We have developed a probe to measure specific heat of Gd-doped PbMo(_6)S(_8), at low temperatures in high magnetic fields up to 12.5 T using a heat pulse method and an a.c. technique. Comparison between these heat capacity measurements and transport measurements provides critical complimentary information about fundamental thermodynamic properties and granularity m superconductors. We have used a tiny, robust, highly sensitive and broadly field independent Cemox thermometer (CX-1030), eliminating the use of bulky gas thermometry or capacitance thermometry. The diameter of the probe is 20 min which facilitates use in our 17 T high field magnet and in free-standing cryostats. Experiments include accurate measurement of temperature oscillations of 10(^-6)K. The measurements and analysis of the data were made fully computer controlled. Measurements on Cu and NbTi demonstrate we achieved an accuracy of ±0.2 K in temperature and a typical accuracy of -10% m the specific heat values quoted. Gd-doped Lead Chevrel phase material Pb(_1-x)Gd(_x)Mo(_6)S(_8) has been fabricated in a controlled environment using simple sintering methods and a Hot Isostatic Press (HIP) operating at pressures up to 2000 atmospheres. Cp has been measured and the properties of the materials including B(_c2)(T) have been determined. HIP processing improves the materials, increasing Tc ~ 15 K and B(_c2)(0) ~ 60 T. These values are amongst the best reported values for the Chevrel phase materials to date. I am personally responsible for taking all the data and its analysis. The modification of the probe were also undertaken by me. The fabrication of the samples was not my work
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:318055 |
| Date | January 1996 |
| Creators | Ali, Salamat |
| Publisher | Durham University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://etheses.dur.ac.uk/5284/ |
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