Computer Modelling and Exafs Study of the Disorder In Cd_1−xPb_xF₂ Mixed Systems

Abstract

We report molecular dynamics and EXFAFS studies of Cd_0.4Pb_0.6F2 mixed system. A striking feature of molecular dynamics studies in Cd_0.4Pb_0.6F₂ is the mobility of F⁻ ions below. T_c calculations of defect activation energies and plots of single ion trajectories in this compound show that fluorine ions migrate predominantly by a near interstitialcy mode of migration. The results obtained from EXAFS studies on local environments around Cd and Pb cations in this system are consistent with the findings from computer simulations on radial distribution functions. The local environment of Pb²⁺ ions is more disordered than that of Cd²⁺ ions.

Key Words:

• Molecular dynamics
• EXAFS
• Cd_0.4Pb_0.6F₂
• mean square displacement
• radial distribution functions