CuKα-radiation (λ=0.154 nm) induced emission-color change in Eu-doped KNaSO4

This paper demonstrates CuK alpha-radiation-induced emission-color change of KNaSO4: Eu3+ in prospect of application in simplified radiation dosimetry. KNaSO4: xEu(3+) (x = 0.002-0.008) was prepared by high-temperature solid-state reaction. The Eu-doped sulfate showed Eu3+ and Eu2+-derived mixed-color emission under ultraviolet (UV) excitation light. Although the Eu2+ emission from the as-made sample was very weak, it became dominant after exposure to CuK alpha radiation because of the reduction of Eu+ . Electron spin resonance spectroscopy revealed that the reduction process was caused by photoelectrons released from SO42-ions. Since both Eu3+ and Eu2+ ions were stable within KNaSO4, emission color regulated by CuK alpha exposure did not vary under UV/visible excitation light. However, the CuK alpha-induced Eu2+ emission showed significant thermal attenuation at 50 degrees C and 150 degrees C. Observed two-step attenuation reflected Eu2+ ions occupying two crystallographically different site.