Publication Details:

Established in 2008

Journal or Publication Title:

Armenian Journal of Physics=Ֆիզիկայի հայկական հանդես

Date of publication:

2015

Volume:

8

Number:

1

ISSN:

1829-1171

Official URL:

Corporate Creators:

International Scientific-Educational Center of NAS RA ; Yerevan Physical Institute

Coverage:

1-6

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.

Date created:

2015-03-13

Format:

pdf

Identifier:

oai:arar.sci.am:23391

Location of original object:

ՀՀ ԳԱԱ Հիմնարար գիտական գրադարան