Effect of Some Mineralizers and Organic Acids on the Structural and Luminescence Properties of Zn2SiO4 : Mn Phosphor Synthesized at Low Temperature by Impregnation – Coprecipitation Method

Suitable mineralizers promote the formation of the desired phases upon sintering, and organic acids have reducing properties that make the Mn2+ ions more stable during synthesis. The purpose of this work is to study the effect of some mineralizers and organic acids as well as sintering temperature on the structural and luminescence properties of manganese-doped zinc orthosilicate phosphor, synthesized at low temperature by impregnation-coprecipitation method. Photoluminescence spectroscopy, XRD, SEM and EDS were used to investigate the samples. The results show that the most suitable mole ratio of the constituents in the precursor is: 1.97 Zn : 0.03 Mn : 1.0 SiO2 : 0.03 H3BO3 : 0.03 CH3COOH. During 45 minutes, the sample calcined at 700 oC is a bi-phase mixture of β-Zn2SiO4 and α-Zn2SiO4, emitting yellow light at 575 nm wavelength when excited by 254 nm UV radiation. Boric acid is the mineralizer for α-Zn2SiO4. At 800 oC, there is a phase transition from the orthorhombic β-Zn2SiO4 to the rhombo H. axes α-Zn2SiO4. The sample calcined at 900 oC is a single-phase zinc manganese borosilicate solid solution with rhombo H. axes structure of α-Zn2SiO4, consisting of fairly uniform spherical particles with size from 0.3-0.5 µm and emitting 525 nm green light with a luminescence intensity of 46% higher than that of the control sample. The resulting luminescent pigment has the potential for security applications.