scholarly journals High-temperature thermomagnetic properties of vivianite nodules, Lake El'gygytgyn, Northeast Russia

2013 ◽  
Vol 9 (1) ◽  
pp. 433-446 ◽  
Author(s):  
P. S. Minyuk ◽  
T. V. Subbotnikova ◽  
L. L. Brown ◽  
K. J. Murdock
Keyword(s):  
Magnetic Susceptibility ◽  
High Temperature ◽  
Magnetic Measurements ◽  
Iron Phosphate ◽  
Northeastern Russia ◽  
Northeast Russia ◽  
Low Field ◽  
Lake El’Gygytgyn ◽  
Monoclinic Pyrrhotite ◽  
Thermomagnetic Properties

Abstract. Vivianite, a hydrated iron phosphate, is abundant in sediments of Lake El'gygytgyn, located in the Anadyr Mountains of central Chukotka, northeastern Russia (67°30′ N, 172°05′ E). Magnetic measurements, including mass-specific low-field AC magnetic susceptibility, field-dependent magnetic susceptibility, hysteresis parameters, temperature dependence of the induced magnetization, as well as susceptibility in different heating media, provide ample information on vivianite nodules. Electron microprobe analyses, electron microscopy and energy dispersive spectroscopy were used to identify diagnostic minerals. Vivianite nodules are abundant in both sediments of cold (anoxic) and warm (oxic) stages. Magnetic susceptibility of the nodules varies from 0.78 × 10−6 m3 kg−1 to 1.72 × 10−6 m3 kg−1 (average = 1.05 × 10−6 m3 kg−1) and is higher than the susceptibility of sediments from the cold intervals. Magnetic properties of vivianite are due to the respective product of oxidation as well as sediment and mineral inclusions. Three types of curves for high-temperature dependent susceptibility of vivianite indicate different degrees of oxidation and inclusions in the nodules. Vivianite acts as a reductant and reduces hematite to magnetite and masks the goethite–hematite transition during heating. Heating vivianite and sulfur mixtures stimulates the formation of monoclinic pyrrhotite. An additive of arsenic inhibits the formation of magnetite prior to its Curie temperature. Heating selective vivianite and pyrite mixtures leads to formation of several different minerals – magnetite, monoclinic pyrrhotite, and hexagonal pyrrhotite, and makes it difficult to interpret the thermomagnetic curves.

scholarly journals Thermomagnetic properties of vivianite nodules, Lake El'gygytgyn, Northeast Russia

2012 ◽  
Vol 8 (5) ◽  
pp. 4989-5027 ◽  
Author(s):  
P. S. Minyuk ◽  
T. V. Subbotnikova ◽  
L. L. Brown ◽  
K. J. Murdock
Keyword(s):  
Magnetic Susceptibility ◽  
Temperature Dependence ◽  
Magnetic Measurements ◽  
Iron Phosphate ◽  
Northeastern Russia ◽  
Northeast Russia ◽  
Low Field ◽  
Lake El’Gygytgyn ◽  
Monoclinic Pyrrhotite ◽  
Thermomagnetic Properties

Abstract. Vivianite, a hydrated iron phosphate, is abundant in sediments of El'gygytgyn Lake, located in the Anadyr Mountains of Central Chukotka, Northeastern Russia (67° 30' N; 172° 05' E). Magnetic measurements, including weight low-field AC magnetic susceptibility, field dependent magnetic susceptibility, hysteresis parameters, temperature dependence of the saturation magnetization, as well as susceptibility in different heating media provide ample information on vivianite. Electron-microprobe analyses, electron microscopy and energy dispersive spectroscopy were used to identify diagnostic minerals. Vivianite nodules are abundant in both sediments of cold (anoxic) and warm (oxic) stages. Magnetic susceptibility of the nodules varies from 0.78 × 10−6 m3 kg−1 to 1.72 × 10−6 m3 kg−1 (average = 1.05 × 10−6 m3 kg−1) and is higher than the susceptibility of sediments from the cold intervals. Magnetic properties of vivianite are due to product of oxidation as well as sediment and mineral inclusions. Three types of curves of high temperature dependence susceptibility of vivianite indicate different degree of oxidation and inclusions in the nodules. Vivianite acts as a reductant and reduces hematite to magnetite and suppresses the goethite-hematite transition during heating. Heating vivianite and sulfur mixture stimulate the formation of monoclinic pyrrhotite. An additive of arsenic inhibits the formation of magnetite prior to its Curie temperature. Heating selective vivianite and pyrite mixtures produces formation of several different minerals – magnetite, monoclinic pyrrhotite, and hexagonal pyrrhotite, and make it difficult to interpret the thermomagnetic curves.

