Microwave Sintering Effect on the Structural and Electrical Properties of Sodium Potassium Niobate Nanocrystallites

Abstract

Nanocrystallite piezoceramics sodium potassium niobates commonly known as KNN having compositional formula Na_0.50K_0.50NbO₃ were synthesized by ceramic technique using high energy ball milling. The sample was calcined at 850 °C by conventional heating technique for 3 h. The calcined composition powders were pelleted and sintered by microwave heating technique at 1050 °C for different durations viz 10 min, 15 min, 20 min and 25 min. X-ray diffraction (XRD) technique studied the structure of the prepared samples and confirmed the formation of an orthorhombic phase in all the samples. The crystallite size evaluated from the XRD data revealed the formation of nanocrystallites of sizes in the range 32–37 nm. Scanning electron microscopy (SEM) revealed the microstructure of the samples. Electrical properties such as dielectric constant, dielectric loss, a. c. conductivity were measured in the frequency range of 10 kHz to 2 MHz by using an impedance analyzer. The frequency variation of these parameters showed the general dispersion behavior. The effect of microwave sintering for different durations on the structural and electrical properties and the results are discussed in the paper.

Keywords:

• Microwave sintering
• orthorhombic phase
• sodium potassium niobate
• nanocrysallite

Acknowledgments

One of the authors (Huidrom Surjalata Devi) acknowledges to Ministry of Human Resource and Development (MHRD), New Delhi for financial support as a fellowship.