Microwave processed Ni1-xMgxFe2O4 with x = 0.0–1.0 are characterized fordc,ac conductivities and dielectric properties as a function of temperature and frequency. Very low dielectric loss tangent is achieved at 5 MHz frequency. Grain and grain boundary contribution towards conductivity is presented on the basis of Nyquist plots and their resistances are evaluated from semi-circular arcs. Equivalent electrical circuits and approximate R-C values are presented for better insight. High dielectric constant of 41 for x = 0.8 sample instigated the possibility of good electromagnetic absorption material. A shift in the transport phenomenon is suggested from band like to polaron hopping with rise in temperature.In addition the electromagnetic interference shielding properties are studied in X-band.The results show that the goodelectromagnetic interference shielding efficiency is achieved for x = 0.4 − 0.6 compositions ranging from 10 to 17 dB (at 8.4 GHz) which is suitable for shielding application. © 2017 Elsevier Ltd

Madhuri W

Department of Physics

School of Advanced Sciences

Vellore Campus

Chandra Babu Naidu K

RoopasKiran S

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

&nbsp;

&nbsp;

VIT University

Materials Research Bulletin

Ferrites are magnetic semiconductors realizing an important role in electrical and electronic circuits where electrical and magnetic property coupling is required. Though ferrite materials are known for a long time, there is a large scope in the improvement of their properties (vice sintering and frequency dependence of electrical and magnetic properties) with the current technological trends. Forth coming technology is aimed at miniaturization and smart gadgets, electrical components like inductors and transformers cannot be included in integrated circuits. These components are incorporated into the circuit as surface mount devices whose fabrication involves low temperature co-firing of ceramics and microwave monolithic integrated circuits technologies. These technologies demand low temperature sinter-ability of ferrites. This article presents low temperature microwave sintered Ni–Mg ferrites of general chemical formula Ni1−xMgxFe2O4 (x=0, 0.2, 0.4, 0.5, 0.6, 0.8, 1) for potential applications as transformer core materials. The series of ferrites are characterized using X-ray diffractometer, scanning electron microscopy, Fourier transform infrared and vibrating sample magnetometer for investigating structural, morphological and magnetic properties respectively. The initial permeability is studied with magnesium content, temperature and frequency in the temperature range of 308 K–873 K and 42 Hz–5 MHz. © 2016 Elsevier B.V.

Journal of Magnetism and Magnetic Materials

Microwave processed NiMg ferrite: Studies on structural and magnetic properties

Magnesium is replaced systematically by zinc in Ni0.2Mg0.8-xZnxFe2O4 (x = 0.2–0.8) prepared by microwave-assisted solid-state reaction route. The structure is confirmed by X-ray diffractograms. An improvement in initial permeability is observed with substituent in Ni0.2Mg0.8-xZnxFe2O4 due to increase in average grain size. The obtained permeability values are varying between 106 and 687 at 1 MHz. The permeability plots revealed that Curie-transition temperature (Tc) is decreasing with increase in zinc. Both x = 0.2 and 0.4 compositions show low relative loss factor of order 10−5 to 10−4, which are exhibiting required magnetic properties for transformer and inductor core applications. © 2016 The American Ceramic Society

International Journal of Applied Ceramic Technology

Effect of Nonmagnetic Zn2+Cations on Initial Permeability of Microwave-Treated NiMg Ferrites

The spinel ferrite of compositions Ni0.2Mg0.8−x ZnxFe2O4 (x = 0.2, 0.4, 0.6, 0.8) are synthesized using microwave double sintering technique. X-ray diffraction study reveals formation of single phase spinel cubic structure. The lattice parameter (a), average crystallite size (D) and bulk density (ρb) are increasing with zinc content. Fourier-transform infrared spectra are recorded to locate octahedral and tetrahedral sites. The dielectric constant (εr), loss tangent (tanδ), ac, dc-electrical conductivities (σac and σdc) are increasing while Curie transition temperature (Tc) and activation energies (Ea) are decreasing with zinc substitution. Power law fit is applied to logσ versus logω plots to evaluate dc-electrical conductivity and exponent (n) at room temperature. Electrical conduction mechanism and relaxation time (τ) are reported from impedance analysis. Hysteresis loop attributes that saturation magnetization (Ms), anisotropy constant (K1) and coercivity (Hc) are decreasing with substituent. Low coercivity of 1.96–2.89 G obtained is suitable for magnetic recording applications. © 2016 Elsevier B.V.

Journal	Data powered by TypesetMaterials Research Bulletin
Publisher	Data powered by TypesetElsevier BV
ISSN	0025-5408
Open Access	0