## Theses and Dissertations @ UNI

#### Availability

Open Access Dissertation

#### Abstract

This research focused on ($Tl\sb{0.5-x}Pb\sb{0.5-x}Eu\sb{2x})Sr\sb{2-y}Ba\sb{y} Ca\sb2Cu\sb3O\sb{z}$ compound to determine the optimum y (Barium concentration), and then studied the effects of doping Eu in Tl, Pb sites. Studies on optimum y give rise to a high quality superconducting material as a target material for sputter deposition of thin films for electronics applications. Samples were prepared as precursor Sr-Ba-Ca-Cu-O first. The appropriate amount of PbO and $\rm Tl\sb2O\sb3$ then were added to form the superconducting compound. Each sample was heat treated at 900$\sp\circ$C for 24 hours twice and the pellets were made under the pressure of 15,000 PSI. The ($Tl\sb{0.5}Pb\sb{0.5})Sr\sb{2-y}Ba\sb{y}Ca\sb2Cu\sb3O\sb{z}$ superconductors with y varying from y = 0 to y = 1.0 were processed and sintered in air inside a Pt crucible at 880$\sp\circ$C for 10min. Sintered samples were characterized using the ac susceptibility and x-ray diffraction measurements. From the AC susceptibility measurements, the critical temperature of the samples (Ba = 0.0 to Ba = 1.0) is between 100$\sp\circ$K and 120$\sp\circ$K. Sample with Ba doping of 0.75 showed the highest T$\sb{c}$ of 118$\sp\circ$K and higher magnitude of $\chi\sp\prime$ indicating the dominance of 1223 phase and higher volume fraction of superconductivity in this superconducting compound. The powder x-ray diffraction measurements indicated that the strongest peak for the 1223 phase is the (105) peak close to 2$\theta$ = 30$\sp\circ$. When Ba is below 0.5, the intensity of (105) peak is slowly increasing and 1212 phase is predominent. When Ba is above 0.5, the intensity of the 1223 peak improves, indicating the growth of significant 1223 phase in the superconductor. Other studies of importance in this research is the doping of Europium in Tl and Pb sites. Europium being a rare-earth metal offers the possibility of magnetic studies using Mossbaur spectroscopy. This gives an unique opportunity to study the structure of TlPbSrBaCaCuO superconductor precisely. A notable observation in the Eu doping superconducting samples is the paramagnetic nature of the samples above the critical temperature.

1996

#### Department

Department of Industrial Technology

5-1996

#### Object Description

1 PDF file (ix, 134 pages)

EN

application/pdf

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