Microcube formation and characterization of cobalt and nickel selenite dihydrate: Thermal, spectral, and dielectric insights

• Published in: Inorganic chemistry communications 2024-10, Vol.168, p.112886, Article 112886
• Main Authors: Naik, Chandan C., Mardolkar, Sudarshana, Salker, A.V.
• Format: Article
• Language: English
• Subjects: Cobalt selenite; Dielectric studies; Metal selenite; Nickel selenite
• ISSN: 1387-7003
• DOI: 10.1016/j.inoche.2024.112886

[Display omitted] •The microcubes were prepared at room temperature by using a precipitation method.•XRD confirmed well-crystallized, isostructural cobalt and nickel selenite dihydrate.•Thermogravimetric analyses revealed key thermal events in the prepared compounds.•IR and Raman studies revealed characteristic bands, validating selenite structure.•SEM showed well-defined microcubes, revealing unique selenite dihydrate morphology.•Dielectric studies showed high values at low frequencies with negligible loss. This paper outlines the template-free preparation of cobalt and nickel selenite dihydrate microcubes using a simple precipitation method from aqueous solutions at room temperature. Structural analysis revealed the formation of pure, well-crystallized isostructural cobalt and nickel selenite dihydrate, exhibiting monoclinic crystal systems of space group P21/n. Thermal analysis showed distinct decomposition patterns for both compounds, highlighting their thermal stabilities. The intermediate formed after water loss were stable up to ∼550 °C, and crystallized before decomposing into their respective oxides via SeO2 sublimation. Scanning electron microscopy (SEM) images illustrated the presence of irregular-sized well-defined microcubes with smooth surfaces and sharp edges, distributed across the material. The formation of these microstructures is likely driven by self-aggregation and the Ostwald ripening process. Dielectric studies on pelletized materials revealed higher dielectric constants at low frequencies with minimal dielectric loss. CoSeO3⋅2H2O exhibited higher dielectric constants than NiSeO3⋅2H2O due to the larger ionic radius of Co2+ ions, which leads to a greater degree of polarization compared to Ni2+ ions. The considerably higher dielectric constant with an insignificant amount of dielectric loss indicates the materials’ potential for applications in dielectric and microwave technologies.