Sermsuk Ratreng

The Preparation and Characterization of Y145 Superconductor

In this research, we synthesized and characterized the physical properties of YBa2Cu3Ox (Y123) and YBa4Cu5Ox (Y145) superconductors by solid state reaction and melt process. The raw materials Y2O3, BaCO3 and CuO were mixed, ground and react in the air atmosphere at 950 °C, at 980 °C for solid state reaction and melt process, respectively. The samples obtained were characterized by the resistivity measurement, SEM, EDX, XRD and DTA. It was found that the critical temperature onset of Y145 is 94 K and 96 K for solid state reaction and melt process, respectively. The samples were inhomogeneous with no impurity. The crystal structures was orthorhombic which a = 3.80446 Å, b = 3.86474 Å and c = 19.37104 Å for Y145 solid state reaction and a = 3.80180 Å, b = 3.86483 Å and c = 19.38194 Å for melt process. The peritectic temperature of Y145 is 1018 °C.

Some properties of YBamCu1+mOy(m = 2, 3, 4, 5) superconductors

We synthesized the YBamCu1+mOy superconductors; m = 2,3,4,5 that were Y123 (YBa2Cu3O7-x), Y134 (YBa3Cu4O9-x), Y145 (YBa4Cu5O11-x), Y156 (YBa5Cu6O13-x), by solid state reaction with the Y2O3, BaCO3 and CuO as the beginning materials. The calcination temperature was 950 C and varied the sintering temperature to be 950 C and 980 C. The resistivity measurement by four-point-probe technique showed that the Tconset of Y123, Y134, Y145, Y156 were at 97 K, 93 K, 91K, 85 K, respectively. The XRD and Rietveld full-profile analysis method were used and found that the crystal structure was in the orthorhombic with Pmmm space group with the ratio c/a were 3.0, 4.0, 5.0 and 6.0 for Y123, Y134, Y145 and Y156, respectively. The oxygen content was characterized by Iodometric titration. The (Cu3+/Cu2+and Oxygen content) were (0.28, 6.83), (0.19, 8.81), (0.13, 10.79), (0.16, 12.92) of Y123, Y134, Y145, Y156 respectively. We also found that the increasing of sintering temperature has reduced the oxygen content and the critical temperature of all samples.

Investigate the Properties of Y211 Doping Effect in the New Superconducting Y7Ba11Cu18Oy Compound

The new superconductors of Y-based compound, Y7Ba11Cu18Oy(Y7-11-18), has been discovered by solid state reaction with the different ratios of raw materials. All obtained samples were analyzed and characterized by XRD and the FULLPROF program. The lattice parameters of Y7-11-18 were a=3.8268 Å, b=3.8810 Å and c= 69.8794 Å. The Y7-11-18 showed the sharp transition curve of resistivity (ρ) at the critical temperature (Tc) =94 K. The doping of Y2BaCuO5 (Y211) showed that the higher Y211, the lower Tc and c lattice parameter. The SEM and EDX micrographs showed the grain size about 1-5 μm and without impurities. The DTA analysis resulted the decreasing of peritectic temperature from 962.74 °C by the higher Y211 contents.

Synthesized and characterization of YBa2Cu3Oy, Y3Ba5Cu8Oy, and Y7Ba11Cu18Oy superconductors by planetary high-energy ball-milling

The bulk samples of milled and unmilled synthesized by conventional solid-state reaction. The powder X-ray diffraction and Rietveld refinement software program characterized crystal structure. The elementary mapping technique was used EDXS. For the onset critical temperature (Tconset) and offset critical temperature (Tcoffset) the four-probes measurement method was utilized. The superconducting compound and non-superconducting compound were incorporated in the samples. The Y123 was highest superconducting compound and lowest the non-superconducting compound. The c lattice parameter of milled samples was longer than unmilled samples. The anisotropy parameter of the milled samples had a lower value than the unmilled samples. The mapping technique showed that the without any impurity and composite of Y, Ba, Cu, and O. The critical temperature of milled, Y358, and Y7-11-18 were higher than unmilled. Conversely, the critical temperatures of milled and unmilled Y123 were closed to Y358 and Y7-11-18.

