Enhanced emission of CaNb₂O₆ : Sm³⁺ phosphor by codoping Na⁺/B³⁺ and the emission properties

Abstract

A series of CaNb₂O₆:xSm³⁺ (0 ≤ x ≤ 10 mol%) and CaNb₂O₆ : Sm³⁺, Na⁺/B³⁺ phosphors were synthesized by the solid-state reaction method in air. Their crystal structures and luminescence properties were investigated and analysed, respectively. Host CaNb₂O₆ emitted blue light with excitation 270 nm. CaNb₂O₆:xSm³⁺ phosphors showed a systematically varied hue from blue to white by changing Sm³⁺ ion concentration from 0 to 10 mol% with excitation of 270 nm and their chromaticity coordinates were the regions from (0.1665, 0.1767) to (0.2484, 0.2260). Luminescence properties of CaNb₂O₆ : Sm³⁺ phosphor were tuned and improved significantly by codoping B³⁺ or Na⁺ ions. Energy transfer between Nb$_{\mathbf {2}}\textit {O}_{\mathbf {6}}^{\boldsymbol {2-}}$ group and Sm³⁺ ion was observed and analysed via luminescence properties. The luminous mechanism was explained by energy level scheme and energy transfer process in CaNb₂O₆ : Sm³⁺ phosphor. The strong excitation band peaking at ∼407 nm indicated that the CaNb₂O₆ : Sm³⁺, Na⁺/B³⁺ phosphor has a potential application in white light-emitting diodes based on near-UV LED chip.