title: Enhanced upconversion emission in ZrO₂-Al₂O₃ composite oxide.
abstract: Aqueous solutions of zirconium oxychloride and aluminum nitrate were coprecipitated and crystallized to form a ZrO2-Al2O3 solid solution. The upconversion (UC) emission from different Er(3+)-doped samples was studied. An enhancement of the green UC emission by as much as 22 times was achieved by co-doping with Yb(3+) and Mo(6+) ions due to an energy transfer at a higher excited-state energy, which partly avoided the non-radiative decay processes at the lower energy levels of Er(3+). The UC emission of the ZrO2-Al2O3 composite system series doped with different agents was enhanced. Excess oxygen vacancies are generated by forming ZrO2-Al2O3 solid solutions, which have an energy level close to the (4)F7/2 level of the Er(3+) ions. The defect state promoted the energy transfer process resulting in an eight-fold increased green UC emission in ZrO2-Al2O3 solid solutions. The solid solutions have a superior color chromaticity of x = 0.25 and y = 0.71 due to the evident enhancement in the green to red emission ratio in the 8ZrO2-2Al2O3 sample.
authors.affiliation: School of Physics & Materials Engineering, Dalian Nationalities University, Dalian 116600, China. congyan@dlnu.edu.cn dong@dlnu.edu.cn.
authors.forename: Yan
authors.initials: Y
authors.lastname: Cong
authors.affiliation: School of Physics & Materials Engineering, Dalian Nationalities University, Dalian 116600, China. congyan@dlnu.edu.cn dong@dlnu.edu.cn.
authors.forename: Bin
authors.initials: B
authors.lastname: Dong
authors.affiliation: School of Physics & Materials Engineering, Dalian Nationalities University, Dalian 116600, China. congyan@dlnu.edu.cn dong@dlnu.edu.cn.
authors.forename: Naisen
authors.initials: N
authors.lastname: Yu
authors.affiliation: School of Physics & Materials Engineering, Dalian Nationalities University, Dalian 116600, China. congyan@dlnu.edu.cn dong@dlnu.edu.cn.
authors.forename: Yangyang
authors.initials: Y
authors.lastname: He
authors.affiliation: School of Physics & Materials Engineering, Dalian Nationalities University, Dalian 116600, China. congyan@dlnu.edu.cn dong@dlnu.edu.cn.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: School of Physics & Materials Engineering, Dalian Nationalities University, Dalian 116600, China. congyan@dlnu.edu.cn dong@dlnu.edu.cn.
authors.forename: Yang
authors.initials: Y
authors.lastname: Yang