title: Microstructure and environment dependence of 2H11/2 --> 4I15/2 upconversion emission in YVO4:Er3+, Yb3+ nanocrystals.
abstract: Upconversion emission of different nanocrystalline YVO4:Er3+, Yb3+ synthesized by a hydrothermal process at low temperature was studied under 980 nm excitation where green [(2H11/2, 4S3/2) --> 4I15/2] and red (4F9/2 --> 4I15/2) emissions demonstrate sensitivity to the local environments of Er3+. Small particle size, high Yb3+ concentration, or high temperature favors the emission of the 2H11/2 --> 4I15/2 transition. Both XRD patterns and Raman spectra have confirmed that crystal lattice distortion of YVO4:Er3+, Yb3+ nanocrystals is more serious when the nanoparticle size is decreasing or Yb3+ concentration is increasing. This distortion is thought to play a key role in the observed spectral properties, which might lead to a new route to improve the monochromatic upconversion emission efficiency in these nanocrystals.
authors.affiliation: Key Laboratory of Excited State Process, Changchun Institute of Optics Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, PR China.
authors.forename: Yajuan
authors.initials: Y
authors.lastname: Sun
authors.forename: Yue
authors.initials: Y
authors.lastname: Chen
authors.forename: Xianggui
authors.initials: X
authors.lastname: Kong
authors.forename: Kefu
authors.initials: K
authors.lastname: Chao
authors.forename: Yi
authors.initials: Y
authors.lastname: Yu
authors.forename: Qinghui
authors.initials: Q
authors.lastname: Zeng
authors.forename: Youlin
authors.initials: Y
authors.lastname: Zhang
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang