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1.
On Ordered Perovskites with Cationic Vacancies. X. Compounds of Type A B B □1/4MVIO6 ? A BIIB □M O24 with AII, BII = Ba, Sr, Ca and MVI = U, W Perovskites of type Ba8BIIB2III□UO24 show polymorphic phase transformations of order disorder type. An 1:1 ordered orthorhombic HT form is transformed into a higher ordered LT modification with a fourfold cell content (four formula units Ba8BIIB□U4O24), compared to cubic 1:1 ordered perovskites A2BMO6. In the series Ba8BaB□W4O24 and Sr8SrB□W4O24 different ordering phenomena are observed. In comparison with 1:1 ordered cubic perovskites A2BMO6, the cell contains eight formula units ABIIB□W4O24. The higher ordered cells with UVI and WVI are face centered, which has its origin in an ordering of cationic vacancies.  相似文献   

2.
On Alkaline Earth Metal Oxoindates. III. Crystal Structure Investigation on SrIn2O4. SrIn2O4 where investigated by X-Ray single crystal methods. (Space group D–Pnam; a = 9.809, b = 11.449, c = 3.265). The similarity of the crystal structure of SrIn2O4 with Ca3In2O6 is discussed.  相似文献   

3.
On Perovskites Ba2B B TeVIO6 Compounds of composition Ba2BBTeVIO6 with BI = Li, Na; BIII = La, Pr, Nd, Sm, Eu, Gd, Tb, Ho, Yb, Y, In, Sc crystallize in a cubic 1:1 ordered perovskite structure. The vibrational spectroscopic investigations show, that more species of TeO6 octahedra are present in the lattice.  相似文献   

4.
Determination of Structures of Ordered Perovskites of the Ba2B MVIO6 Type Intensity calculations on powder patterns of Ba2Y□0.33MVIO6 with MVI = U, W, Te und Ba2Gd0.670.33UO6 lead for the space group Fm3m/O with 8 Ba in 8c, 8/3 BIII and 4/3 □ in 4b, 4 MVI in 4a and 24 O in 24e to R values between 4.3 and 7.6%. Two further models are discussed.  相似文献   

5.
On Hexagonal Perovskites with Cationic Vacancies. XXIV. Rhombohedral 9 L Stacking Polytypes in the Systems Ba3W M □O9?x/2x?2 with MV = Nb, Ta In the system Ba3WNb□O9?x/2x/2 stacking polytypes of rhombohedral 9 L type (sequence (hhc)3; space group R3 m) can be prepared with ~1/3 ? × ? 2. For x = 2(Ba3Nb2□O8□) two modifications are formed. In the corresponding Ta system the phase with is reduced to a smaller region with x ? 1/3.  相似文献   

6.
Photoluminescence of Trivalent Rare Earths in Perovskite Stacking Polytypes Ba2La2?x RE MgW2□O12, Ba6Y2?x RE W3□O18, and Sr8SrGd2?xRE W4□O24 Rhombohedral 12 L stacking polytypes Ba2La2?xREMgW2□O12 show with RE3+ = Pr, Sm, Eu, Tb, Dy, Ho, Er, Tm; the 18 L stacking polytypes Ba6Y2?xREW3□O18 and the polymorphic perovskites Sr8SrGd2?xREW4□O24 with RE3+ = Sm, Eu, Dy, Ho, Er visible photoluminescence. The concentration dependence and the influence of the coordination number of the rare earth are reported.  相似文献   

7.
On Ordered Perovskites with Cationic Vacancies. XI. Compounds of Type A B B □1/4WVIO6 ? A BIIB □W O24 with AII, BII = Ba, Sr Depending on the ionic radii of the two and three valent cations in the perovskites of type ABB □1/4WVIO6 ?; ABIIB □WO24 order disorder phenomena are present. The results of the x-ray and vibrational spectroscopic investigations as well as the diffuse reflectance spectra and the visible photoluminescence are reported.  相似文献   

8.
On Hexagonal Perovskites with Cationic Vacancies. XXXI. Systems BaO? Re2O7? M O5 with MV = Nb, Ta In the systems BaO? Re2O7? MO5 three quaternary oxides are formed, which belong to the perovskite stacking polytypes with cationic vacancies: Ba8Re7/2M□3O24 (MV = Nb, Ta; rhombohedral 24 L type; sequence (hhhhchhc)3; space group R3 m), Ba4Re9/8Ta13/85/4O12 (rhombohedral 12 L type; sequence (hhcc)3; space group R3 m) and the phases Ba5BaRe3/2?xM □O15?xx (MV = Nb, Ta; variants of a hexagonal 5 L type).  相似文献   

