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Charge compensation, electrical and dielectric behavior of lanthanum doped CaCu3Ti4O12 |
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| Authors: | Ashutosh Kumar Dubey Prakash SinghSindhu Singh Devendra KumarOm Parkash |
| Affiliation: | a School of Materials Science and Technology, Institute of Technology, Banaras Hindu University, Varanasi 221005, India b Department of Ceramic Engineering, CET, Bikaner 334004, Rajasthan, India c Department of Ceramic Engineering, Institute of Technology, Banaras Hindu University, Varanasi 221005, India |
| Abstract: | Mechanism of charge compensation on lanthanum, (La3+) substitution on Ca site in calcium copper titanate (CaCu3Ti4O12), and its effect on resulting electrical and dielectric properties has been studied in the present investigation. For this purpose samples were prepared according to two stoichiometries viz. LaxCa(1−3x/2)Cu3Ti4O12 (x ≤ 0.09) and LaxCa(1−x)Cu3Ti4O12 (x = 0.03) by solid state ceramic route. The former represents ionic compensation while the later is in accordance with electronic compensation. Nature of charge carriers is identified by measuring Seebeck coefficient which is found to be negative in the entire range of measurement. In order to understand the mechanism of conduction, ac conductivity is measured as a function of temperature and frequency. Space charge polarization is the dominant polarization mechanism phenomenon at low frequency and high temperature while orientation polarization dominates at low temperature and high frequency. Impedance analysis confirms the formation of internal barrier layers which is responsible for high dielectric constant in these samples. |
| Keywords: | CaCu3Ti4O12 Charge compensation ac conductivity dc conductivity |
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