Synthesis of rock-salt MeO-ZnO solid solutions (Me = Ni2+, Co2+, Fe2+, Mn2+) at high pressure and high temperature

TL;DR

This study synthesizes metastable rock-salt MeO-ZnO solid solutions under high pressure and temperature, analyzing their structural properties and composition ranges, with the NiO-ZnO system showing the broadest stability range.

Contribution

It provides new insights into the high-pressure synthesis and stability ranges of MeO-ZnO solid solutions with rock-salt structure, especially for NiO-ZnO, CoO-ZnO, FeO-ZnO, and MnO-ZnO systems.

Findings

NiO-ZnO solid solutions have the widest composition range (0.3 to 0.8)

CoO-ZnO, FeO-ZnO, MnO-ZnO solutions are stable up to x ≤ 0.5

No rock-salt solid solutions observed in CdO-ZnO system

Abstract

Series of metastable Me1-xZnxO solid solutions (Me = Ni2+, Co2+, Fe2+, Mn2+) with the rocksalt (rs) crystal structure have been synthesized from the binary oxides by quenching from 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 \leq x \leq 0.8) composition range of the existence of individual rock-salt solid solution has been established for the NiO-ZnO system. The bulk rs-Co1-xZnxO, rs-Fe1-xZnxO and rs-Mn1-xZnxO solid solutions may be quenched down to ambient conditions only with twice lower ZnO content, i.e. x \leq 0.5, 0.5 and 0.4, respectively; while formation of rock-salt solid solutions in the CdO-ZnO system has not been observed in the whole concentration range.