Synthesis, Crystal Structure, and Magnetic Properties of Giant Unit Cell Intermetallics R117Co52+δSn112+γ (R = Y, La, Pr, Nd, Ho)

NaSi reacts with MoCl5 and 15-crown-5 in toluene with reduction of Mo(V) to Mo(IV). Work-up in DME yields MoCl4(DME)· 15-crown-5 (1). MoCl4(DME) (2) is prepared more conveniently from MoCl5/DME. 1 and 2 were characterized spectroscopically and by X-ray structure determination. Crystal data: 1, space group P212121 (No. 19), Z = 4, 2765 observed independent reflexions, R = 0.026, cell dimensions (110 K): a = 16.292(4), b = 12.884(3), c = 10.452(2) Å. 2, space group I4̄2d (No. 122), Z = 8, 558 observed independent reflexions, R = 0.037, cell dimensions (292 K): a = b = 9.562(2), c = 23.777(6)Å. The MoCl4(DME) molecule of 1 and 2 forms a distorted octahedron. There are four non-coordinating 15-crown-5 molecules present in the unit cell of 1. The UV/VIS spectrum and the magnetic properties of 2 are discussed.

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New Layered Perovskite Vanadium Oxide with Negative Magnetization

MRS Proceedings ◽

10.1557/proc-275-717 ◽

1992 ◽

Vol 275 ◽

Author(s):

Noburu Fukushima ◽

Shiro Takeno ◽

Shigenori Tanaka ◽

Ken Ando

Keyword(s):

Magnetic Field ◽

Crystal Structure ◽

Magnetic Properties ◽

Vanadium Oxide ◽

Unit Cell ◽

Layered Perovskite ◽

Negative Magnetization

ABSTRACTA new layered perovskite vanadium oxide Sr4V3O8-d was synthesized and its crystal structure and magnetic properties were studied. Sr4V3O8-d has a novel crystal structure, containing a V-0 octahedron and a two-fold V-0 fence in a unit cell. It exhibits negative magnetization below 30 K. when cooled in a magnetic field. This peculiar magnetism is attributed to N-type parasitic ferrimagnetism.

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The crystal structure of eugaAl

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100131899 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1452-1453

Author(s):

H. Brigitte Krause ◽

Yonglin Qian

Keyword(s):

Crystal Structure ◽

Electron Microscope ◽

Zone Axis ◽

Unit Cell ◽

Polycrystalline Specimen ◽

Lattice Constants

A polycrystalline specimen of nominal formula EuGaAl with unknown crystal structure was investigated by various electron microscope techniques; EDS-, SED-, and CBED data were taken on a Philips 400 electron microscope operated at 100kV, HREM data on a Hitachi 9000 microscope operated at 300kV. The EDS data confirmed the composition for the bulk of the material but, in addition, revealed particles with other fractions of the elements. Only the EuGaAl particles were further investigated. The unit cell was determined to be orthorhombic with a ratio: a/b=0.969(2) , a/c=0.234(2) and b/c=0.234(2). The lattice constants are a=4.54(5)Ȧ, b=4.68Ȧ and c=19.97(20)Ȧ. Based on systematic extinctions for hkl reflections with h+l=2n+l, the unit cell was found to be b-centered. CBED patterns of the [001], [100], and [010] zone axes are shown in Fig. 1. The zone axis patterns are in agreement with the above stated data except for diffused (2m+l,2n+l,0)- reflections, not compatible with the above stated systematic absences. But these occurred only occasionally in conjunction with a complicated noncommensurate superlattice pattern.

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