Ultra-Low-Field Squid Magnetic Measurements on High Temperature Ceramic YBaCuO Superconductors

1987 ◽  
Vol 99 ◽  
Author(s):  
D. C. Cronemeyer ◽  
A. P. Malozemoff ◽  
T. R. Mcguire
Keyword(s):  
High Temperature ◽  
Transition Temperature ◽  
Ceramic Sample ◽  
Superconducting Transition Temperature ◽  
Magnetic Measurements ◽  
Zero Field ◽  
Superconducting Transition ◽  
Temperature Range ◽  
Low Field ◽  
The Difference

ABSTRACTWe report ultra-low-field (5 mOe - 1 Oe) magnetic measurements on a ceramic sample of YBaCuO. A positive remanent moment is observed which accurately equals the difference of the field-cooled and zero-field-cooled moments throughout the temperature range. At higher fields this relationship breaks down. A reversible region is observed near the superconducting transition temperature which is independent of field. These results are discussed in the context of recent models.

Low field magnetic measurements of high temperature superconductors

1989 ◽  
Author(s):  
G. Shaw ◽  
S.D. Murphy ◽  
Z.-Y. Li ◽  
A.M. Stewart ◽  
S.M. Bhagat
Keyword(s):  
High Temperature ◽  
Magnetic Measurements ◽  
High Temperature Superconductors ◽  
Low Field

Investigation of Sm → Ca substitution in Bi(Pb)SrCaCuO high temperature superconductor by low field AC magnetic susceptibility

2007 ◽  
Vol 42 (12) ◽  
pp. 4636-4641 ◽  
Author(s):  
Cabir Terzioglu ◽  
Dincer Yegen ◽  
Mustafa Yılmazlar ◽  
Osman Gorur ◽  
Mustafa Akdogan ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
High Temperature ◽  
High Temperature Superconductor ◽  
Ac Magnetic Susceptibility ◽  
Low Field ◽  
Ca Substitution

scholarly journals Rock magnetic properties, magnetic susceptibility, and organic geochemistry comparison in core LZ1029-7 Lake El'gygytgyn, Far Eastern Russia

2012 ◽  
Vol 8 (5) ◽  
pp. 4565-4599 ◽  
Author(s):  
K. J. Murdock ◽  
K. M. Wilkie ◽  
L. L. Brown
Keyword(s):  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Organic Carbon ◽  
Magnetic Measurements ◽  
Organic Geochemistry ◽  
Magnetic Minerals ◽  
Rock Magnetic Properties ◽  
Anoxic Environments ◽  
Lake El’Gygytgyn ◽  
Order Of Magnitude

Abstract. Susceptibility measurements performed on initial short (3–16 m) cores taken from Lake El'gygytgyn exhibited a large range in values. This observation led to the suggestion of widespread magnetite dissolution within the sediments due to anoxic conditions within the lake. Rock magnetic properties and their comparison with magnetic susceptibility, Total Organic Carbon (TOC), and bulk δ13Corg proxies in core LZ1029-7 provide an insight into the character of the magnetic minerals present within the lake and can further the understanding of processes that may be present in the newer long core sediments Susceptibility measurements (χ) of discrete samples corroborate the two order of magnitude difference seen in previous continuous susceptibility measurements (κ), correlating high values with interglacial periods and low values with glacial intervals. Hysteresis parameters defined the majority of the magnetic material to be magnetite of PSD size. TOC values increase while δ13Corg values decrease in one section of LZ1029-7, which is defined as the Last Glacial Maximum (LGM), and help confine the age of the core to approximately 62 kyr. Increases in TOC during the most recent glacial interval suggest increased preservation of organic carbon during these times High TOC and low magnetic susceptibility during the LGM support the theory of perennial ice cover during glacial periods, which would lead to lake stratification and therefore anoxic bottom water conditions. Low temperature magnetic measurements also confirmed the presence of magnetite, but also indicated titanomagnetite, siderite and/or rhodochrosite, and vivianite were present. The latter three minerals are found only in anoxic environments, and further support the notion of magnetite dissolution.

scholarly journals Rock magnetic properties, magnetic susceptibility, and organic geochemistry comparison in core LZ1029-7 Lake El'gygytgyn, Russia Far East

2013 ◽  
Vol 9 (1) ◽  
pp. 467-479 ◽  
Author(s):  
K. J. Murdock ◽  
K. Wilkie ◽  
L. L. Brown
Keyword(s):  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Organic Carbon ◽  
Magnetic Measurements ◽  
Organic Geochemistry ◽  
Far East ◽  
Magnetic Minerals ◽  
Rock Magnetic Properties ◽  
Lake El’Gygytgyn ◽  
Order Of Magnitude

Abstract. Susceptibility measurements performed on initial short (~ 16 m) cores PG1351 taken from Lake El'gygytgyn exhibited a large range in values. This observation led to the suggestion of widespread magnetite dissolution within the sediments due to anoxic conditions within the lake. Rock magnetic properties and their comparison with magnetic susceptibility, total organic carbon (TOC), and bulk δ13Corg proxies in core LZ1029-7, taken from the same site as the previously drilled PG1351, provide an insight into the character of the magnetic minerals present within the lake and can further the understanding of processes that may be present in the newer long core sediments. Susceptibility measurements (χ) of discrete samples corroborate the two order of magnitude difference seen in previous continuous susceptibility measurements (κ), correlating high values with interglacial periods and low values with glacial intervals. Hysteresis parameters indicate that the majority of the magnetic material to be magnetite of PSD size. TOC values increase while δ13Corg values decrease in one section of LZ1029-7, which is defined as the Last Glacial Maximum (LGM), and help confine the age of the core to approximately 62 ka. Increases in TOC during the most recent glacial interval suggest increased preservation of organic carbon during this period. High TOC and low magnetic susceptibility during the LGM support the theory of perennial ice cover during glacial periods, which would lead to lake stratification and therefore anoxic bottom water conditions. Low temperature magnetic measurements confirmed the presence of magnetite, but also indicated titanomagnetite and possibly siderite, rhodochrosite, and/or vivianite were present. The latter three minerals are found only in anoxic environments, and further support the notion of magnetite dissolution.

