Low Temperature Thermal Conductivity
Dr. A.M. Awasthi
Specifications:
  • Temperature Range (resolution ~ 0.5K): 10 to 300K.
  • Thml Cond Range (> 3 decades!): 10 mW/m-K to 50 W/m-K.
  • Accuracy: better than 4%.
  • 10K Precision  (Resolution ? / ): 2%.
  • Sample Size: flat 6-8mm wide x 1-3mm thick.
  • For Relative Values: min. one flat surface (pyramidal shape).
  • Data Collection: 8/Hr (<30K/Tstp ~ 0.5K); 4/Hr (>80K/Tstp ~ 5K).



UGC-DAE Consortium for Scientific Research
( An Autonomous Institute of University Grants Commission, New Delhi )

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Relevant Publications -

  • Hump structure below Tc in the thermal conductivity of MgB2 superconductor, R. Lal, A. Vajpayee, V.P.S. Awana, H. Kishan, and A.M. Awasthi, Physica C 469(2-3), 106 (2009).

  • Physical property characterization of bulk MgB2 superconductor, V.P.S. Awana, A. Vajpayee, M. Mudgel, V. Ganesan, A.M. Awasthi, G.L. Bhalla, and H. Kishan, European Physics Journal B 62(3), 281 (2008).

  • Spin-State Transition in La1-xSrxCoO3 Single Crystals, S. Bhardwaj, D. Prabhakaran, and A.M. Awasthi, AIP Conf. Proc. 1349, 131 (2011).

  • Thermal conductivity measurements of carbon-glass hybrid composites from 300K to 20K, R.S. Praveen, Subhash Jacob, CRL Murthy, P. Balachandran, Suresh Bhardwaj, and A.M. Awasthi, 22nd National Symposium on Cryogenics (NSC22), IISc, Bangalore (2008).

  • Carrier Transport in Nano-Inclusioned Magnesium Diboride, A.M. Awasthi, S. Bhardwaj, V.P.S. Awana, A. Figini Albisetti, and G. Giunchi, arXiv:1205.0112.

Besides being a functional property of technically useful materials, thermal conductivity reveals important information about the various heat carriers in a material, and is of paramount consideration in the designing of equipment operating at and withstanding cryogenic or very high temperatures. For physics studies, it provides relaxation rates, mean free paths, scattering/dissipation mechanisms, and identification of thermal carriers in the materials. Thus, while the equilibrium quantities such as specific heat probe only the density of states for various degrees of freedom, and electrical resistivity refers to the charge- carriers only, the scattering & relaxation character of any heat-carrying excitations is revealed by thermal conductivity alone. Of particular importance is the study of  (T) in the gapped (superconducting, AFM, CDW/SDW) ground states, where other transport coefficients (such as dc resistivity) are of little relevance. For anisotropic and multi-band/gapped superconducting/ordered states, angle-resolved  (T) is proven to be the decisive bulk-probe.