A solid solution series of atacamite type Ni2xMg2−2xCl(OH)3

Abstract

For the first time a complete solid solution series Ni2xMg2−2xCl(OH)3 of an atacamite type alkaline main group metal chloride, Mg2Cl(OH)3, and a transition group metal chloride, Ni2Cl(OH)3, was prepared and characterized by chemical and thermal analysis as well as by Raman and IR spectroscopy, and high resolution laboratory X-ray powder diffraction. All members of the solid solution series crystallize in space group Pnam (62). The main building units of these crystal structures are distorted, edge-linked Ni/MgO4Cl2 and Ni/MgO5Cl octahedra. The distribution of Ni2+- and Mg2+-ions among these two metal-sites within the solid solution series is discussed in detail. The crystallization of the solid solution phases occurs via an intermediate solid solution series, (Ni/Mg)Cl2x(OH)2−2x, with variable Cl: OH ratio up to the 1:3 ratio according to the formula Ni2xMg2−2x Cl(OH)3. For one isolated intermediate solid solution member, Ni0.70Mg0.30Cl0.58(OH)1.42, the formation and crystal structure is presented as well.