scholarly journals Влияние Cr и Ni на формирование фаз в механосинтезированном нанокомпозите на основе Fe-=SUB=-75-=/SUB=-C-=SUB=-25-=/SUB=-

2020 ◽  
Vol 90 (5) ◽  
pp. 787
Author(s):  
А.А. Чулкина ◽  
А.И. Ульянов ◽  
В.А. Волков ◽  
А.Л. Ульянов ◽  
А.В. Загайнов

X-ray diffraction, Mossbauer spectroscopy, and magnetic measurements have been used to study the phase formation and doping during mechanical synthesis (MS) and subsequent annealing of the alloy (Fe0.80Cr0.05Ni0.15)75C25. It has been shown that, after MS, the nanocomposite contains mainly two phases – an amorphous phase and cementite A. During annealing, as a result of crystallization of the amorphous phase, cementite B is formed, in which contains more nickel than in the mechanically synthesized cementite A. As the annealing temperature increases, austenite, which is inhomogeneous in nickel content, is formed. The Curie temperature of this austenite reaches 500 °C. It has been determined that cementite in the mechanosynthesized nanocomposite (Fe,Cr,Ni)75C25 has a higher temperature stabilitythan that in a MS composite (Fe,Ni)75C25.

MRS Advances ◽  
2017 ◽  
Vol 2 (49) ◽  
pp. 2763-2768
Author(s):  
D. K. Tiwari ◽  
S. E. Almanza-Morales ◽  
L. M. Morales-Villagómez ◽  
M.O. Alonso-Pérez ◽  
Prakhar Sengar ◽  
...  

ABSTRACTNanocrystalline MnxZn1-xFe2O4with the varying concentration of Mn (x= 0.25, 0.50) have been synthesized by citrate route method. The effect of annealing temperature on structural and magnetic properties of as-synthesized materials was studied. The X-ray diffraction (XRD) analysis revealed the improved crystallinity and purity of the samples at high temperature annealing. Also, the increase in the annealing temperature yielded nanocrystals with bigger crystallite size. The samples annealed at higher temperature were analyzed by TEM which showed the formation of irregular polycrystalline particles with average size in the range of 150-180 nm. The magnetic measurements were taken using vibrating sample magnetometer and displayed the superparamagnetic behavior of the prepared materials. Also, the increase in magnetization was observed with Mn substitution.


2007 ◽  
Vol 130 ◽  
pp. 171-174 ◽  
Author(s):  
Z. Stokłosa ◽  
G. Badura ◽  
P. Kwapuliński ◽  
Józef Rasek ◽  
G. Haneczok ◽  
...  

The crystallization and optimization of magnetic properties effects in FeXSiB (X=Cu, V, Co, Zr, Nb) amorphous alloys were studied by applying X-ray diffraction methods, high resolution transmission electron microscopy (HRTEM), resistometric and magnetic measurements. The temperatures of the first and the second stage of crystallization, the 1h optimization annealing temperature and the Curie temperature were determined for different amorphous alloys. Activation energies of crystallization process were obtained by applying the Kissinger method. The influence of alloy additions on optimization effect and crystallization processes was carefully examined.


2005 ◽  
Vol 475-479 ◽  
pp. 3729-3732
Author(s):  
Cong Mian Zhen ◽  
Xiao Xia Zhai ◽  
Chengfu Pan ◽  
Xiangfu Nie

FePt/C mutilayer films were successfully prepared by using RF and DC magnetron sputtering system. FePt nanoparticles embedded in a C matrix were formed by consequently annealing. X-ray diffraction (XRD) results show the degree of atomic ordering of the L10 structure increases with higher temperature annealing. Room temperature magnetic measurements reveal that in-plane coercivity HC, and squareness Mr/MS depend on the thickness of carbon layer. Relatively High HC (3245.1Oe) and squareness (0.67) were obtained when the thickness of C layer is 2.0 nm. The carbon layer not only isolates the FePt grain, but also suppresses the growth of fct FePt grains. When the thickness of carbon layer is 2.0 nm, the FePt grain size decreases down to ~20 nm measured by Scan Probe Microscope (SPM). Interactions between particles can be tuned to near zero when we select the proper thickness of C layer.


2014 ◽  
Vol 215 ◽  
pp. 167-172
Author(s):  
Victor G. Myagkov ◽  
A.A. Matsunin ◽  
Y.L. Mikhlin ◽  
Victor S. Zhigalov ◽  
Liudmila E. Bykova ◽  
...  

Solid-state reactions between Ge and Mn films are systematically examined using X-ray diffraction, photoelectron spectroscopy and magnetic measurements. The films have a nominal atomic ratio Ge:Mn = 40:60 and are investigated at temperatures from 50 to 500 °С. It is established that after annealing at ~120 °С, the ferromagnetic Mn5Ge3 phase is the first phase to form at the 40Ge/60Mn interface. Increasing the annealing temperature to 500 °С leads to the formation of the ferromagnetic phase with a Curie temperature TC ~ 360 K and magnetization MS ~ 140-200 emu/cc at room temperature. Analysis of X-ray diffraction patterns and the photoelectron spectra suggests that the increased Curie temperature and magnetization are related to the migration of C and O atoms into the Mn5Ge3 lattice and the formation of the Nowotny phase Mn5Ge3СxOy. The initiation temperature (~120 °С) of the Mn5Ge3 phase is the same both for solid-state reactions in Ge/Mn films, as well as for phase separation in GexMn1-x diluted semiconductors. We conclude that the synthesis of the Mn5Ge3 phase is the moving force for the spinodal decomposition of the GexMn1-x diluted semiconductors.


