Novel NASICON-type Na3.6Y1.8-(PO4)3:xDy3+ phosphor: Structure and luminescence

Single-phase Na3.6Y1.8-x(PO4)3:xDy3+ phosphors were synthesized by high-temperature solid-state reaction. Powder X-ray diffraction study reveals that a homogeneous solid solution with a NASICON-type structure is formed at 0 ≤ x ≤ 0.4. Luminescence properties of the phosphors were studied using the methods of UV and VUV spectroscopy. Narrow emission bands originating from intraconfigurational transitions in Dy3+ were detected in the region 450–800 nm and optimal concentration of the dopant determined. The concentration quenching of Dy3+ emission is shown to be due to dipole-interaction. In addition, two broad bands were detected in the UV and blue spectral regions, which were tentatively ascribed to the intrinsic emission of self-trapped excitons and defect-related centers, respectively. Optical bandgap energy of Na3.6Y1.8(PO4)3 was estimated to Eg ∼ 7.1 eV. Influence of temperature on luminescence characteristics was studied.