Zusammenfassung
Heat capacity C-P(T) (2-300K) and unit cell parameters a(T), b(T), and c(T) (5-300K) of type-VII clathrates SrNi2P4 and BaNi2P4 have been investigated experimentally. The studied compounds are prepared by a two-stage ampoule synthesis. Diffuse maxima of C-P(T) near 5K along with anomalies in temperature dependencies of unit cell parameters below 10K are observed and related to the influence of ...
Zusammenfassung
Heat capacity C-P(T) (2-300K) and unit cell parameters a(T), b(T), and c(T) (5-300K) of type-VII clathrates SrNi2P4 and BaNi2P4 have been investigated experimentally. The studied compounds are prepared by a two-stage ampoule synthesis. Diffuse maxima of C-P(T) near 5K along with anomalies in temperature dependencies of unit cell parameters below 10K are observed and related to the influence of two-level systems in guest-atom substructures. Joint analysis of temperature dependencies of heat capacity and unit cell volume of both clathrates within the frames of the Debye-Einstein model allowed determining characteristic temperatures of the clathrate frameworks and guest atoms as well as parameters of the two-level systems. The relationships of the obtained characteristics and the peculiarities of the crystal structures of SrNi2P4 and BaNi2P4 are discussed.
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