Investigation of Crystalline Phases in the α-Fe_2O_3/α-Al_2O_3 System

Scientific paper - Original scientific paper

• Author: Mira Ristić
• Author: Stanko Popović
• Author: Svetozar Musić
• Author's institution: University of Zagreb; Faculty of Science; (Department of Physics)
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract (english)

Mixtures containing the desired weight ratios of α-Fe2O3 and γ-AlOOH were homogenized in the planetary mill, then pressed into tablets and heated up to 1200 °C. All samples were characterized by X-ray diffraction, Mössbauer spectroscopy, Field emission scanning electron microscopy and Energy dispersive X-ray analysis. Two types of solid solutions of general formula α-(AlxFe1-x)2O3 were found; one solid solution was closely related to α-Fe2O3 the other to α-Al2O3 The terminal solid solubility limits, r = 27.0 ± 0.5 mole ratio of α-Al2O3 in α-Fe2O3 and r = 9.0 ± 0.5 of α-Fe2O3 in α-Al2O3 were determined. The Mössbauer spectra showed a broadening of spectral lines and a decrease in the hyperfine magnetic field of α-Fe2O3 with incorporation of Al3+ ions in the α-Fe2O3 structure. For mole fractions between x = 0.4 and 0.70, the Mössbauer spectra were considered as the superposition of a sextet and quadrupole doublet(s). In this concentration range the samples showed an almost constant value of hyperfine magnetic field. For x = 0.90 and 0.93, the Mössbauer spectra were considered as a superposition of two quadrupole doublets, whereas for x = 0.95 the superposition of two quadrupole doublets and one singlet was considered. The origin of this singlet with the isomer shift close to zero is not clearly understood. FE-SEM showed a strong sintering effect on the particles in all samples in the α-(AlxFe1-x)2O3 system.

• Keywords (english): solid solutions; α-Fe2O3; α-Al2O3; XRD; 57Fe Mössbauer; FE-SEM; EDS
• Language: english
• Publication type: Scientific paper - Original scientific paper
• Publication status: Published
• Peer review: Peer review - international
• Publication version: Published version
• Journal title: Croatica Chemica Acta
• Numbering: vol. 82, no. 2, pp. 397-404
• p-ISSN: 0011-1643
• e-ISSN: 1334-417X
• URN:NBN: urn:nbn:hr:217:338202
• Publication: 2009
• Project: Number: 098-0982904-2952; Title (croatian): Sinteza i mikrostruktura metalnih oksida i oksidnih stakala; Leader: Mira Ristić; Jurisdiction: Croatia; Funding stream: ZP
• Project: Number: 119-0982886-1009; Title (croatian): Struktura i svojstva posebnih nanomaterijala dobivenih suvremenim tehnikama; Leader: Antun Tonejc; Jurisdiction: Croatia; Funding stream: ZP
• Document URL: https://hrcak.srce.hr/39657
• Type of resource: Text
• Access conditions: Open access
• Created on: 2019-10-19 19:16:38