Synthesis of Single Phase Hg-1223 High Tc Superconducting Films With Multistep Electrolytic Process

We report the multistep electrolytic process for the synthesis of high Tc single phase HgBa2Ca2Cu3O8+ (Hg-1223) superconducting films. The process includes : i) deposition of BaCaCu precursor alloy, ii) oxidation of BaCaCu films, iii) electrolytic intercalation of Hg in precursor BaCaCuO films and iv) electrochemical oxidation and annealing of Hg-intercalated BaCaCuO films to convert into Hg1Ba2Ca2Cu3O8+ (Hg-1223). Films were characterized by thermo-gravimetric analysis (TGA) and differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrolytic intercalation of Hg in BaCaCuO precursor is proved to be a novel alternative to high temperature-high pressure mercuration process. The films are single phase Hg-1223 with Tc = 121.5 K and Jc = 4.3 x 104 A/cm2.Comment: 17 Pages, 10 Figures. Submitted to Superconductor Science and Technolog

Studies on Fabrication of Ag/HgBaCaCuO/CdSe Heterostructures by Pulse-Electrodeposition Route

Metal/superconductor/semiconductor (Ag/HgBaCaCuO/CdSe) heterostructures have been successfully fabricated using pulse-electrodeposition technique. The electrochemical parameters are optimized and diffusion free growth of CdSe onto Ag/HgBaCaCuO was obtained by employing under-potential deposition and by studying nucleation and growth mechanism during deposition. The heterostructures are characterized by X-ray diffraction (XRD), full-width at half-maximum (FWHM), scanning electron microscopy (SEM) studies and low temperature four probe electrical resistivity measurements. After the deposition of CdSe the critical transition temperature of HgBaCaCuO films was found be increased from 115 K with Jc = 1.7 x 103 A/cm2 to 117.2 K with Jc = 1.91 x 103 A/cm2. When the heterostructure was irradiated with red He-Ne laser (2 mW), the Tc was further enhanced to 120.3 K with Jc = 3.7 x 103 A/cm2. This increase in superconducting parameters of HgBaCaCuO in Ag/ HgBaCaCuO/CdSe heterostructure has been explained at length in this paper. Keywords. Electrodeposition; Hg-based cuprate; semiconductor; heterostructures; electrical properties. PACS Nos 81.15.Pq; 74.72.Gr; 78.40.Fy; 84.37; 73.40 *E-mail: [email protected], [email protected]: 22 Pages, 12 Figures. Submitted to Semiconductor Science and Technology. Submitted to Semiconductor Science and Technolog

Development and Realization of Iron-Carbon Eutectic Fixed Point at NPLI

The concept of metal-carbon eutectic temperature fixed point has been introduced in 1999 and is extensively being investigated by thermometry researchers to cover the high-temperature range above copper fixed point. Metal-carbon eutectic fixed points also helped to provide direct traceability with reduced associated uncertainty in the high temperature range for thermometry and radiometry applications. In view of this, CSIR-National Physical Laboratory, India (NPLI) has developed iron-carbon (Fe-C, 1153 A degrees C) eutectic fixed point cell in the graphite crucible and realized by using the noble metal thermocouples. The preparation parameters such as design and fabrication of a graphite crucible, Fe:C eutectic composition and filling procedure, furnace profile, melting and freezing plateau measurements, heat flux immersion, inhomogeneity, etc. have been optimized and presented in this paper. The measurement uncertainty of the Fe-C eutectic cell realized with Type-S thermocouple was estimated to be 3.04 mu V (0.25 A degrees C) at coverage factor k = 2

Development and Long-Term Stability Assessment of Co-C Eutectic Fixed Point for Thermocouple Thermometry

The long-term stability assessment on the Co-C eutectic fixed point cell indigenously developed at CSIR-National Physical Laboratory, India is presented. Metal-carbon eutectic fixed points are promising candidates for the direct traceability to high-temperature thermometry and radiometry. The acceptance of any fixed point as a temperature reference cell depends on its repeatability, reproducibility, and long-term stability. In this paper, we report the detailed investigations on development and realization of Co-C cell and comparison of successive 3-year data to evaluate the long-term stability and robustness of cell. We assigned melting transition temperature to Co-C cell by using Type-S thermocouple, calibrated on ITS-90 fixed points. The cell has been subjected for 270h of melt-freeze cycle since its construction in 2014 and exhibits excellent thermo-mechanical stability. The Co-C melting transition temperature and measurement uncertainty were estimated by using the same Type-S thermocouple, for 3years from 2015 to 2017, and overall drift for the cell was estimated to be 0.1 degrees C, after normalizing the drift of the thermocouple

Assessment of platinum versus palladium thermocouple by comparison against photoelectric radiation pyrometer and noble metal thermocouples

431-438Platinum versus palladium (Pt/Pd) thermocouple, fabricated with high purity wires is now-a-days becoming attraction of researchers to find its application as a high temperature precision sensor. The performance of a Pt/Pd thermocouple when measured by two different techniques of contact and non-contact ways of temperature measurement by comparison method, has been investigated. The Pt/Pd thermocouple has been compared in terms of its electromotive force in μV against a calibrated Type-S or Type-R thermocouple in a spherical blackbody temperature source, having emissivity of 0.98 and using a photoelectric linear pyrometer. The high stability tungsten strip lamps were used as reference standard radiation sources for comparing photoelectric pyrometer, which in turn has been used as a transfer standard for accurately determining the temperature of spherical blackbody source. The experimental results have shown a close agreement between two different techniques used and also an evidence on the advance characteristics of Pt/Pd thermocouple over Type-S or R thermocouple in the high temperature range from 800º to 1300ºC. The uncertainty in the comparison from various sources in the measurement for evaluating temperature was estimated to be within ± 0.65ºC at 800°C and ± 0.47ºC at 1300ºC. </span