Spectroscopic investigations of neodymium cyclotriphosphates

In the framework of systematic investigations in the properties of rare-earth cyclotriphosphates, polycristalline samples of La1-xNdxP3O9·3H2O have been synthesized with x=5x10-3, 10-2, 5x10-2, 10-1 and 1. Absorbance spectra were measured at 300 K in the 300-1000 nm region. Fluorescent emissions from the 4F3/2 multiplet were observed at 300 and 6 K under pulsed laser excitations in either the 4F7/2 or 4F3/2 multiplet and the decays of these emissions were measured. These decays are exponential with decay-times on the order of 100 ns for all values of x. No important lengthening is observed as either the Nd concentration is decreased from 100 to 0.5 at% or the temperature is lowered from 300 to 6 K. These results are in contradiction with those obtained for the anhydrous La1-xNdx(PO3)3 compounds prepared by progressively heating the corresponding La1-xNdxP3O9·3H2O powder materials, a fact which shows the predominant role played by the water molecules in the Nd3+ luminescence in the considered hydrated compounds