Raman Studies on Potential substrate Materials of Sr(Al1/2Ta1/2)O3 and Sr(Al1/2Nb1/2)O3 For Htsc

1995 ◽  
Vol 397 ◽  
Author(s):  
Ruiwu Tao ◽  
A.R. Guo ◽  
C.-S. Tu ◽  
I. Siny ◽  
R.S. Katiyar ◽  
...  
Keyword(s):  
Niobium Oxide ◽  
Tantalum Oxide ◽  
Complex Oxide ◽  
Growth Technique ◽  
Disorder Effects ◽  
Ceramic Samples ◽  
Microwave Applications ◽  
Laser Heated ◽  
First Time ◽  
Potential Substrate

ABSTRACTComplex oxide perovskites, namely strontium aluminum tantalum oxide (SAT) and strontium aluminum niobium oxide (SAN) were recently investigated to be potential substrate materials for HTSC films in microwave applications. Single crystals were prepared by laser heated pedestal growth technique (LHPG). We report Raman vibrational spectrum studies on them for the first time. Order-disorder effects of (Al, Ta) and (Al, Nb) sites were studied with particular interests by comparing Raman spectra of single-crystal samples with ceramic samples. Influences of B sites (Ta and Nb) on O-O modes are discussed in relation to their dielectric properties.

Single-crystal rare-earth doped YAG fiber lasers grown by the laser-heated pedestal growth technique

2014 ◽  
Author(s):  
Craig D. Nie ◽  
James A. Harrington ◽  
Yuan Li ◽  
Eric G. Johnson ◽  
Elizabeth F. Cloos ◽  
...  
Keyword(s):  
Rare Earth ◽  
Single Crystal ◽  
Fiber Lasers ◽  
Growth Technique ◽  
Laser Heated ◽  
Rare Earth Doped

Mesoporous tantalum oxide photocatalysts for Schrauzer-type conversion of dinitrogen to ammonia

2005 ◽  
Vol 83 (4) ◽  
pp. 308-314 ◽  
Author(s):  
Chaoyang Yue ◽  
Michel L Trudeau ◽  
David Antonelli
Keyword(s):  
Surface Area ◽  
Tantalum Oxide ◽  
Catalytic Efficiency ◽  
Mesoporous Structure ◽  
Turnover Rates ◽  
Type Conversion ◽  
Electron Hole ◽  
Surface Areas ◽  
Before And After ◽  
First Time

Mesoporous tantalum oxide, Fe3+-doped mesoporous tantalum oxide, and bis(toluene) titanium reduced mesoporous tantalum oxide were used for the first time as Schrauzer-type photocatalysts for the conversion of dinitrogen to ammonia. The materials were characterized by XRD, TEM, XPS, and nitrogen absorption before and after catalytic runs. The results showed low to moderate activities depending on the composition. In contrast to previously studied Ti catalysts, Fe doping and heat pretreatment were not prerequisites for photocatalytic activity, but did improve the turnover rates by up to a factor of two. The optimal Fe loading for the tantalum oxides was found to be 1 wt% and the optimal heating condition at 300 °C for 3 h. Increased surface area and heat treatment were also found to improve activities. Contrary to our expectations, reduction of the mesostructure with bis(toluene) titanium had little effect on the catalytic activity. In spite of the dramatically higher surface areas of the mesoporous tantalum oxides as compared with bulk titanias used previously in this process, the overall catalytic activities were still less than those obtained in the Schrauzer system. This suggests that the increase in diffusion and surface area offered by the mesoporous structure is offset by the smaller crystalline domain sizes in the walls of the structure, leading to poor electron-hole separation and a reduction in catalytic efficiency. Key words: mesoporous, Schrauzer, ammonia, photocatalysis, tantalum oxide.

Ba(Mg1/3Ta2/3)O3single crystal fiber grown by the laser heated pedestal growth technique

1994 ◽  
Vol 75 (9) ◽  
pp. 4704-4708 ◽  
Author(s):  
Ruyan Guo ◽  
A. S. Bhalla ◽  
L. E. Cross
Keyword(s):  
Growth Technique ◽  
Crystal Fiber ◽  
Laser Heated

An investigation of melt-textured high Tc superconductor wires made by laser heated pedestal growth technique

1989 ◽  
Vol 162-164 ◽  
pp. 907-908 ◽  
Author(s):  
G.W. Qiao ◽  
J.S. Zhang ◽  
J.G. Huang ◽  
M. Jiang ◽  
Y.L. Ge ◽  
...  
Keyword(s):  
Growth Technique ◽  
High Tc ◽  
High Tc Superconductor ◽  
Laser Heated

Structure and Transport Properties of Sr0.75-xCaxY0.25Co0.25Mn0.75O3-δ (0 ≤ x ≤ 0.6)

2010 ◽  
Vol 1256 ◽  
Author(s):  
Alexandra Galeeva ◽  
Philipp Napolsky ◽  
Sergey Istomin ◽  
Andrey Gippius ◽  
Dmitry Khokhlov
Keyword(s):  
Transport Properties ◽  
Low Temperatures ◽  
Small Polaron ◽  
Calcium Content ◽  
Complex Oxide ◽  
Dc Conductivity ◽  
Polaron Hopping ◽  
Ceramic Samples ◽  
Distortion Parameters ◽  
Hopping Model

AbstractNew complex oxide Sr0.75-xCaxY0.25Co0.25Mn0.75O3-δ with a perovskite-like structure has been synthesized and characterized. DC and AC transport properties of ceramic samples have been studied in the temperature range 4.2K – 1173K. DC conductivity data at T > 300K are discussed in terms of the small polaron hopping model. Dependence of the polaron activation energy on the calcium content is found to correlate with the change of structural distortion parameters. Both the temperature dependence of DC conductivity and the frequency dependence of the real part of the admittance reveal hopping transport at low temperatures.

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