Synthesis and near-infrared luminescence of La3GaGe5O16:Cr3+ phosphors

Abstract

A novel Cr³⁺-doped La₃GaGe₅O₁₆ phosphor was synthesized by a solid-state reaction, and the phase formation and microstructure, near-infrared (NIR) photoluminescence (PL) properties and PL thermal stability were investigated in detail. The excitation spectrum of La₃GaGe₅O₁₆:Cr³⁺ at 270, 415 and 573 nm corresponded to three spin-allowed Cr³⁺ d–d intra-transitions of ⁴A₂–⁴T₁ (⁴P), ⁴A₂–⁴T₁ (⁴F), and ⁴A₂–⁴T₂ (⁴F), respectively, among which the main red emission peak observed at 700 nm is identified, which is due to the ²E–⁴A₂ transition from Cr³⁺ ions. It is further proved that the dipole–dipole interactions result in the concentration quenching of Cr³⁺ in La₃GaGe₅O₁₆:Cr³⁺ phosphors, and the energy-transfer distance at the quenching concentration was around 26.90 Å. Moreover, thermal quenching luminescence results reveal that La₃GaGe₅O₁₆:Cr³⁺ exhibits good thermal stability. The above results indicate that La₃GaGe₅O₁₆:Cr³⁺ has potential practical applications in luminescence solar concentrators with broad-band absorption.