scholarly journals Nonmagnetic-magnetic transition and magnetically ordered structure in SmS

2021 ◽  
Vol 103 (15) ◽  
Author(s):  
S. Yoshida ◽  
T. Koyama ◽  
H. Yamada ◽  
Y. Nakai ◽  
K. Ueda ◽  
...  
Keyword(s):  
Magnetic Transition ◽  
Ordered Structure ◽  
Magnetically Ordered

scholarly journals Температура магнитного упорядочения оксида трехвалентного железа varepsilon-Fe-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=-

2019 ◽  
Vol 61 (3) ◽  
pp. 478
Author(s):  
Д.А. Балаев ◽  
А.А. Дубровский ◽  
С.С. Якушкин ◽  
Г.А. Бухтиярова ◽  
О.Н. Мартьянов
Keyword(s):  
Iron Oxide ◽  
Ferromagnetic Resonance ◽  
Room Temperature ◽  
Magnetic Transition ◽  
Sharp Decrease ◽  
Magnetic Behavior ◽  
Paramagnetic State ◽  
Trivalent Iron ◽  
Temperature Evolution ◽  
Magnetically Ordered

AbstractThe trivalent iron oxide ε-Fe_2O_3 is a fairly rare polymorphic iron oxide modification, which only exists in the form of nanoparticles. This magnetically ordered material exhibits an intriguing magnetic behavior, specifically, a significant room-temperature coercivity H _C (up to ~20 kOe) and a magnetic transition in the temperature range of 80–150 K accompanied by a sharp decrease in the H _C value. Previously, the temperature of the transition to the paramagnetic state for ε-Fe_2O_3 was believed to be about 500 K. However, recent investigations have shown that the magnetically ordered phase exists in ε-Fe_2O_3 also at higher temperatures and, around 500 K, another magnetic transition occurs. Using the data on the magnetization and temperature evolution of the ferromagnetic resonance spectra, it is shown that the temperature of the transition of ε-Fe_2O_3 particles 3–10 nm in size to the paramagnetic state is ~850 K.

Planar defects in ordered (Ga,In)P

1988 ◽  
Vol 46 ◽  
pp. 902-903
Author(s):  
S. McKernan ◽  
C. B. Carter ◽  
D. Bour ◽  
J. R. Shealy
Keyword(s):  
Electron Diffraction ◽  
Vapor Phase ◽  
Growth Direction ◽  
High Density ◽  
Ordered Structure ◽  
Planar Defects ◽  
Diffraction Patterns ◽  
Ternary Semiconductors ◽  
Anion Species ◽  
Metallic Vapor

The growth of ternary III-V semiconductors by organo-metallic vapor phase epitaxy (OMVPE) is widely practiced. It has been generally assumed that the resulting structure is the same as that of the corresponding binary semiconductors, but with the two different cation or anion species randomly distributed on their appropriate sublattice sites. Recently several different ternary semiconductors including AlxGa1-xAs, Gaxln-1-xAs and Gaxln1-xP1-6 have been observed in ordered states. A common feature of these ordered compounds is that they contain a relatively high density of defects. This is evident in electron diffraction patterns from these materials where streaks, which are typically parallel to the growth direction, are associated with the extra reflections arising from the ordering. However, where the (Ga,ln)P epilayer is reasonably well ordered the streaking is extremely faint, and the intensity of the ordered spot at 1/2(111) is much greater than that at 1/2(111). In these cases it is possible to image relatively clearly many of the defects found in the ordered structure.

Characterisation of planar crystal defects in Y2Fe17Cx (0.6 ≤ x ≤ 1.6) magnetic material by High Resolution Electron Microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 774-775
Author(s):  
W. Coene ◽  
F. Hakkens ◽  
T.H. Jacobs ◽  
K.H.J. Buschow
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Permanent Magnets ◽  
Annealing Treatment ◽  
High Resolution Electron Microscopy ◽  
Crystal Defects ◽  
Ordered Structure ◽  
X Ray ◽  
Planar Crystal ◽  
Resolution Electron

Intermetallic compounds of the type RE2Fe17Cx (RE= rare earth element) are promising candidates for permanent magnets. In case of Y2Fe17Cx, the Curie temperature increases from 325 K for x =0 to 550 K for x = 1.6 . X ray and electron diffraction reveal a carbon - induced structural transformation in Y2Fe17Cx from the hexagonal Th2Ni17 - type (x < 0.6 ) to the rhombohedral Th2Zn17 - type ( x ≥ 0.6). Planar crystal defects introduce local sheets of different magnetic anisotropy as compared with the ordered structure, and therefore may have an important impact on the coercivivity mechanism .High resolution electron microscopy ( HREM ) on a Philips CM30 / Super Twin has been used to characterize planar crystal defects in rhombohedral Y2Fe17Cx ( x ≥ 0.6 ). The basal plane stacking sequences are imaged in the [100] - orientation, showing an ABC or ACB sequence of Y - atoms and Fe2 - dumbbells, for both coaxial twin variants, respectively . Compounds resulting from a 3 - week annealing treatment at high temperature ( Ta = 1000 - 1100°C ) contain a high density of planar defects.

