SVIBOR - Project code: 1-03-069

MINISTRY OF SCIENCE AND TECHNOLOGY

Strossmayerov trg 4, HR - 10000 ZAGREB
tel.: +385 1 459 44 44, fax: +385 1 459 44 69
E-mail: ured@znanost.hr

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Project code: 1-03-069


RESEARCH, DEVELOPMENT AND APPLICATION OF SUPERCONDUCTING MATERIALS


Main researcher: ĐUREK, DANIJEL (9915)



Assistants
Type of research: basic
Duration from: 01/01/91. to 12/31/95.

Papers on project (total): 3
Papers on project quoted in Current Contents: 3
Institution name: AVAC, Zagreb (1048)
Department/Institute: Solid State Physics Laboratory
Address: Kesten brijeg 5
City: 10000 - Zagreb, Croatia
Communication
Phone: 385 (0)1 4580 275
Fax: 385 (0)1 4580 275

Summary: We have studied the diffusive properties of oxygen in Y-Ba-Cu-Osystems at 940 C by measurements of the resistive response timeof the samples subjected to sudden increase of the oxygenpressure from 1 to 5 bars. Increase of oxygen pressure leads todecrease of electric resistance of the samples following theexponential law. This can be connected with the diffusivity ofoxygen atoms from the grain boundaries to the interior. At thesame time mechanical strain changes according to Nabarro-Herringexpression. We have measured relaxation times to be greater than10 seconds. We have also focused on mineral murdochite, a new hightemperature superconductivity candidate. Mineral murdochite hasthe similar structure to the structures of the well-known hightemperature superconductors, but was not synthesized in a purephase in laboratories till now.Further,we have located new compounds Ag2PbOx and Ag5Pb2Ox in the mixed Cu-Pb-Ag-O system.Both compounds have a metallic behaviour of electric resistance (50 microohmcm).Electric resistence of Ag2PbOx increases under high oxygen pressure, while decreases in Ag5Pb2Ox after forced doping with oxygen.Chains of Pb-O and planar Pb-O network are responsible for high electric conductivity of Ag2PbOx and Ag5Pb2Ox respectively.New structures were also obtained by doping of these two compounds with Bi atoms.

Keywords: diffusion,superconductivity,oxygenpressure,resistance,sintering,sy nthesis,murdochite,lead,cuprates,manifold,structure,silver,bismuth ,doping

Research goals: The conditions of high temperature superconductors preparingwere investigated by measuring the electrical resistance duringthermal treatment. The diffusivity of oxygen in these materialsduring sintering was also measured. High pressure cell andfurnace were constructed for studies up to 2000 bars of oxygen.New metallic mineral murdochite was synthesized in a pure phaseand its structural parameters were determined.New metal systems Ag2PbOx and Ag5Pb2Ox are the host materials in search for the new possibly superconducting materials by means of appropriate doping.


COOPERATION - INSTITUTIONS


  1. Name of institution: Laboratoire de Cristallographie C.N.R.S.
    Type of institution: State institute
    Type of cooperation: Systematic exchange of information
    City: 38042 - Grenoble, France

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Last update: 10/15/95
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