Investigation of the up-conversion properties of Er–Yb-doped calcium tantalates with various Ca/Ta ratios

Abstract

Er3+/Yb3+ co-doped calcium tantalate up-conversion (UC) phosphors were synthesized via a parallel synthesis scheme using the gelable citrate complex method. Samples with various Ca/Ta atomic ratios were prepared, and their UC emission properties were compared. Under 980-nm near-infrared laser excitation, α-Ca2Ta2O7: Er3+, Yb3+ showed an extremely weak UC emission intensity and CaTa4O11: Er3+, Yb3+ demonstrated an excellent UC emission intensity. In addition, the local symmetry around the rare-earth dopant ions affected the UC luminescence properties.