Characterization of C12A7 thin films deposited by spray pyrolysis

In this work, conductive C12A7 thin films were deposited by spray pyrolysis method onto glass substrates. The films, structural, optical and electrical properties were investigated as a function of the spray number. X-rays diffraction showed that the deposited films were polycrystalline with a preferential orientation along the (310) planes. Raman spectroscopy confirmed the C12A7 phase and revealed the superoxide radical \( {\text{O}}_{2}^{ - } \) presence. The C12A7 films, optical transmission varied between 57 and 75 % as a function of the spray number. A constant band energy (4.14 eV), determined from UV–visible spectra, was attributed to the electrons transition from the valence band to the occupied cage level. According to the photoluminescence (PL) spectroscopy, two main emission peaks at 1.55 and 2.81 eV were respectively attributed to the formation of the “F⁺-like centers” and the electron transitions from the occupied cage level to the framework conduction band. Another emission peak at about 2.27 eV was attributed to the cages oxygen vacancies defects. The electrical resistivity variation between 10⁻⁴ and 1.36 Ω cm was correlated to the in cages oxygen vacancies produced during films deposition.