2007 ◽  
Vol 21 (18n19) ◽  
pp. 3469-3472 ◽  
Author(s):  
Z. Y. ZHAI ◽  
X. S. WU ◽  
W. ZHANG ◽  
B. QIAN ◽  
Y. M. ZHANG ◽  
...  

The composition of Mn 0.05 Si 0.95 polycrystalline films on (001) Si substrate are prepared by vacuum deposition and post-crystallization processes. X-ray diffraction studies indicate that there are two phases coexist in the film: tetragonal, Mn 4 Si 7 and diamond-like Si (Mn) . The content of Si(Mn) phase increases with increasing the post-annealing temperature. Temperature dependence of the magnetization shows that there are two ferromagnetic phases with Curie temperature of around 50 K and near room temperature, which is confirmed by x-ray magnetic circular dichroism (XMCD).


1990 ◽  
Vol 213 ◽  
Author(s):  
A.R Yavari ◽  
M.D. Baro ◽  
G. Fillion ◽  
S. Surinach ◽  
S. Gialanella ◽  
...  

ABSTRACT:Ordering of the disordered state (obtained by cold-working or by meltspinning) of L12 type Ni,AI,Fe alloys has been monitored by calorimetric, magnetic and X-ray diffraction measurements .It is found that the magnetic moment per atom of the Ni,Al,Fe alloys in the γ-disordered state is about half of that of the LI2 -γ'state. Magnetic measurements such as ours constitute a new tool for studyingthe γ→γ' transition below the Curie temperature.


2007 ◽  
Vol 336-338 ◽  
pp. 79-82 ◽  
Author(s):  
T.J. Zhang ◽  
S.Z. Li ◽  
B.S. Zhang ◽  
W.H. Huang ◽  
R.K. Pan

Ba0.65Sr0.35TiO3 (BST) thin films on p-silicon substrates were deposited by radio frequency magnetron sputtering. The effects of the deposition parameters on the crystallization and microstructure of BST thin films were investigated by X-ray diffraction and filed emission electron microscopy, respectively. The crystallization behavior of these films was apparently affected by the substrate temperature, annealing temperature and sputtering pressure. The improved crystallization can be observed for BST thin films that deposited at higher temperature. The dominant X-ray diffraction peaks became sharper and more intense as the annealing temperature increased. BST thin films deposited at high sputtering pressure of 3.9 Pa exhibited the (110) + (200) preferred orientation. Possible correlations of the crystallization with the sputtering pressure were discussed. The SEM morphology indicated the film was small grains and smooth.


2020 ◽  
Vol 65 (2) ◽  
pp. 174
Author(s):  
N. G. Debelo ◽  
S. Hailemariam

The effect of thermal annealing on thermoluminescence (TL) glow curves of commercially obtained KY3F10:Ho3+ phosphor is investigated, and the result is compared with that of unannealed sample. The samples were annealed at different annealing temperatures: namely, 400, 500, and 600 ∘C. The activation energy (trap depth), which is one of the TL kinetic parameters, is calculated for the annealed and unannealed samples using the variable heating rate (VHR) method. The results show that the thermal annealing has a clear effect on the TL intensities of the glow curves. The maxima of the TL glow curves shift toward a higher temperature region, as the annealing temperature increases. Moreover, the higher the annealing temperature, the shallower the position of the trap beneath the edge of the conduction band. The X-ray diffraction (XRD) pattern of the sample shows a monoclinic structure with unit cell dimensions (in Angstr¨om) a = 10.41, b = 6.73, c = 12.46 match with JCPDS card No. 21-1458.


2004 ◽  
Vol 810 ◽  
Author(s):  
L. J. Jin ◽  
K. L. Pey ◽  
W. K. Choi ◽  
E. A. Fitzgerald ◽  
D. A. Antoniadis ◽  
...  

ABSTRACTThe interfacial reaction between 10 nm Ni(Pt ∼0, 5, 10 at.%) and (100) Si0.75Ge0.25 substrate after rapid thermal annealing between 400 and 800°C has been studied in detail using Micro- Raman spectroscopy. Only monogermanosilicide phase was detected in the temperature range investigated. The evolution of a broad Ni(Pt)SiGe Raman peak into two distinct peaks with increasing annealing temperature is attributed to a Ge out-diffusion from the germanosilicide grains. In addition, Raman spectroscopy further proves that depletion of Ge concentration in the Ni(Pt)SiGe grains reduces at higher temperature by the addition of Pt. The above phenomena were further supported by X-ray diffraction method.


2013 ◽  
Vol 856 ◽  
pp. 294-298
Author(s):  
A. Vyas ◽  
T. Shripathi ◽  
N. Lakshmi ◽  
O.H. Seeck ◽  
A. Vij ◽  
...  

Synchrotron based X-ray diffraction (XRD) and X-ray reflectivity (XRR) were used to study the structural and magnetic properties of ion beam sputtered Fe/Al multilayer sample (MLS) as a function of annealing temperature. The structural studies show substantial intermixing between the layers which results in multilayer of complicated structures i.e. formation of thin intermixed FeAl layer at the interface during deposition, the nucleation and precipitation of disordered FeAl layer, and its subsequent growth to Fe3Al at higher temperature. The results were also supported by TEM measurements. Magnetization decreases with increase in temperature and Curie temperature (Tc) is found to be much less than that of bulk bcc Fe.


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