Structural and Energetic Analysis of Mg_<i>x</i>M_1−<i>x</i>(OH)₂ (M = Zn, Cu or Ca) Brucite-Like Compounds by DFT Calculations

Abstract

Brucite-like mixed hydroxides of the general formula MgxM1−x(OH)2 for M = Zn, Cu or Ca were studied by density functional theory within pseudopotential approximation, plane waves basis set, and periodic boundary conditions. Geometrical parameters and energy analysis were done for different compositions (different values of x in the previous formula). It is shown that substitution of magnesium by zinc and copper leads to stable species in several proportions, whereas a mixed hydroxide containing Mg2+ and Ca2+ is predicted not to be formed, at least in the range of molar ratio we have studied here; that is, 1/4−3/4. The species formed by copper substitution are paramagnetic and present Jahn−Teller distortion in the unit cell.