Effect of Ti compositions for efficiency enhancement of CaTiO3:Er3+, Ni2+ broadband-sensitive upconverters. Issue 66 (24th August 2017)

• Record Type: Journal Article
• Authors: Luitel, Hom Nath; Mizuno, Shintaro; Nonaka, Takamasa; Tani, Toshihiko; Takeda, Yasuhiko
• Is Part Of: RSC advances. Volume 7:Issue 66(2017)
• Page Start: 41311
• Page End: 41320
• Publication Date: 2017-08-24
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c7ra07415h
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : More than 7-fold increase of UC emission was realized in the CaTiO3 :Ni 2+, Er 3+ broadband-sensitive upconverter compared to that in the previously reported CaZrO3 :Ni 2+, Er 3+ . Abstract : Improving the efficiency of upconversion (UC) materials is a hot topic in recent days due to the important applications of UC materials in photovoltaics, photonics devices, photocatalysts, sensors, biological imaging, and therapeutics. Recently, we have reported a broadband-sensitive UC emission in Ni 2+, Er 3+ -codoped perovskites. However, the applications of these perovskites are limited due to their low conversion efficiency. Herein, we realized highly improved UC efficiency in the CaTiO3 :Er 3+, Ni 2+ upconverter as compared to those of the previously reported CaZrO3 and La(Ga, Sc)O3 upconverters. Ti composition plays important roles in stabilizing divalent nickel (Ni 2+ ) in an octahedral coordination, which is the key point for sensitization to Er 3+ emitters. Furthermore, oxygen vacancies and consequently tetrahedral Ni 2+ ions, which kill the luminescence, are suppressed, and as a result, the UC emission intensity is dramatically increased. The 0.1 mole Ti-deficient sample with the (Ca0.8 Er0.10 Li0.10 )(Ti0.894 Ni0.002 Nb0.004 )O2.8 composition exhibited the most intense broadband-sensitive UC emission, which was 264-fold stronger than that of the stoichiometric sample and more than 12 folds as compared to that of the previously reported CaZrO3 :Er, Ni and La(Ga, Sc)O3 upconverters. The highest UC quantum yield of ∼2.53% was realized in the optimized CaTiO3 :Er 3+, Ni 2+ upconverter under 1490 nm laser excitation of ∼1000 W m −2 .