Low field magnetic measurements on high temperature superconductors

1989 ◽  
Vol 25 (5) ◽  
pp. 3512-3514 ◽  
Author(s):  
G. Shaw ◽  
S.D. Murphy ◽  
Z. Li ◽  
A.M. Stewart ◽  
S.M. Bhagat
Keyword(s):  
High Temperature ◽  
Magnetic Measurements ◽  
High Temperature Superconductors ◽  
Low Field

MAGNETIC PROPERTIES OF PSEUDO-BINARY Mn1−xFexSn2 ALLOYS

1993 ◽  
Vol 07 (01n03) ◽  
pp. 867-870 ◽  
Author(s):  
H. SHIRAISHI ◽  
T. HORI ◽  
Y. YAMAGUCHI ◽  
S. FUNAHASHI ◽  
K. KANEMATSU
Keyword(s):  
Field Theory ◽  
Phase Diagram ◽  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
High Temperature ◽  
Magnetic Structure ◽  
Magnetic Phase ◽  
Magnetic Phase Diagram ◽  
Molecular Field ◽  
Magnetic Phases

The magnetic susceptibility measurements have been made on antiferromagnetic compounds Mn1–xFexSn2 and the magnetic phase diagram was illustrated. The high temperature magnetic phases I and III, major phases, were analyzed on the basis of molecular field theory and explained the change of magnetic structure I⇌III occured at x≈0.8.

Suppression of Ferromagnetism in EuxCa1-xB6

2012 ◽  
Vol 190 ◽  
pp. 97-100 ◽  
Author(s):  
V.V. Glushkov ◽  
A.V. Kuznetsov ◽  
I. Sannikov ◽  
A.V. Bogach ◽  
S.V. Demishev ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Curie Temperature ◽  
Single Crystals ◽  
Effective Magnetic Moment ◽  
Paramagnetic State ◽  
Low Field ◽  
Wide Range ◽  
Free Ion ◽  
The Eu

We report the magnetic properties of EuxCa1-xB6 single crystals (0.756x1) studied in the wide range of temperatures (1.8-300 K) and magnetic fields (up to 50 kOe). It was found that low field magnetic susceptibility χ (T) follows the Curie-Weiss law χ~(T-Θp)-1 at high temperatures for all the concentrations studied. The effective magnetic moment of the Eu2+ ion estimated from the data diminishes from the free ion value μeff7.93μB (μB - Bohr magneton) for x=1 to μeff7.3μB for x=0.756. A universal behavior of magnetic susceptibility χ~(T-Θ)-α (α=1.5) is detected close to the Curie temperature TC in the paramagnetic state at both metallic (x>xC~0.8) and dielectric (xC.

MAGNETIC BEHAVIOR OF IRON IONS IN THE P2O5·CaO GLASS MATRIX

2003 ◽  
Vol 17 (24) ◽  
pp. 1271-1275 ◽  
Author(s):  
I. ARDELEAN ◽  
C. ANDRONACHE ◽  
P. PǍŞCUŢǍ
Keyword(s):  
Magnetic Susceptibility ◽  
High Temperature ◽  
Magnetic Moment ◽  
Glass Matrix ◽  
Magnetic Behavior ◽  
Iron Ions ◽  
Ion Content ◽  
Dipole Interactions ◽  
Valence States ◽  
Temperature Susceptibility

The temperature dependence of the magnetic susceptibility of x Fe 2 O 3·(100-x)-[ P 2 O 5· CaO ] glasses with 0<x≤50 mol % have been investigated. These data revealed that the valence states and the distribution of iron ions in the glass matrix depend on the Fe 2 O 3 content. For the glasses with x≤1 mol % only Fe 3+ ions are evidenced. In the case of the glasses with 3≤x≤35 mol % both Fe 3+ and Fe 2 ions co-exist in the P 2 O 5· CaO glass matrix, the Fe 2+ ion content is higher than that of the Fe 3+ ions for glasses with x≥10 mol %. For the glasses with x>35 mol %, the evaluated values of the μ eff indicate either the presence of Fe + ions or the coordination influence on the magnetic moment of iron ions, but the presence of small quantities of the antiferromagnetic or ferrimagnetic interactions between iron ions in studied temperature range cannot be excluded. The high temperature susceptibility results indicate that the iron ions are isolated or participate in dipole-dipole interactions for glasses with x≤35 mol % and are antiferromagnetically coupled for higher contents of Fe 2 O 3.

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