Magnetoimpedance (MI) has been investigated in the laser and microwave annealed Fe66Ni7Si7B20 ribbons. The largest MI [(MI)m] values of the ribbons annealed using laser with energies of 150, 200 and 250 mJ/pulse (mJp) are 25% (at 7 MHz), 30% (at 5 MHz) and 21% (at 7 MHz) respectively. The effect of domain wall pinning on MI was observed as field insensitive regions in the MI profiles in the ribbon annealed using 150 mJp energy. Flower shaped grains in amorphous matrix in the ribbon annealed with 200 mJp energy are responsible for highest (MI)m due to the least anisotropy. In the ribbons annealed for 40, 45 and 50 min at 400 °C using microwaves, (MI)m values are 35% (at 5 MHz), 46% (at 6 MHz) and 29% (at 7 MHz) respectively. The large DC conductivity and the least anisotropy (smallest Hk values) in the ribbon microwave annealed for 45 min at 400 °C resulted in (MI)m reaching its highest value in the ribbons investigated. © 2015 Published by Elsevier B.V.

G. Markandeyulu

Department Of Physics

Ganesh Kotagiri

S.D. Ramarao

Amorphous materials

Anisotropy

Magnetization

MICROWAVES

Nickel

Amorphous matrices

Dc conductivity

DOMAIN-WALL PINNING

FLOWER-SHAPED

Laser annealing

MAGNETO-IMPEDANCE

MICROWAVE ANNEALING

Annealing

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Journal of Magnetism and Magnetic Materials

Microstructure and magnetoimpedance (MI) properties of soft magnetic Co73Fe4.5Mn0.5Nb1.0Si4.2B16.8 ribbons with artificial defects have been investigated. The holes of &lt;0.5 mm diameter were created on 5 cm long amorphous ribbon to study the role of demagnetizatizing fields on MI. The MI ratio [MI(%)] decreased by 21% for ribbon with maximum 7 holes. Present results show that the anisotropy induced by artificial defects strongly influences the MI properties. However Joule annealing at an optimum condition enables one to reduce the anisotropy developed by the defects. © 2016 Elsevier B.V.

Role of artificially created defects on magnetoimpedance of Co73Fe4.5Mn0.5Nb1.0Si4.2B16.8 ribbon

Magnetoimpedance (MI) effect was studied on amorphous Co33Fe33Ni7Si7B20 ribbons that were irradiated with N+1, Ar+2 and Xe+5 ions, at energy of 75 keV. The (MI)m [maximum MI in each case] values are 9.4% and 11%, 9.9% and 6.5%, the largest, for the as-quenched and N+1, Ar+2 and Xe+5 ion irradiated ribbons respectively, at 2 MHz. The (MI)m value of the N+1 ion irradiated ribbon was observed to be the highest, due to an induced in-plane transverse magnetic anisotropy. The saturation magnetizations of the ion-irradiated ribbons are not seen to change with respect to that of the as-quenched ribbon; a small increase in the Ms was observed only upon irradiation with Xe5+ ions. The interaction between the large number of domains, with large uniaxial anisotropy led to large (MI)m values, at frequencies above 8 MHz in the Ar+2 ion irradiated ribbon. © 2015 Published by Elsevier B.V.

Magnetoimpedance studies on ion irradiated Co33Fe33Ni7Si7B20 ribbons

Magnetoimpedance (MI) has been investigated in the as quenched Fe 66-xCoxNi7Si7B20 (x=0, 33 and 66) ribbons. In plane anisotropy was present in as-quenched x=0, 33 and 66 ribbons. The largest MI values for x=0, 33 and 66 ribbons are 25% (at 7 MHz), 26% (at 8 MHz) and 45% (at 8 MHz) respectively. Largest MI values increased with increasing Co due to reduced magnetic anisotropy. Maximum MI values reduced at higher frequencies due to increased anisotropy fields. © 2014 Elsevier B.V.

Physica B: Condensed Matter

Magnetoimpedance studies on as-quenched Fe66-xCo xNi7Si7B20 (x=0, 33 and 66) ribbons

Ribbons of Fe73.5Si13.5B8CuV 3-xAlNbx (x 0, 1.0, 1.5) alloys were prepared by melt-spun technique at the speed of 37 m/s. Crystalline phase derived from Fe 3Si, in an amorphous matrix was observed in all the ribbons. As cast nanocrystalline ribbons were obtained by controlling cooling rates while quenching. The average crystallite sizes was calculated using the Scherrers equation to be 44 nm, 39 nm, and 35 nm in x 0, x 1.0, and x 1.5 ribbons, respectively. Magnetoimpedance measurements were carried out using an LCR meter. Among the investigated samples (x 0, 1.0, 1.5), the largest magnetoimpedance of 61 was obtained for x 1 ribbon annealed at 100 °C for 15 min, at 4 MHz. © 2013 American Institute of Physics.

Fulltext

Journal of Applied Physics

Magnetoimpedance studies in as quenched Fe73.5Si 13.5B8CuV3-xAlNbx nanocrystalline ribbons

Using solid-state reaction route and high-energy ball milling technique Zn 1-xMg xTiO 3 (x = 0-0.5) compositions were synthesized. These ball milled samples were sintered at 1100°C for 2 h and microwave dielectric properties such as dielectric constant (ε'), quality factor (Q), and temperature coefficient of resonant frequency (τ f) were studied. Significant improvement in quality factor of ∼ 65% was observed for x = 0.3. To understand the effect of sintering duration on the microwave dielectric properties, single phase Zn 0.7Mg 0.3TiO 3 samples were sintered at 1100°C for different durations from 2 to 20 h. The grain size increases with sintering duration and it influences to enhance the microwave dielectric properties and as a result, the quality factor further improved by three times. The dielectric constant and temperature coefficient of resonant frequency showed a slight improvement of ∼ 10%-15% with sintering duration. © 2012 The American Ceramic Society.

Journal of the American Ceramic Society

Effect of grain size on the microwave dielectric characteristics of high-energy ball-milled zinc magnesium titanate ceramics

A systematic investigation of the influence of different types of annealing on the magnetoimpedance (MI) effect in melt-spun (Co1-xFe x)89Zr7B4 [x=0, 0.025, 0.05] and (Co0.88Fe0.12)78.4Nb2.6Si 9B9Al ribbons has been carried out in the frequency range 500 kHz13 MHz and under dc magnetic fields (Hdc) up to 80 Oe. In the stress annealed ribbons, the strain-induced transverse anisotropy is seen to result in large MI. Magnetic domains were investigated in the ribbons through magnetic force microscopy. © 2011 Elsevier B.V. All rights reserved.

Stress-MI and domain studies in Co-based nanocrystalline ribbons

A systematic investigation of the influence of Al and V on the magnetoimpedance (MI) effect in melt-spun [formula omitted] ([formula omitted], 1, 1.5, and 3) ribbons has been performed in the frequency range 500 kHz–13 MHz and under dc magnetic field [formula omitted] up to 60 Oe. MI was measured using impedance analyzer employing contact and noncontact methods. MIs of 61% (contact method) and [formula omitted] (noncontact method) were observed for the [formula omitted] ribbon. Transverse and in-plane anisotropies were studied from the MI measurements and ferromagnetic resonance. Magnetic domain structure was studied in the ribbons through magnetic force microscopy. When the ribbon was rotated by 90° from the east-west direction, a 37% change in the MI was observed due to the earth's magnetic field. © 2010, American Institute of Physics. All rights reserved.

Journal	Data powered by TypesetJournal of Magnetism and Magnetic Materials
Publisher	Data powered by TypesetElsevier
ISSN	03048853
Open Access	No