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- ItemRedetermination of EuScO3(Chester : International Union of Crystallography, 2009) Kahlenberg, V.; Maier, D.; Veličkov, B.Single crystals of europium(III) scandate(III), with ideal formula EuScO3, were grown from the melt using the micro-pulling-down method. The title compound crystallizes in an ortho-rhom-bic distorted perovskite-type structure, where Eu occupies the eightfold coordinated A sites (site symmetry m) and Sc resides on the centres of corner-sharing [ScO6] octa-hedra (B sites with site symmetry ). The structure of EuScO3 has been reported previously based on powder diffraction data [Liferovich & Mitchell (2004). J. Solid State Chem. 177, 2188-2197]. The results of the current redetermination based on single-crystal diffraction data shows an improvement in the precision of the structral and geometric parameters and reveals a defect-type structure. Site-occupancy refinements indicate an Eu deficiency on the A site coupled with O defects on one of the two O-atom positions. The crystallochemical formula of the investigated sample may thus be written as A(0.032Eu0.968)BScO2.952.
- ItemRedetermination of terbium scandate, revealing a defect-type perovskite derivative(Chester : International Union of Crystallography, 2008) Veličkov, B.; Kahlenberg, V.; Bertram, R.; Uecker, R.The crystal structure of terbium(III) scandate(III), with ideal formula TbScO3, has been reported previously on the basis of powder diffraction data [Liferovich & Mitchell (2004). J. Solid State Chem. 177, 2188-2197]. The current data were obtained from single crystals grown by the Czochralski method and show an improvement in the precision of the geometric parameters. Moreover, inductively coupled plasma optical emission spectrometry studies resulted in a nonstoichiometric composition of the title compound. Site-occupancy refinements based on diffraction data support the idea of a Tb deficiency on the A site (inducing O defects on the O2 position). The crystallochemical formula of the investigated sample thus may be written as A(0.04Tb0.96) BScO2.94. In the title compound, Tb occupies the eightfold- coordinated sites (site symmetry m) and Sc the centres of corner-sharing [ScO6] octa-hedra (site symmetry ). The mean bond lengths and site distortions fit well into the data of the remaining lanthanoid scandates in the series from DyScO3 to NdScO3. A linear structural evolution with the size of the lanthanoid from DyScO3 to NdScO3 can be predicted.
- ItemExperimental electronic structure of In2O3 and Ga2O3(Bristol : IOP, 2011) Janowitz, C.; Scherer, V.; Mohamed, M.; Krapf, A.; Dwelk, H.; Manzke, R.; Galazka, Z.; Uecker, R.; Irmscher, K.; Fornari, R.; Michling, M.; Schmeißer, D.; Weber, J.R.; Varley, J.B.; Van De Walle, C.G.Transparent conducting oxides (TCOs) pose a number of serious challenges. In addition to the pursuit of high-quality single crystals and thin films, their application has to be preceded by a thorough understanding of their peculiar electronic structure. It is of fundamental interest to understand why these materials, transparent up to the UV spectral regime, behave also as conductors. Here we investigate In2O3 and Ga2O3, two binary oxides, which show the smallest and largest optical gaps among conventional n-type TCOs. The investigations on the electronic structure were performed on high-quality n-type single crystals showing carrier densities of ∼1019 cm-3 (In2O3) and ∼1017 cm-3(Ga2O3). The subjects addressed for both materials are: the determination of the band structure along high-symmetry directions and fundamental gaps by angular resolved photoemission (ARPES). We also address the orbital character of the valence- and conduction-band regions by exploiting photoemission cross.
- ItemCrystal structure of praseodym gallate, Pr4Ga2O9(München : R. Oldenbourg Verlag GmbH, 1999) Gesing, T.M.; Uecker, R.; Buhl, J.-C.Ga2O9Pr4, monoclinic, P121/c1 (No. 14), a = 7.8256(4) Å, b = 11.0322(5) Å, c = 11.4959(7) Å, β = 109.187(3)°, V = 937.4 Å3, Z = 4, R(P) = 0.026, wR(P) = 0.034, R(I)= 0.033, T = 295 K.
- ItemCrystal structure of distrontium lanthanum gallium pentaoxide, Sr2LaGaO5(München : R. Oldenbourg Verlag GmbH, 2000) Gesing, T.M.; Uecker, R.; Buhl, J.-C.GaLaO5Sr2, tetragonal, I4/mcm (No. 140), a = 6.9339(4) Å, c = 11.2823(8) Å, V= 542.4 Å3, Z = 4, R(P) = 0.018, wR(P) = 0.027, R(I) = 0.031, T= 295 K.
- ItemCrystal structure of strontium praseodum gallium oxide, SrPrGaO4(München : R. Oldenbourg Verlag GmbH, 2000) Gesing, T.M.; Uecker, R.; Buhl, J.-C.GaO4PrSr, tetragonal, I4/mmm (No. 139), a = 3.822(1) Å, c = 12.622(2) Å, V = 184.4 Å3, Z = 2, Rgt(F) = 0.028, wR(F2) = 0.082, T = 293 K.
- ItemRefinement of the crystal structure of praseodymium orthoscandate, PrScO3(Berlin : de Gruyter, 2009) Gesing, T.M.; Uecker, R.; Buhl, J.-C.O3PrSc, Prima (no. 62), a = 5.780(1) Å, b = 8.025(2) Å, c = 5.608(1) Å, V= 260.1 Å3, Z = 4, R gr(F) = 0.025, wRref(F2) = 0.060, T= 298 K. © by Oldenbourg Wissenschaftsverlag, München.
- ItemCrystal structure of samarium-strontium-calcium orthoaluminotantalate, (Sm0.40Sr0.50Ca0.10)(Al0.70Ta 0.30)O3(Berlin : de Gruyter, 2010) Gesing, T.M.; Uecker, R.; Zheng, W.; Buhl, J.-C.Al2.90Ca0.45O12Sm 1.59Sr2Ta1.10, tetragonal, I4 (no. 82), a = 5.4174(8) Å, c = 7.643(2) Å, V = 224.3 Å3, Z = 1, Rgt(F) = 0.039, wRref(F 2) = 0.1258 , T = 298 K. © 2014 Oldenbourg Wissenschaftsverlag, München.
- ItemCrystal structure of strontium praseodym trigallium heptaoxide, (Sr0.5Pr0.5)2Ga3O7(München : R. Oldenbourg Verlag GmbH, 1999) Gesing, T.M.; Uecker, R.; Buhl, J.-C.Ga3O7PrSr, tetragonal, P4̄21m (No. 113), a = 8.0198(2) Å, c = 5.2991 (1) Å, V = 340.8 Å3, Z = 2, R(P) = 0.026, wR(P) = 0.040, R(I) = 0.025, T = 295 K.
- ItemCrystal structure of aluminium cyclononaphosphate, Al3P9O27(München : R. Oldenbourg Verlag GmbH, 2000) Fratzky, D.; Schneider, M.; Meisel, M.Al3O27P9, trigonal, P3̄c1 (No. 165), a = 10.935(2) Å, c = 9.191(2) Å, V = 951.8 Å3, Z = 8, Rgt(F) = 0.037, wRref(F2) = 0.094, T = 293 K.