Capacitive, resistive and sensitivity studies of conventional- and plasma-sintered magnesia-stabilized ZrO2@mullite composite
Department of Physics, Faculty of Engineering and Technology (ITER), Siksha ‘O’ Anusandhan Deemed to be University, Khandagiri Square, 751030, Bhubaneswar, Odisha, India
2 Department of Electronics and Communication Engineering, Faculty of Engineering and Technology (ITER), Siksha ‘O’ Anusandhan Deemed to be University, Khandagiri Square, 751030, Bhubaneswar, Odisha, India
Accepted: 25 July 2022
Published online: 10 August 2022
Magnesia (MgO)-stabilized ZrO2@mullite composite was synthesized by using conventional sintering and thermal plasma sintering techniques. The XRD study indicated the formation of orthorhombic mullite phase and stabilization of t-ZrO2 phase in these MgO-added ZrO2@mullite composites. The FTIR study stipulated the presence of Zr-O (zirconia) and Si–O–Al (mullite) bonds in the ZrO2@mullite composite system. Ladder-like interconnected microstructure was formed in the plasma-sintered ZrO2@mullite composite. The room temperature dielectric constant and loss factor of conventional- and plasma-sintered ZrO2@mullite composites were found to be (εr = 3, tanδ = 0.04) and (εr = 6.8, tanδ = 0.07), respectively, at 1 MHz frequency. The conductivity of these composites was of 10−8 order at 300 ℃. The hopping of charge carriers and tunneling of polarons through grain boundaries give rise to conductivity in these ceramic composites. The complex impedance and modulus spectra elucidated that, at higher temperatures, a thermally activated non-Debye-type relaxation process occurs in these ceramic composites. Wideband gaps of 3.23 and 3.21 eV were estimated for conventional- and plasma-sintered mullite-ZrO2 composite from UV–vis spectroscopic study. The current–voltage spectrum recorded for the MgO-stabilized ZrO2@mullite composite confirmed that this can be used as a capacitive component in device fabrications.
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