Structural Studies of the Fast Oxygen Ion Conductor BICOVOX.15 by Single-Crystal Neutron Diffraction at Room Temperature

1998 ◽  
Vol 141 (1) ◽  
pp. 241-247 ◽  
Author(s):  
C. Muller ◽  
M. Anne ◽  
M. Bacmann ◽  
M. Bonnet
Keyword(s):  
Neutron Diffraction ◽  
Single Crystal ◽  
Room Temperature ◽  
Structural Studies ◽  
Ion Conductor ◽  
Oxygen Ion ◽  
Oxygen Ion Conductor

Water Molecule Dispositions in the Cesium Sulfate α- and β-Alums: Single-Crystal Neutron Diffraction Studies of CsM(SO4)2.12H2O (M=V, Rh)

1993 ◽  
Vol 46 (9) ◽  
pp. 1337 ◽  
Author(s):  
JK Beattie ◽  
SP Best ◽  
FH Moore ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Neutron Diffraction ◽  
Water Molecule ◽  
Single Crystal ◽  
Tilt Angle ◽  
Room Temperature ◽  
Bond Angle ◽  
Sulfate Salt ◽  
Cell Dimensions ◽  
Coordinated Water ◽  
Unit Cell Dimensions

Room-temperature single-crystal neutron diffraction studies are recorded for two alums, Cs( Rh /V)(SO4)2.12H2O [cubic, Pa3, a 12.357(5) ( Rh ), 12.434(1)Ǻ (V)], residuals 0.037 and 0.068 for 328 and 164 'observed' reflections, with the intention of defining water molecule hydrogen atom orientations. Whereas the two tervalent hexaaqua cations are similar in size [ rM -O = 2.010(6)Ǻ (M = V) and 2.006(2)Ǻ (M = Rh )] the vanadium salt adopts the β alum modification while rhodium gives an α alum. Significantly, the water coordination geometry is different in the two cases with the tilt angle between the plane of the water molecule and the M-O bond vector being 1° (M = V) and 35° (M = Rh ). The tilt angle for water coordinated to rhodium in CsRh (SeO4)2.12H2O is inferred from the unit cell dimensions to be similar to that of the corresponding sulfate salt and not that which generally pertains for caesium selenate alums. Significant differences in the H-O-H bond angle are found for trigonal planar and trigonal pyramidal water coordination, suggesting that differences in the metal(III)-water interaction are a determinant of the geometry of the coordinated water molecule in the caesium sulfate/ selenate alum lattices.

The Dielectric Loss of Single Crystal and Polycrystalline TiO2

1997 ◽  
Vol 500 ◽  
Author(s):  
Xiaoru Wang ◽  
Alan Templeton ◽  
Stuart J. Penn ◽  
Neil McN. Alford
Keyword(s):  
Dielectric Loss ◽  
Single Crystal ◽  
Mixed Valence ◽  
Dielectric Materials ◽  
Oxygen Stoichiometry ◽  
Ion Conductor ◽  
Microwave Dielectric ◽  
Valence States ◽  
Oxygen Ion Conductor

ABSTRACTThe dielectric loss of single crystal and polycrystalline TiO2 has been studied. In polycrystalline TiO2 the dielectric loss is determined by both the microstructure and by the oxygen stoichiometry. Experiments have been carried out to determine the influence of both the microstructure (particularly porosity) and the oxygen stoichiometry. The TiO2 powder has been doped with partially stabilised zirconia, an oxygen ion conductor, in order to modify the oxygen stoichiometry. Sintered discs have been examined for loss as a function zirconia doping, pore volume and as a function of temperature. The behaviour of the doped and undoped titania powders is significantly different. Since many microwave dielectric materials contain Ti eg Ba-Ti-O, Ba-Nd-Ti-O, (Ba-RE-Ti-O, RE=Rare Earth), Zr-Sn-Ti-O etc it is essential to understand the role of the titanium, particularly as it can exist in mixed valence states, and the role of oxygen and its influence on the dielectric loss.

