Abstract

Sherif G Elsharkawy
Thermal expansion measurements of (Cu0.25Tl0.75)-1234 added by MgO - nano particles
The effect of nano-size MgO (40–60 nm) addition on both granular structure and volume thermal expansion measurements of polycrystalline (Cu0.25Tl0.75)-1234 was studied. The MgO-content x varied from 0.0 to 1.0 wt.% of the sample total mass. Granular investigation using scanning electron microscope revealed that both number and size of voids decreased as x increased from 0 wt.% to 0.6 wt.%. These results were supported by porosity calculation of the samples. The volume thermal expansion was calculated using X-ray powder diffraction from room temperature down to 80 K. The volume thermal expansion coefficient, at room temperature decreased, from 9.3 × 10−5 K−1 to 7.2 × 10−5 K−1 as MgO-concentration increased from 0.0 wt.% to 0.6 wt.% before it increased to 8.9 × 10−5 K−1 for MgO-concentration = 1 wt.%. The Debye temperatures, calculated from the volume thermal expansion coefficient measurements, were reported as a function of MgO-concentration and superconducting transition temperature.