Ba4Ru3O10.2(OH)1.8: a new member of the layered hexagonal perovskite family crystallised from water (original) (raw)
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Ba4Ru3O10.2(OH)1.8: a new member of the layered hexagonal perovskite family crystallised from water
Chemical communications (Cambridge, England), 2016
A new barium ruthenium oxyhydroxide Ba4Ru3O10.2(OH)1.8 crystallises under hydrothermal conditions at 200 °C: powder neutron diffraction data show it adopts an 8H hexagonal perovskite structure with a new stacking sequence, while high resolution electron microscopy reveals regions of ordered layers of vacant Ru sites, and magnetometry shows antiferromagnetism with TN = 200(5) K.
Synthesis, crystal structure, and magnetic properties of new layered hexagonal perovskite Ba8Ta4Ru8/3Co2/3O24
A new hexagonal perovskite-type oxide Ba8Ta4Ru8/3Co2/3O24 was synthesized by the solid-state method at 1573K and characterized by electron diffraction (ED), time-of-flight (TOF) neutron powder diffraction, and magnetic susceptibility. Structure parameters of Ba8Ta4Ru8/3Co2/3O24 were refined by the Rietveld method from the TOF neutron powder diffraction data on the basis of space group P63=mcm and lattice parameters a ¼ 10:0075ð1ÞA ˚ and c ¼ 18:9248ð2ÞA ˚ as obtained from the ED data (Z ¼ 3). The crystal structure of Ba8Ta4Ru8/3Co2/3O24 consists of 8-layered (cchc)2 close-packed stackingof BaO3 layers alongthe c-axis. Corner-shared octahedra are filled by Ta only and face-shared octahedra are statistically occupied by Ru, Co, and vacancies. Similar compounds Ba8Ta4Ru8/3M2/3O24 with M=Ni and Zn were also prepared. Magnetic susceptibility measurements showed no magnetic ordering down to 5K.
Crystal Structure and Magnetic Properties of 6H-Perovskite Ba3NdRu2O9
Journal of Solid State Chemistry, 2001
Magnetic properties of a quaternary oxide Ba 3 NdRu 2 O 9 are reported. This compound adopts the 6H-perovskite structure with space group P6 3 /mmc, in which the cation sites within the face-sharing octahedra are occupied by ruthenium ions and those within the corner-sharing octahedra are occupied by neodymium ions. Powder neutron di4raction, powder X-ray di4raction, magnetic susceptibility, magnetization, and speci5c heat measurements were carried out. It was found that the crystal phase transition and magnetic transition occurred at ca. 120 K and 24 K, respectively. The crystal structure below 120 K is monoclinic with space group C 2/c. Neutron di4raction data collected at 10 K show that Ba 3 NdRu 2 O 9 has a long-range ferromagnetic ordering of Nd 3؉ ions. The ordered magnetic moment of Nd 3؉ ions is 1.65(8) B . The direction of ordered moments is parallel to the c-axis.
Sr4Ru3.05O12: A New Member of the Hexagonal Perovskite Family
Journal of Solid State Chemistry, 1999
Sr 4 Ru 3.05 O 12 crystals have been synthesized under hydrothermal conditions (500°C, 1800 bars). The crystal structure was determined by X-ray single-crystal diffraction. The unit cell is hexagonal and presents a superstructure (a s ؍ (3a b ؍ 9.641(2) A s and c s ؍ c b ؍ 18.186(5) A s. The average structure has been determined (P6 3 mc space group, a b ؍ 5.566(4) A s , c b )5(681.81؍ A s , and Z ؍ 2). The structure refinement converged to R ؍ 0.057 and R w ؍ 0.032 for 186 independent reflections. The crystal structure is based on the 8H (cchc) 2 close-packed stacking of SrO 3 layers with face-sharing octahedra partially occupied by the ruthenium atoms. Electron diffraction observations and high-resolution electron microscopy image observations recognize the X-ray average structure. The superstructure spots appear clearly in the ED patterns and most of the crystals display diffuse streaks along c*, which are consistent with the disorder clearly imaged in the HREM images. Heating Sr 4 Ru 3.05 O 12 crystals leads to the disappearance of the superstructure.
Sr18Ru1.9Bi4.1O33: crystallization of a Ru(V)/Bi(V) oxide from molten hydroxide
Journal of Solid State Chemistry, 2003
Single crystals of a new complex oxide, Sr 18 Ru 1.9 Bi 4.1 O 33 , were precipitated from a mixture of molten alkali and alkaline earth metal hydroxides at 7501C. The structure was determined from a ruby-red crystal using single-crystal X-ray diffraction. Sr 18 Ru 1.88 Bi 4.12 O 33 crystallizes in the space group C2/c (monoclinic) and has unit-cell dimensions: a ¼ 10:2102ð11Þ Å , b ¼ 17:882ð2Þ Å , c ¼ 19:579ð2Þ Å , and b ¼ 102:043ð2Þ1. The structure (refined to R 1 ¼ 4:5%; wR 2 ¼ 9:2%) is an unusual ABO 3 defect perovskite, with 1 12 th of the oxygen positions vacant. All the A sites and half of the B sites are occupied by Sr 2+ , while the remaining B sites are occupied by Bi 5+ or Ru 5+. The oxygen atom vacancies are located within the Bi coordination sphere exclusively. The bonding in the BO 3 sublattice is less covalent than that in the perovskite archetype from which it is derived due to the presence of 50% Sr 2+ on the B sites. Thus, the structure of Sr 18 Ru 1.9 Bi 4.1 O 33 can also be viewed as being made up of isolated bismuthate anions (BiO 5 5À , BiO 5.5 6À and BiO 6 7À) and ruthenate anions (RuO 6 7À) separated by strontium cations.
New 5H hexagonal perovskite-like oxides (the series ALa4Ti3RuO15, where A = Ca, Sr, Ba)
Materials Research Bulletin, 1992
A new series of hexagonal perovskites ALa4Ti3RuO15 with A = Ca, Sr, or Ba has been prepared by solid state reactions. The three compounds are isostructural with Ba5Nb4015. The crystal structure is based on close-packed stacking of (A0.2La0.8)O 3 layers and corresponds to the 5H polytype with a hccch sequence along the c-axis. This structural model corresponds to strings of three octahedra sharing faces which are linked together by two other octahedra sharing only corners. The titanium and ruthenium atoms occupy statistically these octahedral sites in such a way that the middle octahedron of each string remains vacant. Then the structure can be described as blocks of [Ti3RuO15]n 14n-layers perpendicular to the c-axis separated by layers of vacant octahedra. These results have been confirmed by electron microscopy. Conductivity measurements on pellets have shown that the three compounds are semiconductors. The valence state of the ruthenium (Ru 4+) has been confirmed by magnetic susceptibility measurements. MATERIALS INDEX: oxides, perovskites.
Crystallography Reports, 2017
The crystal and magnetic structures of a solid solution of double perovskite Ba 2-x Sr x FeMoO 6 (x = 0-1.6) have been investigated by neutron diffraction. The high-resolution diffraction patterns have provided precise information about the changes in the crystal and magnetic structures with an increase in the strontium content and data on the behavior of the sample microstructure. Replacement of barium with strontium leads to a change in the lattice symmetry from cubic (x = 0, sp. gr. Fm m)) to tetragonal (x = 0.4, sp. gr. I4/m). At x = 1.0, the symmetry is either tetragonal (sp. gr. I4/m) or orthorhombic (sp. gr. Fmmm), and at x = 1.6 the symmetry becomes again tetragonal (sp. gr. I4/m). The values of the Curie temperature and microstrain increase with an increase in the strontium content.