9.
NaAuIn2, a Ternary Auride with Ethane Analogous In2Au6 Building Units and [In2/2] Chains Silver coloured, brittle single crystals of NaAuIn2 were synthesized by the reaction of NaN3, gold-sponge and indium at 500°C. The structure was determined from X-ray single-crystal diffractometry data: space group Cmcm, Z = 4, a = 4.482(1) Å, b = 10.366(2) Å, c = 7.869(2) Å, R/Rw(w = 1) = 0.017/0.020, Z(F) ≥ 3σ(F) = 547 and N(var.) = 16. NaAuIn2 crystallizes in the MgCuAl2-structure type. Gold and indium form a framework structure. [AuIn6/3] layers with trigonal prismatically coordinated gold are connected via In—In contacts along [010] which consist of ethane analogous In2Au6-building units. The In-partial structure consists of saw tooth like [In2/2] chains along [001]. The sodium atoms occupy channel-like cavities within the Au—In framework structure.  相似文献   

10.
On Hexagonal Perovskites with Cationic Vacancies. I. Compounds of the Type Ba2B □2/3ReVIIO6 Compounds of Type Ba2B□2/3ReVIIO6 are formed with BIII = Sm? Gd Ho? Lu, Y, Sc, In (yellow); Tb (black-brown); Dy (yellow-orange). They crystallize with BIII = Sm? Lu, Y and Sc in a rhombohedral layer structure of 12 L-type (space group R3 m; sequence: cchhcchhcchh) with 6 formula units in the unit cell.  相似文献   

11.
On the Crystal Structure of O MF (M = Sb, Ru, Pt, Au) OMF (M = Sb, Ru, Pt, Au) were obtained again, but for the first time investigated by X-ray methods. Colourless OSbF and the rubyred compounds ORuF and OPtF crystallize isostructural in space group Ia3 -Th7 (Nr. 206) with a = 1016(1) pm (Sb), a = 1002.6(9) pm (Ru) and a = 1003.6(9) pm (Pt), Z = 8. Yellow OAuF crystallizes trigonal-rhombohedric in space group R3 -D326 (Nr. 148) with a = 775.9(3) pm, c = 711.7(4) pm, Z = 3.  相似文献   

12.
Vibration spectra and force constants of the series O2PF — S2PF — S2P(CH3). The vibrational spectra of OSPF, S2PF, S2PF(CH3) and S2P(CN) are reported and discussed with O2PF and S2P(CH3). On the basis of a simplified valence-force-field the force constants are calculated and the bonding relations are discussed. In the ions, f PF is lower than in corresponding molecules. The ionic charge is distributed over nearly all atoms of the ions.  相似文献   

13.
On the Crystal Structure of Ba2ZnO3 Single crystals of Ba2ZnO3 were prepared by solid state reaction. It crystallizes monoclinic: space group C ? C12/c1; a = 5.833; b = 11.376; c = 12.585 Å; β = 93.63°; Z = 8. The crystal structure is characterised by [ZnO3] chains along [100]. They are connected by Ba2+ in seven fold oxygen coordination.  相似文献   

14.
19F NMR Spectroscopic Evidence and Calculation of the Statistical Formation of Mixed Cluster Anions [(Mo6Br Cl )F ]2?, n = 0 – 8 The complete system of the innersphere mixed clusters (Mo6BrCl)4+ is formed by exchange of innersphere bound Cli against outersphere bound Bra on tempering the solid [(Mo6Cl)Br] at 500°C for 16 h. After conversion with conc. HCl into (H3O)2[(Mo6BrCl)Cl] and precipitation of the outer Cla with AgBF4 in ethanol, treatment with tetrabutylammonium(TBA)fluoride yields (TBA)2 [(Mo6BrCl)F], a mixture of 22 different species. According to the sets of chemical equivalent fluorine atoms in total 55 19F nmr signals are expected, which are really observed in the high resolution 1D-19F-nmr spectrum. Using increments of chemical shifts, peak intensities and multiplet structures as well as the 2D-19F/19F-COSY spectrum the complete and unambiguous assignment of all resonances is achieved. From the measured integral intensities the distribution of the different compounds is determined, revealing statistical formation of the geometrical isomers.  相似文献   

