Ten Minute Preparation Of Yba2Cu3O7−x Using Barium Hydroxide

1990 ◽  
Vol 180 ◽  
Author(s):  
N. Coppa ◽  
A. Kebede ◽  
J. W. Schwegler ◽  
I. Perez ◽  
R. E. Salomon ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Liquid Phase ◽  
Barium Hydroxide ◽  
Zero Field ◽  
Bunsen Burner ◽  
High Quality ◽  
Diamagnetic Response ◽  
Heat Treated ◽  
Phase Pure ◽  
Response Field

ABSTRACTHigh quality bulk YBa2CuOx−7 was synthesized by fusing stoichiometric amounts of yttrium and copper nitrates and barium hydroxide, in air, using an ordinary Bunsen burner. The starting materials go through a short-lived liquid phase yielding a solid black product which was subsequently heat treated, (900 C, 18–24 h, in air, followed by 500 C, 5 h., in O2). These materials were greater than 99% phase pure with CuO as the only other phase and they exhibited a transition temperature of 92 K, a 15.5% perfect diamagnetic response (field cooled), 76% (zero field cooled). This synthesis represents an improvement over the much more labor and time intensive conventional methods in that it allows high quality materials of various compositions to be prepared quickly

Preparation of YBa2Cu3O7−x using barium hydroxide flux

1990 ◽  
Vol 5 (12) ◽  
pp. 2755-2758 ◽  
Author(s):  
N. Coppa ◽  
A. Kebede ◽  
J. W. Schwegler ◽  
I. Perez ◽  
R. E. Salomon ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Liquid Phase ◽  
Barium Hydroxide ◽  
Bunsen Burner ◽  
High Quality ◽  
Heat Treated ◽  
Phase Pure ◽  
Hydroxide Flux ◽  
Conventional Methods ◽  
Response Field

High quality bulk YBa2Cu3O7−x was synthesized by fusing stoichiometric amounts of yttrium and copper nitrates and barium hydroxide in air, using an ordinary Bunsen burner. The starting materials go through a short-lived liquid phase yielding a solid black product which was subsequently heat treated (900 °C, 18–24 h in air, followed by 500 °C, 5 h in O2). These materials were greater than 99% phase pure with CuO as the only other phase and they exhibited a transition temperature of 92 K, a 15.5% perfect diamagnet response (field cooled). This synthesis represents an improvement over the much more labor and time intensive conventional methods in that it allows high quality materials of various compositions to be prepared quickly.

scholarly journals The Intramolecular Pressure and the Extension of the Critical Point’s Influence Zone on the Order Parameter

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Jose Luis Rivera ◽  
Homero Nicanor-Guzman ◽  
Roberto Guerra-Gonzalez
Keyword(s):  
Transition Temperature ◽  
Critical Temperature ◽  
Liquid Phase ◽  
Order Parameter ◽  
Bulk Liquid ◽  
Influence Zone ◽  
Molecular Potential ◽  
Liquid Phases ◽  
Dynamics Simulations ◽  
Wide Zone

The critical point affects the coexistence behavior of the vapor-liquid equilibrium densities. The length of the critical influence zone is under debate because for some properties, like shear viscosity, the extension is only a few degrees, while for others, such as the density order parameter, the critical influence zone covers up to hundreds of degrees below the critical temperature. Here we show that, for ethane, the experimental critical influence zone covers a wide zone of tens of degrees (below the critical temperature) down to a transition temperature, at which the apparent critical influence zone vanishes, and the transition temperature can be predicted through a pressure analysis of the coexisting bulk liquid phase, using a simple molecular potential. The liquid phases within the apparent critical influence zone show low densities, making them behave internally like their corresponding vapor phases. Therefore, Molecular Dynamics simulations reveal that the experimentally observed wide extension of the critical influence zone is the result of a vapor-like effect due to low bulk liquid phase densities.

scholarly journals Liquid phase epitaxial growth of high quality GaAs on InP using Se‐doped GaAs buffer layer and grating‐patterned substrates

1995 ◽  
Vol 66 (19) ◽  
pp. 2531-2533 ◽  
Author(s):  
Dong‐Keun Kim ◽  
Ju‐Heon Ahn ◽  
Byung‐Teak Lee ◽  
H. J. Lee ◽  
S. S. Cha ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Epitaxial Growth ◽  
Buffer Layer ◽  
Patterned Substrates ◽  
High Quality ◽  
Liquid Phase Epitaxial ◽  
Gaas Buffer Layer ◽  
Liquid Phase Epitaxial Growth

