Armenian Journal of Physics

APPEARANCE OF SEMICONDUCTING (DIELECTRIC) CONDUCTION IN POLYCRYSTALLINE HIGH-TEMPERATURE SUPERCONDUCTING CUPRATES AFTER HEAT TREATMENT

Nikoghosyan, S.K. and Harutunyan, V.V. and Baghdasaryan, V.S. and Mughnetsyan, E.A. and Zargaryan, E.G. and Sarkisyan, A.G. (2015) APPEARANCE OF SEMICONDUCTING (DIELECTRIC) CONDUCTION IN POLYCRYSTALLINE HIGH-TEMPERATURE SUPERCONDUCTING CUPRATES AFTER HEAT TREATMENT. Armenian Journal of Physics, 8 (1). pp. 1-6. ISSN 1829-1171

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Abstract

We present the results of stimulation of semiconductor (insulator) conductivity in polycrystalline HTS cuprates: YBa2Cu3Ox (sample Y) and Bi1.7Pb0.3Sr2Ca2.5Cu3.6Oy (sample B) after heat treatment during 30 minutes at 400°C and 600°C, correspondingly, and slow cooling to room temperature in ambient conditions. The research was carried out by periodic measurement of temperature curves of resistivity r(Т) vs. aging time ta using the direct current four probe technique. During the whole exposure time (528 hrs), the following characteristic parameters were controlled: superconducting transition temperature Тс, r(290К), and α (ratio of r at 178К and 290К). It was shown that from the ta dependences of these parameters, two following processes could be distinguished: the fast ones observed during relatively short periods and the slow ones observed during longer periods of time. In sample Y the fast processes were accompanied by slow monotonous increase in r(290К) correlated with not monotone changes of Тс, whereas in sample B the increase in r(290К) and α correlated with a substantial decrease of Тс. It was revealed that in both samples the slow processes correlated with the formation and increased concentration of semiconducting phase, which as the final result led to metal-insulator transition in them.

Item Type:Article
Subjects:Physics > 72.Electronic transport in condensed matter
Physics > 74.Superconductivity
ID Code:723
Deposited By:Prof. Vladimir Aroutiounian
Deposited On:13 Mar 2015 18:32
Last Modified:13 Mar 2015 18:32

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