Significant differences in NaNbO3 ceramics fabricated using Nb2O5 precursors with various crystal structures
Significant differences in NaNbO3 ceramics fabricated using Nb2O5 precursors with various crystal structures
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DOI：
10.1016/j.ceramint.2019.10.098
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发表时间：
2020-02
影响因子：
5.2
通讯作者：
Wei Li;X. Xia;Jiangtao Zeng;Liaoying Zheng;Guorong Li
中科院分区：
文献类型：
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作者：
Wei Li;X. Xia;Jiangtao Zeng;Liaoying Zheng;Guorong Li
NaNbO3(NN)-based solid solutions show potential applications in energy storage capacitors, strain actuators, and electrocaloric cooling devices. However, NN ceramics with distinct structures, which are prepared using various Nb2O5precursors, have not been studied.在这项工作中，使用了两种类型的Nb2O5前驱体，包括共存的斜方和单斜相（表示为OM）和单一斜方相（表示为O）。系统地研究了相结构、晶粒形貌、烧结特性、铁电性能、介电性能和热膨胀性能。 Rietveld refinement of XRD data revealed that synthesized and sintered samples showed different phase structures. The content of ferroelectric phase (Q phase, space group P21ma) was 82.7% in synthesized NN-OM, whereas it was only 73.2% in synthesized NN-O; it was 33.8% in sintered NN-OM, while it was 18.6% in sintered NN-O. Raman spectra verified that the Q phase in NN-OM was more than that in NN-O. Curie temperature (Tc) of NN-OM was 363 °C, whereasTcof NN-O was only 352 °C.此外，与NN-O相比，NN-OM表现出晶粒尺寸分布不均匀、最佳烧结温度较低、相变温度较高、铁电性能更强、热膨胀位移更大。 Therefore, crystal structure of Nb2O5has a great influence on the structure and performances of NN ceramics.
NaNbO3(NN)-based solid solutions show potential applications in energy storage capacitors, strain actuators, and electrocaloric cooling devices. However, NN ceramics with distinct structures, which are prepared using various Nb2O5precursors, have not been studied. In this work, two types of Nb2O5precursors were used, including coexisting orthorhombic and monoclinic phases (denoted as OM), and single orthorhombic phase (denoted as O). Phase structure, grain morphology, sintering characteristics, ferroelectric performance, dielectric properties, and thermal-expansion properties were systematically investigated. Rietveld refinement of XRD data revealed that synthesized and sintered samples showed different phase structures. The content of ferroelectric phase (Q phase, space group P21ma) was 82.7% in synthesized NN-OM, whereas it was only 73.2% in synthesized NN-O; it was 33.8% in sintered NN-OM, while it was 18.6% in sintered NN-O. Raman spectra verified that the Q phase in NN-OM was more than that in NN-O. Curie temperature (Tc) of NN-OM was 363 °C, whereasTcof NN-O was only 352 °C. Furthermore, compared with NN-O, NN-OM showed an inhomogeneous grain size distribution, lower optimum sintering temperature, higher phase transition temperature, stronger ferroelectric performance, and larger thermal-expansion displacement. Therefore, crystal structure of Nb2O5has a great influence on the structure and performances of NN ceramics.