Structural, Optical, and Temperature Dependent Ferroelectrics Study of Ni-Doped Sodium Zincate

Abstract

The demand for environmentally benign ferroelectric oxides has intensified in recent years, driven both by ecological concerns and the search for high-performance multifunctional materials. Sodium zincate (Na₂ZnO₂) has emerged as a material of interest owing to its chemical robustness, non-toxic nature, and structural adaptability. Nonetheless, its relatively wide electronic bandgap and only moderate ferroelectric activity restrict its usefulness in advanced electronic and optoelectronic systems. In the present work, nickel (Ni) was introduced at the zinc site to overcome these drawbacks, with the aim of simultaneously tailoring the structural, electrical, and optical behavior of Na₂ZnO₂. Polycrystalline ceramics with Ni concentrations ranging from 0 to 10 mol% were fabricated through a conventional solid-state route. High-purity Na₂CO₃, ZnO, and NiO powders were carefully weighed, mixed, and subjected to high-temperature calcination to encourage phase formation. Phase formation and lattice modifications were examined by X-ray diffraction (XRD), with Rietveld analysis providing lattice constants and crystallite size estimates. Microstructural features such as grain size and density were studied via scanning electron microscopy (SEM). Optical absorption spectra were collected in the UV–Visible region, and electronic bandgaps were estimated using the Tauc formalism. Ferroelectric properties were evaluated from polarization–electric field (P–E) hysteresis loops, recorded across a range of operating temperatures.