Temperature‐dependent Raman scattering study of Fe₃O₂BO₃ ludwigite

Abstract

ludwigite crystals in the temperature range from 15 to 300 K. At room temperature ludwigite has an orthorhombic structure belonging to space group D 9 2h . Attempts made to record polarized Raman spectra were successful, and we were able to identify most of the phonons belonging to A 1g species. A careful analysis of the spectra shows that the observed Raman modes do not exhibit variations either in wavenumber or intensity or both with temperature, indicating that the D 9 2h phase does not undergo any structural modification in the temperature range investigated. Also, we observed for Fe 3 O 2 BO 3 ludwigite the appearance of a continuous scattering background in the phonon spectrum for temperatures below 200 K . This background, which is due to electronic transitions between Fe 2+ and Fe 3+ ions, is related to the charge delocalization effect.

Hellandite-(Y)–hingganite-(Y)–fluorapatite retrograde coronae: a novel type of fluid-induced dissolution–reprecipitation breakdown of xenotime-(Y) in the metagranites of Fabova Hoľa, Western Carpathians, Slovakia

“…However, not all the bands can easily be attributed to known causes, according to the published data (Leite et al , 2001; Škoda et al ., 2018; Gorelova et al , 2020). The Raman spectra of all the measured mineral phases, compositionally corresponding to hingganite-(Y), are essentially obscured by strong photoluminescence, as both broad and narrow bands.…”

“…The high number and broadening of the bands results from a varying composition. In the Raman spectra, as in the gadolinite-group minerals, stretching vibrations of REE–O and Fe–O and lattice vibrations are observed in the spectral region 200–750 cm –1 (Leite et al , 2001; Škoda et al , 2018). The vibrations in the 320–600 cm –1 region may be attributed to out-of-plane and in-plane bending vibrations of the (SiO 4 ) 4– tetrahedron.…”

“…8a), which was recalculated, considering that the 532 nm excitation has a centre at ca. 660 nm (Leite et al, 2001;Škoda et al, 2018). The vibrations in the 320-600 cm -1 region may be attributed to out-of-plane and in-plane bending vibrations of the (SiO 4 ) 4tetrahedron.…”

Multicomponent flux growth and composition control of Cu2MnBO5:Ga ludwigites

“…As in the case of orthorhombic ludwigites, 18,25,26 the spectra of the monoclinic ones can be conditionally divided into three ranges: 0-200 cm −1 corresponding to the lattice vibrations, 250-750 cm −1 corresponding to the Me-O octahedral vibrations, and 900-1400 cm −1 corresponding to the [BO 3 ] 3− group vibrations. The intensity of the boronoxygen group vibrations is quite low for all the ludwigites.…”

“…The intensity of the boronoxygen group vibrations is quite low for all the ludwigites. 18,25,26 Thus, this spectral range can hardly be well analyzed. However, the intensity and resolution of the lattice and octahedral vibration ranges are sufficient to make a meaningful conclusion on the concentration phase transition occurring at about x C ≈ 0.15 (Fig.…”