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Far-infrared studies on superconductors and heat-capacity studies on liquid crystals. Final report

Technical Report ·
OSTI ID:5627807
Low temperature (2.6 K < T < 30 K) heat-capacity measurements on one transforming V/sub 3/Si sample show that the electronic heat capacity in the superconducting state is well characterized by the weak-coupling BCS theory. Preliminary characterization of one doped /sup 3/He-cooled-Ge-bolometer for far infrared radiation gave resistance approx. = 3 x 10/sup 6/ ..cap omega.. and sensitivity approx. = 1 x 10/sup 6/ V/W at 0.43 K. Finally, one quasi-adiabatic calorimeter with high resolution and versatility has been built for studying phase transitions between the mesophases in liquid crystals which have low thermal conductivity. Heat-capacity studies have been carried out in two important continuous phase transitions, i.e., smectic A (SmA) - hexatic B and SmA - smectic C (SmC). A phase with hexatic type of ordering was first found in one liquid crystal mesophase, i.e., hexatic B. Unfortunately our results on the continuous SmA-hexatic B transition lead to large critical exponents associated with heat capacity anomaly and cannot be explained by the existing theories. On the other hand, our results on one continuous SmA-SmC transition indicated the importance of retaining sixth order in the mean-field Landau free energy expansion. Our observation resolves many controversial conclusions related to the nature of SmA-SmC transition.
Research Organization:
Minnesota Univ., Minneapolis (USA). School of Physics and Astronomy
DOE Contract Number:
AC02-79ER10461
OSTI ID:
5627807
Report Number(s):
DOE/ER/10461-10; ON: DE84001123
Country of Publication:
United States
Language:
English