Fabrication of large grain YBCO by seeded peritectic solidification

1996 ◽  
Vol 11 (4) ◽  
pp. 786-794 ◽  
Author(s):  
Wai Lo ◽  
D. A. Cardwell ◽  
C. D. Dewhurst ◽  
S-L. Dung
Keyword(s):  
Growth Process ◽  
Melting Process ◽  
Processing Parameters ◽  
Vibrating Sample Magnetometry ◽  
Superconducting Properties ◽  
Solidification Kinetics ◽  
Peritectic Melting ◽  
Superconducting Ceramics ◽  
Peritectic Solidification ◽  
Current Densities

The ability to process large grain, uniform high temperature superconducting ceramics that exhibit high critical current densities at 77 K is essential if the enormous potential of these materials for a range of permanent magnet-type applications is to be realized. We report a study of the fabrication of large grain YBa2Cu3O7−δ by seeded peritectic solidification in which key processing parameters such as the peritectic melting process, the seed-YBCO reaction, and the YBCO solidification kinetics are investigated in detail. Evolution of the sample microstructure during various stages of the growth process, in particular, has been studied extensively. The superconducting properties of specimens cut from different regions of large grain samples have been measured using vibrating sample magnetometry, and the results correlated with the microstructure of the materials.

scholarly journals Importance of the pyrolysis for microstructure and superconducting properties of CSD-grown GdBa2Cu3O7−x-HfO2 nanocomposite films by the ex-situ approach

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Pablo Cayado ◽  
Hannes Rijckaert ◽  
Els Bruneel ◽  
Manuela Erbe ◽  
Jens Hänisch ◽  
...  
Keyword(s):  
Processing Parameters ◽  
Nanocomposite Films ◽  
Ex Situ ◽  
Superconducting Properties ◽  
Critical Temperatures ◽  
Solution Deposition ◽  
Nanoparticle Distribution ◽  
Current Densities ◽  
First Time ◽  
Lower Heating

Abstract For the first time, GdBa2Cu3O7−x nanocomposites were prepared by chemical solution deposition following the ex-situ approach. In particular, ~ 220 nm GdBa2Cu3O7−x-HfO2 (GdBCO-HfO2) nanocomposite films were fabricated starting from a colloidal solution of 5 mol% HfO2 nanoparticles. Hereby, one of the main challenges is to avoid the accumulation of the nanoparticles at the substrate interface during the pyrolysis, which would later prevent the epitaxial nucleation of the GdBCO grains. Therefore, the effect of pyrolysis processing parameters such as heating ramp and temperature on the homogeneity of the nanoparticle distribution has been investigated. By increasing the heating ramp to 300 °C/h and decreasing the final temperature to 300 °C, a more homogenous nanoparticle distribution was achieved. This translates into improved superconducting properties of the grown films reaching critical temperatures (Tc) of 94.5 K and self-field critical current densities ($${J}_{\mathrm{c}}^{\mathrm{sf}}$$ J c sf ) at 77 K of 2.1 MA/cm2 with respect to films pyrolyzed at higher temperatures or lower heating ramps.

Fabrication, Structural, and Spectroscopic Investigation of Tb-Doped Lu3Al5O12 Phosphor

2005 ◽  
Vol 20 (11) ◽  
pp. 2934-2939 ◽  
Author(s):  
Yikun Liao ◽  
Danyu Jiang ◽  
Tao Feng ◽  
Jianlin Shi
Keyword(s):  
Particle Size ◽  
Crystallization Temperature ◽  
High Performance ◽  
Growth Process ◽  
Solution Combustion Synthesis ◽  
Processing Parameters ◽  
Solution Combustion ◽  
Urea Content ◽  
Emission Intensity Ratio ◽  
Combustion Synthesis Technique

A simple solution combustion synthesis technique was explored to produce Tb3+-doped Lu3Al5O12 (LuAG:Tb) phosphor with particle size in the range from about 25 to 900 nm by using glycine, urea, and the mixture of them as fuels. The effects of processing parameters such as type of fuel, fuel-to-oxidizer ratio and the composition of the complex fuel were studied. An increase in phosphor brightness and a decrease in crystallization temperature with increasing urea content in the fuel were observed. The integrated emission intensity ratio of the 5D3–7Fj transition to the 5D4–7Fj transition as a function of Tb concentration in LuAG was also investigated. It is very interesting that the growth process of the particles exhibited two steps when the content of urea in the complex fuel increased from 0 to 1.0. By tailoring the glycine-to-urea ratio in the fuel, an excellent fuel was found and high performance phosphors were obtained.

