Point Defects Characterization in Quenched δ-Ni2Si as Deduced from Isothermal Magnetic Susceptibility Measurements

2008 ◽  
Vol 273-276 ◽  
pp. 312-317
Author(s):  
Adib Jennane ◽  
O. Sassi ◽  
J. Aride ◽  
Jean Bernardini ◽  
Gérard Moya
Keyword(s):  
Activation Energy ◽  
Magnetic Susceptibility ◽  
Point Defects ◽  
Magnetic Measurements ◽  
Subsequent Formation ◽  
Vacancy Clusters ◽  
Isothermal Susceptibility ◽  
Break Up

The behaviour of quenched defects in Ni2Si compound is studied by isothermal susceptibility magnetic measurements. In the range of temperature 553-593K, where an enhancement of susceptibility has been previously detected by isochronal measurements, an activation energy (EA=2.5 ± 0.2 eV) is determined. This value is in agreement with the break-up of 3D nickel vacancy clusters, formed at lower temperatures, and the subsequent formation of nickel rich defects via the released vacancies.

Interplay between spin crossover and exchange interaction in iron(III) complexes

2009 ◽  
Vol 81 (8) ◽  
pp. 1357-1383 ◽  
Author(s):  
Roman Boča ◽  
Ivan Nemec ◽  
Ivan Šalitroš ◽  
Ján Pavlik ◽  
Radovan Herchel ◽  
...  
Keyword(s):  
Experimental Data ◽  
Magnetic Susceptibility ◽  
Exchange Interaction ◽  
Spin Crossover ◽  
Magnetic Measurements ◽  
Spin States ◽  
Magnetic Exchange Interaction ◽  
Magnetic Exchange ◽  
Simultaneous Fitting ◽  
Polynuclear Metal Complexes

In the dinuclear and polynuclear metal complexes exhibiting the low-spin (LS) to high-spin (HS) transition, the spin-crossover phenomenon interferes with the magnetic exchange interaction. The latter manifests itself in forming spin-multiplets, which causes a possible overlap of the band originating in different reference spin states (LL, LH, HL, and HH). A series of dinuclear Fe(III) complexes has been prepared; the iron centers are linked by a bidentate bridge (CN-, and diamagnetic metallacyanates {Fe(CN)5(NO)}, {Ni(CN)4}, {Pt(CN)4}, and {Ag(CN)2}). Magnetic measurements confirm that the spin crossover proceeds on the thermal propagation. This information has been completed also by the Mössbauer spectral (MS) data. A theoretical model has been developed that allows a simultaneous fitting of all available experimental data (magnetic susceptibility, magnetization, HS mole fraction) on a common set of parameters.

scholarly journals Point Defects Observed in D-T neutron irradiated Copper, Silver and Gold at 288 K with a Rotating Target in FNS_JAERI

2000 ◽  
Vol 650 ◽  
Author(s):  
Y. Shimomura ◽  
K. Sugio ◽  
H. Ohkubo ◽  
I. Mukouda ◽  
C. Kutsukake ◽  
...  
Keyword(s):  
Neutron Source ◽  
Neutron Irradiation ◽  
Point Defects ◽  
Thin Foil ◽  
Energy Research ◽  
Vacancy Clusters ◽  
Fusion Neutron ◽  
Fusion Neutron Source ◽  
Damage Cascade ◽  
Rotating Target

ABSTRACTA 14 MeV D-T(fusion) neutron irradiation was carried out at fusion neutron source facility (FNS) in Japan Atomic Energy Research Institute (JAERI). Specimen temperature was controlled to 288 K. Fluence was 6.1 × 1017to 1.1 × 1021 n/m2. Both TEM thin foil and bulk specimens were irradiated at the same position. At 1018 n/m2, defects observed were single isolated dot defects. With increasing fluence, dot defects changed to complicate structure and made groupings. In a dot group, interstitial clusters and vacancy clusters were observed together. The present result was explained by the modeling that point defects in a nascent damage cascade move in crystal at 288 K and form their defect groupings.

Magnetic properties of undoped and Co-doped n-type β–FeSi2.5 single crystals

2002 ◽  
Vol 17 (11) ◽  
pp. 2960-2965 ◽  
Author(s):  
E. Arushanov ◽  
L. Ivanenko ◽  
D. Eckert ◽  
G. Behr ◽  
U. K. Rößler ◽  
...  
Keyword(s):  
Activation Energy ◽  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
External Field ◽  
Single Crystals ◽  
Spin Glasses ◽  
Paramagnetic Centers ◽  
Temperature Dependent ◽  
Paramagnetic Curie Temperature ◽  
Co Doped

Results of magnetization and magnetic susceptibility measurements on undoped and Co-doped FeSi2.5 single crystals are presented. The temperature dependence of the magnetic susceptibility of the Co-doped sample in the range of 5–300 K can be explained by temperature-dependent contributions due to paramagnetic centers and the carriers excited thermally in the extrinsic conductivity region. The values of the paramagnetic Curie temperature and activation energy of the donor levels were estimated. It is also shown that the magnetic susceptibility of Co-doped samples cooled in zero external field and in a field are different. This resembles the properties of spin-glasses and indicates the presence of coupling between magnetic centers.

