131 research outputs found
Preparation of high crystalline nanoparticles of rare-earth based complex pervoskites and comparison of their structural and magnetic properties with bulk counterparts
A simple route to prepare GdSrMnO nanoparticles by
ultrasonication of their bulk powder materials is presented in this article.
For comparison, GdSrMnO nanoparticles are also prepared by
ball milling. The prepared samples are characterized by X-ray diffraction
(XRD),field emission scanning electron microscope (FESEM), energy dispersive
X-ray (EDX), X-ray photoelectron spectroscope (XPS), and Superconducting
Quantum Interference Device (SQUID) magnetometer. XRD Rietveld analysis is
carried out extensively for the determination of crystallographic parameters
and the amount of crystalline and amorphous phases. FESEM images demonstrate
the formation of nanoparticles with average particle size in the range of
50-100 nm for both ultrasonication and 4 hours (h) of ball milling. The bulk
materials and nanoparticles synthesized by both ultrasonication and 4 h ball
milling exhibit a paramagnetic to spin-glass transition. However, nanoparticles
synthesized by 8 h and 12 h ball milling do not reveal any phase transition,
rather show an upturn of magnetization at low temperature. The degradation of
the magnetic properties in ball milled nanoparticles may be associated with
amorphization of the nanoparticles due to ball milling particularly for milling
time exceeding 8 h. This investigation demonstrates the potential of
ultrasonication as a simple route to prepare high crystalline rare-earth based
manganite nanoparticles with improved control compared to the traditional ball
milling technique.Comment: 9 pages, 6 figure
Lorentz TEM imaging of stripe structures embedded in a soft magnetic matrix
N\'eel walls in soft magnetic NiFe/NiFeGa hybrid stripe structures surrounded
by a NiFe film are investigated by high resolution Lorentz transmission
electron microscopic imaging. An anti-parallel orientation of magnetization in
1000 nm wide neighboring unirradiated-irradiated stripes is observed by forming
high angle domain walls during magnetization reversal. Upon downscaling the
stripe structure size from 1000 nm to 200 nm a transition from a discrete
domain pattern to an effective magnetic medium is observed for external
magnetic field reversal. This transition is associated with vanishing ability
of hosting high angle domain walls between adjacent stripes. The investigation
also demonstrated the potentiality of Lorentz microscopy to image periodic
stripe structures well under micron length-scale.Comment: 7 pages, 6 figure
Size dependent magnetic and electrical properties of Ba-doped nanocrystalline BiFeO
Improvement in magnetic and electrical properties of multiferroic BiFeO
in conjunction with their dependence on particle size is crucial due to its
potential applications in multifunctional miniaturized devices. In this
investigation, we report a study on particle size dependent structural,
magnetic and electrical properties of sol-gel derived
BiBaFeO nanoparticles of different sizes ranging from
12 to 49 nm. The substitution of Bi by Ba significantly suppresses
oxygen vacancies, reduces leakage current density and Fe state. An
improvement in both magnetic and electrical properties is observed for 10 %
Ba-doped BiFeO nanoparticles compared to its undoped counterpart. The
saturation magnetization of BiBaFeO nanoparticles increase
with reducing particle size in contrast with a decreasing trend of
ferroelectric polarization. Moreover, a first order metamagnetic transition is
noticed for 49 nm BiBaFeO nanoparticles which
disappeared with decreasing particle size. The observed strong size dependent
multiferroic properties are attributed to the complex interaction between
vacancy induced crystallographic defects, multiple valence states of Fe,
uncompensated surface spins, crystallographic distortion and suppression of
spiral spin cycloid of BiFeO.Comment:
Engineering magnetic domain-wall structure in permalloy nanowires
Using Lorentz transmission electron microscopy we investigate the behavior of
domain walls pinned at non-topographic defects in Cr(3 nm)/Permalloy(10
nm)/Cr(5 nm) nanowires of width 500 nm. The pinning sites consist of linear
defects where magnetic properties are modified by a Ga ion probe with diameter
~ 10 nm using a focused ion beam microscope. We study the detailed change of
the modified region (which is on the scale of the focused ion spot) using
electron energy loss spectroscopy and differential phase contrast imaging on an
aberration (Cs) corrected scanning transmission electron microscope. The signal
variation observed indicates that the region modified by the irradiation
corresponds to ~ 40-50 nm despite the ion probe size of only 10 nm. Employing
the Fresnel mode of Lorentz transmission electron microscopy, we show that it
is possible to control the domain wall structure and its depinning strength not
only via the irradiation dose but also the line orientation.Comment: Accepted for publication in Physical Review Applie
Pemanfaatan Energi Matahari Sebagai Backup Energi Listrik Pada Beban Rumah Tangga 450 VA
This time enlarge of electric power is needed but supply of electric power is too limit. To solve this problem so are needed alternatives energy. Like a solar energy to change the unrenewable energy. To use the solar energy are needed solar cell to change from solar energy to electric powers. The electric powers are produced by a solar cell with 50 WP until ± 19,1 volt and the max current that flow of its are about 1,67 ampere. After that, the electrical powers save in battery and the Voltage output of this battery are raised by boost converter until 175 volt as Voltage input of the inverter. The inverter changes from DC voltage of this to AC voltage 125 volt and this electric power ready to supply the household device. Keyword: solar cell, boost converter, inverter
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