Microstructure and Property Study of La2Mo1.5W0.5O9/Ag Composites

2010 ◽  
Vol 663-665 ◽  
pp. 620-624
Author(s):  
Chun Li ◽  
Da Li ◽  
Qian Feng Fang
Keyword(s):  
Solid State Reaction Method ◽  
Second Phase ◽  
Doping Amount ◽  
Conventional Solid State Reaction ◽  
Single Phase Sample ◽  
Ion Conductor ◽  
Oxygen Ion ◽  
Direct Current Conductivity ◽  
Oxygen Ion Conductor ◽  
Sample Density

Based on the oxygen ion conductor La2Mo1.5W0.5O9, a series of Ag2O doped samples La2Mo1.5W0.5O9/Ag were prepared with conventional solid-state reaction method. The effects of Ag2O doping on the microstructure and electrical conductivity have been investigated by XRD, FESEM and direct current conductivity measurements. With the increase of Ag2O doping, the grain was further refined and compacted, meanwhile, Ag diffusion distribution in the form of second-phase appear at grain boundary. The sample density and conductivity also gradually increased with the increasing of doping amount. The conductivity of the composite specimen La2Mo1.5W0.5O9 /Ag has a great enhancement when the concentration of Ag2O is around 27 wt%, which is eight times higher than that of the single-phase sample.

Activity of Bi2O3 in Bi2O3Y2O3 oxygen ion conductor

1992 ◽  
Vol 98 (1) ◽  
pp. 206-209 ◽  
Author(s):  
Keqin Huang ◽  
Changzhen Wang ◽  
Xiuguang Xu
Keyword(s):  
Ion Conductor ◽  
Oxygen Ion ◽  
Oxygen Ion Conductor

A Composite Ionic-Electronic Conductor in the (Ca,Sr,Ba)-Bi Oxide System

2000 ◽  
Vol 658 ◽  
Author(s):  
James K. Meen ◽  
Oya A. Gökçen ◽  
I-C. Lin ◽  
Karoline Müller ◽  
Binh Nguyen
Keyword(s):  
Polymorphic Transformation ◽  
Alkaline Earth ◽  
Binary Systems ◽  
Bulk Composition ◽  
Stability Limit ◽  
Rhombohedral Phase ◽  
Ion Conductor ◽  
Electronic Conductor ◽  
Oxygen Ion ◽  
Oxygen Ion Conductor

ABSTRACTThe rhombohedral alkaline earth-bismuth oxide phase, an oxygen ion conductor, does not coexist stably with electronic conductors in any of the three binary systems, Ca-Bi-O, Sr-Bi-O, Ba-Bi-O. A thermodynamically stable composite of a rhombohedral phase that contains Ba and Sr or Ca or both with the electronic conductor BaBiO3 may be synthesized. The rhombohedral phase appears to have complete mutual miscibility of the alkaline earth elements. The composi- tions of rhombohedral phase that coexist with BaBiO3 in the Sr-Ba-Bi ternary system and the Ca- Sr-Ba-Bi quaternary systems are described. The value of ionic conductivity of the rhombohedral phase (at a constant Bi: [Ca+Sr+Ba]) is not dependent on the relative amounts of Ca, Sr, and Ba. The temperature at which the rhombohedral phase undergoes a polymorphic transformation from a low-temperature (2) form that is a weak ion conductor to a high-temperature (β1) form that is a much better oxygen ion conductor. The temperatures of the polymorphic transformation and of the upper stability limit of the rhombohedral phase both depend strongly on Ca: Sr: Ba. The β1 form develops in the Ba-Bi system at the lowest temperatures and at the highest ones in the Ca- Bi system. On the other hand, the Ca-Bi phase has greater thermal stability than its Ba ana- logues. The temperature range over which a useful composite conductor can operate is, there- fore, strongly dependent upon the bulk composition of the system.

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