Red shifts of the yellow emission of YAG:Ce3+ due to tetragonal fields induced by cationic substitutions

Abstract

Wave function theory ab initio embedded cluster calculations show that Ce³⁺-doped transformed aluminum garnets resulting from Y₃Al₅O₁₂:Ce³⁺ after cationic substitutions that enhance the tetragonal field around Ce³⁺, have their lowest 4f–5d transition red-shifted with respect to the yellow phosphor YAG:Ce³⁺ used in GaN blue-LED based lighting devices. Red shifts in the range of 1000–3000 cm⁻¹ are found in 33 transformed garnets of the types M^IV₂M^IIIM^II₂Al₃O₁₂:Ce³⁺, M^IV₂M^IAl₅O₁₂:Ce³⁺, and M^IVM^IIIM^IIAl₅O₁₂:Ce³⁺. This result shapes the design of new red phosphors by enhancing the tetragonal field around Ce³⁺ via cationic substitutions made in Ce³⁺-doped aluminum garnets.