Enhanced upconversion luminescence induced by structrual evolution of lanthanum niobate phosphor. Issue 2 (March 2015)

• Record Type: Journal Article
• Authors: Sun, Panpan; Dai, Pengpeng; Yang, Jikai; Zhao, Chengjiu; Zhang, Xintong
• Is Part Of: Ceramics international. Volume 42:Issue 2:Part B(2016)
• Page Start: 3009
• Page End: 3016
• Publication Date: 2015-03
• Subjects: Yb3+-Er3+ system -- Lanthanum niobate -- Structural variation -- UC luminescence -- Solid-state reaction; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2014.10.136
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: A series of Yb 3+ -Er 3+ coactivated La(Nb 1-x V x )O4 (0≤ x ≤1) upconversion (UC) emission phosphors are prepared by high-temperature solid-state reaction method. Experimental results demonstrate that the introduction of V 5+ expands and distorts the unit cell volume of LaNbO4, and induces structural transformation of LaNbO4 from Phase 1 with monoclinic fergusonite structure (0< x ≤0.2) to Phase 2 with tetragonal scheelite structure (0.25≤ x ≤0.5) to Phase 3 with monoclinic monazite structure ( x =1). Under 976 nm excitation, continuously enhanced green UC emission is observed in Phase 1 with gradual replacement of Nb 5+ with the V 5+ (0< x ≤0.2). At x =0.2, the luminescence intensity is enhanced 1.3 times than that of the pristine sample. In Phase 2 and Phase 3, the intensity of green UC emission is decreased gradually with increasing the V 5+ concentration. Based on the XRD results and crystal structural analysis, the enhanced luminescence is attributed to the lowered symmetry around La 3+ ions (Er 3+ ions), which relaxes the parity-forbidden selection rules of Er 3+ luminescent centers. This study provides a useful approach in developing UC luminescence materials with controllable optical properties based on variations in local coordination environments through composition substitutions.