Articles - Nano Progress

Abstract

This work reports the effect of milling on the structural, microstructural, electrical, and piezoelectric properties of NaNbO₃ (NN) ceramics synthesized using a solid-state reaction method. X-ray diffraction studies exhibited that the lattice structure of milled and un-milled NN samples is orthorhombic with a space group Pmc21. The average particle size and lattice strain were found to 203 nm and 0.05 un-milled samples whereas they were 37 nm and 0.2 for 10 h milled samples. FTIR spectra indicated a shift in peak position with milling time. SEM image showed the formation of small grains ~1.2 µm for 10 h milled NN samples which is advantageous for dielectric applications in high density integrated circuits. An increase in the values of dielectric constant from 377 to 698, d33 from 29 to 37, and a drop in critical temperature from 426°C to 352°C at 1 kHz were registered for un-milled and milled samples. A negative temperature coefficient of resistance behaviour was noticed from the impedance and ac conductivity analyses. The correlated barrier hopping model successfully explains the charge transport mechanism in the present ceramic system and ac conductivity data obeyed Jonscher’s universal power law. A marked increment in d33 with smaller particle size was observed with the increasing milling hour that could make NN a promising lead-free piezoelectric material for piezo-sensing/detection and energy harvesting applications.