研究目的
To study the dependence of thermal conductivity with temperature for Sn(Pb)2P2S(Se)6 ferroelectrics-semiconductors and explain the observed behavior through various physical mechanisms.
研究成果
The study demonstrates the potential of the intrinsic origin of the phosphorous chalcogenides lattice anharmonicity for the design of materials with ultralow thermal conductivity. The strong lattice anharmonicity is related to the relaxations of the 5s2 electron lone pairs of Sn2+ cations together with valence fluctuations in (P2S6)4? groups.
研究不足
The study does not reach very low temperatures where the heat transfer regime changes from diffusive to ballistic, and the exact position and width of phase transitions do not exactly coincide in heat capacity and thermal diffusivity measurements.
1：Experimental Design and Method Selection:
The study involved measuring thermal diffusivity of Sn(Pb)2P2S(Se)6 samples using a high resolution ac photopyroelectric calorimetry in a broad temperature range.
2：Sample Selection and Data Sources:
Single crystals of various compositions were grown by vapor transport method.
3：List of Experimental Equipment and Materials:
High resolution ac photopyroelectric calorimetry was used for thermal diffusivity measurements.
4：Experimental Procedures and Operational Workflow:
Well polished plane-parallel plates were used for measurements, with their faces perpendicular to certain crystallographic axes.
5：Data Analysis Methods:
Thermal conductivity was calculated using the constitutive equation combining thermal diffusivity data with specific heat data from literature.
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