Thermo-elastic property of Ca(OH){sub}2 portlandite

摘要

An equation of state (EoS) for Ca(OH){sub}2 portlandite has been obtained through measurements of pressure and temperature dependence of volume by means of in-situ X-ray observation. The bulk modulus and its pressure derivative at zero pressure calculated using third-order Birch-Mumaghan's equation of state is 33.1 GPa and 4.2 at 300 K, respectively. The unit cell parameters and the volumes have been also determined at 573 K and 673 K. Temperature derivatives of the bulk modulus and its pressure derivative have been calculated to be-0.022 Gpa/K and 0.0072 K{sup}(-1), respectively. Thermal expansion coefficient of portlandite has been calculated from the EoS. The pressure dependence of entropy has been obtained from the present thermo-elastic parameters.