagnetic ordering, claimed in the literature to coexist with the valence fluctuations in Ce 2 Rh 3 Ge, has been revealed to be an extrinsic effect due to impurity contribution.

A novel ternary intermetallic germanide CeIrGe 2 has been studied by means of x-ray diffraction, magnetization, specific heat and electrical resistivity measurements, performed in wide ranges of temperature and external magnetic fields. The compound crystallizes in an orthorhombic structure of the CeNiSi 2 -type (space group Cmcm ). It exhibits a Kondo lattice behavior and orders antiferromagnetically at 4 K.

The novel cerium germanide Ce2IrGe3 was studied by means of x-ray diffraction, magnetic, electrical transport and heat capacity measurements. The compound was found to crystallize with slightly disordered hexagonal structure of Ce2CoSi3-type. The experimental results revealed that Ce2IrGe3 is a ferromagnetic-like Kondo lattice that orders at T C = 4 K .

Two novel ternary rare-earth aluminides, CePd 3 Al 2 and LaPd 3 Al 2 , were obtained by arc-melting the elements and subsequent annealing at 800 °C. Their crystal structures were determined from the single-crystal X-ray diffraction data. The compounds crystallize with their own structure type: space group Pnma , Z = 4, Pearson symbol oP 24, а = 7.491(2) A, b = 4.3575(17) A, ≿ = 13.123(4) A for CePd 3 Al 2 and а = 7.474(7) A, b = 4.3755(17) A, ≿ = 13.323(9) A for LaPd 3 Al 2 . The physical behavior of the Ce-based material was studied by means of magnetic, electrical resistivity and heat capacity measurements carried out down to 0.4 K. The compound was characterized as an antiferromagnetic heavy-fermion system with the Neel temperature T N = 1 K and the Kondo energy scale of about 2 K.

The new ternary intermetallic with high content of germanium, CeRuGe 5 , was found in the course of reinvestigation of the Ce-Ru-Ge system at 700 °C. The compound crystallizes in the tetragonal structure of new type (space group I 4/ mcm ) with the unit cell parameters: a = 6.1414(6) A, c = 13.751(3) A, Z = 4, Pearson symbol tI 28. The structure of CeRuGe 5 can be presented as [CeGe 3 ] and [RuGe 2 ] slabs alternating along the tetragonal c -axis. It is shown that the new structure of CeRuGe 5 and the known before structure of Sm 2 Ru 5 Ga 9 are derivatives from the common prototype – HoCoGa 5 . By means of magnetic, heat capacity and electrical transport measurements, the novel compound CeRuGe 5 was established to be a metallic Curie-Weiss paramagnet due to stable 4 f 1 electronic configuration of trivalent Ce ions. No intrinsic long-range magnetic ordering was found down to 1.7 K.

Phase relations in the ternary system Ce–Ir–Si have been established and the isothermal section at 950 °C was constructed based on X-ray powder diffraction, scanning electron microscopy, and electron probe microanalysis techniques on 83 alloys, which were prepared by arc melting under argon or powder reaction sintering. Among the 15 ternary compounds observed at 950 °C 8 phases have been reported earlier. Based on powder X-ray diffraction data the crystal structures for 6 new ternary phases were assigned to known structure types: τ6 – Ce3IrSi3 (Ta3B4-type), τ8 – Ce3Ir4Si4 (U3Ni4Si4-type), τ10 – Ce6Ir30Si19 (Sc6Co30Si19-type), τ12 – Ce2Ir12Si7 (Ho2Rh12As7-type), τ13 – Ce3Ir2−xSi2+x (Sm3Ir2Si2-type), and τ14 – Ce3Ir3Si2 (Ce3Rh3Si2-type). For another new compound τ1 – Ce4Ir27Si69 (at.%), which has homogeneity region along 27 at.% of Ir, the reflections were indexed in hexagonal lattice symmetry with cell parameters close to high-temperature IrSi3−x phase.

