Synthesis of YBa2Cu3O7 and YBa2Cu4O8 superconductors via carbonate coprecipitation (original) (raw)
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Simultaneous coprecipitation of the hydroxides for preparing YBa2Cu3O7 superconductors
Journal of Materials Science Letters, 1989
The recently discovered YBazCu307 superconducting material is generally prepared using the standard ceramic technique. The practical limitations of the standared ceramic technique however make it difficult to achieve homogeneous fine particles of the oxide mixture, which is one of the prerequisites for making a good-quality superconductor.
Synthesis and characterization of YBa2Cu3O7−x. Superconducting materials
Materials Research Bulletin, 1988
YBa2Cu307. X superconducting materials have been obtained from oxalate coprecipitation and metalloorganic decomposition. Resistivity and magnetic measurements confirm the superconducting behavior below 90 K. Calorimetric measurements reveal the role of impurities in the specific heat evolution.
Effect of solution pH on the synthesis of the YBa2Cu4O8 superconductor via an EDTA solution process
1997
High critical temperature, T c , YBa 2 Cu 4 O 8 superconducting oxides have been prepared by a solution technique using ethylenediaminetetraacetic acid (EDTA) as complexing agent. The use of an appropriate complexing agent leads to complete mixing of the Y3>, Ba2> and Cu2> cations, and thus facilitates formation of YBa 2 Cu 4 O 8 at a lower temperature. The effect of pH on the homogeneity of samples is discussed. The superconducting YBa 2 Cu 4 O 8 sample with T c :80 K was obtained after heat treatment at 820°C. Characterization of the sample by X-ray diffraction (XRD), thermal analysis, scanning electron microscopy (SEM), electronprobe microanalysis (EPM), electrical resistivity, magnetic susceptibility and other spectroscopic analyses are reported.
Materials Letters, 1993
The YBazCusO, superconducting powder was synthesized by the oxalate coprecipitation process. The particle size was controlled by sintering the precursor powder at various temperatures in flowing nitrogen or oxygen atmosphere with subsequent annealing at lower temperature in flowing oxygen atmosphere. The resulting powders with a T, = 92 K had a particle size range from 0.5 to 1.3 urn. Characterizations of the YBa#LtsO, powders by X-ray diffraction (XRD), scanning electron microscopy (SEM) and magnetic susceptibility measurements are reported.
Physica C: Superconductivity, 1997
A new synthetic route is developed to prepare a hydroxide precursor for the superconductor YBa2Cu30 7_ ~. In an inert atmosphere and at low temperature the yttrium, barium and copper hydroxides are co-precipitated by adding the metal perchlorates and sodium hydroxide together. The analysis of the precursor proved the absence of CIO~-and Na ÷ ions. The thermal treatment (12 h calcinating at 950°C, 36 h sintering at 950°C and 6 h annealing at 400°C) gives a superconductor YBa2Cu30 7_ ~ with a transition temperature of 90.2 K. © 1997 Elsevier Science B.V.
Physica C: Superconductivity, 2004
We report systematic studies of AC magnetic susceptibility and transport properties of Y 1-x Ca x Ba 2 Cu 3 O z bulk samples with 0≤x≤0.4. Single phase materials, reduction of carrier concentration and decrease of T c to 83K were obtained at doping levels up to 20%. For Y 0.7 Ca 0.3 Ba 2 Cu 3 O z sample the improvement of grains boundary transport and screening capabilities has been observed as a result of the optimal ratio between carrier concentration and impurity phase BaCuO 2 presence. The appearance of bulk pinning and nonlinear effects starting at the highest temperature were detected also.
Formation of Superconducting YBa2Cu3Oy through Sol-Gel Method
Journal of the Ceramic Society of Japan, 1988
The preparation of superconducting YBa2Cu3Oy through sol-gel method was performed using an acetate aqueous solution. Conditions of gelation and conversion of gel to YBa2Cu3Oy ceramics were investigated, applying thermal analysis, infrared absorption spectroscopy and X-ray diffraction techniques. Transparent gel was obtained from the acetate solution with cation mole ratio of Y:Ba:Cu=1:2:3 by adjusting the initial pH of the solution. Formation of Cu metal, Cu2O and BaCO3 below 400•Ž was found to occur during heat treatment of the gel. Above 600•Ž the heated sample turned into a mixture of Y2O3, BaCO3 and CuO, which finally transformed into the single phase of YBa2Cu3Oy at 910•Ž. The resultant material showed good high Tc superconductivity.
The effect of calcination conditions on the superconducting properties of Y−Ba−Cu−O powders
Journal of Thermal Analysis, 1995
Calcination conditions of the precursor powders, i.e. temperature, type of atmosphere and duration, were determined with a view to obtain superconducting powders with the most advantageous physico-chemical properties. Investigated were powders in the Y-Ba-Cu-O system prepared by the sol-gel method. Thermogravimetrie examinations of the powders have revealed that the decomposition kinetics of BaCO3 determines the formation rate of the superconducting phase. It follows from the decomposition kinetics of BaCO3 that the process is the most intensive in argon, whereas in static air and oxygen it is the slowest. The phase composition analysis (XRD) and low-temperature magnetic susceptibility measurements of t.he calcinated powders, confirm the above mentioned changes in the decomposition kinetics. The reaction of barium carbonate can be completed if the calcination process is conducted at the temperature of 850~ for 25 h, yielding easily sinterable powders for obtaining single-phase superconducting bulk samples with advantageous functional parameters.