Study on the formation of solid solution when synthesizing manganese-doped zinc alkaline earth silicate luminescent pigment by impregnation - precipitation method

Abstract

This work refers to the research results on the ability to form solid solution when synthesizing the manganese-doped zinc alkaline earth silicate luminescent pigment in the form of Zn_1,97-xM_xMn_0,03SiO₄ (M is magnesium, calcium, strontium and barium) by the precipitation-impregnation method. The samples were characterized by thermal analysis, X-ray diffraction spectroscopy, luminescence under UV lamp and luminescence spectroscopy at 254 nm excitation wavelength. The results show that when heating the corresponding precipitated precursor at 900 ^oC for 45 minutes, in general, the ability to form solid solutions decreases when the size difference of alkaline earth metal ions with Zn²⁺ ions increases. Specifically, Mg²⁺ ions create single-phase solid solutions with x varying from 0 to 1. Ca²⁺ ions form solid solutions when x changes from 0 to 0.6. When x = 0.8; in addition to the main phase Zn₂SiO₄, it also creates Ca₂ZnSi₂O₇ with tetragonal structure. The Ba²⁺ ions form solid solutions when x varies from 0 to 0.5. When x = 0.6, in addition to Zn₂SiO₄, there is also BaZn₂Si₂O₇. The Sr²⁺ ions form a solid solution when x = 0.2. For samples with x ≥ 0.4, in addition to Zn₂SiO₄, there is also Sr₂ZnSi₂O₇; SrZn₂Si₂O₇/SrO.2ZnO.2SiO₂. The single - phase solid solutions all have the rhombo H structure of Zn₂SiO₄, and all have higher luminescence than the multiphase samples. The sample with the largest x, the sample Zn_0,97Mg_1,0Mn_0,03SiO₄ had the highest luminescence, emitting green light corresponding to the wavelength of 525 nm when excited by 254 nm UV light.