Raman spectroscopic detection of vacancies in LaFeO3

By coupling Raman measurements and first-principles investigations on bulk lanthanum orthoferrite (LaFeO3), we have demonstrated that the Raman peak around 620 cm-1 usually observed in these samples is a signature of vacancies within the material. This Raman peak can be used as a fast and non-destructive detection test, to determine whether a LaFeO3 sample contains a non-negligible quantity of vacancies. Finally, using first-principles calculations, we propose an infrared spectroscopic method to differentiate the chemical nature of vacancies (oxygen, iron, or lanthanum).