Abstract

Laser induced fluorescence spectra of Eu_0.2Tb_0.8P₅O₁₄₊ crystals is studied at various temperatures in the 40-550°K range: a) Linewidth (steady state) experiments Fluorescence linewidth experiments show that the linewidths of the ⁵D₀ → ⁷F₁ triplet of Eu³⁺ change linearly with temperature in the 300-500°K range and do not demonstrate critical behaviour near the ferroelastic phase transition which is expected to occur at about 440 K in this crystal. Such a phase transition is accompanied by a strong reduction of the sound velocity, v, of some of the low $\overrightarrow{\text{p}}$ acoustic modes⁽¹⁾, and an enormous increase of the linewidths Δν is expected, at first sight, near T_c on account of Δν^αv⁻⁵ dependence⁽²⁾.

© 1984 Optical Society of America