Synthesis of a scheelite barium molybdate: Structural, topological, electrical, and transport properties for negative temperature coefficient thermistor application

Abstract

Preliminary structural analysis of Scheelite barium molybdate BaMoO4 (BMO) ceramic using NTREOR-09 and McMaille methods has confirmed the tetragonal symmetry with room temperature X-ray diffraction (XRD) spectrum. Further, other structural parameters like crystallite size and compressive lattice strain are found to be of 31 nm and −0.00151 respectively. The topographical study of scanning electron microscope (SEM) image confirms the polycrystalline nature with no other impurities in the sample. Detailed analysis of dielectric permittivity (εr), and loss (tanδ) supports Maxwell-Wagner and Koop's phenomena. The non-overlapping small polaron tunnelling (NSPT) and correlated barrier hopping (CBH) model have emphasis on transport mechanism. The presence of semiconducting behavior of the scheelite material at various temperatures and frequencies examined by complex impedance and modulus spectra. The value of grain resistance decreases as temperature increases demonstrating the existence of negative temperature coefficient (NTCR) behavior of the material. The increase of the value of thermistor constant (β) (67.339, 516.613, and 772.485 in the different high-temperature range) suggests an efficient application of the material for NTC-thermistor.