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

Single-phase Na 3.6 Y 1.8- x (PO 4 ) 3 : x Dy 3+ 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 Dy 3+ were detected in the region 450–800 nm and optimal concentration of the dopant determined. The concentration quenching of Dy 3+ 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 Na 3.6 Y 1.8 (PO 4 ) 3 was estimated to E g ∼ 7.1 eV. Influence of temperature on luminescence characteristics was studied. • Single-phase Na 3.6 Y 1.8- x (PO 4 ) 3 :xDy 3+ phosphors with NASICON-type structure were synthesized for the first time. • The highest light output was obtained for Dy3+ concentration 0.04 mol%. • The concentration quenching of Dy3+ emission is due to the dipole-dipole interaction. • Two broad bands in the UV and blue regions were tentatively ascribed to the intrinsic emission and defect-related centers. • Optical bandgap energy of Na3.6Y1.8(PO4)3 was estimated to Eg ~ 7.1 eV.