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Matéria (Rio de Janeiro)

versão On-line ISSN 1517-7076

Resumo

BENAVIDEZ, E.  e  GONZALEZ OLIVER, C.J.R.. Influence of yttrium deficiency on the sintering of YBaCuO (123) ceramics. Matéria (Rio J.) [online]. 2006, vol.11, n.2, pp.155-161. ISSN 1517-7076.  http://dx.doi.org/10.1590/S1517-70762006000200009.

In this work the densification of YBa2Cu3O7-x (or 123) ceramic starting from compacts with two compositions having lower Y-contents relative to the superconducting cationic Y:Ba:Cu ratios equal to 1.0:2.0:3.0 were analyzed. Thermal evolution of the powders was monitored by DTA-TG, under O2-flow, up to the peritectic decomposition temperature, Tp»1050ºC. The sintering/densification behavior of these compacts was followed by dilatometric runs under the same DTA-TG conditions. The main sintering mechanisms were analyzed using theoretical models fitted to the densification curves allowing the calculation of the apparent sintering enthalpies. According to dilatometric and DTA-TG runs, the liquid phase sintering (LPS) mechanism controls 85% of the total shrinkage in compact of composition Y0,7Ba2,0Cu3,3Ox (C2) presenting an early grain growth (GG) contribution to densification from 860ºC. It should be noted no GG was detected in compact of composition Y0,7Ba2,3Cu3,1Ox (C1) at temperatures lower than 900ºC. From 900ºC the LPS is thought to be present by the rearrangement stage and then, in the range 930-975ºC, the solution-precipitation process in LPS would be the main densification mechanism.

Palavras-chave : YBa2Cu3Ox; sintering; densification; DTA-TG; dilatometry.

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