Applied Physics a-Materials Science & Processing
The terahertz dielectric response of LuFe(2)O(4) is investigated by terahertz time-domain spectroscopy over a temperature range of 6-290 K. It is revealed that besides the central mode associated with the charge-ordered state, a soft TO(1) mode at below similar to 240 K is identified indicating the existence of displacing ferroelectricity, in addition to the charge-ordering-induced ferroelectricity at below 320 K. The anomaly of the soft mode at similar to 180 K reflects the magnetoelectric correlation between the soft TO(1) mode and the spin/charge fluctuations revealed recently. Finally, the magnetic property at below similar to 240 K is discussed.
关键词:
system lufe2o4;charge;polarization
Quanling PENG
,
S.M.McMurry
,
J.M.D.Coey
材料科学技术（英文）
Permanent magnet rings are presented, which exploit the image effect in the surrounding circular iron shields. The theory is given for a general permanent ring when the magnetization orientation φ at each coordinate angle ψ changes by φ=(n+1)ψ, where n is a positive or negative integer. For the uniformly magnetized case n=-1, the permanent ring produces no field in its bore, and the field is that of a dipole outside. When the ring is surrounded by a soft iron shield, its field becomes uniform in the bore, and zero outside the ring. The field can be varied continuously by moving the iron shield along the magnet axis. A small variable field device was constructed by using NdFeB permanent rings, which produced a field flux density of 0～0.5 T in the central region.
关键词:
External magnetic field
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null
,
null
QIN Ziqiang YU Zongsen University of Science and Technology Beijing
,
Beijing
,
China QIN Ziqiang Department of Metal Physics
,
University of Science and Technology Beijing
,
Beijing
,
China
金属学报(英文版)
The segregation of sulphur at iron/graphite interfaces in both grey and nodular iron was in- vestigated with AES.Sulphur was found to nonequilibratorily segregate at the interfaces in grey iron,but not in nodular iron.Such different behaviors of segregation,which will exagger- ate the difference of grey and nodular iron in sulphur content at iron/graphite interfaces, might be derived from the difference of solidification process between the two irons.
关键词:
cast iron
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null
,
null
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null
LI Ke-qing
,
NI Wen
,
ZHU Ming
,
ZHENG Mei-juan
,
LI Yuan
钢铁研究学报(英文版)
A laboratory experiment was carried out to extract iron from oolitic iron ore by a deep reduction and magnetic separation technique. The raw coal with fixed carbon of 66.54% was used as the reductant. The iron was successfully extracted from the oolitic iron ore which otherwise is nearly impossible to be separated due to its extremely fine-grain and mosaic nature. The results showed that an iron recovery rate of 90.78% and an iron content of 92.53% of iron concentrate could be obtained by such a technique. The optimized roast temperature is 1200 ℃ and time is 60 min. The subsequent magnetic separation was performed by using a magnetic field intensity of 111 kA·m-1 and a grinding fineness less than 45 μm of 96.19% for the sintered product.
关键词:
oolitic hematite
,
deep reduction
,
magnetic separation
M. Bahgat
,
null
材料科学技术（英文）
Iron carbides are very promising metallurgical products and can be used for steelmaking process, where it plays as an alternative raw material with significant economic advantages. Also it has many other applications, e.g. catalysts, magnets, sensors. The present review investigates the different properties and uses of the iron carbides. The commercial production and the different varieties for the iron carbides synthesis (gaseous carburization, mechanochemical synthesis, laser pyrolysis, plasma pyrolysis, chemical vapor deposition and ion implantation) were reviewed. Also the effect of different factors on the carburization process like gas composition, raw material, temperature, reaction time, catalyst presence and sulfur addition was indicated.
关键词:
Iron carbides
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null
,
null
,
null
Science
The microstructure in the surface layer of a pure iron plate was refined at the nanometer scale by means of a surface mechanical attrition treatment that generates repetitive severe plastic deformation of the surface layer. The subsequent nitriding kinetics of the treated iron with the nanostructured surface layer were greatly enhanced, so that the nitriding temperature could be as low as 300C, which is much lower than conventional nitriding temperatures (above 500degreesC). This enhanced processing method demonstrates the technological significance of nanomaterials in improving traditional processing techniques and provides a new approach for selective surface reactions in solids.
关键词:
surface nanocrystallization;copper
Materials Chemistry and Physics
The co-operation behavior of iron and phosphorus in clectrodeposition of Zn-Fe-P alloy onto copper from light acid chloride solutions (LACS) was investigated by means of cyclic voltammetry and steady-state polarization techniques. It was found that, under the experimental conditions, the phosphorous and the iron promote the reduction of each other and their contents in Zn-Fe-P coating change synchronously, which has been interpreted theoretically in the view of quantum chemistry. The theoretical results showed that, because the orbital radius of 4S of iron atom is shorter than that of zinc atom, the overlapping integral of iron and phosphorus (SFe-P) is smaller than that of zinc and phosphorus (SZn-P) which resulted in the synchronous variation of the contents of the phosphorus and the iron in the electrodeposits, and which also showed that there exist the cooperative effect of phosphorus with iron series metal among their co-depositing coatings. (C) 2002 Elsevier Science B.V. All rights reserved.
关键词:
electrodeposition;Zn-Fe-P alloy;cyclic voltammetry;light acid;chloride solution;alloys
C.Huang
,
B.Song
,
J.H.Mao
,
Q.Lin
,
P.Zhao
金属学报(英文版)
By using of electrolytic pure iron, the specimens containing different oxide content were made in a Mo wire furnace. The DTA method was employed to measure the undercooling of liquid iron during solidification. The relations between the cleanness of liquid iron and undercooling, thermodynamic driving force of nucleation, the nucleus forming energy, as well as the critical radius of nucleus have been investigated. The results showed that with the increase of cleanness of liquid iron the undercooling and thermodynamic driving force increased, while the nucleus forming energy and critical radius of nucleus decreased.
关键词:
pure iron
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null
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null
WANG Mingyu
,
LOU Taiping
,
ZHANG Li
,
SUI Zhitong
钢铁研究学报(英文版)
Owing to smelting vanadiumtitanium magnetite ore, the amount of iron entrainment in slag as droplets is far higher than that in conventional BF slag. However, the iron droplets can be easily settled by blowing air into the molten slag. The results show that more than 80% of iron droplets in titania bearing slag can be settled and separated after treatment. The temperature rise of molten slag during the oxidizing process and the decreased viscosity caused by the component change of slag as well as air stirring in slag both accelerate the iron droplets settling. The vanadium content in the settled iron droplets and the original iron droplets was obtained by chemical analysis. The possible reason for the increased vanadium in the settled iron droplets was discussed by thermodynamic principles.
关键词:
titania bearing slag;oxidation;viscosity change;temperature change;phase separation
