Ca/Sr ratio dependent structure and up-conversion luminescence of (Ca1−xSrx)In2O4 : Yb3+/Ho3+ phosphors

Abstract

Up-conversion (UC) phosphors of (Ca_1−xSr_x)In₂O₄ : Yb³⁺/Ho³⁺ (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, 1.0) were prepared. Based on the crystal structure evolution of these series solid solution samples, which were characterized by Rietveld refinement, the variation of UC luminescent properties was discussed in detail. Sr and Ca occupied one position and Yb/Ho dissolved in the In ion site in the (Ca_1−xSr_x)In₂O₄ lattice. With increasing Sr substituting Ca atoms, the cell parameters and cell volumes of these samples increased linearly, and distortions of (Ca/Sr)O₈ polyhedron were formed. The distortions on crystal structures showed a negative relation with UC luminescent intensities in these series phosphors.