Raman Phonons in RPO(4) Crystals

摘要

Orthophosphates formed by elements in the first half of the lanthanide transition series (La, Pr, Nd, Sm, Eu and Gd) are structural analogs to the monoclinic mineral monazite. This mineral is characterized by an almost unique combination of properties that make its synthetic forms attractive as possible hosts for the long-term storage of actinide wastes. Crystals of lanthanide orthophosphates were grown by dissolving and by reacting lanthanide oxides in molten lead pyrophosphate at high temperatures. The LnPO4 crystals which formed on cooling were separated by dissolving the lead phosphate matrix in boiling concentrated nitric acid. Lanthanide oxides highly pure were used in all measurements.