| Full text | |
| Author(s): |
Total Authors: 4
|
| Affiliation: | [1] Universidade de São Paulo. Instituto de Física - Brasil
[2] Universidade de São Paulo. Instituto de Física - Brasil
[3] Universidade de São Paulo. Instituto de Física - Brasil
[4] Hebrew University. Department of Inorganic and Analytical Chemistry - Israel
Total Affiliations: 4
|
| Document type: | Journal article |
| Source: | Brazilian Journal of Physics; v. 32, n. 3, p. 731-738, 2002-09-00. |
| Abstract | |
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: | 00/07362-5 - Lina Ben Dor | The Hebrew University of Jerusalem - Israel |
| Grantee: | Renato de Figueiredo Jardim |
| Support Opportunities: | Research Grants - Visiting Researcher Grant - International |
| FAPESP's process: | 99/10798-0 - Study of intergranular phenomena in ceramic oxides |
| Grantee: | Reginaldo Muccillo |
| Support Opportunities: | Research Projects - Thematic Grants |
| FAPESP's process: | 98/11522-6 - New investigations using magnetization-step method. |
| Grantee: | Xavier Gratens |
| Support Opportunities: | Scholarships in Brazil - Post-Doctoral |