title: Ligand field modification around Cu2+ ions in sodium borate glass by codoping.
abstract: Understanding the effect of codoping on the properties of photonic glasses is important for improving their properties. The effect of codoping on the ligand field around Cu(2+) ions in a sodium borate glass is examined using optical absorption spectroscopy, continuous-wave electron paramagnetic resonance, and three-pulse electron-spin-echo envelope-modulation. Glass with a composition of 0.1CuO·5Na(2)O·95B(2)O(3) was codoped with 2 mol % of Al(3+), Si(4+), P(5+), Zr(4+), or La(3+) oxide. Three codoping effects are found: strengthening the ligand field, as observed for Zr-codoping, which induces a large blue shift of the optical absorption peak of Cu(2+); weakening the ligand field, as observed for P-codoping, which causes a red shift of the Cu(2+) absorption peak; and almost no effect on the ligand field, which is observed for Al-, Si-, and La-codoping. Coordination structure models based on local charge neutrality are proposed for the codoped glasses. The mechanism of the codoping effect is revealed by elucidating the local structure around Cu(2+).
authors.affiliation: Frontier Research Center, Tokyo Institute of Technology, Nagatuta-cho, Midori-ku, Yokohama, Japan. funabiki@lucid.msl.titech.ac.jp
authors.forename: Fuji
authors.initials: F
authors.lastname: Funabiki
authors.forename: Satoru
authors.initials: S
authors.lastname: Matsuishi
authors.forename: Hideo
authors.initials: H
authors.lastname: Hosono