Optical characterization and microstructure of BaTiO3 thin films obtained by RF-magnetron sputtering

et al. 2011

This study reports the effect of Cr addition on the structural and superconducting properties of Bi 1.8 Sr 2.0 Crx Ca 1.1 Cu 2.1 O y superconductor with x = 0, 0.1, 0.3, 0.5 0.7, and 1 by means of X-ray analysis (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and resistivity measurements. The samples studied in this work were prepared using the standard solid-state reaction method. Zero resistivity transition temperatures (T c ) are qualitatively estimated from the dc resistivity measurements. The zero resistivity transition temperatures are obtained to decrease from 81 K to 53 K with the increase in Cr addition. Moreover, the phase and lattice parameters were determined from XRD measurements. Based on the refinement of cell parameters done by considering the structural modulation, the Cr addition was confirmed by an increase of the lattice parameter a and decrease of the cell parameter a of the samples in comparison with that of the undoped sample (Cr0). As for the microstructure and element composition analyses on the surface of the samples produced, SEM and EDS measurements were investigated. According to the measurements, not only were the grain sizes of the samples noted to decrease, but also the surface morphology and grain connectivity were obtained to degrade with increase in the

Section: Electrical Resistivity Measurementssupporting

confidence: 63%

Investigation of Structural and Superconducting Properties of Cr Added Bi-2212 Superconducting Ceramics

Yıldırım

Yücel

et al. 2011

“…Besides, the broadening of the resistive transition increases as the Mn content enhances (Fig. 1), confirming the presence of impurities and weak links between the superconducting grains [37], which is supported by the SEM measurements. As a result, the T c values of the samples produced in this work are observed to considerably decrease with the increase of the Mn addition.…”

Section: Electrical Resistivity Measurementssupporting

confidence: 69%

Effect of Mn Addition on Structural and Superconducting Properties of (Bi, Pb)-2223 Superconducting Ceramics

Yıldırım

Yücel

et al. 2011

This study deals with the effect of Mn addition on the structural and superconducting properties of Bi 1.8 Pb 0.4 Sr 2 Mn x Ca 2.2 Cu 3.0 O y ceramics with x = 0, 0.03, 0.06, 0.15, 0.3 and 0.6 by means of X-ray analysis (XRD), scanning electron microscopy (SEM), electron dispersive X-ray (EDX), resistivity, and transport critical current density (J c ) measurements. Zero-resistivity transition temperatures (T c ) of the samples produced via the standard solidstate reaction method are estimated from the dc resistivity measurements. Moreover, the phase fraction and lattice parameters are determined from XRD measurements while the microstructure, surface morphology and element composition analyses of the samples are investigated by SEM and EDX measurements, respectively. It is found that T c values are obtained to decrease from 109 K to 85 K; likewise, J c values are observed to reduce from 3200 A/cm 2 to 125 A/cm 2 with increasing Mn addition. According to the refinement of cell parameters done by considering the structural modulation, the Mn addition is confirmed by both an increase of the lattice parameter a and a decrease of the cell parameter c of the samples in comparison with that of the pure sample (Mn0). SEM measurements show that not only the surface morphology and grain connectivity are seen to degrade but the grain sizes of the samples are found to decrease with the increase of the Mn addition as well. The EDX results reveal that the elements used for the prepara-

“…It is apparent from the table that the offset critical temperatures of the films prepared in this work are observed to be in a range of 54.9-79.7 K. The T-3 obtains the maximum T offset Table 3, indicating that the annealing time and temperature affect dramatically on the broadening of the resistive transition of the samples produced in this work. One can see from the table the minimum T c is about 8.4 K for the T-3 film whereas the maximum T c is about 39.9 K for the T-4 film, resulting from the presence of impurities, grain misorientations and weak links between the superconducting grains [55]. These results are supported by the SEM measurements.…”

Section: Electrical Resistivity Measurementssupporting

confidence: 69%

Effect of Annealing Time and Temperature on Microstructural and Superconducting Properties of (Bi,Pb)-2212 Thin Films Produced by Magnetron Reactive Sputtering

Varılcı

2012

This study deals with the role of various annealing time (1 h, 2 h, 4 h, 6 h and 8 h) and temperature (840 and 850°C) on the microstructural and superconducting properties of thin films with the aid of scanning electron microscopy (SEM), X-Ray analysis (XRD), electron dispersive X-Ray (EDX), resistivity and transport critical current density (J c ) measurements. The T c , J c , variation of transition temperatures, hole-carrier concentration, grain size, phase purity, lattice parameter, surface morphology, element distribution, crystallinity and resistivity (at room temperature) values of the films prepared are compared with each other. Critical transition temperatures (T c ) of the samples are deduced from the dc resistivity measurement while critical current density values are estimated from the critical current and total cross-sectional area values. It is found that maximum T c of 79.7 K and J c of 1520 A/cm 2 are observed for the film annealed at 840°C for 6 h as against 54.9 K and 30 A/cm 2 (minimum values), respectively, for the film annealed at 840°C for 4 h. Moreover, SEM images indicate that the former has the best crystallinity, grain connectivity and largest grain size. Based on these results, T c and J c values of the samples studied are found to depend strongly on the microstructure. Additionally, EDX results show that the elements used for the preparation of all the samples are observed to distribute homogeneously. As for the XRD results, all the samples exhibit the polycrystalline superconducting phase with the changing intensity This study is devoted to Gulnur Ozdemir on the occasion of her 26th Birthday. of diffraction lines. According to the refinement of cell parameters done by considering the structural modulation, the largest lattice parameter a and c are obtained for the film annealed at 840°C for 8 h. To sum up, the aim of the present study is not only to investigate the changes of microstructural and superconducting properties of the samples fabricated in the varied time and temperature but to determine the best ambient for the film fabrication and show the feasibility of obtaining Bi-2212 film with tailored structure, as well.