Characterizations of YBa5Cu6Ox Superconductor Synthesized by Melt Process

The YBa5Cu6Ox (Y156) superconductors were synthesized by melt process method with sintering at 980 °C. The samples were characterized by the SEM, EDX, XRD and resistance measurement. The critical temperature onset () and the critical temperature offset () were found at 90 K and 80 K respectively. The crystal structures was orthorhombic performed by Rietveld full-profile analysis method with lattice parameter a = 3.80078 Å, b = 3.89068 Å and c = 22.94436 Å. The c/a ratio was 6.04 and the anisotropy was 2.33. The lower c/a ratio and higher anisotropic were found as increasing the sintering temperature with little change in a and b-axis value. We found that as increasing of sintering temperature, the critical temperature was decreased but the anisotropy was increased.

Effect of Silver Addition on the New Y3Ba8Cu11Ox Superconductors

The Y3-8-11 superconductors and silver composite superconductors were synthesized by solid state reaction. The standard four probes method was used to measure the critical temperature (Tc), and the XRD technique (FULLPROF PROGRAM) was used to determine the lattice parameters, space group and phase compositions. It was found that the pure Y3-8-11 has the lowest Tc onset about 95 K, and the more silver doped concentration, have the higher Tc offset and Tc onset. The samples have both superconducting phase and non-superconducting phase. The silver doped samples have higher superconducting phase. The Pmmm space group was corresponding as to superconducting phase. The non-superconducting phase exhibite in Y211 and BaCuO2 with Pbnm and Im-3m, respectively. The surface of the silver doped sample is much smoother and denser compared to the undoped samples without impurities.

Fabrication of the New Y257 Bulk Superconductor by Melt Process

The Y257 superconductor was prepared by the melt process. The critical temperature of the sample is lower than sample prepared by solid state reaction. The sample are composed of 60% of superconducting phase and 40% of non-superconducting phase. The superconducting phase was orthorhombic structure and Pmmm space group symmetry. The EDX mapping indicated Y, Ba, Cu and O elements intermittently distribute in the sample. The TEM measurements indicated the SAD pattern of the single crystal and the polycrystalline. The DTA measurements indicated that the onset temperature were initially observed at around 999.848°C and offset temperature at 1018.680°C. The sample show the thermal reaction with endothermic reaction.

The Comparative Study of Y123 and Y13-20-33 Superconductors Synthesized by Melt Process

Abstract. In this research, we synthesized and investigate the physical properties of YBaCuO superconductor; Y123 and Y13-20-30. The melt process was used for heat treatment of our samples. We found that the critical temperature onset of Y13-20-33 and Y123 were at 90 K and 94 K, respectively. The morphology of Y123 superconductor has flat surface and more clear grain boundary than Y13-20-33 superconductor. However, more melted of grain boundary were found on Y13-20-33. Both samples were the orthorhombic crystal structure that c/a ratio of Y13-20-33 was higher than of Y123 superconductor.

The Synthesis of YBa 3 Cu 4 O x Superconductor and Comparison with YBa 2 Cu 3 O x

In this research, the Y123 (YBa2Cu3Ox) and Y134 (YBa3Cu4Ox) superconductors were synthesized by solid state reaction and melt process, respectively. The crystal structure of all the samples were then determined using the Rietveld full-profile analysis method to indicate orthorhombic structure. The resistivity measurements showing Tc onset of Y123 lower than Y134 for solid state reaction but higher than Y134 melt process. However, the critical temperature off-set of Y134 has lower than of Y123. The SEM and EDX show that all samples were inhomogeneous. The SEM micrograph for solid state reaction Y123 has many pores between the grain and the grain size clearly demonstrated and bigger than Y134. It was seen that these pores are party eliminated in melt process samples. FTIR spectra detected the trace of carbonate residue in all samples.