MÖssbauer Study of Changes in Olivine After Heating in Air

Kądziołka-Gaweł, Mariola; Adamczyk, Zdzisław; Kalinowski, L.

doi:10.3749/canmin.1700074

Cited by 7 publications

(4 citation statements)

References 22 publications

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“…Current hypothesis suggests that Mg-rich olivine (forsterite) has precipitation of magnetite Fe 3 O 4 (Fe 2+ Fe 3+ 2 O 4 ) along the defects and crystallite boundaries, similar to those observed in volcanic olivines at 600 • C and 900 • C HTA under O 2 environment [5]. Complex phase modifications between Fe-oxides and silicates are expected including formation of magnetic FeO which has IR active absorption bands [6,7].…”

Section: Introductionmentioning

confidence: 68%

Four-polarisation camera for anisotropy mapping at three orientations: micro-grain of olivine

Juodkazis¹,

Kamegaki²,

Smith³

et al. 2023

Preprint

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Four-polarisation camera was used to map absorbance of olivine micro-grains before and after high temperature annealing (HTA). It is shown that HTA of olivine xenolith at above 1200◦C in O2 flow makes it magnetised. Different mode of operation of polariscope with polarisation control before and after the sample in transmission and reflection modes was used. The reflection type was assembled for non-transparent samples of olivine after HTA. Sample for optical observation in transmission was placed on an achromatic plastic quarter-wavelength wave-plate as a sample holder. Inspection for sample’s birefringence (retardance) as well as absorbance can be made. A best fit of transmitted intensity or transmittance T (hence absorbance A = − log10 T ) becomes accessible by simple best-fit using only three orientations (from measured four orientations by the camera). When intensity of transmitted light at one of the orientations was very low due to cross-polarised condition (polariser-analyser arrangement), the three-points fit can be used. Three-point fit in transmission and reflection modes was validated for T (θ) = Amp × cos(2θ − 2θshif t) + of f set, where amplitude Amp, offset of f set and orientation azimuth θshif t are extracted for each pixel via the best fit.

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Section: Introductionmentioning

confidence: 68%

Four-polarisation camera for anisotropy mapping at three orientations: micro-grain of olivine

Juodkazis¹,

Kamegaki²,

Smith³

et al. 2023

Preprint

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“…However, olivine diffraction lines are still visible on the X-ray diffractogram after heating the sample to 1000 o C. It can suggest that at this temperature we have forsterite in the sample. Augite structure is much more stable at high temperatures in comparison to olivine (Khisina et al 2005;Kądziołka-Gaweł et al 2019). Small changes observed for this compound are oxidation of Fe 2+ ions to Fe 3+ ions.…”

Section: Ismentioning

confidence: 85%

“…Additionally, the result of annealing the sample at 500 o C is appearance of ferric doublet with hyperfine parameters IS = 0.41 mm/s and QS = 0.92 mm/s on Mössbauer spectrum. This component can be related to the formation of superparamagnetic nanoparticles of Fe 2 O 3 (Brown et al 1998;Barcova et al 2003;Rivas-Sanchez et al 2009) as a result of oxidation of Fe 2+ ions in the olivine structure (Kądziołka-Gaweł et al 2019). It indicates that the decomposition of the olivine structure starts at this temperature.…”

Section: Discussionmentioning

confidence: 96%

High temperature transformation of iron-bearing minerals in basalt: Mössbauer spectroscopy studies

2022

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The high temperature decomposition of basalt from Lower Silesia (Poland) was followed by Mössbauer spectroscopy investigation. The Fe content of the sample was ~9.0 at.%. The X-ray diffraction analysis shows that augite (37%) and olivine (12%) are major Fe-bearing mineral components. The sample also contains significant amount of anorthite (22%) and nepheline (17%). The sample was heated at various temperatures between 200°C and 1100°C for three hours. Up to a temperature of 500°C changes in contribution of Fe-bearing minerals are insignificant. Heating in the temperature range from 500°C to 1100°C leads to a systematic increase in contribution of iron oxides at the cost of contribution of silicate minerals, like augite and olivine. Mössbauer spectrum obtained after heating at 1100°C showed hematite as the main iron oxide phase. The ratio of Fe3+/Fetot in the non-heated sample was equal to 0.51 and after heating at 1100°C this ratio amounted to 0.89.

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“…We show here that olivine in xenoliths becomes magnetized after high-temperature annealing (HTA) above 1300 • C in O 2 flow. Current hypotheses suggest that Mg-rich olivine (forsterite) has precipitations of magnetite Fe 3 O 4 (Fe 2+ Fe 3+ 2 O 4 ) along the defects and crystallite boundaries, similar to those observed in volcanic olivines at 600 • C and 900 • C HTA under an O 2 environment [7]. Complex phase modifications between Fe oxides and silicates can be expected, including formation of magnetic FeO, which has active IR absorption bands [1,2].…”

Section: Introductionmentioning

confidence: 82%

Four-Polarisation Camera for Anisotropy Mapping at Three Orientations: Micro-Grain of Olivine

Kamegaki,

Smith,

Ryu

et al. 2023

Coatings

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A four-polarisation camera was used to map the absorbance of olivine micro-grains before and after high-temperature annealing (HTA). It is shown that HTA of olivine xenoliths at above 1200 °C in O2 flow makes them magnetised. Different modes of operation of the polariscope with polarisation control before and after the sample in transmission and reflection modes were used. The reflection type was assembled for non-transparent samples of olivine after HTA. The sample for optical observation in transmission was placed on an achromatic, plastic, quarter-wavelength waveplate as a sample holder. Inspection of the sample’s birefringence (retardance), as well as absorbance, was undertaken. The best fit for the transmitted intensity or transmittance T (hence, absorbance A=−log10T) is obtainable using a simple best fit with only three orientations (from the four orientations measured by the camera). When the intensity of transmitted light at one of the orientations is very low due to a cross-polarised condition (polariser–analyser arrangement), the three-point fit can be used. The three-point fit in transmission and reflection modes was validated for T(θ)=Amp×cos(2θ−2θshift)+offset, where the amplitude Amp, offset offset, and orientation azimuth θshift were extracted for each pixel via the best fit.

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MÖssbauer Study of Changes in Olivine After Heating in Air

Cited by 7 publications

References 22 publications

Four-polarisation camera for anisotropy mapping at three orientations: micro-grain of olivine

Four-polarisation camera for anisotropy mapping at three orientations: micro-grain of olivine

High temperature transformation of iron-bearing minerals in basalt: Mössbauer spectroscopy studies

Four-Polarisation Camera for Anisotropy Mapping at Three Orientations: Micro-Grain of Olivine

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