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Papers by Elena Sergienko
Springer Geophysics, 2018
We measured the low-field magnetic susceptibility and natural remanent magnetization (NRM) for an... more We measured the low-field magnetic susceptibility and natural remanent magnetization (NRM) for an extensive collection of irghizites, tektite-like impact glasses from the Zhamanshin meteorite crater, Kazakhstan. For a small subset of samples, more detailed magnetic measurements, scanning electron microscopy and microprobe analysis have been carried out. In agreement with a previous study (Rochette et al. 2015), *95% of samples showed relatively low magnetic susceptibility ranging from 45 to 300 Â 10 −9 m 3 /kg. Combining susceptibility and NRM data, we are able to classify irghizites into "normal" (susceptibility <300 Â 10 −9 m 3 /kg, NRM < 4 Â 10 −6 A m 2 /kg) and "anomalous" groups. Detailed rock magnetic experiments and microscopic observation confirm this dichotomy. Normal irghizites contain very little ferrimagnetic material which, in addition, is predominantly in superparamagnetic state, implying an extremely small, on the order of a few nm, grain size. In contrast, anomalous samples exhibit magnetic properties consistent with much larger, µm to 10s of µm, ferrimagnetic grains, which were observed microscopically as well. We propose that this difference between two groups of samples is related to the initial temperature of the impact melts from which they were formed. Normal irghizites likely originate from the spray of a strongly overheated melt with initial temperatures up to 2500-3000°C, cooling extremely fast, while anomalous ones could have been formed from less hot and slower cooling melt.
Magnetochemistry, 2021
Magnetotactic bacteria (MTB) belong to several phyla. This class of microorganisms exhibits the a... more Magnetotactic bacteria (MTB) belong to several phyla. This class of microorganisms exhibits the ability of magneto-aerotaxis. MTB synthesize biominerals in organelle-like structures called magnetosomes, which contain single-domain crystals of magnetite (Fe3O4) or greigite (Fe3S4) characterized by a high degree of structural and compositional perfection. Magnetosomes from dead MTB could be preserved in sediments (called fossil magnetosomes or magnetofossils). Under certain conditions, magnetofossils are capable of retaining their remanence for millions of years. This accounts for the growing interest in MTB and magnetofossils in paleo- and rock magnetism and in a wider field of biogeoscience. At the same time, high biocompatibility of magnetosomes makes possible their potential use in biomedical applications, including magnetic resonance imaging, hyperthermia, magnetically guided drug delivery, and immunomagnetic analysis. In this review, we attempt to summarize the current state of ...
High-coercivity magnetic minerals in archaeological ceramics: New insights from remanence acquisi... more High-coercivity magnetic minerals in archaeological ceramics: New insights from remanence acquisition and demagnetization measurements at elevated temperatures
Magnetochemistry
Artificial glasses containing nanoscale inclusions of iron oxides, including magnetite and hemati... more Artificial glasses containing nanoscale inclusions of iron oxides, including magnetite and hematite, were obtained via the method of the high-temperature melting of rocks. The main factors influencing the magnetic properties of glasses are the composition of the initial charge and the conditions of cooling of the melt. The data of magnetic granulometry and frequency-field dependencies of magnetic susceptibility showed the presence of a sufficiently large superparamagnetic fraction in the samples. Coordinated theoretical modeling using two independent models that take into consideration possible the chemical inhomogeneity of particles and magnetostatic interaction between them made it possible to calculate hysteresis characteristics corresponding to the experiment and to estimate ferrimagnetic concentrations in the samples, including the superparamagnetic fraction.
Springer Geophysics, 2018
We report low-temperature magnetic properties of predominantly mafic rocks from the Mesoproterozo... more We report low-temperature magnetic properties of predominantly mafic rocks from the Mesoproterozoic Ropruchey sill, Karelia. Based on microscopic observations, the studied rocks can be classified into two groups, granodiorites and gabbro-diorites, with different magnetic mineralogy. In granodiorites, the only magnetic mineral is stoichiometric magnetite characterized by a Verwey transition temperature of 120-121 K. In gabbro-diorites, the magnetic mineralogy is also dominated by magnetite, which however contains 2-3% of Ti substitution atoms, lowering the Verwey transition temperature to 94-103 K. In addition, the gabbro-diorites appear to contain some amount of a more Ti-rich titanomagnetite, as well as another, yet unidentified magnetic phase, manifesting itself by a peculiar temperature and frequency-dependent behavior of magnetic susceptibility.
Journal of magnetism …, 2005
Suspensions of bacterial magnetosomes are investigated with respect to magnetic losses. Mean core... more Suspensions of bacterial magnetosomes are investigated with respect to magnetic losses. Mean core diameter of about 30nm results from TEM, XRD and magnetic analysis. Specific loss power is determined from hysteresis loops, susceptibility spectra and calorimetry with ...
