Soft chemical routes to the synthesis of extended solid solutions of wurtzite ZnO–MO (M=Mg,Co,Ni)

Spray pyrolysis and gel decomposition have been used to generate extended solid solutions of MO (M=Mg,Co and Ni) in the wurtzite modification of ZnO through kinetic limitations. Both routes yield a significantly greater extent of solution of CoO as compared to MgO and NiO. Published lattice stabilities for the wurtzite modifications of MO and the rock-salt form of ZnO are used to develop free energy–composition curves to relate the ease of solution to the driving force for partitioning. Reasons for the absence of single-phase rock-salt-based solid solutions are discussed.