Effect of high-energy ball milling on the electrical properties of NaTaO3 ceramic

Abstract

In this work, the effect of high energy milling time on the structural and electrical properties of NaTaO3 (NT) ceramics synthesized using standard solid-state reaction method was investigated. X-ray diffraction studies indicated that the unit cell structure for all samples is orthorhombic (space group: Pnma). FTIR spectra also confirmed the formation of NT without any new phase. The NT ceramics prepared with 10 h milled powder showed the formation of small grain sizes (∼1.2 µm) which is beneficial for dielectric applications in high density integrated devices. The NT ceramics prepared with the 10 h milled powder exhibited superior dielectric properties, i.e. enhancement in ε′ value (from 290 to 1270) and reduction in tg δ (from 0.59 to 0.23) at 1 kHz compared to the ceramics prepared with the unmilled powder. Impedance analysis indicated the negative temperature coefficient of resistance (NTCR) character with non-Debye type of dielectric relaxation. The correlated barrier hopping model successfully explains the mechanism of charge transport in the present ceramic samples. The values of remnant polarization and coercive field of the poled samples prepared with the unmilled and 10 h milled powders were found to be 0.71 µC/cm2 and 2.03 kV/cm and 8.74 µC/cm2 and 4.14 kV/cm, respectively. The field dependent polarization studies at room temperature indicated that NT is a promising lead-free electrostrictive material for industrial applications.

Keywords

• NaTaO3
• lead-free electroceramics
• milling
• structure
• dielectric and ferroelectric properties