Photoluminescence and temperature-dependent luminescence of Ca5(PO4)3OH doped Eu3+ phosphors

In most hosts, the electric dipole transition (EDT) of Eu3+ is usually more intense than the magnetic dipole transition (MDT); however, this is not the case with Ca5(PO4)3OH. Herein, Ca5(PO4)3OH was doped with different Eu3+ concentrations to obtain the maximum emission intensity. The X-ray powder diffraction confirmed that the material crystallised in a single hexagonal Ca5(PO4)3OH phase. The photoluminescence showed two prominent peaks at 573 and 628 nm ascribed to the 5D0-7F1 (MDT) and 5D0-7F2 (EDT) of Eu3+, respectively. The luminescence intensities of the MDT and EDT were comparable when excited with a 305 nm xenon lamp, but when excited with a 325 nm Cd–He laser, the luminescence intensity of the MDT surpassed that of the EDT. The International Commission on Illumination chromaticity coordinates diagram showed that the material emitted a red-orange colour, suggesting it's potential application in red-orange colour displays. The temperature-dependent luminescence was measured, and the relative temperature sensitivities were determined in four different wavelength ranges, suggesting this material's potential application in luminescence thermometry.