The crystal structure of Yb 2 PdGe 6 was studied by powder X-ray diffraction technique. The compound in both as-cast and annealed forms crystallizes with the orthorhombic structure of the Ce 2 GaGe 6 -type (space group Cmce ) that can be modelled as a sequence of AlB 2 -type slabs, quadrangular antiprismatic slabs, and distorted αPo-type slabs propagating along the crystallographic c direction. The low-temperature physical properties of Yb 2 PdGe 6 were determined by means of magnetic susceptibility and electrical resistivity measurements. The compound was characterized as an intermediate valent material because of a highly unstable 4 f shell of Yb ions.

A novel ternary compound Ce 3 RuSn 6 was synthesized as a single phase polycrystalline alloy. Its crystal structure was solved by direct methods and refined from the single crystal X-ray diffraction data down to R1 = 0.038 for 1021 independent reflections with I > 2σ(I) and 36 variable parameters. The compound crystallizes with an orthorhombic unit cell of the Yb 3 CoSn 6 type (space group Cmcm , lattice parameters: a = 4.6744 (4), b = 16.8542 (15), c = 13.3227 (12) A), in which Ce atoms occupy two independent crystallographic sites. Physical behavior in Ce 3 RuSn 6 was studied by means of magnetic susceptibility, electrical resistivity and heat capacity measurements, performed down to 0.4 K in magnetic fields up to 9 T. The compound exhibits ferromagnetic ordering below T C = 3 K. Its thermodynamic and electrical transport properties in the paramagnetic and ordered states are strongly influenced by Kondo effect with the characteristic temperature very close to T C .

New ternary intermetallic compound Ce2Ru2Al was prepared in polycrystalline form, and its crystal structure was determined from both powder and single crystal X-ray diffraction data. The aluminide was found to crystallize with an orthorhombic structure (space group Cmce) with the lattice parameters: a = 5.8914(4) A, b = 9.9603(6) A, and c = 6.9551(4) A. The derived unit cell is an ordered variant of the binary La2Ni3 type, where one of two Ni sites is fully occupied with Ru atoms, while another one accommodates Al atoms. The structure of Ce2Ru2Al can be regarded as a sequence of atomic layers normal to b-axis. The remarkable structural feature is a short distance between Ce and Ru atoms equal to 2.7816(4) A. Magnetic measurements revealed that Ce ions in Ce2Ru2Al possess unstable 4f shell that leads to intermediate valence behavior of the compound. Similar valence instability was observed before for other Ce intermetallics with short Ce–Ru bonds.

The atomic order of the new polymorphic modification of the equiatomic stannide CeRuSn was established from single crystal X-ray diffraction data. The new modification of CeRuSn can be described as a superstructure of CeCoAl-type with tripling of the subcell along the c axis. Space group C 2/ m , lattice parameters a = 11.5702(12) A, b = 4.7529(5) A, c = 15.2414(16) A, β = 103.511(2)°, Z = 12. The structure was refined to R 1 = 0.034 for 1806 F 2 and 55 variables. The new modification has three independent crystallographic Ce sites, two of which form strongly shortened Ce–Ru contacts d Ce1 – Ru2 = 2.267 A, d Ce3 – Ru1 = 2.434 A and d Ce3 – Ru3 = 2.429 A.

The formation of novel ternary cerium germanide with the chemical composition Ce33.3Ir22.2Ge44.5 (at.%) was established. As derived from powder X-ray diffraction data, the compound crystallizes with two polymorphic modifications. The high-temperature modification, established for as-cast alloy, possesses a tetragonal ThSi2-type structure and can be named as Ce(IrxGe1-x)2, x = 0.32. The low-temperature modification forms in the course of heat treatment at 1073 K, crystallizes with an orthorhombic structure of its own type and can be labeled as Ce3Ir2-xGe4+x, x = 0.02. Both structures belong to the AlB2 structural family and are closely related to each other. In both modifications, statistical mixtures of Ir and Ge atoms occupy same crystallographic sites. As found by means of magnetization measurements, the two structural variants of Ce33.3Ir22.2Ge44.5 (at.%) exhibit very similar magnetic properties. Both polymorphs are Curie-Weiss paramagnets with strong crystalline electric field features observed at low temperatures.

