Structural, magnetic and electrical properties of the hexagonal ferrites MFeO{sub 3} (M=Y, Yb, In)

• Published in: Journal of solid state chemistry 2012-06, Vol.190
• Main Authors: Downie, Lewis J., Goff, Richard J., Kockelmann, Winfried, Forder, Sue D., Parker, Julia E., Morrison, Finlay D., Lightfoot, Philip
• Format: Article
• Language: English
• Subjects: CRYSTALLOGRAPHY; DIELECTRIC MATERIALS; ELECTRICAL PROPERTIES; FERRITE; FERRITES; HCP LATTICES; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; IRON 57; LATTICE PARAMETERS; MAGNETIC SUSCEPTIBILITY; MOESSBAUER EFFECT; NEUTRON DIFFRACTION; NEUTRONS; SPACE GROUPS; SYMMETRY; TEMPERATURE RANGE 0065-0273 K; X-RAY DIFFRACTION
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/J.JSSC.2012.02.004

The hexagonal ferrites MFeO{sub 3} (M=Y, Yb, In) have been studied using a combination of neutron and X-ray powder diffraction, magnetic susceptibility, dielectric measurements and {sup 57}Fe Moessbauer spectroscopy. This study confirms the previously reported crystal structure of InFeO{sub 3} (YAlO{sub 3} structure type, space group P6{sub 3}/mmc), but YFeO{sub 3} and YbFeO{sub 3} both show a lowering of symmetry to at most P6{sub 3}cm (ferrielectric YMnO{sub 3} structure type). However, Moessbauer spectroscopy shows at least two distinct Fe sites for both YFeO{sub 3} and YbFeO{sub 3} and we suggest that the best model to rationalise this involves phase separation into more than one similar hexagonal YMnO{sub 3}-like phase. Rietveld analysis of the neutron diffraction data was carried out using two hexagonal phases as a simplest case scenario. In both YFeO{sub 3} and YbFeO{sub 3}, distinct dielectric anomalies are observed near 130 K and 150 K, respectively. These are tentatively correlated with weak anomalies in magnetic susceptibility and lattice parameters, for YFeO{sub 3} and YbFeO{sub 3}, respectively, which may suggest a weak magnetoelectric effect. Comparison of neutron and X-ray powder diffraction shows evidence of long-range magnetic order in both YFeO{sub 3} and YbFeO{sub 3} at low temperatures. Due to poor sample crystallinity, the compositional and structural effects underlying the phase separation and possible magnetoelectric phenomena cannot be ascertained. - Graphical abstract: Hexagonal MFeO{sub 3} (M=Y, Yb) exhibit phase separation into two YMnO{sub 3}-like phases. Variable temperature crystallographic, electrical and magnetic studies suggest weak correlations between electrical and magnetic responses and long-range magnetic order at low temperature. Highlights: Black-Right-Pointing-Pointer Multi-technique study of multiferroic hexagonal MFeO{sub 3}. Black-Right-Pointing-Pointer Phase separation into two similar hexagonal phases. Black-Right-Pointing-Pointer Weak coupling of electrical and magnetic responses. Black-Right-Pointing-Pointer Long-range magnetic order at low T.