Micro- and Nanocrystalline NiO Synthesized by Joule Heating and Thermal Oxidation Methods: A Comparative Study

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• Nickel oxide (NiO) is a stable, p-type semiconductor material crucial for oxide-based microdevices.
• Current synthesis methods for NiO often require high temperatures, long processing times, or complex chemical routes, driving the need for sustainable alternatives.

Purpose of the Study:

• To develop a fast, low-cost, and energy-efficient synthesis route for micro- and nanocrystalline NiO.
• To investigate and compare the microstructural properties of NiO fabricated via Joule heating (JH) versus vapor-solid (VS) methods.
• To analyze the influence of growth parameters on NiO characteristics produced by JH.

Main Methods:

• Fabrication of micro- and nanocrystalline NiO using a Joule heating (JH) process.
• Characterization of NiO samples through Raman spectroscopy and cross-sectional analysis.
• Comparative study with NiO synthesized via vapor-solid (VS) thermal treatments.

Main Results:

• The JH process yields a highly reproducible and controllable NiO microcrystalline structure compared to VS methods.
• Cross-sectional analysis reveals distinct inner/outer regions in JH-grown NiO with varying microstructure, composition, and properties due to controlled oxidation.
• Raman spectroscopy confirms the structural integrity and reproducibility of NiO synthesized via JH.

Conclusions:

• Joule heating presents a viable, sustainable, and efficient alternative for fabricating high-quality NiO microcrystals.
• The JH method offers superior control over NiO microstructure and properties compared to conventional VS techniques.
• This study highlights the potential of JH for scalable and cost-effective production of NiO for advanced technological applications.