The crystal structures of LaPd 2 Ge and LaPdGe 3 have been refined by X-ray diffraction on powdered polycrystalline samples. These ternaries crystallize in YPd 2 Si ( Pnma ) and BaNiSn 3 ( I 4 mm ) structure types, respectively. As revealed by electrical resistivity, thermoelectric power and specific heat measurements, the former compound is superconducting below 0.6 K, which is not the case for the latter one (at least down to 0.3 K). Moreover, LaPdGe 3 was found to be a typical metal in comparison to LaPd 2 Ge which is rather a semimetal.

The crystal structure of the novel intermetallic Yb ∼3 Pt ∼4 Si 6− x was determined by single crystal X-ray diffraction: space group P 2 1 / m (No. 11); a = 8.4560(3) A, b = 4.2109(2) A, c = 12.7864(5) A, β = 99.537(2)°, R F = 0.046, wR2 = 0.132. The title compound is a disordered variant of the Y 3 Pt 4 Ge 6 type. It is characterized by the intergrowth of slabs cut from the ThCr 2 Si 2 and YIrGe 2 types of structures.

The crystal structure of Dy 2 PdGe 6 was studied by X-ray diffraction on single crystal. Space group Cmca (No. 64), a = 8.1337(16), b = 8.0208(16), c = 21.441(4) A, V = 1398.8 A 3 , Z = 8, 1259 unique reflections with I > 2 σ ( I 0 ) in refinement (2 Θ max = 75.81°), down to R 1 = 0.029, w R 2 = 0.071. The title compound represents an ordered derivative from the Ce 2 GaGe 6 -type. The crystal structure can be presented as a sequence of the AlB 2 -type slabs, quadrangular antiprisms slabs, and distorted αPo-type slabs along the c direction. The atomic order in Dy 2 PdGe 6 derived from the single crystal data was confirmed by X-ray powder diffraction with cell parameters a = 8.1348(6), b = 8.0145(5), c = 21.4396(14) A.

The crystal structure of the novel compound Ce 3 Rh 5 Si was solved by means of powder diffraction pattern analysis using the charge-flipping method. The refinements yielded the space group Pnma and the orthorhombic unit cell parameters: a = 1.52632(2) nm, b = 0.55092(1) nm, and c = 0.75302(1) nm. A characteristic feature of the crystal structure of Ce 3 Rh 5 Si are vertex-sharing [Rh 4 ] and [Rh 3 Si] tetrahedra, which form a three-dimensional framework with Ce atoms located inside truncated tetrahedral voids. The structure exhibits close relationship with those of CeRh 2 (MgCu 2 -type) and Ce 2 Rh 3 Si (Y 2 Rh 3 Si-type). Magnetic and electrical resistivity measurements of Ce 3 Rh 5 Si were performed down to 2 K. The compound was characterized as a Pauli paramagnet with metallic character of the electrical conductivity.

Polycrystalline samples of the intermetallic compounds Dy 2 PdGe 6 and La 2 PdGe 6 which crystallize in the orthorhombic structure ( Cmca space group) were studied by means of magnetic, electrical resistivity, specific heat and differential thermoelectric power measurements. The Dy-germanide is an antiferromagnet below 25(1) K and at low temperature and above magnetic fields of 3.5 T it exhibits a metamagnetic behaviour. Especially the specific heat measurements point to well-localized 4 f -electrons in this compound. Whereas the isostructural La-germanide is a nonmagnetic material taken here as a reference compound. A good overall fit of the resistivity to a general Bloch–Gruneisen formula indicates its metallic character in contrast to the Dy-germanide being a semimetallic-like conductor. For the latter compound in its ordered state the electrical resistvity, specific heat and thermoelectric power are dominated by electron–magnon scattering with antiferromagnetic spin-wave spectrum typical of anisotropic antiferromagnetic systems. The observed Schottky anomaly yields an assumed crystal field scheme of low-energy lying levels. Its thermoelectric power behaviour achieves medium positive values at high temperatures, indicating a hole domination in electrical transport properties. On the other hand, S ( T ) below T N for Dy- and in the whole temperatures measured for La-based compounds is negative, pointing to their electron carrier origin.

