Thermal Transport Properties of Two-dimensional Layered Material CuInP2Se6

doi:10.15541/jim20260035

Abstract

Abstract:

Two-dimensional layered CuInP₂Se₆ crystals have attracted extensive attention owing to the ferroelectricity and various unique optical properties. However, the lack of research on their thermal properties hindered their further application. In this study, dense polycrystalline CuInP₂Se₆ was prepared by vapor transport combined with spark plasma sintering (SPS), and its thermal stability and thermal transport properties were investigated systematically. Thermogravimetric analysis results show that CuInP₂Se₆ does not decompose or undergo phase transitions in the temperature range of 300-740 K. Within the temperature range of 300-623 K, the thermal conductivity decreases from 0.63 W·m^-1·K^-1to 0.35 W·m^-1·K^-1 parallel to the SPS pressing direction, and from 1.34 W·m^-1·K^-1 to 0.93 W·m^-1·K^-1 perpendicular to the SPS pressing direction. To explore the key factors influencing the thermal conductivity of CuInP₂Se₆, corresponding theoretical calculations and sound velocity measurements were carried out. Results reveal strong phonon scattering inside the material, and CuInP₂Se₆ possesses a low transverse sound velocity (V_T=1199 m·s^-1) and strong lattice anharmonicity (γ=1.83). The low thermal conductivity of CuInP₂Se₆ originates from the synergistic effect of strong phonon scattering, low sound velocity, and strong lattice anharmonicity. This study provides theoretic mechanism and experimental data for application of CuInP₂Se₆.

Key words: two-dimensional layered material, CuInP₂Se₆, thermal transport, low thermal conductivity

CLC Number:

O551

CHENG Zhipeng, LIN Chensheng, YAN Tao, LUO Min, YANG Shunda. Thermal Transport Properties of Two-dimensional Layered Material CuInP₂Se₆[J]. Journal of Inorganic Materials, 2026, 41(10): 1380-1386.

Figures/Tables 7

Fig. 1 Schematic illustration of the preparation of CI-PX and CI-CZ samples

Fig. 2 Crystal structures of CuInP2Se6 Crystal structures of CuInP2Se6 viewed along (a) a- and (b) c-axes; (c) Internal structural details of CuInP2Se6, including [P2Se6] groups, [CuSe6] octahedra and [InSe6] octahedral. Colorful figures are available on website

Fig. 3 (a) XRD patterns and (b, c) SEM images of CuInP2Se6 samples (a) Powder before SPS, CI-PX and CI-CZ; (b) CI-PX; (c) CI-CZ

Fig. 4 EDS elemental mappings of CI-PX

Fig. 5 Thermogravimetric curve and lattice thermal conductivity of CuInP2Se6 (a) Thermogravimetric analysis (TGA) and differential thermal analysis (DTA); (b) Temperature-dependent lattice thermal conductivities of CuInP2Se6 parallel and perpendicular to the pressure direction, and reported thermoelectric materials[18-23]

Table 1 Sound velocities and γ of CI-PX and CI-CZ samples

Sample	V_L/(m•s^-1)	V_T/(m•s^-1)	γ
CI-PX	2283	1199	1.83
CI-CZ	2554	1365	1.77

Fig. 6 Theoretical calculation plots and visualization of atomic vibration modes for CuInP2Se6 (a) Phonon dispersion curves of CuInP2Se6; (b) Projected phonon density of states (PDOS) of CuInP2Se6; (c) γ of CuInP2Se6; (d) Calculated phonon group velocity spectra of CuInP2Se6; Vibration modes of (e) longitudinal acoustic branch and (f) low-frequency optical branch. Colorful figures are available on website

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Thermal Transport Properties of Two-dimensional Layered Material CuInP₂Se₆

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