Tailoring the structural, optical, and dielectric properties of nanocrystalline niobate ceramics for possible electronic application

Abstract

In the past decades, magnesium niobate materials have been extensively investigated due to their exceptional dielectric characteristics at microwave frequencies and are widely employed in microwave dielectric resonators. In present research, the nanocrystalline MgNb2O6 having an orthorhombic crystal structure with P b c n space group was successfully synthesized at 1000oC using a chemical route. X-ray diffraction (XRD), Raman spectroscopy, FESEM, impedance analyzer, and diffuse reflectance spectroscopy (DRS) were used to characterize the prepared phase. The average crystallite size, unit cell volume and the X-ray density of the prepared material were evaluated to be 52.55 nm, 407.65 A˚3 and 4.9865 g/cm3, respectively. The molecular bending and stretching vibrations of metal oxide bonds were examined by Raman spectroscopy, which ranged from 232 cm−1 to 1007 cm−1. FESEM analysis of the prepared ceramics revealed uniformly distributed grains with clear grain boundaries bearing the average grain size of 0.78 µm. A high direct band gap of 2.97 eV was investigated from DRS. The impedance analysis of the prepared phase revealed a decrease in the capacitance and dielectric constant between 40 Hz to 10 MHz. At 10 MHz frequency, the dielectric constant of the material was found to be 13.15. The loss tangent also displayed a systematic decrease with the increase in frequency from 40 Hz to 10 MHz.