Synthesis of Magnesium–Aluminum Spinel at High Pressures and High Temperatures in the Mg₂B₂O₅–Al, MgO–Al₂O₃, and MgO–Al₂O₃–Al Systems

The possibility of MgAl₂O₄ synthesis at high pressures and high temperatures (by the HPHT method) has been studied for за Mg₂B₂O₅–Al, MgO–Al₂O₃, and MgO–Al₂O₃–Al systems. It has been established that, for the Mg₂B₂O₅–Al system, the highest quantity of MgAl₂O₄ is observed at a pressure of 2GPa and a temperature of 1600°C. A further increase in temperature and pressure leads to a growth in the content of boron-containing phases. For the MgO–Al₂O₃ and MgO–Al₂O₃–Al systems, as well as for the Mg₂B₂O₅–Al system, the MgAl₂O₄ phase content is observed to decrease with an increase in the compaction pressure. It’s indicate that an increase in pressure suppresses the interaction between the initial components for all the systems. The addition of aluminum as a liquid-phase component makes it possible to extend the pressure range, within which the MgAl₂O₄ phase is observed to form, to evidence that this approach to MgAl₂O₄ synthesis is promising for further application.