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 GEOLOGICAL AND MAGNETIC SUSCEPTIBILITY MAPPING OF MOUNT GIOUCHTA (CENTRAL CRETE)

2017 ◽  
Vol 43 (1) ◽  
pp. 289 ◽  
Author(s):  
E. Kokinou ◽  
E. Kamberis ◽  
A. Sarris ◽  
I. Tzanaki
Keyword(s):  
Magnetic Susceptibility ◽  
Spatial Distribution ◽  
Stress Field ◽  
Magnetic Measurements ◽  
Strain Analysis ◽  
Geological Structure ◽  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Western Slope ◽  
Strain Pattern

Giouchta Mt. is located south of Heraklion city, in Crete. It is an N-S trending morphological asymmetric ridge, with steep western slope whilst the eastern slope represents a smoother relief, composed of Mesozoic limestone and Eocene- lower Oligocene flysch sediments of the Gavrovo -Tripolis zone. The present study focuses on the geological structure of Mt. Giouchta. Field mapping and tectonic analysis is performed for this purpose. The dominant structures are contractional in nature, deformed by normal faulting related to the extensional episodes initiated in Serravallian times. The strain pattern in the area is revealed from strain analysis. It is inferred that the orientation of the stress field in the area has changed several times: the N-S, stress field which was dominant during Late Serravallian times changed to NE-SW (in Late Serravallian? - Early Tortonian) and subsequently to WNW-ESE (Early to Middle Tortonian) to become NW-SE in Late Tortonian. This orientation changed also during the Quaternary times trending from NW-SE (Early Pleistocene) to ENE-WSW (Middle Pleistocene-Holocene). In addition to the above, surface soil samples were collected in the wider area of mount Giouchta and they were analyzed in order to determine the magnetic susceptibility. GIS techniques were used for mapping the spatial distribution of the geological features and the magnetic measurements on the topographic relief of the area. Statistical analysis techniques were also applied in order to investigate the relation of faulting and magnetic susceptibility. Maps representing the spatial distribution of the above measurements were created by using appropriate interpolation algorithms.

scholarly journals Environmental monitoring of soil pollution in urban areas (a case study from Heraklion city, Central Crete, Greece)

2017 ◽  
Vol 47 (2) ◽  
pp. 963
Author(s):  
E. Kokinou ◽  
C. Belonaki ◽  
D. Sakadakis ◽  
K. Sakadaki
Keyword(s):  
Magnetic Susceptibility ◽  
Urban Areas ◽  
Magnetic Measurements ◽  
Topographic Map ◽  
Near Surface ◽  
Thermomagnetic Analysis ◽  
Geological Features ◽  
Digital Elevation ◽  
Elevation Model

Main scope of the present study is to combine topographic and geological data, magnetic susceptibility and thermomagnetic analysis in order to investigate the magnetic properties of the near surface soils in possible polluted urban areas. For this purpose, a power plant with a dense traffic net around it, located in the NW section of Heraklion city in Crete was selected to be the study area. Surface soil samples have been collected from the area under investigation and they were analyzed in order to estimate the spatial distribution of the magnetic susceptibility. Loci of high values of the magnetic susceptibility within the study area gave rise to further proceed to thermomagnetic analysis of the selected samples. GIS techniques were used for mapping the magnetic measurements on the various topographic and geological features of the area. The digital elevation model was created by the digitization of the topographic map contours (1:5000 scale maps). The combination of the above techniques indicate high values of the magnetic susceptibility especially in the northeastern part of the investigated area, possibly related to pollution due to the presence of heavy metals.

Ferromagnetic interactions in a dicyanamide-bridged multinuclear metal-organic framework [Pr3NH]+ [Mn(dca)3]−·H2O

2019 ◽  
Vol 74 (6) ◽  
pp. 485-489
Author(s):  
Yuan Huang ◽  
Xiu-feng Yu ◽  
Zhen Rong ◽  
Yi-chun Ai ◽  
Kun Qian ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
Magnetic Measurements ◽  
Metal Organic Framework ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
Magnetic Susceptibility Data ◽  
X Ray ◽  
Susceptibility Data ◽  
Metal Organic ◽  
Ferromagnetic Interactions

AbstractA new complex [Pr3NH]+ [Mn(dca)3]− · H2O (dicyanamide = dca−) was synthesized, in which the Mn2+ cations are bridged by end-to-end dca anions to form three-dimensional [Mn(dca)3]nn− networks and tripropylammonium cations reside in the cavities of these networks. The complex has been characterized by single-crystal X-ray diffraction, infrared spectroscopy, elemental analysis, and magnetic measurements. Magnetic susceptibility data indicate ferromagnetic interactions among the MnII ions.

