The Effect of the Conditions of Extractive–Pyrolytic Synthesis on the Luminescence Characteristics of Inorganic Luminophores Based on Mixed Oxides of Rare-Earth and Rare Elements

Abstract

The general conditions of the synthesis of luminophores based on mixed oxides of rare-earth and rare elements by a low-temperature extractive–pyrolytic method are discussed. The dependence of the relative integral intensity of luminescence on the pyrolysis temperature of the precursors is studied on the example of samples of luminophores based on oxides of europium Eu₂O₃ and terbium Tb₄O₇; europium, terbium, yttrium, and praseodymium oxysulfides; europium phosphates Eu₃PO₇ and Eu(PO₃)₃ and phosphate Eu(PO₃)₃:Eu²⁺ doped with a Eu²⁺ ion; terbium phosphates TbPO₄ and Tb(PO₃)₃; mixed phosphates La_0.8Ce_0.15Tb_0.05PO₄ and La_0.8Ce_0.15Tb_0.05(PO₃)₃; europium polyniobates EuNb₃O₉ and EuNb₅O₁₄; europium polytantalates EuTa₃O₉, EuTa₅O₁₄, and EuTa₇O₁₉; terbium polytantalates TbTa₃O₉, TbTa₅O₁₄, and TbTa₇O₁₉; and europium ortho- and metaborates La_0.95Eu_0.05BO₃ and La_0.95Eu_0.05(BO₂)₃ including La_0.03Eu_0.05Bi_0.05BO₃ and La_0.90Eu_0.05Bi_0.05(BO₂)₃ doped with bismuth ions. It is found that, according to the data of X-ray diffraction, individual compounds are formed at temperatures as low as 600°C. Increasing the pyrolysis temperature of the precursors to the optimum temperature leads to a gradual growth in the relative integral intensity of the bands in the luminescence spectra. The luminescence spectra of the samples of luminophores based on compounds of europium or terbium consist of a series of bands corresponding to the ⁵D₀–⁷F_j  transitions between the multiplets (j = 0, 1, 2, 3, 4) characteristic of the Eu₃₊ ion (in the region of 550–750 nm) or ⁵D₄–⁷F_j transitions (j = 1–6) characteristic of the Tb³⁺ ion (in the region of 500–650 nm), respectively.