The specific features of phononic and magnetic subsystems of type-VII clathrate EuNiP.

A type-VII clathrate with a Eu2+ guest embedded into a Ni-P covalent framework, EuNi2P4, was synthesized by a standard two-stage ampoule synthesis and confirmed to crystallize in the orthorhombic space group Fddd with unit cell parameters a = 5.1829(1) Å, b = 9.4765(1) Å, and c = 18.

Crystal lattice disorder and characteristic features of the low-temperature thermal properties of higher borides.

Heat capacity C(T) and lattice parameters a(T), b(T) and c(T) of LuBSi borosilicide are experimentally studied as a function of temperature in the range of 2-300 K. The results are compared with those of pseudo-isostructural LuB boride. At the lowest temperatures, it is shown that the C(T) dependence of borosilicide changes linearly with temperature.

Effect of the cation sublattice composition of tin-based type-I clathrates on their low-temperature thermal properties.

We performed an experimental study on thermal properties of the Sn18In6As21.5I8 clathrate by measuring temperature dependencies of its heat capacity (2-300 K) and thermal expansion (5-300 K). By comparing the results with those published previously for Sn-based clathrates Sn24P19.

Dynamics of the crystal structure of tin-based type-I clathrates with different degrees of disorder in their cationic frameworks.

The temperature dependencies of heat capacity, C(T), and cubic unit cell parameter, a(T), were experimentally obtained in the range of 2-300 K for the compounds SnPI, SnZnPI, and SnZnPI, which belong to a family of type-I clathrates. The experimental data were analyzed in the frames of the Debye-Einstein approximation, further accounting for the contributions of positional disorder in the clathrate frameworks as well as those of defect modes arising from the distribution of guest atoms over unequal in energy but close in space positions inside the framework cages. By fitting the experimental data, the Debye and Einstein characteristic temperatures describing the dynamics of the framework and guest atoms, respectively, were obtained.

Structural irregularities and peculiarities of low-temperature thermal properties of SnPBr clathrate.

Temperature changes of the heat capacity and unit cell parameters of SnPBr clathrate were experimentally determined in the temperature range of 2 to 300 K. The data obtained were analyzed using Debye-Einstein approximation and taking into account the impact of both disorder in the host matrix and the presence of vacancies in the framework. Anomalous negative contribution to the thermal expansion was revealed and related to the defect mode influence on the clathrate thermal properties as a result of vibrations of two-level systems (TLS).