Structural, Spectroscopic, and Electronic Properties of Cubic G0-Rb₂KTiOF₅ Oxyfluoride

Abstract

The G0-Rb 2 KTiOF 5 single crystals with dimensions up to nearly a centimeter in size have been prepared by slow solidification method. The elpasolite-related crystal structure of G0-Rb 2 KTiOF 5 has been refined by Rietveld method at T = 298 K (space group Fm3̅ m, Z = 4, a = 8.880(1) Å, V = 700.16(2) Å 3 ; R B = 2.66%). The wide optical transparency range of 0.25−9 μm and forbidden band gap of E g = 3.87 eV have been obtained for the G0-Rb 2 KTiOF 5 crystal. Dominating photoluminescence bands at 3.36 and 2.33 eV are related to free and self-trapped excitons, respectively. The electronic structure of G0-Rb 2 KTiOF 5 has been evaluated by X-ray photoelectron spectroscopy and calculated with the first-principles methods. A good agreement between theoretical and experimental results has been achieved. Chemical bonding effects have been discussed for all metal ions using binding energy difference parameters and a wide comparison with related oxides and fluorides. The competition between O 2− and F − ions for metal valence electrons has been found.

Crystal growth and electronic structure of low-temperature phase SrMgF4

“…Detailed information on the efficient methods of halide charge preparation and growth set up can be found elsewhere [15][16][17]30,[36][37][38]. The main problem is to avoid oxide and hydroxide contaminations.…”

“…These crystals possess specific structural and bonding effects, nonlinear optical characteristics and a wide transparency window from the vacuum violet to mid-infrared range [7][8][9][10][11][12][13][14][15][16][17]. Moreover, fluorides are efficient hosts for rare-earth dopants and the materials are widely applied in the laser technique and creation of nanophotonical phosphors [18].…”

Comment on “The Effect of Barium Substitution on the Ferroelectric Properties of Sr2Nb2O7 Ceramics,” J. Am. Ceram. Soc., 96 [4] 1163–70 (2013)

“…The quality of the XPS measurements seems to be good, and, as it appeared, the interpretation of XPS results given in Ref. can be developed using the BE difference (ΔBE) method . The BE difference parameters are insensitive to surface charging effects and BE scale calibration methods, and they are particularly suitable for the comparative analysis of XPS results measured by different spectrometers.…”

“…As to chemical bonding, lower DBE M values in oxides indicate a higher mean M-O bond ionicity level. [4][5][6][7]9,10 The following DBE M values can be calculated using the results from Ref.[1]: DBE Sr = BE (O 1s) À BE (Sr 3d 5/2 ) = 529.6 À 133.1 = 396.5 eV, DBE Ba = BE (O 1s) À BE (Ba 3d 5/2 ) = 529.6 À 779.5 = À249.9 eV and DBE Nb = BE (O 1s) À BE (Nb 3d 5/2 ) = 529.6 À 206.9 = 322.7 eV. It should be pointed that the BE (Ba 3d 5/2 ) and BE (Ba 3d 3/2 ) are evidently mixed in Ref.…”

“…As to chemical bonding, lower DBE M values in oxides indicate a higher mean M-O bond ionicity level. [4][5][6][7]9,10 The following DBE M values can be calculated using the results from Ref.…”