The Effect of the Pressure for the Formation of YBa2Cu3O7–d Bulk Ceramics with Domestic Microwave Oven
Masato Ohmukai
DOI: 10.4236/eng.2011.311136   PDF    HTML   XML   6,114 Downloads   9,629 Views   Citations

Abstract

We fabricated YBa2Cu3O7–d bulk ceramics with a domestic microwave oven and investigated the effect of pressure at the press procedure. If the pressure was not high enough, the ratio of BaCuO2 phase became large, estimated from x-ray diffraction (XRD) measurements. We found that the pressure should be 700 kgf/cm2 at least in order to suppress the BaCuO2 phase.

Share and Cite:

Ohmukai, M. (2011) The Effect of the Pressure for the Formation of YBa2Cu3O7–d Bulk Ceramics with Domestic Microwave Oven. Engineering, 3, 1095-1097. doi: 10.4236/eng.2011.311136.

1. Introduction

High Tc superconductors are well known nowadays. Technical developments of this kind of superconductors are so attractive to be applied to practical use. Among various materials, YBa2Cu3O7–d (YBCO) has been significantly well studied in the wide range of the field on superconducting in a bulk [1] or porous [2] ceramics as well as in a thin-film form. This material is surely supposed to be the most reliable high Tc superconductor. Nowadays, sophisticated study has been performed: the YBCO/metal interface and its application [3,4], YBCO composites with Ag [5] or polymer [6]. Comprehensive survey of current knowledge on this material is described in a book [7].

The bulk ceramic superconductor of YBCO is usually produced by means of sintering process. Since this process is based on a solid chemical reaction, it requires long time and high temperature maintained with a large amount of energy. Baghurst et al. reported microwave syntheses for the formation of YBCO ceramics [8] for the merit of low cost of energy.

Kato et al. reported [9] that a domestic microwave oven was capable to grow YBCO ceramics. This report symbolized that the weak microwave could be applied to form YBCO ceramics effectively. The advantage of this method is surely low energy cost for the processing. One different thing is that BaO was required as a starting material instead of BaCO3.

The interesting method was applied to a continuous growth process by Marinel et al. [10] in such a way that a starting material was passed through a microwave cavity. This is similar to floating zone method for the growth of single crystal of silicon. We expect that the microwave processing will be widely used as a rapid and lowcost method for superconductors.

For the production of YBCO bulk ceramics, a press procedure to form a pellet is known to be one of key points. It is because YBCO is formed by solid phase reactions. We investigated the effect of the pressure on the obtained YBCO characteristics in the microwave procedure.

2. Experimental Details

Commercially available Y2O3, BaO2 and CuO powder at the atomic ratio of Y:Ba:Cu = 1:2:3 (totally 12 g) were mixed and milled in a mortar for 20 min. A fraction of the mixed powder (3 g) was pressed mechanically to be a pellet with the dimensions of 20 mm in diameter and 3 mm in thickness. The pressure was varied between 80 and 2000 kgf/cm2. We did not use any binder materials through the experiment.

The coin-formed pellet was surrounded by an additional mixed powder of 5.5 g and wrapped by a quartz glass wool (2.18 g) and put in a crucible. These surroundings were important to suppress heat dissipation during heating and to absorb enough oxygen into the pellet. The pellet was heated for 25 min. at the microwave power of 200 W and then cooled down naturally. The domestic microwave oven we used was a EM-B1(W) type manufactured by Sanyo Co. Ltd. This oven was useful because the output power of microwave was continuously varied between 50 and 500 W. The frequency was 2.45 GHz.

The samples were investigated by an XRD measurement with RAD-IIA diffractometer (Rigaku, Japan). The x-ray from Cu target whose wavelength was 0.15405 nm was used. The pellet was put on the diffractometer without any process. In the measurements, the θ-2θ method was employed.

3. Results and Discussion

Figure 1 shows XRD pattern when the pellet was pressed at 160 kgf/cm2. The Miller indices are assigned to those of YBCO. The other non-labeled structures may derived from the existence of impurities such as starting materials that did not react enough or other phase. A relatively strong impurity structure situated around 30 degrees corresponds to three reflections by (5 3 0), (6 0 0) and (6 1 1) planes in BaCuO2, assigned with JPCDS card of x-ray diffraction data.

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1] I. L. Landau, J. B. Willems and J. Hullinger, “Detailed Magnetization Study of Superconducting Properties of YBCO Ceramic Spheres,” Journal of Physics C, Vol. 20, No. 9, 2008, p. 5222.
[2] P. Fiertek, B. Andrzejewski and W. Sadowski, “Synthesis and Transoport Properties of Porous Superconducting Ceramics of YBa2Cu3O7–δ,” Reviews on Advanced Materials Science, Vol. 23, 2010, pp. 52-56.
[3] C. Acha, “Dynamical Behaviour of the Resistive Switching in Ceramic YBCO/Metal Interfaces,” Journal of Physics D, Vol. 44, 2011, p. 345301. doi:10.1088/0022-3727/44/34/345301
[4] K. Repsas, A. Laurinavicius, A.-R. Vaskevicius and F. Anisimovas, “Microwave Detection at Metal-High-Tc Superconducting Ceramics Point Contact,” Lithuanian Journal of Physics, Vol. 51, 2011, pp. 25-28. doi:10.3952/lithjphys.51105
[5] N. D. Kumar, T. Rajasekharan and V. Seshubai, “YBCO/ Ag Composites through a Perform Optimized Infiltration and Growth Process Yield High Current Densities,” Superconductor Science and Technology, Vol. 24, No. 8, 2011, p. 5005. doi:10.1088/0953-2048/24/8/085005
[6] R. Abraham, S. Thomas P, S. Kuryan, J. Issac, K. Nanadakumar and S. Thomas, “Structural and Mechanical Properties of YBCO-Polystyrene Composites,” Journal of Applied Polymer, Vol. 118, 2010, pp. 1027-1041.
[7] G. Krabbes, G. Fuchs, W.-R. Canders, H. May and R. Palka, “High Temperature Superconductor Bulk Materials,” Wiley-VCH, Berlin, 2006. doi:10.1002/3527608044
[8] D. R. Baghurst, A. M. Chippindale and D. M. P. Mingos, “Microwave Syntheses for Superconducting Ceramics,” Nature, Vol. 332, 1988, p. 311. doi:10.1038/332311a0
[9] M. Kato, K. Sakakibara and Y. Koike, “Rapid Preparation of YBa2Cu3O7–X with Tc - 90K Using a Domestic Microwave Oven,” Japanese Journal of Applied Physics, Vol. 36, 1997, pp. L1291-L1293. doi:10.1143/JJAP.36.L1291
[10] S. Marinel, G. Desgardin, J. Provost and B. Raveau, “A Microwave Melt Texture Growth Process of YBa2Cu3O7–d,” Materials Science and Engineering: B, Vol. 52, No. 1, 1998, pp. 47-54. doi:10.1016/S0921-5107(97)00274-2

Copyright © 2024 by authors and Scientific Research Publishing Inc.

Creative Commons License

This work and the related PDF file are licensed under a Creative Commons Attribution 4.0 International License.