Structural and superconducting properties of melt-grown Y–Ba–Cu–O superconductors

1996 ◽  
Vol 11 (10) ◽  
pp. 2406-2415 ◽  
Author(s):  
R. Gopalan ◽  
T. Rajasekharan ◽  
T. Roy ◽  
G. Rangarajan ◽  
V. Ganesan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Strain Field ◽  
Crack Width ◽  
Growth Process ◽  
Critical Radius ◽  
Radius Of Curvature ◽  
Superconducting Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron

YBa2Cu3O7 (123) samples with varying Y2BaCuO5 (211) concentrations (0 mol%, 20 mol%, 28 mol%, and 50 mol%) were synthesized by the melt-growth process. Microstructural characterizations were done using x-ray diffraction (XRD), optical microscopy, scanning electron microscopy, and transmission electron microscopy (TEM). It was found that 123 platelet width, crack width between the platelets, and 211 particle size decreased systematically with increasing 211 concentration. TEM study showed that there is a critical radius of curvature (rc ≤ 0.2 μm-0.3 μm) of the 123/211 interface where defects/contrasts of strain field start to appear, and these defects are believed to be responsible for pinning the magnetic flux. Microhardness measurements showed that Vickers hardness (VHN) increases with increasing 211 content. Critical current density (Jc) values obtained from magnetization measurements using a SQUID magnetometer were found to increase in melt-grown samples by the addition of 211 content.

SG and SSR approach in the preparation of precursors and influence on superconducting properties of Tl-1223 superconductors

2020 ◽  
Author(s):  
Ioseb Metskhvarishvili ◽  
T.E. LOBZHANIDZE ◽  
G.N. DGEBUADZE ◽  
B.G. BENDELIANI ◽  
M.R. METSKHVARISHVILI ◽  
...  
Keyword(s):  
Solid State ◽  
Ambient Pressure ◽  
Sol Gel ◽  
Heat Treatments ◽  
Superconducting Transition ◽  
Superconducting Properties ◽  
Step Method ◽  
Chemical Homogeneity ◽  
Wet Chemistry ◽  
Current Densities

Abstract The paper presents the comparative analysis of the Sol-gel (SG) and solid-state reaction (SSR) route for the synthesis of precursors for thallium-based superconductors. Samples were prepared a two-step method and by sealed quartz tube technique in ambient pressure. Heat treatments of precursors showed that to obtain high-purity precursors, without any carbonate contamination for SG methods is sufficient to heat treatments at 915oC temperatures and for SSR methods 945oC. The diamagnetic onset temperature of the superconducting transition for the TlBa2Ca2Cu3O8+δ samples prepared by precursors SG at 915oC and SSR at 945oC is about T = 120 K and full screening of applied ac magnetic fields observed at T ≈ 102 K and T ≈ 94 K, respectively. The value of Jc transport critical current densities for SSR obtained 128 A/cm2, whereas for the SG sample and exactly 174 A/cm2. We could conclude that the, using the wet chemistry offers some advantages in comparison with the classical solid-state ceramics processing, especially, better chemical homogeneity and higher reactivity of the precursor powder.

Effects of a liquid carbon dopant on the superconducting properties of MgB2

2010 ◽  
Vol 1254 ◽  
Author(s):  
Hyo Jin. Kim ◽  
Bong Kun. Lee ◽  
Chan Joong. Kim ◽  
Kyu Mann. Lee ◽  
Hai Woong. Park
Keyword(s):  
Heat Treatment ◽  
Carbon Doping ◽  
Chemical Doping ◽  
Superconducting Properties ◽  
Liquid Media ◽  
Liquid Carbon ◽  
Boron Powder ◽  
Carbon Doped ◽  
Current Densities ◽  
Liquid Type

AbstractVarious types of chemical doping have been reported as very effective methods to improve the superconducting properties of MgB2 superconductor. Specially, carbon doping via liquid type of carbon-containing compounds have been shown better superconducting properties. In this work, the liquid type of glycerin (C3H8O3) was used as a carbon dopant in MgB2 synthesis. The glycerin was mixed with a liquid media at a different ratio and then pretreated with refined boron powder. Then carbon doped MgB2 superconductor was synthesized through subsequent heat treatment of the pretreated boron powder with magnesium powder. Variation of the amount of carbon dopants and viscosity of the liquid media was correlated with critical current densities and other superconducting properties of MgB2 bulk. The effects of liquid carbon dopants on the superconducting properties also compared with those of solid dopants.

scholarly journals Development of a Fluorine-Free Polymer-Assisted-Deposition Route for YBa2Cu3O7−x Superconducting Films

Coatings ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 966
Author(s):  
Mircea Nasui ◽  
Ramona Bianca Sonher ◽  
Traian Petrisor ◽  
Sorin Varodi ◽  
Cornelia Pop ◽  
...  
Keyword(s):  
Superconducting Films ◽  
Single Step ◽  
Precursor Powder ◽  
Superconducting Properties ◽  
Epitaxial Relationship ◽  
Ybco Films ◽  
Out Of Plane ◽  
Growth Method ◽  
Current Densities ◽  
Kinetics Of

