Study on the properties of Sm3+-Doped CaTbAl3O7 phosphors

Abstract

New single phase and adjustable emission phosphors have attracted a lot of attention because of the good luminous properties. In this work, Sm³⁺ doped CaTbAl₃O₇ phosphors are prepared in air by solid-state method. The crystal structure, concentration dependent spectra, lifetimes, and luminescence properties are investigated. Because of the 4f⁸ → 4f⁷5d¹ and 4f → 4f transitions of Tb³⁺ ion, host (CaTbAl₃O₇) shows an excitation spectrum in the range of 220–520 nm under monitored at 544 nm and emits yellow-green light under excitation 248, 284, and 368 nm due to the ⁵D₄ → ⁷F_J (J = 0, 1, 2, 3, 4, 5, and 6) transitions of Tb³⁺ ion. CaTbAl₃O₇:Sm³⁺ under monitored 598 nm contains the excitation spectral peaks of both CaTbAl₃O₇ and Sm³⁺ ion. With excitation at 368 nm, CaTbAl₃O₇:Sm³⁺ glows orange-red light, its PL spectrum has both host (CaTbAl₃O₇) and Sm³⁺ ion contributing, and the chromaticity coordinates are about (0.5499, 0.4351). Under excitation 402 nm, the red-orange emission of CaTbAl₃O₇:Sm³⁺ is only the contribution of Sm³⁺ ion and the chromaticity coordinates are about (0.5823, 0.4168). The energy transfer process from Tb³⁺ in host (CaTbAl₃O₇) to Sm³⁺ ions can be confirmed via the spectral properties. We explain the luminous mechanism of CaTbAl₃O₇:Sm³⁺ by the energy level diagrams of Tb³⁺ and Sm³⁺.