The crystal structure of the novel compound Yb3Pt23Si11 has been determined from powder X-ray diffraction data to be isotypic with cubic Ce3Pt23Si11 (space group F m 3 ¯ m ; a = 1.68052(5) nm). Magnetic susceptibility, electrical resistivity and heat capacity measurements, performed down to 0.4 K, revealed that Yb3Pt23Si11 is a moderately enhanced paramagnetic compound with fairly unstable 4f electronic shell.

Five novel cerium-based ternaries Ce2Rh3.1Si0.9 ,C e 4Rh12Si, Ce8Rh21.9Si3.1, CeRh1.82Si0.18 and CeRh3Si0.125 were studied by means of magnetic susceptibility and electrical resistivity measurements. All these phases were found to be Pauli paramagnets with metallic type of electrical conductivity.

We have studied chemical interaction of the intermetallic compound NdRh3 with hydrogen at pressures of up to 0.2 GPa. The structural changes in the intermetallic matrix in different stages of the hydrogenation process have been followed using synchrotron X-ray diffraction. The results demonstrate that hydrogen absorption leads to an irreversible change in lattice symmetry from hexagonal to cubic.

Two series of intermetallic alloys, RT2Si and RTSi2, have been synthesized from stoichiometric compositions. The crystal structures of EuPt1+xSi2−x (CeNiSi2-type), CeIr2Si (new structure type), YbPd2Si and YbPt2Si (both YPd2Si-type) have been elucidated from X-ray single crystal CCD data, which were confirmed by XPD experiments. The crystal structures of LaRh2Si and LaIr2Si (CeIr2Si-type), {La,Ce,Pr,Nd}AgSi2 (all TbFeSi2-type), and EuPt2Si (inverse CeNiSi2-type) were characterized by XPD data. RT2Si/RTSi2 compounds were neither detected in as-cast alloys Sc25Pt50Si25, Eu25Os25Si50 and Eu25Rh25Si50 nor after annealing at 900 °C. Instead, X-ray single crystal data prompted Eu2Os3Si5 (Sc2Fe3Si5-type) and EuRh2+xSi2−x (x=0.04, ThCr2Si2-type) as well as a new structure type for Sc2Pt3Si2 (own type).

Phase relations in the ternary system Ce–Pd–Si have been established for the isothermal section at 8001C based on X-ray powder diffraction and EMPA techniques on about 130 alloys, which were prepared by arc-melting under argon or powder reaction sintering. Eighteen ternary compounds have been observed to participate in the phase equilibria at 8001C. Atom order was determined by direct methods from X-ray single-crystal counter data for the crystal structures of t8—Ce3Pd4Si4 (U3Ni4Si4type, Immm; a ¼ 0.41618(1), b ¼ 0.42640(1), c ¼ 2.45744(7) nm), t16—Ce2Pd14Si (own structure type, P4/nmm; a ¼ 0.88832(2), c ¼ 0.69600(2) nm) and also for t18—CePd1� xSix (x ¼ 0.07; FeB-type, Pnma; a ¼ 0.74422(5), b ¼ 0.45548(3), c ¼ 0.58569(4) nm). Rietveld refinements established the atom arrangement in the structures of t5—Ce3PdSi3 (Ba3Al2Ge2-type, Immm; a ¼ 0.41207(1), b ¼ 0.43026(1), c ¼ 1.84069(4) nm) and t13—Ce3� xPd20+xSi6 (0rxr1, Co 20Al3B6-type, Fm3 ¯ m; a ¼ 1.21527(2) nm). The ternary compound Ce2Pd3Si3 (structure-type Ce2Rh1.35Ge4.65, Pmmn; a ¼ 0.42040(1), b ¼ 0.42247(1), c ¼ 1.72444(3) nm) was detected as a high-temperature compound, however, does not participate in the equilibria at 8001C. Phase equilibria in Ce–Pd–Si are characterized by the absence of cerium solubility in palladium silicides. Mutual solubility among cerium silicides and cerium–palladium compounds are significant whereby random substitution of the almost equally sized atom species palladium and silicon is reflected in extended homogeneous regions at constant Cecontent such as for t2—Ce(PdxSi1� x)2 (AlB2-derivative type), t6—Ce(PdxSi1� x)2 (ThSi2-type) and t7—CePd2� xSi2+x. The crystal structures of compounds t4—Ce� 8Pd� 46Si� 46, t12—Ce� 29Pd� 49Si� 22, t15—Ce� 22Pd� 67Si� 11, t17—Ce� 5Pd� 77Si� 18 and t18—CePd1� xSix (x� 0.1) are still unknown.

