Cobalt ferrite nanoparticles under high pressure

Abstract

Articles you may be interested inMicrostructure and magnetic properties of MFe2O4 (M = Co, Ni, and Mn) ferrite nanocrystals prepared using colloid mill and hydrothermal method J. Appl. Phys. 117, 17A328 (2015) We report by the first time a high pressure X-ray diffraction and Raman spectroscopy study of cobalt ferrite (CoFe 2 O 4 ) nanoparticles carried out at room temperature up to 17 GPa. In contrast with previous studies of nanoparticles, which proposed the transition pressure to be reduced from 20-27 GPa to 7.5-12.5 GPa (depending on particle size), we found that cobalt ferrite nanoparticles remain in the spinel structure up to the highest pressure covered by our experiments. In addition, we report the pressure dependence of the unit-cell parameter and Raman modes of the studied sample. We found that under quasi-hydrostatic conditions, the bulk modulus of the nanoparticles (B 0 ¼ 204 GPa) is considerably larger than the value previously reported for bulk CoFe 2 O 4 (B 0 ¼ 172 GPa). In addition, when the pressure medium becomes non-hydrostatic and deviatoric stresses affect the experiments, there is a noticeable decrease of the compressibility of the studied sample (B 0 ¼ 284 GPa). After decompression, the cobalt ferrite lattice parameter does not revert to its initial value, evidencing a unit cell contraction after pressure was removed. Finally, Raman spectroscopy provides information on the pressure dependence of all Raman-active modes and evidences that cation inversion is enhanced by pressure under non-hydrostatic conditions, being this effect not fully reversible. V C 2015 AIP Publishing LLC. [http://dx

In-situ high-pressure x-ray diffraction study of zinc ferrite nanoparticles

“…This fact contrasts with our recent findings on partially inverse CoFe2O4 spinel nanoparticles. In this case, the bulk modulus of the nanoparticles (K = 204 GPa) is considerably larger than the value previously reported for bulk CoFe2O4 (K = 172 GPa) [10]. It is known that the particle size could strongly influence the compressibility of nanoparticles, as shown for anatase-type TiO2 [33].…”

“…3 Although many high-pressure studies have been performed on bulk spinel oxides, investigation of nanoparticles under pressure is scarce. Indeed, one of the few compounds already studied at high pressure in the nanoparticle form is CoFe2O4 [10]. It is a very wellknown fact, that due to the high surface-to-volume ratio, nanomaterials might show a different high-pressure behavior than bulk materials [11,12].…”

“…GPa. The results obtained for the nanoparticles are compared with the bulk and the highpressure behavior of cobalt ferrite nanoparticles [10].…”

XDS: a flexible beamline for X-ray diffraction and spectroscopy at the Brazilian synchrotron

“…Novel experimental techniques at LNLS, e.g. X-ray total scattering, X-ray diffraction at high pressures, resonant/non-resonant X-ray emission spectroscopy with high energy resolution and XAS at high energies (above 18 keV) are becoming routine at XDS (Boita et al, 2014;Saleta et al, 2014;Saccone et al, 2015;Hunt et al, 2015).…”

High pressure in-situ X-ray diffraction study on Zn-doped magnetite nanoparticles

“…The pressure behavior of nanoparticles is often quite different from bulk materials. In particular,one of the effects seen on nanoparticles is Hall-Petch strengthening [11] (e.gas occurred in other spinel oxide: CoFe 2 O 4 nanoparticles [12]). Doping a material can also cause changes in the high…”