A novel two-step field-assisted sintering method to prepare (MgCoNiCuZn)O high entropy oxide

Abstract

A two-step sintering experiment of (MgCoNiCuZn)O high entropy oxide was performed to lower the flash onset temperature and shorten the process time. The flash onset temperature was efficiently minimized by regulating the first step heating process due to the variation of the conductivity and density of the compacts. The lowest onset temperature was only 307 °C at a 300 °C first step sintering. Subsequently, the as-sintered material with mainly rock-salt structure can be obtained in just 20 s soaking time after the field-assisted flash sintering procedure. The unusual densification was mainly caused by the higher configuration entropy and significant temperature gradients resulted from the preferential Joule heating of grain boundaries. This novel two-step sintering method would promote the rapid synthesize of high entropy oxides.

Keywords

• Joule heating
• Conductivity
• Oxygen vacancies
• Partial reduction
• Flash sintering