Growth and Characterization of Bulk Superconductor Material by Dapeng Chen Chengtian Lin Andrey Maljuk & Fang Zhou

Author:Dapeng Chen, Chengtian Lin, Andrey Maljuk & Fang Zhou
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham

Although the HRTEM is a nice tool to observe the intergrowth, the preparation of samples by ion-beam milling after cut perpendicular to Bi-2223 layers is special, sophisticated and time-consuming procedure. Also HRTEM technique is a local probe. Another method to identify a possible Bi-2212 intergrowth in Bi-2223 sample is magnetic measurements of SC transition in zero-field cooled (ZFC) regime. Researchers observed a small (usually <2%) step-like decrease in the magnetization at around 80 K [76, 79] on the good quality samples originated from Bi-2212 intergrowth. It was shown in [80] that XRD technique is a more sensitive tool for the intergrowth detection than ZFC magnetic measurements. Effects of oscillated broadening and peak shift of the (0 0 L) Bragg reflections were demonstrated for the Bi-2223 crystals [80]. This diffraction phenomena is well known for a random intergrowth of a secondary phase (here is Bi-2212). The oscillation amplitude is proportional to the defects concentration if it is relatively low. It enables the authors to estimate the content of intergrowth defects to be about 2 wt% even for the “intergrowth-free” samples according to ZFC measurements. This approach was found to be rather universal being applicable for other layered Bi-based superconductors [81]. Thus, not only the growth of Bi-2223 crystals is a hard task but the correct characterization of as-grown samples requires a special attention, too.

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