材料期刊网

采用YBa_2Cu_3O_(+δ)(简称YBCO)多晶陶瓷超导粉末与硅橡胶(110型)按不同质量比进行配料, 经过特殊的制备工艺, 合成不同含量的超导YBCO/硅橡胶高分子复合材料, 分别测量样品的压敏效应和介电特性. 结果表明, 在不同应力作用下, 样品电阻值的变化范围在1～4个数量级. 样品电阻值随测量温度的降低(300~50 K)呈下降趋势, 测量温度降到90 K时, 样品电阻值发生突变, 但在90~50 K没有观察到超导零电阻现象. 室温下, 样品的介电常数随频率的增加(1 kHz~5 MHz)而减小, 介电损耗随测量频率的增大先增大后减小. 随着YBCO含量的增加, 形成的超电容网络微观结构也就越多, 样品的电阻逐渐减小电流加大, 导致超电容中电解质的极化强度有所增加, 两者共同作用的结果导致样品的介电常数、介电损耗均随着YBCO含量的增加而增大.

Pressure sensitive superconductor/polymer composites were prepared using silicone rubber and high temperature superconductor YBa_2Cu_3O_(7+δ)(YBCO)powder at different mass ratios. The piezoresistance and the dielectric properties of the composite samples at room temperature were measured. It was found that the resistance of all samples decreases exponentially with increasing pressure: application of different pressurees could result in a decease of 1～4 orders of magnitude in resistivity. Both resistivity and its sensitivity to external pressure vary with the superconductor filler content. The electrical resistivity was also measured as a function of temperature for samples from 300～50 K. The result shows that the change of resistivity is considerably larger. There are sharp decreases in the resistivity of superconductor/polymer composite samples below 90 K, but the sample ofsuperconduction with zero resistivity was not found from 90～50 K. The dielectric content and dielectric loss of thecomposite at room temperature decrease with increasing frequency in the range from 1 000 Hz to 5 MHz. It is foundthat both dielectric constant and dielectric loss are strongly dependent on the YBCO content. With increasing YBCO content, the dielectric constant and dielectric loss of all samples are larger.