THERMAL EXPANSION ANOMALIES AT THE MAGNETIC TRANSITION OF Mn3Ga1-xAlxC (x ≤ 0.05)

1988 ◽  
Vol 49 (C8) ◽  
pp. C8-159-C8-160
Author(s):  
T. Suzuki ◽  
T. Kanomata ◽  
T. Kaneko
Keyword(s):  
Thermal Expansion ◽  
Magnetic Transition

Layered transition metal carboxylates: synthesis, structural aspects and observation of multi-step magnetic transition through phase diagram

2013 ◽  
Vol 42 (41) ◽  
pp. 14836 ◽  
Author(s):  
Rupam Sen ◽  
Dasarath Mal ◽  
Armandina M. L. Lopes ◽  
Paula Brandão ◽  
João P. Araújo ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Transition Metal ◽  
Magnetic Transition ◽  
Metal Carboxylates ◽  
Layered Transition Metal ◽  
Structural Aspects

scholarly journals Complex magnetic properties associated with competing local and itinerant magnetism in $${\text {Pr}}_2 {\text {Co}}_{0.86} {\text {Si}}_{2.88}$$

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mily Kundu ◽  
Santanu Pakhira ◽  
Renu Choudhary ◽  
Durga Paudyal ◽  
N. Lakshminarasimhan ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Neutron Diffraction ◽  
Single Phase ◽  
Magnetic Transition ◽  
Muon Spin Rotation ◽  
Antiferromagnetic Coupling ◽  
Diffraction Measurement ◽  
Zero Field ◽  
Crystalline Electric Field ◽  
X Ray

AbstractTernary intermetallic compound $${\text {Pr}}_2 {\text {Co}}_{0.86} {\text {Si}}_{2.88}$$ Pr 2 Co 0.86 Si 2.88 has been synthesized in single phase and characterized by x-ray diffraction, scanning electron microscopy with energy dispersive x-ray spectroscopy (SEM-EDX) analysis, magnetization, heat capacity, neutron diffraction and muon spin rotation/relaxation ($$\mu$$ μ SR) measurements. The polycrystalline compound was synthesized in single phase by introducing necessary vacancies in Co/Si sites. Magnetic, heat capacity, and zero-field neutron diffraction studies reveal that the system undergoes magnetic transition below $$\sim$$ ∼ 4 K. Neutron diffraction measurement further reveals that the magnetic ordering is antiferromagnetic in nature with an weak ordered moment. The high temperature magnetic phase has been attributed to glassy in nature consisting of ferromagnetic clusters of itinerant (3d) Co moments as evident by the development of internal field in zero-field $$\mu$$ μ SR below 50 K. The density-functional theory (DFT) calculations suggest that the low temperature magnetic transition is associated with antiferromagnetic coupling between Pr 4f and Co 3d spins. Pr moments show spin fluctuation along with unconventional orbital moment quenching due to crystal field. The evolution of the symmetry and the crystalline electric field environment of Pr-ions are also studied and compared theoretically between the elemental Pr and when it is coupled with other elements such as Co. The localized moment of Pr 4f and itinerant moment of Co 3d compete with each other below $$\sim$$ ∼ 20 K resulting in an unusual temperature dependence of magnetic coercivity in the system.

Quantification of Starch Order in Physically Modified Rice Flours Using Small-Angle X-ray Scattering (SAXS) and Fourier Transform Infrared (FT-IR) Spectroscopy

2021 ◽  
pp. 000370282110282
Author(s):  
Daitaro Ishikawa ◽  
Jiamin Yang ◽  
Tomoyuki Fujii
Keyword(s):  
Infrared Spectroscopy ◽  
Small Angle ◽  
Water Sorption ◽  
Order Parameter ◽  
Rice Flour ◽  
Ordered Structure ◽  
X Ray ◽  
Glucose Unit ◽  
X Ray Scattering ◽  
Ray Scattering

The purpose of this study was to understand the ordered structure of starch in rice flour based on a physical modification with non-heating, milling, and water sorption through the structural evaluation of rice flour using small-angle X-ray scattering (SAXS) and infrared spectroscopy within the 4000–100 cm−1 region. The SAXS pattern of the samples with low moisture contents subjected to milling yield a band within the 0.4–0.9 nm−1 of the q range owing to a lamellar repeat of starch with an ordered structure in rice flour. We proposed an order parameter using the intensity of the SAXS band to quantify the order structure of starch in rice flour, and the true density was negatively correlated with the order parameter. Infrared band at 990 cm−1 in COH bending mode applied to the hydroxyl group of C6 shifted to a low wavenumber corresponding to the order parameter. A linear correlation was found between the order parameter and the 990 cm−1 and band at 861 cm−1 owing to COC symmetrical stretching of glycoside bond and CH2 deformation of the glucose unit of starch, 572, 472, and 436 cm−1, owing to the pyranose ring in the glucose unit of starch. The identified infrared bands are effective for quantifying the ordered structure of starch at the lamellar level. When subjected to water sorption, the band position at 990 cm−1 shifted to a higher wavenumber above a water activity of 0.7. This result revealed that the water-induced transition of glass to rubber of starch in rice flour can be clearly evaluated through infrared spectroscopy using the band at 990 cm−1. In addition, the band at 861 cm−1 also shifted to a higher wavenumber, whereas those at 572 and 436 cm−1 did not show a significant shift. These results indicate that water sorption slightly affects the internal structure and may mainly affect the surface of starch.

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