دانلود رایگان مقاله کاهش Sr در کشت آهن استرونتیوم تیتانیت و تغییر ساختار سطح محلی

Abstract

Local surface structure of single crystal strontium titanate SrTiO3 (001) samples implanted with Fe in the range of concentrations between 2 × 1014 to 2 × 1016 Fe/cm2 at 30 keV has been investigated. In order to facilitate Fe substitution (doping), implanted samples were annealed in oxygen at 350 ◦C. Sr depletion was observed from the near-surface layers impacted by the ion-implantation process, as revealed by Rutherford Backscattering Spectrometry (RBS), X-ray photoelectron spectroscopy (XPS), X-ray Absorption Near Edge Spectroscopy (XANES), and Atomic Force Microscopy (AFM). Hydrocarbon contaminations on the surface may contribute to the mechanisms of Sr depletion, which have important implications for Sr(Ti1-xFex)O3- materials in gas sensing applications.

5. Conclusions

Strontium titanate single crystals were implanted with 30 keV Fe ion at several doses in the range from 2 × 1014 to 2 × 1016 ion/cm2 and then annealed in oxygen atmosphere at 350 ◦C. The implantation resulted in structural disordering, and also, in depletion of Sr content which was observed in all implanted samples as evident from RBS analysis. Post-implantation anneal-ing induced recrystallization and caused Fe incorporation into the host crystal structure. The ion irradiation induced defects increased STO surface reactivity with the gases from the ambient environment. In the presence of carbon contamination itled to formation of strontium carbonate on the surface of Fe implanted, and implanted and O2 annealed STO samples. The oxidation state of Fe changed from Fe0 in as-implanted STO to Fe3+/Fe2+ in implanted and oxygen annealed STO samples. The FEFF9 calculation implied that Fe can substitute for both Ti sites and Sr sites forming Sr1-yTi1-xFex+yO3- phase in O2 annealed Fe-implanted STO samples.