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Intergranular Tunnelling and Field-Induced Percolation Fluctuation of Granular Composites (La1-zAgzMnO3)/(MnO2/Mn2O3) 下载免费PDF全文
We investigate the giant magnetoresistance of composites (La1-xAgzMnO3)1-υ(MnO2/Mn2O3)υ. The magnetoresistive property of the composites shows the characteristics of intergranular tunnelling. A conductivity leap has been observed around y = 0.7. The composite (La0.926Ag0.074MnO3)0.698(MnO2/Mn2O3)0.302 has been found to show the greatest magnetoresistance in the samples. Its room-temperature MR ratio reaches 24% under a field of 1.8T. These phenomena suggest a percolation transformation and a kind of field-induced fluctuation in percolation in the samples investigated. 相似文献
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用简易声强计测量声强 总被引:1,自引:0,他引:1
本文介绍作者装置的一台简易声强计,实测误差与理论分析结果符合良好。组成声强计传感器的两个传声器之间的相对相移对测量结果有明显的影响,特别是在频率低端会产生很大的误差,作者通过使用倒向平均法降低了误差。消声室和混响室里的模拟实验结果证实了声强测量能可靠地在现场确定声源的声功率。 相似文献
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