RT Journal Article
T1 Synthesis, crystal structure, site occupancy and magnetic properties of aluminum substituted M-type Sr hexaferrite SrFe_(12-x)Al_(x)O_(19) nanoparticles
A1 Saura Múzquiz, Matilde
A1 Eikeland, Anna Zink
A1 Stingaciu, Marian
A1 Andersen, Henrik Lyder
A1 Avdeev, Maxim
A1 Christensen, Mogens
AB The synthesis of aluminum-substituted strontium hexaferrite nanoparticles (SrFe_(12-x)Al_(x)O_(19) with x = 0–3), via three different preparation methods, is investigated. The synthesis methods are hydrothermal autoclave (AC) synthesis, a citrate sol–gel (SG) synthesis, and a solid-salt matrix (SSM) synthesis. Evaluation of macroscopic magnetic properties and of lattice parameters obtained by Rietveld analysis of powder X-ray diffraction (PXRD) data indicate that successful substitution of Al into the crystal structure is only achieved for the SG method. For the SG sample with x = 3, the coercivity was found to increase by 73% to 830 kA/m, while the saturation magnetization was reduced by 68% to 22.6 Am^(2)/kg compared to the nonsubstituted x = 0 SG sample. The SSM and AC samples did not show any significant changes in their magnetic properties. To examine the nature of the Al insertion in detail, neutron powder diffraction (NPD) data were collected on the SSM and SG samples. Combined Rietveld refinements of the PXRD and NPD data confirm that effective substitution of the Al ions is only achieved for the SG sample and reveal that Al occupies mainly the (2a)_(Oh) and (12k)_(Oh) sites and to a lesser extent the (4e)_(BP), (4f)_(Oh) and (4f)_(Td) sites. Moreover, the relative degree of site occupation varies with increasing Al substitution. The intrinsic magnetization according to the refined atomic magnetic moments and Al site occupation fractions was extracted from the NPD data and compared with the measured macroscopic magnetization. A remarkable agreement exists between the two, confirming the robustness and accuracy of the Rietveld analysis.
PB American Chemical Society
SN 0897-4756
YR 2025
FD 2025-01-20
LK https://hdl.handle.net/20.500.14352/118861
UL https://hdl.handle.net/20.500.14352/118861
LA eng
NO Saura-Múzquiz, M., Eikeland, A. Z., Stingaciu, M., Andersen, H. L., Avdeev, M., & Christensen, M. (2025). Synthesis, Crystal Structure, Site Occupancy, and Magnetic Properties of Aluminum-Substituted M-Type Sr Hexaferrite SrFe12-xAl x O19 Nanoparticles. Chemistry of Materials.
NO European Commission
NO Independent Research Fund Denmark  Agency for Danish Agency for Science and Higher Education
NO Danish Center for Synchrotron and Neutron Science (DanScatt)
NO Ministerio de Ciencia e Innovación (España)
NO Agencia Estatal de Investigación (España)
NO Comunidad de Madrid
NO Australian Centre for Neutron Scattering
NO Australian Nuclear Science and Technology Organisation
NO Aarhus University Centre for Integrated Materials Research (iMAT)
DS Docta Complutense
RD 26 dic 2025