Understanding the AC conductivity and permittivity of trapdoor chabazites for future development of next-generation gas sensors
Understanding the AC conductivity and permittivity of trapdoor chabazites for future development of next-generation gas sensors
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DOI：
10.1016/j.micromeso.2017.10.032
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发表时间：
2018-04-01
影响因子：
5.2
通讯作者：
Bowen, Chris R.
中科院分区：
文献类型：
--
作者：
Bordeneuve, Helene;Wales, Dominic J.;Bowen, Chris R.
合成了K+菱沸石（KCHA）、Cs+菱沸石（CsCHA）和Zn 2+菱沸石（ZnCHA），并对其进行了研究，以将它们的晶体结构的差异与它们的热稳定性、含水量和在一定温度范围内的频率依赖性交流（AC）电导率、介电常数和相角联系起来。所示的材料表现出普遍的介电响应，这是典型的材料组成的导电和绝缘区域。由于孔隙的存在，三种菱沸石在室温下显著水合，因此通过将菱沸石加热至高温以确保去除所有不同能量类型的水来实现脱水状态。在从完全脱水状态开始的冷却循环期间，测定KCHA（0.66 +/- 0.10）eV、CsCHA（0.88 +/- 0.01）eV和ZnCHA（0.90 +/- 0.01）eV的阳离子迁移活化能，以提供活化能的准确测量。在高达710摄氏度和低于200摄氏度的温度下观察到材料的良好热稳定性，电性能可以受到水合水平的强烈影响。总体而言，确定了当水合或脱水时，KCHA在所研究的三种菱沸石中具有最高的电导率和最低的阳离子迁移活化能，因此具有最有前途的电学性质，可用作下一代电基气体传感器中的气敏材料。
Synthetic K+ chabazite (KCHA), Cs+ chabazite (CsCHA) and Zn2+ chabazite (ZnCHA) have been synthesized and investigated in order to relate the differences in their crystalline structures to their thermal stability, moisture content and frequency dependent alternating current (AC) conductivity, permittivity and phase angle at a range of temperatures. The materials are shown to exhibit the universal dielectric response, which is typical of materials consisting of both conductive and insulating regions. Due to the presence of porosity, the three chabazites were hydrated significantly at room temperature and so the dehydrated state was achieved by heating the chabazites to high temperatures to ensure that all different energetic types of water were removed. Cation migration activation energies for KCHA (0.66 +/- 0.10) eV, CsCHA (0.88 +/- 0.01) eV and ZnCHA (0.90 +/- 0.01) eV were determined during the cooling cycle from the fully dehydrated state to provide an accurate measurement of the activation energies. Good thermal stability of the materials was observed up to 710 degrees C and below 200 degrees C the electrical properties can be strongly influenced by hydration level. Overall, it was determined that when either hydrated or dehydrated, KCHA had the highest conductivity and lowest cation migration activation energy of the three studied chabazites and thus has the most promising electrical properties for potential use as a gas sensing material in next-generation electrical-based gas sensors.