Evolution of the spectral and structural characteristics of borates formed during the interaction of lanthanum and scandium oxides with a potassium tetraborate melt

Abstract

The structure, morphology, IR spectra, as well as luminescence spectra and luminescence excitation spectra of europium-doped borates formed during the interaction of lanthanum and scandium oxides with a potassium tetraborate melt at 970oC with the general formula La0.99-xScxEu0.01BO3 were studied. It is shown that with an increase in the Sc3+ concentration, three compounds are successively formed: LaBO3, LaSc3(BO3)4, and ScBO3. At 0≤ x≤ 0.26, the samples are single-phase and have the structure of LaBO3 aragonite. Within the range of 0.26<x<0.75, the samples are two-phase and contain the structures of LaBO3 aragonite and LaSc3(BO3)4 huntite. At 0.75≤ x≤0.85, LaSc3(BO3)4 is observed. Within the range of 0.85<x≤0.97, the samples are two-phase and consist of LaSc3(BO3)4 huntite and ScBO3 calcite. At 0.97<x≤0.99, the ScBO3 samples have a calcite structure. Correspondence between the structure and spectral characteristics of these compounds was established. Keywords: phosphors for LEDs, rare earth orthoborates, X-ray diffraction analysis, IR spectroscopy, luminescence spectra.