Yanchevskii O Z, V'yunov O I, Plutenko T O, Belous A G, Trachevskii V V, Matolínová I, Veltruská K, Kalinovych V, Lobko Ye
Dept. Solid State Chemistry, V. I. Vernadsky Institute of General and Inorganic Chemistry of the National Academy of Science of Ukraine, Acad. Palladin Ave. 32/34, 03142, Kyiv, Ukraine.
G.V. Kurdyumov Institute of Metal Physics of the National Academy of Science of Ukraine, Acad. Vernadskii Ave. 36, 03680, Kyiv, Ukraine.
Heliyon. 2023 Jul 21;9(8):e18523. doi: 10.1016/j.heliyon.2023.e18523. eCollection 2023 Aug.
Ceramics with nominal chemical composition CaCuTiO (CCTO), CaCuTiAlOF (CCTOAF), and CaMgCuTiAlOF (CCTOMAF) were prepared by the solid-state reactions technique. Using SEM, EDX, XPS, EPR, NMR, and complex impedance spectroscopy, the microstructure, elements distribution, chemical composition of grains and grain boundaries, and the dielectric response of ceramics were investigated. In the ССТО, CCTOAF, and CCTOMAF series, the average grain size increases, the degree of copper segregation at the grain boundaries is inversely related to grain size, and the dielectric loss decreases from 0.071 to 0.047 and 0.030, respectively, while dielectric permittivity ε' at 1 kHz is 5.6 × 10, 7.1 × 10, and 4.3 × 10, respectively. Additives of Al, Mg, F and milled particles (ZrO, AlO, and SiO) can either partially introduce into the perovskite structure or form low-melting eutectics at the grain boundaries, causing abnormal grain growth. The presence of copper ions in various oxidation states, as well as evidence of exchange spin interactions between them, was confirmed in all samples.
采用固态反应技术制备了名义化学组成为CaCuTiO（CCTO）、CaCuTiAlOF（CCTOAF）和CaMgCuTiAlOF（CCTOMAF）的陶瓷。利用扫描电子显微镜（SEM）、能谱仪（EDX）、X射线光电子能谱（XPS）、电子顺磁共振（EPR）、核磁共振（NMR）和复阻抗谱，研究了陶瓷的微观结构、元素分布、晶粒和晶界的化学成分以及介电响应。在CCTO、CCTOAF和CCTOMAF系列中，平均晶粒尺寸增大，晶界处铜的偏析程度与晶粒尺寸成反比，介电损耗分别从0.071降至0.047和0.030，而1kHz时的介电常数ε'分别为5.6×10、7.1×10和4.3×10。Al、Mg、F添加剂和研磨颗粒（ZrO、AlO和SiO）要么部分引入钙钛矿结构，要么在晶界形成低熔点共晶物，导致异常晶粒生长。在所有样品中均证实了不同氧化态铜离子的存在以及它们之间交换自旋相互作用的证据。
