排序方式: 共有117条查询结果,搜索用时 113 毫秒
111.
112.
113.
114.
本文报道了用Co-Ni-Ba-O_2合成的氧化物半导体材料制成的热敏电阻温度计。使用温区为2.8—100K,电阻从几十千欧姆光滑地变化到几十欧姆。相对灵敏度[—dR/dT×1/R]从4.2 K的60%/K左右变化到100 K的1.5%/K左右,达到了实用要求。此温度计的特点是可在强磁场下使用,在4.2 K、7T情况下,磁阻引起的温度变化为1.5~2.0%。温度计的磁阻变化可套用经验公式100×△R/R=c_1H~2/(1+c_2H~2)×T~(-1.5)。当温度不变时(T=4.2K),磁场引起的电阻变化与此公式相符。当磁场不变,磁阻随温度的升高而减小。 相似文献
115.
对La2CuO4掺锌样品在不同降温速率下(330K保温30min后,分别以6Kh和02Ks的速率冷却至42K)电阻率(42—330K)和热导率(80—300K)随温度的变化关系进行了研究.实验结果表明,在不同降温速率下,热导率和电阻率都受到很大影响.快速降温过程使得130K以上的热导率减小,而热导率最小值出现在130K,且与降温速率无关.而低温下的热导率不受降温速率变化的影响.样品在高温区(T高于125K)电阻率随降温速率的增大而增大,低温区电阻率的非线性行为可用变程跳跃行为来描述.所有样品的热导率和电阻率在反铁磁相变温度都没有出现反常,这与能带理论框架下预期的结果和Anderson电荷自旋分离理论发生了矛盾,对此进行了讨论,并用极化子理论进行了自洽解释.
关键词:
La2CuO4
热导率
电阻率 相似文献
116.
117.
Crystal structure, electrical properties and Raman spectra of BaBi1-xPbxO3 are reported. The result of x-ray diffraction shows that the specimen is pure, and the lattice parameters decrease continuously in the semiconducting range, whereas it vibrates similarly to a sine wave in the superconducting range, which is ascribed to the existence of oxygen vacancies and the function of breathing modes of Bi(Pb)O6. The temperature dependence of resistivity indicates that the electrical property of the samples is connected sensitively with the crystal structures. Raman spectra show that the specimen becomes disorder when x increases, and the critical temperature To depends not only on the deformation potential of the soft A19 mode derived from the Bi(Pb)O6 rigid rotation, but also on the energy shift of the mode. 相似文献