Effect of Pressure on Thermal Stability and Decomposition of KDP Crystal

Effect of pressure on thermal behavior of KDP crystals is investigated by using the in-situ infrared reflective spectra. Compared with that under normal atmosphere, the onset temperature of decomposition under pressure of 1 MPa is improved to from 210 °C to 213 °C, suggesting that the thermal stability of KDP is enhanced. Under pressure of 2 MPa, the thermal stability is deteriorated and KDP begins to decompose at 183 °C. Under normal atmosphere KDP decomposes in route of translating to K₄P₂O₇ firstly, and then to KPO₃. Under pressures of 1 MPa and 2 MPa, KDP translates to KPO₃ directly without any other polymeric intermediates.