Characterisations of new Nd3+-doped scheelite-type molybdates for laser materials

Abstract

The necessity to develop new laser materials was our motivation to study a new family of molybdates activated by the Nd3+ions, which crystallizes in the scheelite-type structure (the tetragonal symmetry, the space group I41/a). A series of Cd1-3xNd2x-xMoO4solid solutions with concentration of Nd3+ions from 0.1 to 66 mol% with respect Cd2+ions have been successfully synthesized by a high-temperature annealing, using CdMoO4and Nd2(MoO4)3as the starting materials. Structural and spectroscopic characterizations of Nd3+in substitution of Cd2+were carried out. The Nd3+ions in this matrix most probably occupy two non-equivalent symmetry sites (see Fig. 45.1). The substitution of Cd2+by trivalent Nd3+ cations leads to the formation of cationic vacancies in a framework (which are denoted in the chemical formula as _) and its concentration depends essentially on the composition of initial CdMoO4/Nd2(MoO4)3mixtures. The analysis of the morphology using SEM reveals high homogeneity of the sphericalshape products with the average grain size of about 10μm. The optical analysis and the laser performance parameters suggest Cd1-3xNd2x_xMoO4as a potential laser powder material: both the values of the absorption cross-section and the very strong emission of the4F3/2→44I11/2laser channel of Nd3+recorded under Xe lamp excitation or OPO laser pumping, as well as, the radiative lifetimes of IR luminescence are appropriate for potential applications of this phosphor as a solidstate laser. Our earlier studies have shown that the presence of the cationic vacancies in the framework may significantly improve the laser parameters (Guzik et al., J Mater Chem 22:14896, 2012).