Wang Jiaqi, Gao Qilong, Sanson Andrea, Sun Qiang, Liang Erjun
Key Laboratory of Materials Physics of Ministry of Education, and School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450052, China.
Department of Physics and Astronomy, University of Padova, Padova I-35131, Italy.
Inorg Chem. 2022 Aug 29;61(34):13239-13243. doi: 10.1021/acs.inorgchem.2c01722. Epub 2022 Aug 16.
High structure flexibility can lead to large negative thermal expansion (NTE), but the reason is not clear. In this work, first-principles calculations have been carried out to investigate the relationship between NTE and structure flexibility in Zn(CN)-type compounds. Smaller bulk modulus corresponds to larger compressibility, thus making the crystal structure more flexible and more suitable for NTE. It indicated that the ionic nature of the bond and the bond length jointly affect the structural flexibility and then act on the transverse vibration of C and N atoms. The results of lattice dynamic suggested that higher structural flexibility promotes a greater number of low-frequency optical modes with negative Grüneisen parameters, resulting in a larger NTE. This work also gives us new insight into the design of NTE materials.
