• JUDE FERNANDEZ

      Articles written in Bulletin of Materials Science

    • Structural and optical analyses of sol–gel synthesized hafnium-doped barium calcium titanate

      JUDE FERNANDEZ B BINDHU M PRABU K Y SANDHYA

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      Materials that integrate more than one useful property in single- and multi-phase structures are known as multifunctional materials. Most of them fall in the category of ABO$_3$ perovskite type and in recent times, these materialshave attracted considerable attention from engineers and scientists around the globe for electronic devices of the future. Among the perovskites, barium titanate-based structures have emerged at the top for modern research in advanced materials. In this study, polycrystalline Ba$_{0.85}$Ca$_{0.15}$Ti$_{(1–x)}$Hf$_x$O$_3$, x = 0.00, 0.05, 0.10, 0.15, materials were synthesized by sol–gel combustion technique and their optical properties were studied. X-ray diffraction (XRD) confirmed that,Ba$_{0.85}$Ca$_{0.15}$Ti$_{(1–x)}$Hf$_x$O$_3$ crystallized at 1000°C with tetragonal symmetry having P4mm space group. In addition to XRD, the presence of the tetragonal phase was confirmed using Raman spectroscopy. The crystallite sizes computed using Scherrer equation were found to range from 15 to 18 nm. Fourier transform infrared spectroscopy analysis showed a significant peak at 565 cm$^{-1}$, confirming the formation of the metal oxide-based ceramics. Ultraviolet-Visible-near-IRspectroscopy of Ba$_{0.85}$Ca$_{0.15}$Ti$_{(1–x)}$Hf$_x$O$_3$ showed a slight increase in bandgap energy with the increase of Hf$^{4+}$. Photoluminescence spectra confirmed the composition of three colours (blue, green and red) with the intensity of emission increasing with Hf$^{4+}$ doping.

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