Thermal expansion coefficient and bulk modulus of silicides

Abstract

The volumetric thermal expansion coefficient α V is discussed in relation to the bulk modulus B 0 for transition-metal disilicides (TrSi2), alkaline-Earth metal disilicides (AeSi2), Mg2Si, and Si clathrates. For this purpose, the α V of CoSi2 at 300 K is determined to be 3.1 × 10−5 K−1 using powder X-ray diffraction measurements at temperatures ranging from 300 to 835 K. AeSi2 and Mg2Si have B 0 values ranging from 27.9 to 52.9 GPa, while the values for α V range from 3.2 × 10−5 to 4.8 × 10−5 K−1. TrSi2 including CoSi2 has larger B 0 values ranging from 148.9 to 243 GPa and smaller α V values ranging from 2.3 × 10−5 to 3.3 × 10−5 K−1 than AeSi2. Si clathrates have intermediate values of α V and B 0, which are in between those of TrSi2 and AeSi2. Thus, the silicides with small B 0 values tend to have large α V values.