Synthesis-Dependent First-Order Raman Scattering in SrTiO₃Nanocubes at Room Temperature

Abstract

Raman spectroscopy was used to demonstrate that the lattice dynamics of SrTiO 3 (STO) nanoparticles strongly depends on their microstructure, which is in turn determined by the synthetic approach employed. First-order Raman modes are observed at room temperature in STO single-crystalline nanocubes with average edge lengths of 60 and 120 nm, obtained via sol-precipitation coupled with hydrothermal synthesis and a molten salt procedure, respectively. First-order Raman scattering arises from local loss of inversion symmetry caused by surface frozen dipoles, oxygen vacancies, and impurities incorporated into the host lattice. The presence of polar domains is suggested by the pronounced Fano asymmetry of the peak corresponding to the TO2 polar phonon, which does not vanish at room temperature. These noncentrosymmetric domains will likely influence the dielectric response of these nanoparticles.

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

“…This Fano-like behaviour has been observed in other perovskite nanoparticles [35,36] and thin films [34,[40][41][42].…”

“…4a. By comparing these Raman spectra with the published data [24,[33][34][35][36][37][38][39], three firstorder phonon modes were identified at approximately 171, 540 and 800 cm -1 corresponding to the TO 2 , TO 4 and LO 4 modes, respectively. The frequencies of the TO 2 and TO 4 / LO 4 modes have been determined by fitting with Fano and Lorentzian line shapes, respectively.…”

Nanostructuring perovskite oxides: the impact of SrTiO3 nanocube 3D self-assembly on thermal conductivity

“…Ti and Sr sites at edges and corners of the cubes have lower oxygen coordination compare to bulk species. This type of reconstruction, where SrTiO 3 nanocube shaped particles show rounded edges and corners as well as faceting has been observed experimentally 38 and implies that under-coordinated environments reconstruct to regain oxygen coordination. The TiO 2 -rich interface has edge and corner sharing TiO 6 octahedra in different directions of the interface plane as shown in Fig.…”

Characterization of aerosols from RDD surrogate compounds produced by fast thermal transients

“…550 and 800 cm −1 ). As explained in literature [27,28], defects, size effects or strains can break the symmetry of the crystal and allow the detection of first-order Raman bands. Moreover, for the particles with a cut-off size AED of 1 µm, the spectrum was similar to that of the SrTiO 3 crystal.…”