Polymer assisted deposition (PAD) was used as an environmentally friendly, non-fluorine, growth method for superconducting YBa2Cu3O7−x (YBCO) films. The kinetics of the thermal decomposition of the precursor powder was studied by thermogravimetry coupled with mass spectrometry (TG-QMS). YBCO films were spin coated on (100) SrTiO3 (STO) single crystalline substrates, followed by a single step thermal treatment under wet and dry O2 and O2/N2 mixture. The as-obtained films were epitaxially grown having a [001]YBCO||[001]STO out-of-plane epitaxial relationship and exhibited good superconducting properties with Tc (R = 0) > 88 K, transition widths, ΔT ≈ 2 K and critical current densities as high as 2.3 MA/cm2 at 77 K and self magnetic field.

scholarly journals Rapid Pyrolysis of SmBa2Cu3O7-δ Films in CSD-MOD Using Extremely-Low-Fluorine Solutions

Coatings ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 31 ◽  
Author(s):  
Minjuan Li ◽  
Pablo Cayado ◽  
Manuela Erbe ◽  
Alexandra Jung ◽  
Jens Hänisch ◽  
...  
Keyword(s):  
Crystallization Temperature ◽  
Chemical Solution Deposition ◽  
Growth Process ◽  
Chemical Solution ◽  
Superconducting Properties ◽  
Heating Rates ◽  
Critical Temperatures ◽  
Solution Deposition ◽  
Rapid Pyrolysis

SmBa2Cu3O7-δ (SmBCO) films have been prepared by chemical solution deposition starting from extremely-low-fluorine solutions (7% fluorine with respect to standard full trifluoroacetate solutions). Smooth and homogeneous SmBCO films could be achieved at heating rates of up to 20 °C/min during pyrolysis. The best films were achieved at a crystallization temperature of 810 °C and 50 ppm of oxygen partial pressure. At these conditions, the ~270 nm thick SmBCO films grow mostly c-axis-oriented with J c sf values at 77 K of ~2 MA/cm2 and critical temperatures Tc of up to 95.0 K. These results demonstrate that using extremely-low-fluorine solutions is very attractive since the production rate can be largely increased due to the solutions’ robustness during pyrolysis retaining a remarkable quality of the grown films. Nevertheless, further optimization of the growth process is needed to improve the superconducting properties of the films.

YBCO Bulk Superconductors with Sm Addition

2017 ◽  
Vol 891 ◽  
pp. 483-488 ◽  
Author(s):  
Daniela Volochová ◽  
Vitaliy Antal ◽  
Jozef Kováč ◽  
Pavel Diko
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Superconducting Properties ◽  
Ybco Bulk ◽  
Pinning Centers ◽  
Bulk Superconductors ◽  
Powder Addition ◽  
Current Densities ◽  
Precursor Powders

The influence of Sm addition on the microstructure and superconducting properties of Y-Ba-Cu-O (YBCO) bulk superconductors has been studied. Precursor powders YBa2Cu3O7-δ (Y-123), Y2O3 and CeO2 were enriched with different amounts of SmBa2Cu3Oy (Sm-123) or Sm2O3 powders with the aim to increase critical current density, Jc,by introducing additional pinning centers. YBCO bulk superconductors with SmBa2Cu3Oy (Y123-Sm) or Sm2O3 (Y123-SmO) powder addition were prepared by the optimized top seeded melt growth process in the form of single grains. Microstructure analysis revealed that Sm2O3 addition leads to a higher amount of smaller Y2BaCuO5 (Y-211) particles, what is related to high critical current densities (Jc ~ 7 x 104 A/cm2) of the YBCO samples with Sm2O3 addition in low magnetic fields. The effect of Sm addition in the form of SmBa2Cu3Oy as well as Sm2O3 powder on Y2BaCuO5 particle size, critical temperature, Tc, and critical current density, Jc, is reported.

Y-BA-CU-O SUPERCONDUCTING CERAMICS

1987 ◽  
Vol 01 (05n06) ◽  
pp. 255-258
Author(s):  
SHUNBAO TIAN ◽  
XIAOFEI LI ◽  
TINGLIAN WEN ◽  
ZUXIANG LIN ◽  
SHICHUN LI ◽  
...  
Keyword(s):  
Grain Size ◽  
Chemical Composition ◽  
Processing Condition ◽  
Superconducting Materials ◽  
Structure Model ◽  
Superconducting Properties ◽  
Final Structure ◽  
Superconducting Ceramics

Polycrystalline Y-Ba-Cu-O superconducting materials have been studied. It was found that chemical composition and processing condition may play an important role in the final structure and superconducting properties. The density has been determined and compared with the calculated value according to the structure model reported by Bell Labs. The grain size and the morphology of the materials were observed by SEM.

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