By means of X-ray diffraction, scanning electron microscopy and energy dispersive
X-ray spectroscopy, the phase equilibria in the {Ce,Gd}-{Ti,Zr}-{Sn,Sb} systems were
established. Isothermal sections of the phase diagrams of the systems at 600°C, in the
whole or partial concentration ranges, were built for the first time. The existence of 15
new ternary compounds at 600°C has been established.
13 new stannides and plumbides of the ZrFe6Ge4 structure type (Pearson code hR33,
space group I4/mmm) were synthesized: RTi6Sn4 (R = La, Ce, Pr, Nd, Sm) and RTi6Pb4
(R = Y, Gd, Tb, Dy, Ho, Er, Tm, Lu). The crystal structures of the ternary antimonides
Ce2Ti7Sb12 (structure type La2Ti7Sb12, oS56-14, Cmmm) and Gd2Ti11Sb14 (structure type
Sm2Ti11Sb14, oP64-10, Pnma), the new antimonide Ce0,08(3)Zr1,92(3)Sb (structure type
UGeTe, tI12, I4/mmm), as well as of the binary antimonide Gd2Sb5 (structure type Dy2Sb5,
mP28, P21/m), were determined. In the Gd-Zr-Sb system, the existence of an extended23
homogeneity region along the isoconcentrate 33.3 at.% Sb was established for the phase
Gd1-xZr1+xSb (x = 0-0.905(18)) (structure type UGeTe, tI12, I4/mmm).
It was established that the systems R-{Ti,Zr}-{Sn,Sb} are characterized by the
formation of a small number of ternary compounds. They form at relatively low contents
of rare-earth metal (≤40 at.%).
One of the main differences between the systems with Sn and Sb is the absence of
significant solid solubility of the third component in the binary compounds in the systems
with Sn, and its presence in the systems with Sb. Among the {Ce,Gd}-{Ti,Zr}-Sb systems,
the solid solubility of the third component is higher in the systems with Zr than with Ti,
and higher in the systems with Gd than with Ce.
The influence of the size factor on the formation of compounds with ZrFe6Ge4-type
structures was estimated. It was established that compounds of this structure type (RT6M4)
form at the approximate ratio of the atomic radii of the elements r(R) : r(T) : r(M) =
1,2-1,34 : 1-1,03 : 1-1,06.
The structures of the ternary stannides and antimonides are layered. In the structures
of the Ce2Ti7Sb12 and Gd2Ti11Sb14 compounds, three-dimensional frameworks, formed by
the coordination polyhedra of the Ti atoms, are present. A common feature of many of the
investigated compounds is an atom arrangement according to the principles of closepacked structures with the corresponding polyhedra (octahedra, cuboctahedra and
anticuboctahedra).
The density of electronic states (DOS) distribution in the investigated compounds
indicates metallic type of conductivity. An analysis of the distribution of the electron
localizability indicator (ELI) indicates metallic type of bonding for the isotypic
compounds SmTi6Sn4 and YTi6Pb4, with a fraction of covalent bonding between the Sn
atoms. For the YZrSb compound, a minor ionic constituent of the chemical bonding was
observed.
