Incorporation of P5+ and P3− from phosphate precursor in TiO2:P coatings produced by PEO: XPS and DFT study

TORRES-CERON, DARWIN AUGUSTO; AMAYA-RONCANCIO, S.; RIVA, JULIETA SOLEDAD; VARGAS-EUDOR, ALDEMIR; ESCOBAR-RINCON, DANIEL; RESTREPO-PARRA, ELISABETH

SURFACE AND COATINGS TECHNOLOGY

ELSEVIER SCIENCE SA

Año: 2021 vol. 421

0257-8972

he study of the incorporation of P ions in TiO2 coatings was carried out in this work using Plasma Electrolytic Oxidation (PEO) technique, which was analyzed using XPS and compared with simulations using DFT. The synthesis was carried out using the PEO technique making variations of the useful duty cycle between 10 and 50%. The solution used is composed of Na3PO4 and NaOH, with a process duration of 7 min. The TiO2/P coatings were characterized by XPS with high resolution spectra and analyzed by deconvolution of the spectra. The XPS results showed the incorporation into the crystal lattice of P ions in the form of phosphate ions [(PO4)3−] and phosphide ions (P3−). Density functional theory (DFT) calculations were carried out to demonstrate the formation of various structural defects in titanium dioxide systems. The results show the coexistence of TiO2, TiO2/PO4 and TiO2/P. In this case, the reduction of phosphorus from P5+ to P3− favors the generation of titanium pho