Ortiz-Mosquera Jairo F, Nieto-Muñoz Adriana M, Rodrigues Ana C M
Programa de Pós-graduação em Ciência e Engenharia de Materiais, Universidade Federal de São Carlos, CP 676, 13565-905 São Carlos, SP, Brazil.
Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, CP 676, 13565-905 São Carlos, SP, Brazil.
ACS Appl Mater Interfaces. 2020 Mar 25;12(12):13914-13922. doi: 10.1021/acsami.9b23065. Epub 2020 Mar 12.
In this study, we synthesize glass-ceramics of the new NaGe(SiO)(PO) NASICON (Na super-ionic conductor) series to evaluate the effect of Si/P substitution on the structural, microstructural, and electrical properties of the NaGe(PO) system. From X-ray diffraction, the presence of the NASICON phase is confirmed in all glass-ceramics. An expansion of the unit cell volume suggesting an increase in the bottleneck of the NASICON structure is also observed. Impedance spectroscopy allowed the separation of grain and grain boundary contributions. We observe that the grain conductivity is higher than the specific grain boundary conductivity in all of the investigated compositions (0 ≤ ≤ 0.8). The Si/P substitution causes an enhancement of about 2 and 3 orders of magnitude in the grain and specific grain boundary conductivities, respectively. This behavior is attributable to the introduction of new charge carriers (Na) in the NASICON structure and a decrease in the activation energy. Finally, the lowest activation energy for grain (0.586 eV) is observed in the = 0.6 sample, which indicates the easiest displacement of ions in the investigated series, suggesting that this composition presents the most suitable bottleneck size for (Na) sodium ion conduction.
在本研究中，我们合成了新型NaGe(SiO)(PO) NASICON（钠超离子导体）系列微晶玻璃，以评估Si/P取代对NaGe(PO)体系的结构、微观结构和电学性能的影响。通过X射线衍射，证实了所有微晶玻璃中均存在NASICON相。还观察到晶胞体积的扩大，这表明NASICON结构的瓶颈增大。阻抗谱能够分离出晶粒和晶界的贡献。我们观察到，在所有研究的成分（0≤≤0.8）中，晶粒电导率高于比晶界电导率。Si/P取代分别使晶粒电导率和比晶界电导率提高了约2个和3个数量级。这种行为归因于NASICON结构中引入了新的电荷载流子（Na）以及活化能的降低。最后，在=0.6的样品中观察到最低的晶粒活化能（0.586 eV），这表明在所研究的系列中离子位移最容易，这表明该成分呈现出最适合（Na）钠离子传导的瓶颈尺寸。
