Red emission from a novel rare earth free oxide-based CaO–0.5Al₂O₃–0.5Nb₂O₅:Mn⁴⁺ phosphor with high water-resistance property

A 657 nm red emission from a novel rare earth free oxide-based CaO–0.5Al₂O₃–0.5Nb₂O₅:xMn⁴⁺ (0.001 ≤ x ≤ 0.008) phosphors with high water-resistance property were prepared by solid-state reaction method. The composition and structure of the as-prepared phosphors was studied. Under relative ultraviolet (331/365 nm) and blue (465 nm) light excitation, the as-prepared phosphor presents a 657 nm red emission that assigned to the ²E_g → ⁴A_2g transition of Mn⁴⁺ ions. The red light source in CaO–0.5Al₂O₃–0.5Nb₂O₅:Mn⁴⁺ system was discussed, and the water resistance property of the phosphor was also investigated. The as-prepared phosphor presents more proper red emission position than those of similar oxide-based Mn⁴⁺-activated phosphors and shows excellent water-resistance property compared with commercial used K₂SiF₆:Mn⁴⁺ phosphor. With the further optimization of its photo-luminescent properties, the as-prepared CaO–0.5Al₂O₃–0.5Nb₂O₅:Mn⁴⁺ phosphors may find its potential application in the field of white LEDs.