Behavior of Bi1.7Pb0.3Sr2Ca2Cu3O x at high temperature

Carefully prepared and well-characterized Bi1.7Pb0.3 Sr2Ca2Cu3Ox samples were studied by means of differential scanning calorimetry, thermogravimetry, and room and high temperature x-ray diffraction in different atmospheres. It is found that the decomposition of Bi1.7Pb0.3Sr2Ca2Cu3Ox strongly depends on the given conditions. In argon atmosphere, the sample begins to decompose at 850 °C, and finally decomposes mainly into Bi2Sr2CuOx, Cu2O, CaO, and (Sr,Ca)2O3; in air, it decomposes at 880 °C, into Bi2Sr2CuOx, Bi2Sr2CaCu2Ox, Bi1.7Pb0.3Sr2Ca2Cu3Ox, and (Sr,Ca)O; in oxygen, it decomposes at 900 °C, into Bi2Sr2CuOx, Bi2Sr2CaCu2Ox, Bi1.7Pb0.3Sr2Ca2Cu3Ox, and (Sr,Ca)2O3. The process of the melting was in situ studied by high temperature x-ray diffraction and a quenching method. This study gives some hints for growing single crystals of Bi1.7Pb0.3Sr2Ca2Cu3Ox and how to introduce pinning centers into Bi2Sr2CaCu2Ox and Bi1.7Pb0.3Sr2Ca2Cu3Ox.