Investigation of anomalously weak quenching of Nd3+ ion luminescence in La1–xNdxP5O14

An investigation was made of the temperature and concentration dependences of the lifetime and probability of nonradiative relaxation of the excited metastable state ⁴F_3/2 of Nd³⁺ in a La_1–xNd_xP₅O₁₄ crystal. This crystal exhibited an anomalously weak concentration quenching of the Nd³⁺ luminescence, which made it possible to use high activator concentrations and made NdP₅O₁₄, a promising crystal for the fabrication of miniature lasers of the type required in integrated optics and optical communication systems. The experimental results obtained are in good agreement with recent non-Soviet work on spectroscopic and luminescence properties of this crystal. An interpretation is given of two experimental observations not accounted for earlier: the concentration quenching of the luminescence is independent of temperature and the constant of nonradiative decay of the excited metastable state of Nd³⁺ is a linear function of the concentration. It is concluded that the concentration quenching of the luminescence begins under energy supermigration conditions and the supermigration mechanism should occur also in other systems with high Nd³⁺ concentrations. Conditions are formulated for a weak concentration quenching of the luminescence from the ⁴F_3/2 metastable state of Nd³⁺.