Number of the records: 1
Hematite: Morin temperature of nanoparticles with different size
- 1.
SYSNO ASEP 0505935 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title Hematite: Morin temperature of nanoparticles with different size Author(s) Kubániová, D. (CZ)
Kubíčková, L. (CZ)
Kmječ, T. (CZ)
Závěta, K. (CZ)
Nižňanský, D. (CZ)
Brázda, P. (CZ)
Klementová, Mariana (UACH-T) RID, SAI, ORCID
Kohout, J. (CZ)Number of authors 8 Source Title Journal of Magnetism and Magnetic Materials. - : Elsevier - ISSN 0304-8853
Roč. 475, APR (2019), s. 611-619Number of pages 9 s. Action Joint European Magnetic Symposia /9./ JEMS 2018 Event date 03.09.2018 - 07.09.2018 VEvent location Mainz Country DE - Germany Event type WRD Language eng - English Country NL - Netherlands Keywords Finite-scaling model ; Morin transition ; Mössbauer spectroscopy ; Spin-reorientation transition ; alfa-Fe2O3 Subject RIV CA - Inorganic Chemistry OECD category Inorganic and nuclear chemistry Method of publishing Open access with time embargo (01.04.2021) Institutional support UACH-T - RVO:61388980 UT WOS 000458152000087 EID SCOPUS 85057739897 DOI 10.1016/j.jmmm.2018.11.126 Annotation A spin-reorientation transition from a weakly ferromagnetic (WF) to an antiferromagnetic (AF) spin ordering in hematite (α-Fe2O3) during cooling occurs at Morin temperature (TM∼264 K for bulk). The transition is strongly size dependent and TM generally decreases with the decreasing volume of the particles. For particles smaller than approximately ∼20 nm, the Morin transition may be even suppressed and disappears entirely as near-surface spins deviate strongly from the antiferromagnetic easy axis. We report an investigation on nanoparticles prepared by hydrothermal method and sol–gel technique (in silica) of pure α-Fe2O3 phase as confirmed by XRD (space group R-3c, lattice parameters a = 5.038(2) Å c = 13.772(12) Å) differing in the median size derived by TEM: 5.6 nm, 26 nm, 42 nm and 103 nm. By means of Mössbauer spectra acquired between 4.2 and 300 K, we determined the relative concentrations of magnetic phases (WF and AF) within the 57Fe enriched sample and searched for the best finite-scaling theoretical model (mean-field, 3D Heisenberg, Ising) describing the derived size dependence of Morin temperature of the nanoparticles with a log-normal size distribution. The comparison of relevant parameters derived from the fit of experimental data by theoretical model is consistent with the 3D Heisenberg model with scaling parameter λ = 1.4, Morin temperature of bulk material TM(∞) = 265(1) K and correlation length ξ0 = 8.1(2) nm or Ising model with λ = 1.6, TM(∞) = 265(1) K and ξ0 = 9.4(2) nm. Workplace Institute of Inorganic Chemistry Contact Jana Kroneislová, krone@iic.cas.cz, Tel.: 311 236 931 Year of Publishing 2020 Electronic address http://hdl.handle.net/11104/0297265
Number of the records: 1