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本文研究了YBa_2Cu_(3-x)Fe_xO_(7-δ)(0≤x≤0.4)高温氧化物多晶超导体系的电阻,超声声速和超声衰减随温度的变化特性。对于超导样品,声速-温度曲线出现三次明显异常,首先是在超导转变温度附近声速呈现一极小值,表明样品中出现声子软化现象,其次分别在170K和240K附近声速发生两次大的突变,同时超声衰减曲线也相应地出现两个峰,而不超导的样品(x=0.40)只有170K和240K两处出现超声异常,而低温下无明显的声子软化现象,这说明,高温超导相变的发生会导致样品的弹性性质发生变化,而240K处体系发生的相变同高温超导电性无必然的联系,文中还初步讨论了170K超声异常的起因。
In this paper, the resistance, ultrasonic velocity and ultrasonic attenuation of YBa_2Cu_ (3-x) Fe_xO_ (7-δ) (0≤x≤0.4) polycrystalline superconducting system with temperature were investigated. For the superconducting sample, the acoustic velocity-temperature curve appears three distinct anomalies. The first is that the sound velocity shows a minimum value near the superconducting transition temperature, indicating the phenomenon of phonon softening in the sample, followed by the sound velocity twice at 170K and 240K respectively , While the ultrasonic decay curve also showed two peaks correspondingly, while the non-superconducting sample (x = 0.40) showed only ultrasonic abnormalities at 170K and 240K, but no obvious phonon softening phenomenon at low temperature, The occurrence of high-temperature superconducting phase transformation will lead to changes in the elastic properties of the sample. However, the phase transition at 240K is not necessarily related to high-temperature superconductivity. The cause of 170K ultrasonic anomalies is also discussed preliminarily.