Structure, photoluminescence and thermal properties of Ce3+, Mn2+ co-doped phosphosilicate Sr7La3[(PO4)2.5(SiO4)3(BO4)0.5](BO2) emission-tunable phosphor

Abstract

A single phase emission-tunable Ce³⁺,Mn²⁺ co-doped phosphosilicate Sr₇La₃[(PO₄)_2.5(SiO₄)₃(BO₄)_0.5](BO₂) phosphor was synthesized by a solid-state reaction. Commonly blue and orange broad band emissions from Ce³⁺ and Mn²⁺ are detected under excitation at 351 nm. Combined with the crystallographic data from Rietveld refinements, the blue and orange bands can be fitted by the Gaussian function in accordance with the three different sites. By adjusting the ratio of Ce³⁺/Mn²⁺, warm-white light is generated with a correlated color temperature of 2500–4500 K. The mechanism of energy transfer between Ce³⁺ and Mn²⁺ has also been carefully investigated by the photoluminescence spectra and decay times. The thermal properties from 20 to 250 °C present an abnormal changing trend. With the increase in temperature, the Ce³⁺ or Mn²⁺ single-doped samples show excellent thermal properties, while for the Ce³⁺ and Mn²⁺ co-doped sample, the thermal properties are severely degenerated. Based on a configurational coordinate diagram, an underlying mechanism for thermal quenching is proposed which can reasonably explain the phenomenon. What is more, the mechanism could be helpful for understanding the thermal properties of phosphors co-doped with multiple activators as a reference.