Springer Geophysics, 2018
We measured the low-field magnetic susceptibility and natural remanent magnetization (NRM) for an... more We measured the low-field magnetic susceptibility and natural remanent magnetization (NRM) for an extensive collection of irghizites, tektite-like impact glasses from the Zhamanshin meteorite crater, Kazakhstan. For a small subset of samples, more detailed magnetic measurements, scanning electron microscopy and microprobe analysis have been carried out. In agreement with a previous study (Rochette et al. 2015), *95% of samples showed relatively low magnetic susceptibility ranging from 45 to 300 Â 10 −9 m 3 /kg. Combining susceptibility and NRM data, we are able to classify irghizites into "normal" (susceptibility <300 Â 10 −9 m 3 /kg, NRM < 4 Â 10 −6 A m 2 /kg) and "anomalous" groups. Detailed rock magnetic experiments and microscopic observation confirm this dichotomy. Normal irghizites contain very little ferrimagnetic material which, in addition, is predominantly in superparamagnetic state, implying an extremely small, on the order of a few nm, grain size. In contrast, anomalous samples exhibit magnetic properties consistent with much larger, µm to 10s of µm, ferrimagnetic grains, which were observed microscopically as well. We propose that this difference between two groups of samples is related to the initial temperature of the impact melts from which they were formed. Normal irghizites likely originate from the spray of a strongly overheated melt with initial temperatures up to 2500-3000°C, cooling extremely fast, while anomalous ones could have been formed from less hot and slower cooling melt.
Magnetochemistry, 2021
Magnetotactic bacteria (MTB) belong to several phyla. This class of microorganisms exhibits the a... more Magnetotactic bacteria (MTB) belong to several phyla. This class of microorganisms exhibits the ability of magneto-aerotaxis. MTB synthesize biominerals in organelle-like structures called magnetosomes, which contain single-domain crystals of magnetite (Fe3O4) or greigite (Fe3S4) characterized by a high degree of structural and compositional perfection. Magnetosomes from dead MTB could be preserved in sediments (called fossil magnetosomes or magnetofossils). Under certain conditions, magnetofossils are capable of retaining their remanence for millions of years. This accounts for the growing interest in MTB and magnetofossils in paleo- and rock magnetism and in a wider field of biogeoscience. At the same time, high biocompatibility of magnetosomes makes possible their potential use in biomedical applications, including magnetic resonance imaging, hyperthermia, magnetically guided drug delivery, and immunomagnetic analysis. In this review, we attempt to summarize the current state of ...
High-coercivity magnetic minerals in archaeological ceramics: New insights from remanence acquisi... more High-coercivity magnetic minerals in archaeological ceramics: New insights from remanence acquisition and demagnetization measurements at elevated temperatures
Magnetochemistry
Artificial glasses containing nanoscale inclusions of iron oxides, including magnetite and hemati... more Artificial glasses containing nanoscale inclusions of iron oxides, including magnetite and hematite, were obtained via the method of the high-temperature melting of rocks. The main factors influencing the magnetic properties of glasses are the composition of the initial charge and the conditions of cooling of the melt. The data of magnetic granulometry and frequency-field dependencies of magnetic susceptibility showed the presence of a sufficiently large superparamagnetic fraction in the samples. Coordinated theoretical modeling using two independent models that take into consideration possible the chemical inhomogeneity of particles and magnetostatic interaction between them made it possible to calculate hysteresis characteristics corresponding to the experiment and to estimate ferrimagnetic concentrations in the samples, including the superparamagnetic fraction.
Springer Geophysics, 2018
We report low-temperature magnetic properties of predominantly mafic rocks from the Mesoproterozo... more We report low-temperature magnetic properties of predominantly mafic rocks from the Mesoproterozoic Ropruchey sill, Karelia. Based on microscopic observations, the studied rocks can be classified into two groups, granodiorites and gabbro-diorites, with different magnetic mineralogy. In granodiorites, the only magnetic mineral is stoichiometric magnetite characterized by a Verwey transition temperature of 120-121 K. In gabbro-diorites, the magnetic mineralogy is also dominated by magnetite, which however contains 2-3% of Ti substitution atoms, lowering the Verwey transition temperature to 94-103 K. In addition, the gabbro-diorites appear to contain some amount of a more Ti-rich titanomagnetite, as well as another, yet unidentified magnetic phase, manifesting itself by a peculiar temperature and frequency-dependent behavior of magnetic susceptibility.
Journal of magnetism …, 2005
Suspensions of bacterial magnetosomes are investigated with respect to magnetic losses. Mean core... more Suspensions of bacterial magnetosomes are investigated with respect to magnetic losses. Mean core diameter of about 30nm results from TEM, XRD and magnetic analysis. Specific loss power is determined from hysteresis loops, susceptibility spectra and calorimetry with ...