Abstract
Abstract Effect of praseodymium (Pr 3+ ) substitution at Ca 2+ site in calcium copper titanate, CaCu 3 Ti 4 O 12 (CCTO), has been investigated. Compositions with x =0.10 and 0.20 were synthesized in the system Ca (1−3 x /2) Pr x Cu 3 Ti 4 O 12 by chemical route. Crystal structure is remained cubic. X-ray diffraction and field-emission scanning electron macrographs indicate the presence of secondary phases such as CaTiO 3 and CuO. X-ray photoelectron spectroscopy suggests the substitution of Ca 2+ by Pr 3+ /Pr 4+ . Low temperature admittance spectroscopy identified two deep trapping levels at 0.098 and 0.073 eV for x =0.20 and 0.078 and 0.060 eV for x =0.10. High temperature impedance spectroscopy shows that the grain boundary potential is 0.40 eV and 0.48 eV for x =0.20 and x =0.10 samples respectively. Pr 3+ doping decreases dielectric loss in the bulk at low temperature but increases the dc leakage due to the lower value of grain boundary potential.
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