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A new member of the series of Th7 Fe3 -type derivative structures, h-(Pd0.86 Cu0.14 )7 B3 (≡Pd6.02 Cu0.98 B3 , unique structure type Pd6 CuB3 , space group P63 cm, a=12.9426(9) A, c=4.8697(4) A, single-crystal X-ray diffraction (XRD) data) was obtained from as cast alloys and alloys annealed at 600-650 °C. Further substitution of Cu by Pd led to formation of a Mn7 C3 -type structure, o-(Pd0.93 Cu0.07 )7 B3 (≡Pd6.51 Cu0.49 B3 , space group Pnma, a=4.8971(2) A, b=7.5353(3) A, c=12.9743(6) A, single-crystal XRD). Isotypic LT h-(Pt0.70 Cu0.30 )7 B3 (≡Pt4.90 Cu2.10 B3 ) was observed in the Pt-Cu-B system as a low-temperature (LT) phase (T≤600 °C) (powder XRD), whereas the Th7 Fe3 -type (high-temperature (HT) h-(Pt0.73 Cu0.27 )7 B3 ≡Pt5.11 Cu1.89 B3 , space group P63 mc, a=7.4671(1) A, c=4.9039(1) A, powder XRD) proved to be stable at high temperature. The three structures are built of columns of face connected metal octahedra and columns of metal tetrahedra alternatingly fused by common faces and vertices. Boron atoms are found in trigonal prisms formed by metal atoms. The volumes of the three new Th7 Fe3 -type derivative borides relate as 1:2:3. Superconductivity was discovered for Pt4.9 Cu2.1 B3 (Pd6 CuB3 -type) and Pt5.1 Cu1.9 B3 (Th7 Fe3 -type) below 0.67 and 0.66 K, respectively. Despite the close value of the transition temperature the values of the upper critical field at 0 K differ as 0.37 T and 0.27 T for the two compounds.

(Pt1-xCux)3Cu2B (x = 0.33) (I) and Pt9Cu3B5 (II) are prepared by repeated arc melting of the elements (Ta foil in evacuated quartz tubes, 600 °C, 240 h).

EuPt4B (I), Eu3Pt7B2 (II), and Eu5Pt18B6-x (III) are synthesized by arc melting of the constituent elements using excess Eu due to its high volatility.

The 850 °C isothermal sections of the title systems are characterized by powder and single crystal XRD.

Hydrogen absorption and desorption properties of the (Hf,Zr) 2 Fe quasibinary alloys (Ti 2 Ni structure type) and the oxygen-stabilised compound Zr 4 Fe 2 O 0.6 with the filled-Ti 2 Ni type of structure, have been studied and discussed in relation to their phase-structural and chemical composition. The crystallographic characteristics, hyperfine parameters and magnetic properties of the hydrogenated alloys have been determined.

The phase equilibria at 600°C of the ternary system Y–Cu–Pd in the range 0–25 at.% Y have been investigated by means of X-ray powder diffraction and microscopic analyses. Three ternary compounds were found to occur: YCu 1.20 Pd 1.80 , YCu 2–1.75 Pd 1–1.25 and YCu 3.77 Pd 1.23 . The crystal structure was determined for two compounds: YCu 1.20 Pd 1.80 has the TiNi 3 structure type, sp. gr. P6 3 /mmc, a =5.732(1), c =9.383(2) A, YCu 3.77 Pd 1.23 has the AuBe 5 str. type, sp. gr. F43m, a =7.078(2) A. The Cu and Pd atoms randomly occupy crystallographic sites in both structures. The electrical resistivity of the ternary compounds is of the metal type and obeys the Bloch–Gruneisen function within the temperature range 4.2–300 K. None of the ternary compounds of the system superconduct above 4.2 K. The traces of superconductivity observed in some alloys are suggested to arise from an unresolved quaternary compound.

The effect of chemical composition on ground state properties of Ce 2 Pd 2 ln, YbCu 4 Au and YbCu 4 Ag, showing more or less extended homogeneity ranges, has been shortly reviewed. The ternary indides Ce 2 Pd 2+2x ln 1-x and Ce 2+x Pd 2 ln 1-x form two branches of solid solutions, and the magnetic properties of these compounds are strongly influenced by composition, which drives the system from ferromagnetic to antiferromagnetic behaviour through the stoichiometric point Ce 2 Pd 2 ln. Similarly, YbCu4Au, which is located along the YbCu 5-x Au x solid solution, is at the crossover between two kinds of disordered sublattices, and the ground state properties follow a non-monotonic behaviour through the point of crystallographic order YbCu 4 Au. YbCu4Ag is located at one end point of the YbCu 5-x Ag x solid solution and the system exhibits a systematic variation of ground state properties along the solid solution.