Structure and Luminescent Characteristics of Ba3Tb(PO4)3 Doped with Eu3+ Ions

It was shown that, unlike the series of phosphates with the compositionM3Ln(PO4)3 (M2+ = Ca, Sr, Ba; Ln3+ = Eu and others) with structures of the eulitine type, characterized by cationic disordering, the luminescence spectra of Ba3Tb(PO4)3 doped with Eu3+ ions depend significantly on the excitation wavelength. This arises from localization of the Eu3+ ions in the Ba3Tb(PO4)3 matrix at two nonequivalent crystallographic positions (Tb, Ba). From study of the excitation spectra and the kinetics of luminescence quenching it was concluded that energy is transferred effectively from the Tb3+ to the Eu3+ during excitation in the UV and visible regions of the spectrum.