Synthesis and luminescent properties of trivalent rare-earth (Eu3+, Tb3+) ions doped nanocrystalline AgLa(PO3)4 polyphosphates

The AgLa(PO3)4 phosphors activated with trivalent rare-earth (Eu3+, Tb3+) ions were prepared by a sol-gel synthesis method. The crystal structure of the compound was studied by X-ray diffraction patterns and found to be crystallized in the monoclinic system with a space group P21/c, indicating the calculated lattice parameters of a = 10.08 Å, b =  13.12 Å, and c = 7.314 Å. The Fourier-transform infrared spectrum, photoluminescence excitation/emission spectra, and decay curves were examined to study the optical properties. The analysis of the Eu3+ ions related emission spectrum revealed the presence of highly symmetric sites for the activator ions. The Tb3+ ions related emission spectrum exhibited a 5D3 emission due to the prolonged calcination at high temperatures, which reduces the residual hydroxyl ions. The optical properties show that this host material is suitable for phosphor materials and laser crystals.