Tungsten trioxide powder is a new type of infrared ultraviolet shielding material, whose phase change is very complex. Therefore, the related research on the phase change of tungsten trioxide will help to understand the characteristics of the raw material of this type of thermal insulation material.
Phase Change of Tungsten Trioxide
Tungsten trioxide has at least five structural phase transitions in the temperature range from -40°C to 740°C, and the corresponding crystal structures are monoclinic phase, triclinic phase at low temperature, monoclinic phase at room temperature, orthorhombic phase and tetragonal phase with the increase of temperature. The temperature of phase change is related to the thermal history of the material. And there is a significant thermal hysteresis effect. The distorted twisting and tilting of tungsten oxide octahedron and displacement of tungsten atoms from the octahedral center to the octahedral edge are the source of all phase changes. At the same time, the phase change not only depends on temperature, but depends on other factors such as grain size.
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