Synthesis and properties of nanocrystalline materials based on LaPO4

A study of the processes in which lanthanum orthophosphate nanocrystalline powders with rhabdophane and monazite structure and crystallite size of about 10 nm are formed demonstrated that, at temperatures of up to 500°C, nanocrystalline lanthanum orthophosphate with rhabdophane structure loses crystal hydrate water and is transformed at 520–540°C to a nanocrystalline phase with monazite structure. This transition is not associated with as change in the crystallite size because nanocrystals of the anhydrous lanthanum orthophosphate phase with monazite structure retain a size of about 10 nm both at the instant of the structural transformation and up to temperatures of 600–700°C. The technological modes were determined in which nanocrystalline lanthanum orthophosphate powders with monazite structure can be obtained and the powders are used for sintering of ceramic materials with porosity on the level of 5–7%.