RESEARCH, DEVELOPMENT AND APPLICATION OF SUPERCONDUCTING MATERIALS
Main researcher
: ĐUREK, DANIJEL (9915) Assistants
MANOJLOVIĆ, VELJKO (129255)
PAIĆ, NADJA (141122)
DUŽEVIĆ, DAVOR (78962)
MEDUNIĆ, ZVONKO (900242)
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.
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
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 Other information about the project.