Investigation of luminescent properties of Ca_0.3Sr_0.7Al₂O₄:Tb³⁺,Eu³⁺ excited using different excitation sources

The structure and luminescent properties of Tb³⁺-Eu³⁺ co-activated Ca_0.3Sr_0.7Al₂O₄ powder phosphor prepared via solution combustion (SC) method were investigated. The phosphor was analyzed using UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron (XPS), time of flight secondary ion mass spectroscopy (ToF-SIMS), photoluminescence spectroscopy, synchrotron radiation spectroscopy and cathodoluminescence spectroscopy. In particular, the unintended reduction of Eu³⁺ to Eu²⁺ was illustrated from the ToF-SIMS, XPS and luminescent spectroscopy data. This reduction is known to occur under certain conditions and possible mechanisms for the reduction are discussed. The chemical imaging performed with ToF-SIMS illustrated how individual ions were distributed in the crystal. Tunable luminescence was observed when the phosphor was optically-excited by different excitation sources including a 325 nm He-Cd laser, synchrotron radiation and high energy electrons. This phosphor was evaluated for application in different types of light emitting devices.