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E. Oliber, E. Benavidez, G. Requena, J. Fiscina, C. Gonzalez Oliver:
"High temperature reactions, densification and the peritectic decomposition of YBa2-xSrxCu3O 7-δ (YBSCO) superconducting ceramics";
Physica C: Superconductivity and its Applications, 384 (2003), 3; 247 - 257.

For YBSCO ceramics (YBa2−xSrxCu3O7−δ with x=0, 0.2, and 0.4) solid state reactions, liquid phase formation and densification behavior up to the peritectic temperature (Tp) are characterized by differential thermal analysis (DTA) and dilatometer runs at controlled heating rates. There is an increase in the Tp from DTA when x is increased. Incremental growth in densification is detected at Tnot, vert, similar950-975 °C which is assigned to the formation of a liquid phase as indicated by the endothermic peak in the DTA run. For Tgreater-or-equal, slantedTp the thickness of the pellets (measured continuously with the dilatometer) continued to decrease owing to the peritectic melting of the main (1 2 3) or (1 2 3)Sr (orthorhombic/tetragonal phase doped with Sr) phases. After an initial viscous flow decrease in height (time exponent close to one), the systems continued to densify with a time law approaching either t1/3 or t1/2. Such isothermal time behaviours are associated to the coarsening stage of the (2 1 1) crystals precipitated in the peritectic liquid. Peritectic decomposition for Sr containing ceramics was significantly slower than that for the undoped ceramics at roughly similar temperatures. The latter can be related to a lower diffusivity/solubility of Y in the doped peritectic liquid. From calibrated X-ray diffractometry it was found the (2 1 1) phase was definitely doped with Sr, meaning also the peritectic liquid could contain some levels of strontium.

n.v.

Y(Ba2−xSrx)Cu3O7−δ superconductors; Sintering; Differential thermal analysis; Peritectic melting

http://dx.doi.org/10.1016/S0921-4534(02)01963-9