Quality Improvement of CNT by Thermal Treatment and Enhancement of Properties of CNT/Polymer Composites

2018 ◽  
Vol 772 ◽  
pp. 23-27
Author(s):  
Takashi Amemiya ◽  
Toshiyuki Yasuhara
Keyword(s):  
Polymer Composites ◽  
Mechanical Characteristics ◽  
Polymer Matrix Composites ◽  
Lower Surface ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Matrix Composites ◽  
High Quality ◽  
Heat Treated ◽  
Double Wall

Since CNTs (carbon nanotubes) have excellent electrical and mechanical characteristics, their application as fillers for polymer matrix composites is expected to have great potential. The purpose of this study is to clarify the effect of CNT’s crystallinity quality, which is given by high temperature treatment (i.e. annealing), on the properties of CNT/polymer composites. In this study, double wall type CNT (DWNT) and multi wall type CNT (MWNT) were used and heat treated at up to 2000°C to achieve highly improved crystallinity. Electrical and mechanical properties of the CNT/polymer composites were compared with the various CNT’s crystallinity qualities as measured by ID/IG ratios. As a result, although the composites with higher quality CNTs showed considerably lower surface resistivities, however the same composites had lower Young's modulus and tensile strengths. The reason is thought to be that the high quality CNT has low surface activity and weak adhesion between the polymer and the CNT surface. This suggests that CNTs with higher quality do not always contribute to the improvement to the properties of CNT/polymer composites.

Comparison of Microstructure and Mechanical Properties of Semi-Solid Castings Produced Using Billets Made by EMS and SEED

2014 ◽  
Vol 217-218 ◽  
pp. 332-339 ◽  
Author(s):  
Xiao Kang Liang ◽  
Da Quan Li ◽  
Pascal Côté ◽  
Stephen P. Midson ◽  
Qiang Zhu
Keyword(s):  
Mechanical Properties ◽  
Cross Section ◽  
Dendritic Structure ◽  
Casting Process ◽  
Grain Structure ◽  
High Quality ◽  
Microstructure And Mechanical Properties ◽  
Grain Structures ◽  
Heat Treated ◽  
Semi Solid

The spheroidal grains in billets used for semi-solid casting are generally manufactured by electromagnetic stirring (EMS) during the casting process. This method however, is not economically applicable for small quantities of the thixo billets. Swirled Enthalpy Equilibration Device (SEED) has been developed as a rheocasting process, and the SEED process is of interest for developing new thixo alloys, as well as for optimizing the thixocasting processes for high quality components. The objective of this paper is to compare the microstructure and mechanical properties of aluminum alloy 319s billets and castings produced using EMS and SEED feed materials. The experimental results show that for as-cast billets made from SEED process, a well-developed spheroidal grain structure is distributed throughout the cross-section of the billet, while for as-cast EMS billets, the grain structure is inhomogeneous, i.e., a dendritic structure was present adjacent to the surface of the billet, while a uniform, spheroidal structure was present at the centre. After the thixocasting process, however, the both SEED and EMS billets have well-developed, spheroidal grain structures. Mechanical properties of thixocast and T61 heat treated components are comparable for the both SEED and EMS billets.

Growth and characterization of high-quality GaInAsSb layers on GaSb substrates by liquid-phase epitaxy

1992 ◽  
Vol 35 (4) ◽  
pp. 523-528 ◽  
Author(s):  
Meng-Chyi Wu ◽  
Chi-Ching Chen ◽  
Ching-Ting Lee
Keyword(s):  
Liquid Phase ◽  
Liquid Phase Epitaxy ◽  
High Quality

Liquid Phase Epitaxial Growth and Characterization of High Quality GaInAsSb/InAs for Photodiodes

1993 ◽  
Vol 32 (S3) ◽  
pp. 125
Author(s):  
Gong Kan ◽  
Tomuo Yamaguchi ◽  
Isao Suzuki ◽  
Mitsuru Aoyama ◽  
Masashi Kumagawa ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Epitaxial Growth ◽  
High Quality ◽  
Liquid Phase Epitaxial ◽  
Liquid Phase Epitaxial Growth
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