Use of Raman microscopy and band-target entropy minimization technique to differentiate physical mixture from chemical mixture in mixed metal oxides

Raman microscopy has been applied to characterize physical and chemical mixtures of mixed metal oxides. The obtained Raman mapping data were first subjected to singular value decomposition to obtain the right singular vectors, and the right singular vectors were then subjected to band-target entropy minimization (BTEM) to recover the pure component spectra of the observed species present in the sample. Subsequently, these resolved pure component spectral information was used to differentiate the physical and chemical mixtures. In addition, BTEM is also able to recover the pure component spectra of both unstable compound and its degradation product due to laser irradiation. In current study, the physical mixture of Mn2O3 and Co3O4, and the chemical mixture of CoMn2O4 spinel oxide were investigated.