The Missile Academy of the Air Force Engineering University (Beijing Academy of Railway Sciences) rang. Through X-ray diffraction analysis and scanning electron microscope observation, the sample was determined to be a perovskite structure, and a high temperature superconducting ceramic material with a zero resistance of 98K was obtained. Good diamagnetic. At the same time, the process conditions for firing a new system of TlBaCaCu2y were also discussed. A Tl-based superconducting ceramic material with zero resistance of 116.5 K was obtained. The material has good diamagnetic resistance.
The sample with the zero-resistance transition temperature of 1:2:C is also basically single-phase, and it has a simple orthogonal structure.
The lattice constant of the orthogonal unit cell was calculated from the diffraction data. Under normal conditions (room temperature): a = 0.3821 nm, b = 0.3898 nm, and c = 1.1695 nm. The data agrees well with the theoretical value of 2.1.2. The calcium copper oxygen system has a tetragonal structure. The lattice constants of the tetragonal unit cells were calculated from the diffraction data. Under normal conditions (room temperature), a=b is very close.
2.2 Measurement of resistance The four-lead method was used to measure the resistance of the superconducting sample. This reduces the influence of the lead resistance and the contact resistance on the measured value (because of the low temperature), which indicates that the sample has a uniform particle size and thus makes its superconducting phase connectivity. With good compactness, it was determined that the sample had a zero resistance temperature of up to 98K. The energy ratio of the metal element of the sample was approximately r(Y):r(Ba):r(Cu)1:2:3, which was in good agreement with the chemical composition before sintering.
98K and 116.K high temperature superconducting ceramic materials, the material has a good diamagnetic. It can be considered that accurate chemical composition, proper sintering temperature, sintering environment, and slow cooling are the key to obtaining high-temperature superconducting materials.
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