Spark plasma sintering of lead phosphovanadate Pb3(VO4)1.6(PO4)0.4

Lead phosphovanadates can be used as reactants for the synthesis of iodoapatite. Because of its high chemical durability, iodoapatite has considerable potential interest for immobilizing radioactive iodine. Iodine-bearing compounds must be synthesized and consolidated at low temperatures to avoid iodine volatilization. Spark plasma sintering (SPS) thus appears to be a suitable sintering process because of its short processing time. This paper deals with spark plasma sintering of lead phosphovanadate powder prepared mechanically by attrition and planetary ball milling. The influence of sintering parameters such as the heating rate, temperature, and holding time on the degree of densification and the microstructure of bulk materials is discussed. The bulk characteristics were directly correlated with the shrinkage curves. The powder characteristics were determined (grain size and size distribution, specific area, crystallite size, etc.) to explain the singular sintering behavior of the attrited powder; we also investigated whether the latter exhibited the same singular behavior during conventional sintering and hot pressing.