Structural characterisation of slightly Fe-doped SrTiO3 grown via a sol–gel hydrothermal synthesis

Abstract

A detailed structural study of the incorporation of Fe into SrTiO 3 nanoparticles is reported. Slightly irondoped strontium titanate nanoparticles with 0, 1, 3 and 5 mol% concentration of iron were grown using a sol-gel hydrothermal process and characterised using Raman scattering, X-ray photoelectron and X-ray diffraction spectroscopy. The amorphisation of the nanostructures was observed as the iron content increased, which was confirmed by the TEM images. The XPS results indicated that the oxidation states of the Sr atoms were maintained in 2?. However, a mixture of Fe 3? and Fe 4? atoms was observed as the Fe content increased, resulting in a significant number of oxygen vacancies in the perovskite structure. The analysis of Raman spectra indicated that the intensity, linewidth and frequency shift of the TO 4 phonon can be used as an indicator of the Fe content as well as a local temperature probe for future thermal analysis. Graphical abstract Temperature evolution of the Raman spectra of STO:Fe 1 mol%. The peaks with star correspond to the second-order processes. (b) Temperature dependence of the TO 4 phonon mode. Blue dots denote measured Raman spectra, and the red solid lines are the Lorentzian fits to respective spectra.

Influence of Annealing Temperatures on the Structural, Morphological,Crystalline and Optical properties of BaTiO3 and SrTiO3 Nanoparticles

“…Where ρ is the theoretical density of BaTiO 3 which is 6.017 g/cm 3 and that of SrTiO 3 is 4.81 g/cm 3 [11]. The estimated results are shown in Table 1 above.…”

“…The strong and sharp diffraction peaks inFigures 2 and 3suggest that BaTiO3 and SrTiO 3 nanoparticles have good crystalline nature. At high annealing temperatures (800 and 900°C), no diffraction peaks are seen for carbonates, confirming the complete removal of BaCO 3 and SrCO 3 impurities.…”

“…In this study, highly crystalline BaTiO 3 and SrTiO 3 nanoparticles were synthesized by bi-modal distribution solution process followed by annealing at different temperatures. Perovskite materials with the formula ABO 3 with A being a metal, B, Titanium and O, Oxygen had gained wide attention due to their applications in different technological field [1].…”

“…The A atoms are larger than the B atoms and have 12-fold cuboctahedral coordination. The B cation is in a 6-fold coordination surrounded by an octahedron of anions [3]. The relative ion size requirements for stability of the cubic structure of perovskite is quite stringent hence slight buckling and distortion can result in the production of several lower-symmetry distorted perovskite with a reduced A and B cation coordination numbers [4].…”

“…At high annealing temperatures (800 and 900°C), no diffraction peaks are seen for carbonates, confirming the complete removal of BaCO 3 and SrCO 3 impurities. Moreover, the high peak intensity at higher annealing temperature is related to the reduction of the hydroxyl (OH -) on the BaTiO3 and SrTiO 3 unit cells in a lattice defect of their cubic structures. The UV-Vis absorption spectra of BaTiO 3 and SrTiO 3 nanoparticles are shown in Figures 4 and 5.…”