paratellurite

Paratellurite is the name given to the less common and high-temperature crystalline form of tellurium dioxide. It is one of two polymorphs of TeO2, the other being the more stable low-temperature form, tellurite. Paratellurite has a tetragonal crystal structure and is stable above 425 degrees Celsius. Its optical properties differ significantly from tellurite, exhibiting a much higher refractive index and birefringence, making it of interest for optical applications. However, its relatively high transition temperature and tendency to revert to tellurite upon cooling limit its widespread use in standard conditions. Research has explored methods to stabilize paratellurite at lower temperatures, often through doping or the creation of glasses, to harness its unique optical characteristics. These efforts are driven by its potential in areas such as acousto-optic devices and nonlinear optics. The synthesis of paratellurite typically involves high-temperature processes, such as controlled cooling of molten tellurium dioxide or solid-state reactions at elevated temperatures.