Melting of Bi2Sr2CaCu2O8 + x Ceramics under Uniform Compression

The effect of quasi-hydrostatic pressure (10 MPa) on the melting point of Bi-2212 ceramics and their phase composition after melting is studied. The results demonstrate that compressive stress increases the melting point of Bi-2212 by about 60DGC. Melting at normal pressure leads to the precipitation of the Cu-poor phase (Sr,Ca)CuO2, whereas under quasi-hydrostatic pressure the Cu-rich phase (Sr,Ca)14Cu24041 is formed. The likely reason for the increase in the melting point of Bi-2212 is that uniform compression prevents release of apical oxygen, thereby inhibiting the structural disordering and enhancing the thermal stability of the material.