The crystal structures of ternary compounds RPt3−xSi1−y(R=Y, Tb, Dy, Ho, Er, Tm, Yb) have been elucidated from X-ray single crystal CCD data. All compounds are isotypic and crystallize in the tetragonal space group P4/mbm. The general formula RPt3−xSi1−y arises from defects: x≈0.20, y≈0.14. The crystal structure of RPt3−xSi1−y can be considered as a packing of four types of building blocks which derive from the CePt3B-type unit cell by various degrees of distortion and Pt, Si-defects.

Ternary intermetallic CeRu 0.88 In 2 was synthesized by arc-melting from elemental Ce, Ru, and In under an argon atmosphere. The crystal structure of CeRu 0.88 In 2 was determined from single-crystal X-ray diffraction data: a = 4.5449(11) A, b = 10.014(2) A and c = 7.6854(10) A; space group Cmcm , Z = 4, MgCuAl 2 type. The structure is formed of three-dimensional framework of [Ru 0.88 In 2 ], in the infinite pentagonal channels of which Ce atoms are disposed. Similar to the other known ternary compounds of the Ce–Ru–In system, CeRu 0.88 In 2 exhibits unusually short Ce–Ru contact equal to 2.530(4) A, which in addition is the shortest one in the raw of LTIn 2 compounds with MgCuAl 2 structure type (L = La, Ce, Pr, Nd, Sm, Eu, Gd, Yb; T = Rh, Pd, Au).

The ternary intermetallic Ce 16 Ru 8 In 37 was synthesized by arc-melting from elemental Ce, Ru, and In under an argon atmosphere. The crystal structure of Ce 16 Ru 8 In 37 was determined from the single-crystal X-ray diffraction data: a = 4.7451(1) A, b = 9.3518(2) A, c = 32.6162(7) A; space group Immm , Z = 1. The architecture of the crystal structure of Ce 16 Ru 8 In 37 is based on CeIn 3 units with cubic Cu 3 Au-type and can be presented as consisting of two different slabs: CeIn 3 -like slab of composition Ce 4 In 14.5 and a slab of composition Ce 4 Ru 4 In 4 .

The dynamic magnetic response of the intermediate-valence compound EuCu2Si2 has been studied using inelastic neutron scattering. At low temperatures, strong renormalization of the 7F0 → 7F1 spin-orbit transition energy is detected; it is likely to be related to partial delocalization of the f electrons of Eu. An increase in the temperature increases the valence instability of europium and results in further changes in the magnetic excitation spectrum parameters and the appearance of an intense quasi-elastic component.

The electronic and magnetic properties of the ternary cerium compounds Ce 2 PdGe 6 and Ce 2 PtGe 6 are reported within the context of measurements of electrical resistivity, magnetoresistivity, and magnetic susceptibility. Ce 2 PdGe 6 orders magnetically at T N = 11.5 K , and Ce 2 PtGe 6 at T N = 9.9 K . In the ordered region, the magnetization as well as the magnetoresistance reveal anomalous behaviour for both compounds, which are ascribed to metamagnetic transitions into a field-induced ferromagnetic state.

The crystal and magnetic structures of U(Pd 1− x M x ) 2 Ge 2 compounds with M=Fe, Co, Ru are studied by neutron powder diffraction and μSR. The effects of M doping and external applied pressure on the crystal and magnetic structures are compared. We find that even at small M-doping level the magnetic structure drastically changes, while the values of the lattice parameters and interatomic distances change only slightly. In contrast, a high external pressure modifies the crystal structure more significantly, while the magnetic structure remains the same. These observations allow us to conclude that the drastic changes of magnetic structure of U(Pd 1− x M x ) 2 Ge 2 compounds with increased M doping could result from modifications of the RKKY indirect exchange interactions owing to a variation of conduction-electron number per U atom, rather than from lattice contraction.

