Thermal decomposition behavior of praseodymium oxides, hydroxides, and carbonates

Thermal decomposition behavior was studied for Pr(6)O(11), Pr(2)O(3), Pr(OH(3)), and Pr(2)(CO(3))(3) center dot xH(2)O. In the course of transformation, the intermediate species were different for each starting material, as well as the surface area and morphology of the final thermal decomposition products. During thermal decomposition in the temperature range of 200A degrees C up to 1400A degrees C, mass losses for each species were attributed to the removal of hydroxide and carbonate species based on changes in the infrared bands for each powder for hydroxide groups at a parts per thousand integral 3600 cm(-1) and carbonate groups at a parts per thousand integral 1300-1500 cm(-1). X-ray diffraction analysis identified the final decomposition product at 1400A degrees C for each species as Pr(6)O(11) regardless of the starting material. A decrease in surface area and increase in equivalent particle radius for each final Pr(6)O(11) product is attributed to sintering. The presence of hydroxyl and carbonate groups in the Pr(6)O(11), Pr(2)O(3), Pr(OH(3)), and Pr(2) (CO(3))(3) center dot xH(2)O precursor dictate the morphology of thermally decomposed Pr(6)O(11).