Heterovalent element substitution is an effective way to optimize functional properties of the Y-Ba-Cu-O high-temperature superconductors. In this study, we analyze the effect of Y-Ca substitution on microstructure and critical current in YBa₂Cu₃O_6.8 ceramics with transmission electron microscopy and magnetometry. The obtained results reveal that the substitution of Y³⁺ by Ca²⁺ initiates the formation of complicated microstructure consisting of Y(Ca)-123 matrix with multiple defects of different types and fine nanoscale Y-211 particles coherently coupled with the matrix. Depending on Ca doping, various microstructural defects such as dislocations, stacking faults, and effects associated with cationic disorder are observed. The magnetic and superconducting properties in Ca-substituted compositions Y-123 are discussed in terms of the sample microstructure morphology and the specificity of coupling between the basic Y(Ca)-123 phase and impurity particles of the Y-211 phase. We find that shape type and dispersion of the Y-211 precipitations are crucial to regulating both the critical current and the critical temperature in the ceramics.

异价元素置换是优化 Y-Ba-Cu-O 高温超导体功能特性的有效途径。在本研究中，我们使用透射电子显微镜和磁力计分析了 Y-Ca 取代对 YBa ₂ Cu ₃ O _6.8陶瓷微观结构和临界电流的影响。所得结果表明，Y ³⁺被Ca ²⁺取代开始形成由具有多种不同类型缺陷的 Y(Ca)-123 基体和与基体相干耦合的细纳米级 Y-211 颗粒组成的复杂微结构。根据 Ca 掺杂，可以观察到各种微观结构缺陷，例如位错、堆垛层错以及与阳离子无序相关的影响。根据样品微观结构形态和基本 Y(Ca)-123 相与 Y-211 相杂质颗粒之间耦合的特异性，讨论了 Ca 取代组合物 Y-123 的磁性和超导性能。我们发现 Y-211 沉淀的形状类型和分散对于调节陶瓷中的临界电流和临界温度至关重要。