Studies of disorder in Cd_1-xPb_xF₂ mixed crystals

Abstract

The local environments of Cd and Pb cations in Cd_1-x Pb _x F₂ as a function of x have been measured by means of extended X-ray absorption fine structure (EXAFS). The compositional dependence of disorder has been studied and reveals that the second shell structures for the Cd- and Pb-edges decrease with concentration for x < 0.6 and are completely washed out at <x = 0.6. An increase in the second shell structure is observed as x increases from 0.6. However, the high values of the Debye—Waller factors on the Pb edges suggest a high degree of disorder around the Pb cations in the whole of Cd_1-x Pb _x F₂ mixed crystals.

Key Words:

• EXAFS
• PbF₂
• CdF₂
• Cd_0.4Pb_0.6F₂
• Cd_1-x Pb _x F₂