We report lSR studies on a Ce 3 Pd 20 Si 6 polycrystalline sample. Zero-"eld measurements were undertaken to gain information on the magnetic ordering at low temperatures. Below 0.4 K the increase of the muon-spin depolarization rate re#ects the development of a quasi-static ordering of magnetic moments of electronic origin probably randomly oriented. In transverse-"eld studies a clear frequency shift was observed. This fact may be ascribed to the increase of the total-magnetic moment of the superparamagnetic cube containing 8 Ce2 atoms and their ferromagnetic ordering with decreasing temperature. ( 2000 Elsevier Science B.V. All rights reserved.

The neutron diffraction and magnetic susceptibility studies have shown that the magnetic structure of UPd 2 Ge 2 changes dramatically even under very low iron doping. Though the general magnetic structure of pure UPd 2 Ge 2 and of 1%Fe-doped samples is the same, the temperature intervals of existence of different magnetic phases are different. The values of transition temperatures, where (i) the `square’ modulated longitudinal spin-density wave (LSDW) structure with the propagation vector k =(0; 0; k z = 3 4 ) starts to transform into the sinusoidal modulated LSDW structure and (ii) the commensurate phase transforms into incommensurate one, shift under the 1%Fe doping to the higher temperatures (from 50 to 65 K and from 80 to 90 K, respectively). In the pure and 1%Fe-doped UPd 2 Ge 2 , the magnetic transition from the commensurate to incommensurate phase is accompanied by the drastic decrease of the propagation vector k z . In the 2%Fe-doped sample, besides the Neel point of T N =135 K, we have found two additional characteristic temperatures of 65 and 93 K. Below 65 K, the material has a simple antiferromagnetic (AF) structure with the propagation vector k =(0; 0; 1) and, at 65 K T T N , the magnetic structure is LSDW with sinusoidal modulation. Over almost the total region 65 K T T N , the LSDW magnetic structure is incommensurate. Only at about 93 K, the propagation vector passes the commensurate value of 3 4 , whereas k z > 3 4 at 65 T k z 3 4 at 93 K T T N . We have found that the magnetic susceptibility and the uranium magnetic moment are sensitive to the k z > 3 4 ⇒k z 3 4 transition. With increasing iron concentration to x ⩾0.15, the simple AF structure with k =(0; 0; 1) develops over all temperature region up to the Neel point. Below T N , the uranium magnetic moments are always parallel to the tetragonal c -axis.

The crystal structure of the new intermetallide Ce 3 Pd 14 Ge 5 was investigated by X-ray monocrystal diffraction method. It is found that the elementary cell belongs to space group Pnma, Z =4, a =0.9033(2) nm, b =0.9082(2) nm, c =1.8142(2) nm.

A novel ternary compound has been found at the 1:2:1 position among the Yb–Pd–Si phases, where YbPd 2 Si crystallises in the ordered Fe 3 C -structure. YbPd 2 Si is characterised by Kondo lattice features at higher temperatures and, presumably, antiferromagnetism at 2.1 K. A quasi-quartet crystal field ground state governs the physics at low temperature.

Copyright (c) 1997 Elsevier Science S.A. All rights reserved. A novel ternary compound Ce 3 Pt 23 Ge 11 crystallises in a new structure type with space group F 3m and a=1.71833(9) nm. Here we present the results of magnetic, electrical and specific heat measurements, obtained on the single crystal and polycrystalline samples. This compound is a metal with normal Ce 3+ magnetic behaviour. Although the specific heat at low temperatures rises rapidly to a large value of 2.5 J/Ce-mol K at 0.38 K, we have not detected any phase transition down to this temperature. Only in the temperature range 0.1-1 K a small decrease in the resistivity value can be detected with an inflection point at approximately 0.3 K.

