Low-Tc and high-Tc superconducting detectors for high pressure

An experimental procedure has been accomplished to detect high pressures by a specific method, which is based on the dependence of the superconducting critical temperature T c on the external pressure P. For the realization of such kind of measurements a beryllium-bronze multiplicator has been built to create, control and maintain high pressures and different kinds of superconducting sensors have been placed inside it to perceive the pressure and its increase or decrease. The construction and sizes of the high-pressure bomb are suitable to fulfil these requirements. Using oil-pentane mixtures as working media, the arrangement of the multiplicator provides long time stationary pressure conditions for the experiments. From the point of view of sensitivity, In and Sn seem to be the best materials, the critical temperature of which changes by about 1 K in the pressure interval of 1-18 000 bar. The qualitative relation between T c and P can be expressed by - dT c ∼ PT c , but due to nonlinear character of the function T c = f(P) its actual shape can be determined individually for different ranges of pressure on the basis of measurements. As far as the pressure dependence of the critical temperature of high-T c superconductors is concerned, the coefficient dT 0 /dP has average values of 0.64 K kbar -1 , 0.04 K kbar -1 and 0.1 K kbar -1 for La-Ba-Cu-O, Y-Ba-Cu-O and Hg-Ba-Ca-Cu-O compounds, respectively, giving a good starting condition to fabricate pressure detectors from them.