title: Mixed-Metal Carbonate Fluorides as Deep-Ultraviolet Nonlinear Optical Materials.
abstract: Noncentrosymmetric mixed-metal carbonate fluorides are promising materials for deep-ultraviolet (DUV) nonlinear optical (NLO) applications. We report on the synthesis, characterization, structure-property relationships, and electronic structure calculations on two new DUV NLO materials: KMgCO3F and Cs9Mg6(CO3)8F5. Both materials are noncentrosymmetric (NCS). KMgCO3F crystallizes in the achiral and nonpolar NCS space group P6̅2m, whereas Cs9Mg6(CO3)8F5is found in the polar space group Pmn21. The compounds have three-dimensional structures built up from corner-shared magnesium oxyfluoride and magnesium oxide octahedra. KMgCO3F (Cs9Mg6(CO3)8F5) exhibits second-order harmonic generation (SHG) at both 1064 and 532 nm incident radiation with efficiencies of 120 (20) × α-SiO2and 0.33 (0.10) × β-BaB2O4, respectively. In addition, short absorption edges of <200 and 208 nm for KMgCO3F and Cs9Mg6(CO3)8F5, respectively, are observed. We compute the electron localization function and density of states of these two compounds using first-principles density functional theory, and show that the different NLO responses arise from differences in the denticity and alignment of the anionic carbonate units. Finally, an examination of the known SHG active AMCO3F (A = alkali metal, M = alkaline earth metal, Zn, Cd, or Pb) materials indicates that, on average, smaller A cations and larger M cations result in increased SHG efficiencies.
authors.affiliation: Department of Chemistry, University of Houston , 112 Fleming Building, Houston, Texas 77204-5003, United States.
authors.forename: T Thao
authors.initials: TT
authors.lastname: Tran
authors.affiliation: Department of Materials Science and Engineering, Northwestern University , 2220 Campus Drive, Evanston, Illinois 60208-3108, United States.
authors.forename: Joshua
authors.initials: J
authors.lastname: Young
authors.affiliation: Department of Materials Science and Engineering, Northwestern University , 2220 Campus Drive, Evanston, Illinois 60208-3108, United States.
authors.forename: James M
authors.identifier: 0000-0003-0508-2175
authors.initials: JM
authors.lastname: Rondinelli
authors.affiliation: Department of Chemistry, University of Houston , 112 Fleming Building, Houston, Texas 77204-5003, United States.
authors.forename: P Shiv
authors.identifier: 0000-0003-1787-1040
authors.initials: PS
authors.lastname: Halasyamani