An investigation on luminescence properties of La2CaO4:Sm3+ red-emitting phosphor

Sm3+-doped La2CaO4 is successfully synthesized via high-temperature solid-state method in air. The crystal structure of samples is confirmed by the X-ray diffractometer patterns. The spectral properties of samples are investigated. The excitation spectrum of La2CaO4:Sm3+ covers the region from 250 to 550 nm due to the O2−–Sm3+ charge transfer band and the f–f transitions of Sm3+ ion. Under excitation at 409 nm, La2CaO4:Sm3+ phosphor shows red emission with chromaticity coordinates (0.5936, 0.4056). The emission spectrum of La2CaO4:Sm3+ contains four spectral bands in the range of 550–750 nm owing to the 4G5/2 → 6H5/2, 6H7/2, 6H9/2, and 6H11/2 transitions of Sm3+ ion. The optimal Sm3+ concentration in La2CaO4:Sm3+ is ~ 8 mol%. The optimal sintering temperature of La2CaO4:Sm3+ phosphor is ~ 1150 °C. The lifetime of La2CaO4:Sm3+ decreases from 744.7 to 613.9 µs with increasing Sm3+ concentration from 2 to 12 mol%. The luminous mechanism is explained by the energy level diagram of Sm3+ ion.