15.
Magnetic interactions in some oxyfluoroferrites of spinel structure with the formula ZnxMe2?xO4?xFx (M = Fe, Co, Ni) Whereas the ferromagnetic spin arrangement of the B-cations is not modified by the Zn2+?Fe3+ substitution in the ZnFe[Fe2+Fe3+]O4?xFx (0 ≤ x ≤ 0,50) spinel, this same substitution leads to a spin canting in the ZnFe[Co2+Fe3+]O4?xFx and ZnFe[Ni2+Fe3+]O4?xFx (0 ≤ x ≤ 0,80) simples. The difference in the magnetic behaviors with regard to the AB and BB interactions can be explained on the basis of the magnetic exchange theory.  相似文献   

16.
On the Formation of Polysulphane Diphosphonates by the Reaction of Monothiophosphonate with Disulphane Diphosphonate In acid solution SPO reacts with S2P2O forming higher polysulphane diphosphonates. The formation of S3P2O and S4P2O is proved by evaluation of the double labelling with 35S? 32P after high paper electrophoresis.  相似文献   

17.
The Crystal Chemistry of Copper Rare-Earth Oxotungstates: (I): triclinic-α-CuTbW2O8, (II): monoclinic-CuInW2O8 and (III): monoclinic-CuYW2O8 Single crystals of (I), (II) and (III) were prepared by recrystallisation in closed systems and examined by X-ray technique. (I): space group C? P1 , a = 7.3080, b = 7.8945, c = 7.1476 Å, α = 115.23, β = 116.21, γ = 56.98°, Z = 2; (II): space group C? C2/c, a = 9.6576, b = 11.6496, c = 4.9863 Å, β = 91.17°, Z = 4; (III): space group C? P2/n, a = 10.0504, b = 5.8214, c = 5.0224 Å, β = 94.23°, Z = 2. The crystal structures are discussed with respect to calculations of the coulombterms of lattice energy and possible valence states of Cu2+ and Mo5+.  相似文献   

18.
The Crystal Structure of Perovskites A NiIIMVIO6. II. Sr2NiWO6 The results of an X-ray single crystal study of the perovskite Sr[NiIIWVI](6)O6, ordered in the octahedral sites, are given. While Sr[NiIITeVI](6)O6 crystallizes in a monoclinically deformed structure of the perovskite (elpasolite) type, showing a phase transition to a tetragonal lattice at 675 °K, Sr[NiIIWVI](6)O6 is tetragonal already at 298°K (space group: C; a = b = 5.559 Å; c = 7.918 Å; Z = 2). The Ni? O distances found for the tungsten compound are nearly identical with those of the tellurium perovskite. In contradiction to crystal field theory very different values of the ligand field parameter Δ (ca. 25%) are observed for these two compounds however. Obviously this effect is caused by the rather different kind of bonding within the NiO6 polyhedra in the two compounds. On the basis of the structural results the Ni? O-bonding in the two perovskites is discussed in dependence of the next nearest cationic environment.  相似文献   

19.
On Hexagonal Perovskites with Cationic Vacancies. XXX. 5 L Stacking Polytypes in the Systems BaO — Re2O7? Sb2O5 and BaO? WO3? Sb2O5 In the systems BaO? Re2O7? Sb2O5 and BaO? WO3? Sb2O5 phases of composition Ba5BaRe Sb□O15?xx (x = 0 up to x ? 3/4) and Ba5BaWSb□O15?x/2x/2 (x ? 3/2 up to x ? 2) are existent, which have an orthorhombic distorted 5 L structure. The pure Sb compound has to be formulated as Ba3BaSb2O9 and crystallize in an orthorhombic variant of the hexagonal BaTiO3 type.  相似文献   

20.
Preparation and Spectroscopic Characterization of the Cluster Anion [(Mo6Cl )(CF3COO) ]2? On heating of [(Mo6Cl)Cl]2? in dichloromethane with trifluoroacetic acid the new stable cluster anion [(Mo6Cl)(CF3COO)]2? is formed by elimination of HCl. The (Mo6Cl) unit remains unattacked. The 19F nmr spectrum exhibits a downfield shifted singulett as compared to free CF3COO? indicating the equivalence of all trifluoroacetate ligands, which unidentate coordination is deduced from characteristic i. r. frequencies of the carboxyl groups. The most intense i.r. band at 501 cm?1 is assigned to the antisymmetric Mo? Oa vibration, the most intense Raman line at 319 cm?1 to the breathing mode of the Cl cube.  相似文献   

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