Structural and photoluminescent properties of Gd3+ doped barium aluminate phosphor

Abstract

Gd3+-doped barium aluminate was synthesized using a conventional solid-state technique and annealed at 1200 °C. The X-ray powder diffraction results confirmed the formation of a hexagonal structure with the space group of P6322 for the studied phosphors. The average crystallite size of 75 nm was calculated using Scherrer's equation based on the X-ray line broadening of all the major diffraction peaks. The shape, distribution, and level of agglomeration of the synthesized samples were confirmed using a field emission scanning electron microscope and energy-dispersive X-ray spectroscopy. The distribution of various ions in the host and doped sample was confirmed using time-of-flight secondary ion mass spectroscopy equipped with a Bi+ ion gun. UV–Visible spectroscopy was employed to record the reflectance of the studied samples, and bandgaps were calculated using the Kubelka-Munk function. The bandgaps were found to be in the range of 3.96–4.75 eV, confirming the formation of a room-temperature wide bandgap semiconductor. Photoluminescence spectroscopy was used to record the excitation and emission spectra of all the samples, which displayed an intense peak at 314 nm attributed to the 6P7/2 → 8S7/2 transition. Moreover, all samples displayed an additional peak in the emission spectrum at a wavelength of 627 nm, which was subsequently confirmed to be generated by second-order diffraction. The decay time for all the Gd3+ doped samples was calculated for λex of 274 nm and λem of 314 nm and was observed to be a few microseconds. The strong emission peak in the wavelength range of Ultraviolet-B has the potential to be utilized for phototherapy to treat skin problems that respond to photons in the range of 312–315 nm.