Impact of Buffered Layer Growth Conditions on Grown-In Vacancy Concentrations in Molecular Beam Epitaxy Silicon Germanium

2004 ◽  
Vol 809 ◽  
Author(s):  
Kareem M. Shoukri ◽  
Yaser M. Haddara ◽  
Andrew P. Knights ◽  
Paul G. Coleman ◽  
Mohammad M. Rahman ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Buffer Layer ◽  
Point Defects ◽  
Growth Temperature ◽  
Silicon Germanium ◽  
Molecular Beam ◽  
Growth Conditions ◽  
Layer Growth ◽  
Vacancy Clusters ◽  
Temperature And Growth

ABSTRACTSilicon-Germanium (SiGe) has become increasingly attractive to semiconductor manufacturers over the last decade for use in high performance devices. In order to produce thin layers of device grade SiGe with low concentrations of point defects and well-controlled doping profiles, advanced growth and deposition techniques such as molecular beam epitaxy (MBE) are used. One of the key issues in modeling dopant diffusion during subsequent processing is the concentration of grown-in point defects. The incorporation of vacancy clusters and vacancy point defects in 200nm SiGe/Si layers grown by molecular beam epitaxy over different buffer layers has been observed using beam-based positron annihilation spectroscopy. Variables included the type of buffer layer, the growth temperature and growth rate for the buffer, and the growth temperature and growth rate for the top layer. Different growth conditions resulted in different relaxation amounts in the top layer, but in all samples the dislocation density was below 106 cm−2. Preliminary results indicate a correlation between the size, type and concentration of vacancy defects and the buffer layer growth temperature. At high buffer layer growth temperature of 500°C the vacancy point defect concentration is below the PAS detectable limit of approximately 1015 cm−3. As the buffer layer growth is decreased to a minimum value of 300°C, large vacancy clusters are observed in the buffered layer and vacancy point defects are observed in the SiGe film. These results are relevant to the role played by point defects grown-in at temperatures below ∼350°C in modeling dopant diffusion during processing.

Enhancement of Diffusion Due to Irradiation

1965 ◽  
Vol 20 (4) ◽  
pp. 527-532 ◽  
Author(s):  
W. Schule
Keyword(s):  
Activation Energy ◽  
Steady State ◽  
Production Rate ◽  
Point Defects ◽  
Aluminium Alloys ◽  
Annealed Specimen ◽  
Fast Neutrons ◽  
State Equilibrium

It is shown that in α-copper-aluminium alloys interstitials are able to change sites with the copper and aluminium atoms by diffusion. The activation energy for migration of interstitials could be determined to be 0.82 eV. In a well annealed specimen the interstitials and vacancies annihilate nearly exclusively by pair recombination. The production rate of free interstitials is found to be slightly larger than that of free vacancies during an irradiation with fast neutrons. The excess interstitials, which are supposed to originate from depleted zones, form clusters acting as sinks, at which essentially interstitials anneal out. Due to these sinks another steady state equilibrium („fixed vacancy case“) among point defects and sinks is achieved by repeated irradiations.

High Temperature and High Pressure Synthesis and Magnetic Properties of Arsenic-Based Filled Skutterudite Compounds

2019 ◽  
Vol 289 ◽  
pp. 85-92
Author(s):  
Chihiro Sekine ◽  
Toshihide Osanai ◽  
Hariharan Ponmani ◽  
Atachariya Phuangyod ◽  
Yukihiro Kawamura ◽  
...  
Keyword(s):  
High Pressure ◽  
Magnetic Properties ◽  
Electrical Resistivity ◽  
Magnetic Susceptibility ◽  
Magnetic Measurements ◽  
Spin Fluctuations ◽  
Filled Skutterudite ◽  
Lattice Constants ◽  
Pressure Synthesis ◽  
New Superconductor

We have succeeded in synthesizing new arsenic-based filled skutterudite compounds CaFe4As12and BaOs4As12under high pressure. These compounds have lattice constants of 8.3288 and 8.5809 Å, respectively. The magnetic properties of CaFe4As12and BaOs4As12have been studied by means of electrical resistivity, magnetic susceptibility and magnetization measurements. The electrical resistivity and magnetic measurements indicate that CaFe4As12is a nearly ferromagnetic metal with spin fluctuations of Fe 3delectrons and BaOs4As12is a new superconductor with a transition temperature around 3 K.

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