Crystal Growth and High-Pressure Effects of Bi-Based Superconducting Whiskers

Abstract

Three growth methods were tested for producing high-transition temperature superconducting Bi 2 Sr 2 Ca n –1 Cu n O 2 n +4+δ whiskers, employing different ways to focus a compressive stress and size effect of the precursors. First, thermographic imaging was used to investigate thermal stress from temperature distribution in the precursors during growth annealing. To enhance thermal stress in the precursors, a thermal cycling method and a Ag-paste coating method were proposed and found to significantly accelerate the whisker growth. The use of pulverized precursors also promoted whisker growth, possibly due to contribution from the vapor–liquid–solid growth mechanism. The obtained whiskers revealed the typical composition, diffraction patterns, and superconducting properties of the Bi-2212 phase. The proposed methods were able to stably produce longer whiskers compared to the conventional method. Using the obtained whiskers, electrical transport measurements under high pressure were successfully performed up to around 50 GPa.

Pressure-induced superconducting-insulating phase transition in copper oxide superconductors

“…其中, 在 4.9-23.1 GPa范围内观察到的电阻曲线"双台阶"现象, 分别对应二维和三维超导转变, 与我们之前的研究结果一致 [47] ; (c), (f) 过 掺杂(OD)样品在1.0-49.0 GPa压力范围内的电阻-温度曲线. 这三种样品在临界压力(P i )以上均表现出相同的类似绝缘态的行为 (1) 除了我们获得的接近量子相变点的实验数据 (见图4红线连接的数据)外, 仅有Matsumoto等人 [64] 的 实验结果(见图4蓝色五角星)表现出了明显的量子相…”