Synthesis of rock-salt MeO–ZnO solid solutions (Me=Ni ²⁺, Co²⁺, Fe²⁺, Mn²⁺) at high pressure and high temperature

Abstract

A series of metastable Me_1−x Zn _x O solid solutions (Me = Ni²⁺, Co²⁺, Fe²⁺, Mn²⁺) with the rock-salt (rs) crystal structure have been synthesized from binary oxides by quenching at 7.7 GPa and 1450–1650 K. Phase composition of the samples, as well as structural properties and stoichiometry of synthesized solid solutions, have been studied by X-ray powder diffraction, both conventional and with synchrotron radiation. The widest (0.3 ≤x≤0.8) composition range of the existence of individual rs solid solution has been established for the NiO–ZnO system. The bulk rs-Co_1−x Zn _x O, rs-Fe_1−x Zn _x O and rs-Mn_1−x Zn _x O solid solutions may be quenched down to ambient conditions with only twice as low ZnO content, i.e. x≤0.5, 0.5 and 0.4, respectively; while formation of rs solid solutions in the CdO–ZnO system has not been observed in the entire concentration range.

Keywords:

• zinc oxide
• high pressure
• solid solution

Acknowledgements

X-ray diffraction measurements with synchrotron radiation were carried out during beamtime allocated to Project I-20070033 EC at HASYLAB-DESY. This work has been partially supported by the Russian Foundation for Basic Research (project no. 06-03-33042). PS Sokolov is grateful to the French Ministry of Foreign Affairs for the funding provided (BGF fellowship no. 2007 1572).