Structural studies of Cs₂(Cd_0.29Hg_0.71)I₄ and Cs₂(Cd_0.34Hg_0.66)I₄

Abstract

The crystals of two Cs₂(Cd_xHg_1-x)I₄ compounds have been grown from aqueous solution in the molar ratios CsI:CdI₂:HgI₂=4:1:1. They are isomorphous at room temperature and the compositions, according to the structure refinements, are Cs₂(Cd_0.29Hg_0.71)I₄ and Cs₂(Cd_0.34Hg_0.66)I₄ which is confirmed by SEM-EDX analyses. The triple iodides, both crystallizing in monoclinic <i>P2</i>₁<i>./m </i> with average unit cell dimension <i>a </i>= 7.76, <i>b </i>= 8.39, c = 11.03 Å and β = 110.3°, are isostructural with the room temperature phases of CS₂CdI₄, <i>a </i>= 7.827(1), <i>b </i>= 8.397(1), <i>c</i> = 11.050(1) Å,b = 110.76°,and Cs₂HgI_4, <i>a </i>= 7.734(1), <i>b </i>= 8.386(1), c = 11.019(1)Å, β = 110.06°.The (Cd,Hg) atoms are randomly distributed in the crystals and Vegard's law is obeyed.