Measurements of temperature and field dependent bulk properties have been carried out on ${{\mathrm{Ce},\mathrm{La}}}_{3}{\mathrm{Pd}}_{4}{\mathrm{Si}}_{4}$. Rietveld refinements of x-ray powder intensity data confirm the orthorhombic ${\mathrm{U}}_{3}{\mathrm{Ni}}_{4}{\mathrm{Si}}_{4}$-type structure for both compounds. While ${\mathrm{La}}_{3}{\mathrm{Pd}}_{3}{\mathrm{Si}}_{4}$ exhibits superconductivity below 2 K together with some indications of a two gap scenario, the former can be characterized as a Kondo lattice system in presence of crystalline electric field splitting. Due to the closeness of a quantum critical point, distinct non-Fermi-liquid features dominate the low temperature physics of ${\mathrm{Ce}}_{3}{\mathrm{Pd}}_{4}{\mathrm{Si}}_{4}$.

Metamagnetic transitions in CePd5Ge3 were investigated by means of low-temperature magnetization, magnetic susceptibility, electrical resistivity and magnetoresistivity measurements. In transverse magnetic fields applied in a direction close to the b-axis the antiferromagnetic structure of the compound undergoes two successive transitions, first to a spin-flop phase and then to a paramagnetic phase with field-induced ferromagnetic-like alignment of the Ce magnetic moments. In contrast, a single anomaly occurs in the magnetic field dependences of the resistivity in a transverse magnetic field applied close to the c-axis, which reflects a direct transition from antiferromagnetic to paramagnetic state. Such behavior is in agreement with theoretical descriptions of metamagnetic transitions in uniaxial antiferromagnets. The experimental magnetic and electrical transport data indicate that the b-axis is the easy axis of magnetization in CePd5Ge3.

The crystal structure of the new ternary silicide CePt 3 Si [space group P 4 mm , a =4.072(1) A, c =5.442(2) A, Z =1, V =90.25(5) A 3 , R =0.0437 for 153 structure factors] was determined from single-crystal X-ray diffraction. The compound belongs to the CePt 3 B structure type of intermetallic compounds.

The crystal structure of the compound CeRh 2 Si was studied by X-ray single crystal diffraction methods and refined to R F =0.038: space group Cmcm , a =4.0413(9) A, b =17.730(3) A, c =4.0675(9) A, V =291.45(10) A 3 , Z =4. The structure belongs to a structure type that can be considered as a site exchange variant of the known CeNiSi 2 structure type (CeSiRh 2 ) with slightly different axial ratios.

The crystal structure of the intermetallic compound Ce 3 Ru 4 Al 12 has been studied. The experiment was carried out using the X-ray single crystal diffraction technique. It was established that the structure belongs to the Gd 3 Ru 4 Al 12 structure type, which is related to the EuMg 5.2 type. Ce 3 Ru 4 Al 12 has the space group P6 3 /mmc, a = 8.8652(10) A, c = 9.5700(2) A, V = 651.4(2) A 3 , and Z = 2.

The crystal structure of the compound Ce3Pt23Ge11 has been determined by X-ray analysis of a single crystal (Enraf-Nonius CAD-4 autodiffractometer, Mo Kα radiation, 276 independent reflections, R-factor 0.0735 in isotropic approximation). This structure has been found to belong to a new structural type: space group F 4 3m, a = 17.1833(9) A , Z = 8 . The coordination polyhedra of the cerium atoms are compressed cubes, those of platinum have eight or 10 apexes and those of germanium are either trigonal prisms with an additional atom or cubes. The magnetic properties of Ce3Pt23Ge11 at low temperatures (4–100 K) were investigated. A diffuse magnetic phase transition at around 10 K was detected.

The crystal structure of the new intermetallic compound Ce 4 Pd 29 Si 14 , was determined by X-ray single-crystal diffraction method revealing space group Fm3m with a =1.8010(2) nm and Z =4.

The crystal structure of the new compound Ce 3 Pd 5 Si was investigated by X-ray single crystal diffraction method. The compound crystallizes in a new structure type, space group Imma Z =4, a =1.3027(4) nm, b =0.7377(4) nm, c =0.7580(4) nm.

