Structural phase transformation and equations of state of calcium chalcogenides at high pressure

The equations of state and pressure induced structural phase transformation of calcium chalcogenides have been investigated by using a three-body pote ntial approach. The calculated compression curves of CaS, CaSe and CaTe obt ained so have been compared with recently measured energy dispersive X-ray data. The accuracy of the present model in reproducing the equations of sta te and phase transition pressure of calcium chalcogenides are in general go od agreement with the experimental data. For CaS, CaSe and CaTe the phase t ransition pressures going from the NaCl to the CsCl phase have been observe d are 39, 37 and 34.5 GPa, respectively, close to the experimental values. The systematic behavior among the calcium chalcogenides under compression a nd the stability of the structure have been also discussed. The B1(NaCl) ph ase is found to be higher in energy than the B3 (CsCl) phase and more stabl e at zero pressure.