The frequency range is 100 Hz to 100 kHz. The doping on ZnO has been done with Cu, Cd and Ru. In come cases ac conductivity increases with doping and in certain cases ac conductivity decreases with doping. Please, can you all suggest some applications. References as attachments are very much welcome.
Dear Dr. Ghosh:
Considering that the limit the solubility went observed during ceramic preparation, then a set of solid-solutions based on the ZnO was prepared. In this sense, dopind of ZnO that is a poor semiconductor with band gap close to 3,2 eV should induce the creation of sub-level at the gap. Then, the electrical conductivity characteristic was modifyed. Seems that an enhanced semiconducting ceramic set can be expected.
Unfortunately, a simple measurement at room temperature gives small information about new properties of solid-solutions prepared.
Also, at a same doping level, a distinct distribution of grain size in the ceramic can be expected.
Depending on the processing parameters as temperature of sintering, time of sintering and atmosphere, others parameters that grain size distribution can be changed as electrical and dielectrical parameters. In fact, typically, from impedance measurements ZnO based ceramics exhibits both grain and grain-boundary phenomena. In this sense, some analysis about the set of cations chosen at doping seems be useful.
Cations Ru can exhibits a several valences as states being the states equal to II, III and IV are most common. Well, if states III and IV be possible, a priori it is possible that complex defects be created. Similar approach can be considered at doping with Cu that can exhibits several valences. Only Cd have the same valence state of Zn. Depending on the balance defect, distinct electrical properties can be expected as a function of temperaure. As a whole, seems possible that ZnO doped with Ru might exibit properties associated with temperature, in this sense, it is possible that a temperature sensor can emerge. Similar event can be expected as a function of doping with Cu.
By completeness, thermistor materials, temperature sensor, can also exhibit some properties involving gas sensing and or vapor (H2O and others phase vapor of polar substances) sensing.
Typically, vapor sensor, gas sensor and temperature sensor (PTC OR NTC) operate in ac corrent, at 50 or 60 Hz, or then at frequency equal to zero.
Kind regards
Marcos Nobre (M. A. L. Nobre)
Thanks Sir Marcos for the quite interesting answer and my regards follow
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