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(Reference retrieved automatically from SciELO through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Preparation and general physical properties of polycrystalline PrBa2Cu3O7-y obtained from sol-gel precursors

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V. A. Meza ; X. Gratens ; R. F. Jardim ; L. Ben-Dor
Total Authors: 4
Document type: Journal article
Source: Brazilian Journal of Physics; v. 32, n. 3, p. 731-738, Set. 2002.

Polycrystalline samples of PrBa2Cu3O7– y were prepared through two different routes: (a) mixing Pr6O11, BaCO3, and CuO; (b) sol-gel precursors. The samples were heat-treated in the temperature range 700 <= T <= 930 ºC and under different atmospheres, (Argon and air). Oxidation of these compounds, based on the results of thermogravimetric analysis, TGA, was performed at low temperatures, from 300 to 400 ºC, for time intervals as long as 120 h. The crystal structure was determined by measurements of X-ray powder diffraction and revealed that samples heat-treated at 810 ºC in Ar and for 130 h have a tetragonal structure with lattice parameters c <FONT FACE=Symbol>~</FONT> 11.88 Å. Oxygenated PrBa2Cu3O7-y samples were found to have an orthorhombic structure with lattice parameter c ranging from 11.72 to 11.75 Å. Electrical resistivity rho(T) measurements performed on these compounds revealed a semiconductor-like behavior in the temperature range 77 <= T <= 300 K. The magnetic susceptibility chi(T) data showed a paramagnetic-like behavior from 5 to 300 K and a clear contribution of the crystalline electrical field (CEF) below 150 K. We have also found an antiferromagnetic ordering associated with the Pr sub-lattice at T N <FONT FACE=Symbol>~</FONT> 17 K. Evidence of super-conductivity was not observed on our samples, in agreement with most of the results reported in the literature. (AU)

FAPESP's process: 98/11522-6 - New investigations using magnetization-step method
Grantee:Xavier Gratens
Support type: Scholarships in Brazil - Post-Doctorate
FAPESP's process: 99/10798-0 - Study of intergranular phenomena in ceramic oxides
Grantee:Reginaldo Muccillo
Support type: Research Projects - Thematic Grants
FAPESP's process: 00/07362-5 - Lina Ben Dor | The Hebrew University of Jerusalem - Israel
Grantee:Renato de Figueiredo Jardim
Support type: Research Grants - Visiting Researcher Grant - International