Low temperature Raman Study on Spinel CO₃O₄

Tah, Twishum (2025) Low temperature Raman Study on Spinel CO₃O₄. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS Dissertation of Twishum Tah (20MS115)) 20MS115_Thesis_file.pdf - Submitted Version Download (2MB)

Abstract

This thesis provides an extensive investigation into the structural and vibrational properties of cobalt oxide (Co3O4) by employing detailed low-temperature Raman spectroscopy, offering an in-depth examination of potential phase transitions at cryogenic conditions. Co3O4, a spinel oxide with considerable interest in fields such as energy storage, catalysis, sensors, and electronic devices, has traditionally been examined predominantly under ambient conditions. However, its detailed low-temperature properties remain insufficiently characterized, leading to a significant gap in condensed matter physics literature and limiting the exploitation of its full technological potential. In this comprehensive study, we have synthesized highly crystalline Co3O4 samples via solidstate reaction methods optimized to ensure reproducibility and purity. The samples underwent rigorous characterization through advanced techniques, including Xray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX), validating both their crystal structure and chemical homogeneity. Subsequent to characterization, an extensive low-temperature Raman spectroscopy campaign was executed, covering temperatures systematically from ambient conditions down to nearliquid helium temperatures. This experimental setup enabled precise detection and monitoring of subtle spectral variations, frequency shifts, and alterations in phonon linewidths, which are sensitive indicators of structural changes, electronic alterations, or lattice dynamics modifications at reduced temperatures. Significantly, our experimental observations reveal distinct anomalies within specific Ramanactive phonon modes, including pronounced frequency shifts, mode splitting, and variations in relative intensities, clearly indicative of previously undocumented low-temperature structural or electronic phase transitions. These findings are analyzed comprehensively within the framework of lattice distortion phenomena, electron-phonon coupling effects, and symmetry-breaking processes, further corroborated by comparison with relevant theoretical models from condensed matter physics.

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