Phase transition of NaGaO2 at high pressure and high temperature

This work presents a comprehensive study on phase transition in NaGaO2 under high pressure and temperature (P–T) conditions. X-ray diffraction (XRD) was used to identify the phase composition of the recovered samples. Our results revealed that NaGaO2 could undergo a structural phase transition from orthorhombic β - NaGaO2 to hexagonal α - NaGaO2 under high pressure and temperature. The pressure–temperature phase boundaries of NaGaO2 were determined up to 5 GPa and 2073 K. The hexagonal α - NaGaO2 sample recovered from higher pressure and temperature exhibited a highly (003) preferred orientation. Besides, a reversible transition from α - to β - NaGaO2 was observed above 473 K under normal-pressure condition. The high-pressure melting curve of NaGaO2, for the first time, was measured by using in-situ thermal measurement.