The ternary intermetallic compound CeRu 3− x Al 10+ x ( x = 0.17) crystallizes in the orthorhombic system, space group Imma , a = 4.2213(1) A, b = 12.5014(3) A, c = 17.6689(4) A, Z = 4. It is closely related to NdCo 3 Ga 9 and can be regarded as a substructure of U 2 Co 6 Al 19 . Trigonal prismatic and cuboctahedral coordination is typical for Al and Ru atoms, the coordination polyhedron of the Ce atom is a pentagonal prism with five additional atoms. The structure can be described as a 3D network of aluminium and ruthenium atoms, forming distorted pentagonal channels along [1 0 0], where the cerium atoms are located.

The crystal structures of the compounds Dy18Pt50+xSi16−x (x = 0.28) (I) and Y18Pt50+xSi16−x (x = 0.56) (II) have been investigated by means of single crystal techniques (Nonius KappaCCD diffractometer, ω- and φ-scans, Mo Kα radiation). Both compounds belong to a new structure type (space group P4/mbm, Z = 1, a = 18.7778(2) A, c = 4.0897(1) A (I) and a = 18.7777(3) A, c = 4.0891(1) A (II)) closely related to the Er36Pt102−xSi32 (x = 2.6) type of structure (space group P42/mnm, Z = 1, a = 18.6723 A, c = 8.1734 A). Coordination numbers for three crystallographically independent Dy and Y atoms are 18, 15 and 12 and for Pt atoms range from 9 to 12, distorted cuboctahedra being typical for most of the Pt-atom polyhedra. Triangular prisms with three additional atoms are characteristic for coordination polyhedra of silicon atoms. The peculiarity of the defects of the Pt and Si atom positions as well as the relationship with the Er36Pt102−xSi32 structure is discussed.

The new ternary indides CePd 2 In 4 and CePt 2 In 4 were synthesized by arc-melting of the elements and subsequent annealing at 770 K for 1 month. The crystal structure of both the compounds was refined from the single crystal X-ray data. CePd 2 In 4 and CePt 2 In 4 crystallize in the orthorhombic NdRh 2 Sn 4 -type structure (space group Pnma), a = 18.449(3) A, b = 4.5647(6) A, c = 7.4145(15) A, V = 624.4(2)A 3 , R F = 5.96% for CePd 2 In 4 , a = 18.460(4) A, b = 4.5299(13) A, c = 7.2670(16) A, V = 607.7(3) A 3 , R F = 7.47% for CePt 2 In 4 .

The crystal structures of the new compounds Ce 2 Rh 12 Si 7 and Ce 6 Rh 30 Si 19 , extracted from an ingot of composition Ce 9.5 Rh 56.9 Si 33.6 , were investigated by X-ray single crystal diffraction methods. The title compounds crystallize in the hexagonal space group P 6 3 / m with unit cell parameters a =9.706(1) A, c =3.8394(3) A and a =15.698(2) A, c =3.8571(4) A, respectively. Ce 2 Rh 12 Si 7 and Ce 6 Rh 30 Si 19 represent members of a family of hexagonal structures with a short unit cell parameter c ≈3.7 A and with general formula R n ( n +1) T 6( n 2 +1) M 4 n 2 +3 , where R is the rare earth, T the transition metal, and M the element of the IV or V main group. Ce 2 Rh 12 Si 7 crystallizes with the Ho 2 Rh 12 As 7 type, ignoring the disordered arrangement of non-metal atoms on the c -axis. The structure of Ce 6 Rh 30 Si 19 is closely related to that of Sc 6 Co 30 Si 19 .

The new cerium ternary compounds Ce/sub 3/Pt/sub 4/Ge/sub 6/ and Ce/sub 2/Pt/sub 7/Ge/sub 4/ with novel crystal structure types have been prepared and characterized. We present transport and magnetic properties of these compounds in temperature range (2-300) K. Behavior of resistivity and magnetisation is similar, both compounds demonstrate Kondo-like features and possible magnetic transition near the helium temperature. >