Exotic magnetism on the quasi-FCC lattices of the d3d^3 double perovskites La2_2NaB′'O6_6 (B′' == Ru, Os)

We find evidence for long-range and short-range ($\zeta$ $=$ 70 \AA~at 4 K) incommensurate magnetic order on the quasi-face-centered-cubic (FCC) lattices of the monoclinic double perovskites La$_2$NaRuO$_6$ and La$_2$NaOsO$_6$ respectively. Incommensurate magnetic order on the FCC lattice has not been predicted by mean field theory, but may arise via a delicate balance of inequivalent nearest neighbour and next nearest neighbour exchange interactions. In the Ru system with long-range order, inelastic neutron scattering also reveals a spin gap $\Delta$ $\sim$ 2.75 meV. Magnetic anisotropy is generally minimized in the more familiar octahedrally-coordinated $3d^3$ systems, so the large gap observed for La$_2$NaRuO$_6$ may result from the significantly enhanced value of spin-orbit coupling in this $4d^3$ material.Comment: 5 pages, 4 figure

Ca\u3csub\u3e4\u3c/sub\u3eIrO\u3csub\u3e6\u3c/sub\u3e, Ca\u3csub\u3e3\u3c/sub\u3eMgIrO\u3csub\u3e6\u3c/sub\u3e and Ca\u3csub\u3e3\u3c/sub\u3eZnIrO\u3csub\u3e6\u3c/sub\u3e

Single crystals of tetracalcium iridium hexaoxide, Ca4IrO6, tricalcium magnesium iridium hexaoxide, Ca3MgIrO6, and tricalcium zinc iridium hexaoxide, Ca3ZnIrO6, were prepared via high-temperature flux growth and structurally characterized by single-crystal X-ray diffraction. The three compounds are isostructural and adopt the K4CdCl6 structure type, comprised of chains of alternating face-shared [CaO6], [MgO6] or [ZnO6] trigonal prisms and [IrO6] octahedra, surrounded by columns of Ca2+ ions. Formula: Ca4IrO6, Ca3.34Mg0.66IrO6 and Ca3.50Zn0.50IrO

JOURNAL OF FIRST TRIP OF UNIVERSITY OF CALIFORNIA TO JOHN DAY BEDS OF EASTERN OREGON

32 pagesThe journal is Dr. Miller's account of the University of California field expedition into the John Day Basin of Central Oregon in 1899. This expedition, as well as many that followed from that institution, was led by Dr. John C. Merriam. It began a long association of the University of California with that area of Oregon, an association which still continues. Although the events of this journal occurred over seventy years ago, they by no means represent the first investigation of the area, for these beds were already famous when Miller first saw them. Condon had first seen them forty years previously, and such well known paleontologists as Marsh and Cope among many others had collected there. It was not until the work of Merriam and his students from the University of California began that any real understanding of the geology of the area or the sequence of the faunas present was developed

Crystal growth, Structure Determination and Magnetism of a New Hexagonal Rhodate: Ba9Rh8O24

Single crystals of Ba9Rh8O24, grown from a molten potassium carbonate flux, crystallize in the spacegroup R¯3c with lattice parameters of a = 10.0899(4) and c = 41.462(2) Å. Magnetic measurements on oriented single crystals reveal the existence of magnetic anisotrop

Bis[μ-1,2-bis(2-pyridyl)ethyne-\u3csub\u3eK\u3c/sub\u3e\u3csup\u3e2\u3c/sup\u3eN:N\u27]bis[aquadinitratocadmium(II)]

Two twisted 1,2-bis(2-pyridyl)ethyne ligands bridge two Cd2+ centers in the C2-symmetric title complex, [Cd2(NO3)4(-C12H8N2)2(H2O)2]. The bridging ligands arch across one another creating a `zigzag loop\u27 molecular geometry. Two nitrate ions and a water molecule complete the irregular seven-coordinate Cd-atom environment. The dihedral angles between the equivalent pyridyl ring planes of the two independent ligands are 67.2 (1)°. Owater-HOnitrate hydrogen bonding creates two-dimensional layers parallel to the ab plane. Formula: [Cd2(NO3)4(C12H8N2)2(H2O)2

Sm\u3csub\u3e2\u3c/sub\u3eNaIrO\u3csub\u3e6\u3c/sub\u3e, A Monoclinically Distorted Double Perovskite

Single crystals of the lanthanide-containing iridate, disamarium sodium iridium hexaoxide, Sm2NaIrO6, were prepared via high-temperature flux growth and structurally characterized by single-crystal X-ray diffraction. The compound crystallizes in the monoclinic space group P21/n and is a double perovskite, consisting of a 1:1 ordered rock-salt-type lattice of corner-shared NaO6 and IrO6 distorted octahedra. Samarium occupies the eightfold coordination site generated by the connectivity of the octahedra

Structure Determination of Ba\u3csub\u3e8\u3c/sub\u3eCoRh\u3csub\u3e6\u3c/sub\u3eO\u3csub\u3e21\u3c/sub\u3e, a New Member of the 2H-Perovskite Related Oxides

Single crystals of Ba8CoRh6O21 were grown out of a potassium carbonate flux. The structure was solved by a general method using the superspace group approach. The superspace group employed was R3m(00γ)0s with a = 10.0431(1) Å, c1 = 2.5946(1) Å and c2 = 4.5405(1) Å, V = 226.60(1) Å3. Ba8CoRh6O21 represents the first example of an m = 5, n = 3 member of the A3n+3mA\u27nB3m+nO9m+6n family of 2H hexagonal perovskite related oxides and contains chains consisting of six consecutive RhO6 octahedra followed by one distorted CoO6 trigonal prism. These chains in turn are separated from each other by [Ba]∞ chains

\u3cem\u3eCatena\u3c/em\u3e-Poly[[Bis(α-Thenoyltrifluoroacetonato)Copper(II)]-μ-1,4-Di-4-Pyridyl-2,3-Diazabuta-1,3-Diene]

In the one-dimensional title polymer, [Cu(C8H4F3O2S)2(C12H10N4)]n or [Cu(L)2(tta)2] [tta is -thenoyltrifluoroacetonato and L is 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene], Cu2+ lies on a center of inversion. It is axially coordinated by two pyridyl N atoms from two different L ligands and equatorially coordinated by four O atoms from two chelating tta ligands. The ligand L propagates the one-dimensional chain structure by serving as a bridging ligand between two Cu octahedra via Cu-N coordinate bonds