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Redetermination of terbium scandate, revealing a defect-type perovskite derivative
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.
Crystal structure of distrontium lanthanum gallium pentaoxide, Sr2LaGaO5
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.
Crystal structure of samarium-strontium-calcium orthoaluminotantalate, (Sm0.40Sr0.50Ca0.10)(Al0.70Ta 0.30)O3
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.
Crystal structure of distrontium praseodym gallium pentaoxide, Sr2PrGaO5
GaO5PrSr2, tetragonal, I4/mcm (No. 140), a = 6.8441(2) Å, c = 11.2534(4) Å, V = 527.1 Å3, Z = 4, R(P) = 0.035, wR(P) = 0.052, R(I) = 0.038, T = 295 K. © by Oldenbourg Wissenschaftsverlag.
Experimental electronic structure of In2O3 and Ga2O3
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.
Crystal structure of strontium praseodum gallium oxide, SrPrGaO4
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.
Crystal structure of strontium praseodym trigallium heptaoxide, (Sr0.5Pr0.5)2Ga3O7
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.
Crystal structure of praseodym gallate, Pr4Ga2O9
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.
Refinement of the crystal structure of praseodymium orthoscandate, PrScO3
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.
Crystal structure of strontium praseodym aluminate, SrPrAlO4
AlO4PrSr, tetragonal, I4/mmm (No. 139), a = 3.736(1) Å, c = 12.532(3) Å, V = 174.9 Å3, Z = 2, Rgt(F) = 0.010, wR(F2); = 0.021, T = 293 K.