Maruti K. Rendale, S.N. Mathad and Vijaya Puri
The present communication aims to investigate the influence of cobalt substitution on the structural, mechanical and elastic properties of nickel–zinc ferrite thick films. The…
Abstract
Purpose
The present communication aims to investigate the influence of cobalt substitution on the structural, mechanical and elastic properties of nickel–zinc ferrite thick films. The changes observed in the crystallite size (D), lattice constant (a), texture coefficient [TC(hkl)] and mechanical and elastic properties of the thick films due to cobalt substitution have been reported systematically.
Design/methodology/approach
Ni–Zn ferrites with the stoichiometric formula Ni0.7−xCoxZn0.3Fe2O4 (where, x = 0, 0.04, 0.08, 0.12, 0.16 and 0.20) were synthesized via solution combustion technique using sucrose as the fuel and poly-vinyl-alcohol as the matrix material. The thick films of the ferrites were fabricated on alumina substrates by the screen printing method. The thickness of the films was 25 μm, as measured by the gravimetric method. The thick films were subjected to X-ray diffraction and Fourier transform infrared spectroscopy.
Findings
The detailed study of variation of lattice parameter (a), sintering density, micro-strain and elastic properties with cobalt (Co+2) substituted was carried out. The remarkable increase in lattice parameter (from 8.369 A° to 8.3825 A°), bulk density and average grain size (69-119 nm) with the cobalt content was due to larger ionic radius of Co2+ compared to Ni2+. Texture analysis [TC(hkl)] reveals all thick films have adequate grain growth in the (311) plane direction. The main absorption bands of spinel ferrite have appeared through infrared absorption spectra recorded in the range of 300-700 cm−1.
Originality/value
The variation in stiffness constants (for isotropic material, C11 = C12), longitudinal elastic wave (Vl), transverse elastic wave (Vt), mean elastic velocity (VMean), rigidity modulus (G), Poisson’s ratio(s) and Young’s modulus (E) with cobalt (Co+2) composition has been interpreted in terms of binding forces found.
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M.K. Rendale, S.D. Kulkarni, D.C. Kulkarni and Vijaya Puri
The purpose of this paper is to investigate the effect of Mg2+substitution on the magnetic and electrical properties of Li0.35−x Mg2x Zn0.3 Fe2.35−xO4 thick films synthesized with…
Abstract
Purpose
The purpose of this paper is to investigate the effect of Mg2+substitution on the magnetic and electrical properties of Li0.35−x Mg2x Zn0.3 Fe2.35−xO4 thick films synthesized with polyvinyl alcohol (PVA) matrix.
Design/methodology/approach
The nanoferrites Li0.35−x Mg2x Zn0.3 Fe2.35−xO4 (x=0, 0.07, 0.14, 0.21, 0.28 and 0.35) were synthesized by chemical technique using aqueous solution of PVA (the matrix) and thick films were fabricated by screen printing technique. The DC magnetic hysteresis measurements, AC magnetic susceptibility and DC electrical resistivity were measured as a function of temperature.
Findings
The lattice parameter of thick film Li0.35−x Mg2x Zn0.3 Fe2.35−xO4 (x=0, 0.07, 0.14, 0.21, 0.28 and 0.35) increases with the substitution of Mg2+ions for Li1+and Fe3+. The surface morphology of the thick films showed the grain size increasing with Mg2+substitution till x=0.21 and then decreasing for the higher concentrations of magnesium. The magnetic moment nB (μB) computed from the Ms obtained by extrapolation of the magnetization curve showed a gradual decrease with the composition till x=0.21, beyond which a sudden decrease was observed. The resistivity of the films at room temperature had variation with composition x, similar to that of magnetic moment. The activation energies ΔEF and ΔEP were found to vary with composition x of the ferrite system.
Originality/value
The paper reports, for the first time, the magnetic and electrical properties of fritless Li0.35−xMg2xZn0.3Fe2.35−xO4 thick films using PVA polymer matrix. Up to x=0.21 (Mg2+), grain size increases and Curie temperature decreases beyond which reverse effect takes place.
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M.K. Rendale, S.D. Kulkarni and Vijaya Puri
The aim of this paper is to investigate permittivity of nano structured Ni0.7‐xCoxZn0.3Fe2O4 thick films at microwave frequencies.
Abstract
Purpose
The aim of this paper is to investigate permittivity of nano structured Ni0.7‐xCoxZn0.3Fe2O4 thick films at microwave frequencies.
Design/methodology/approach
Nanosized Ni0.7‐xCoxZn0.3Fe2O4 ferrites with x=0, 0.04, 0.08 and 0.12 were prepared by sucrose precursor technique using the constituent metal nitrates. Thick films of the ferrites were fabricated on alumina substrates by screen‐printing technique. Microwave dielectric constant (ε′) and the loss factor (ε″) for the thick films were measured by VSWR slotted section method in the 8‐18 GHz range of frequencies. Microwave attenuation properties were studied using a waveguide reflectometer set up.
Findings
Both the ε′ and ε″ were found to vary with frequency and composition x. It is observed that, value of ε′ increases with increase in x, due to the increase in bulk density and reduction in porosity of the material, that resulted due to the substitution of cobalt in Ni‐Zn ferrite. The microwave transmission loss offered by the thick films was found to increase with the increase in cobalt concentration x. Within the band width of 4 GHz (from 12‐16 GHz), all the films except that with x=0.04 offered the reflection loss of less than 3 dB.
Originality/value
The dielectric constant of Ni0.7‐xCoxZn0.3Fe2O4 thick films have been reported for the first time. These thick films provide scope for cost effective planar ferrite devices.
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N. Patil, N.B. Velhal, R. Pawar and Vijaya Puri
The purpose of this article is to study the effect of ferrite content on electric, magnetic and microwave properties of screen-printed y(Ni0.4Co0.2Cd0.4Fe2O4) + (1 �…
Abstract
Purpose
The purpose of this article is to study the effect of ferrite content on electric, magnetic and microwave properties of screen-printed y(Ni0.4Co0.2Cd0.4Fe2O4) + (1 − y)Pb(Zr0.52Ti0.48)O3 (y = 0.0, 0.15, 0.30, 0.45, 1.0) thick films on alumina.
Design/methodology/approach
Thick films of ferrite–ferroelectric composite on alumina substrate have been delineated using screen printing technique. The structural analysis was carried out using X-ray diffraction method and scanning electron microscopy. The DC electrical resistivity was measured using the two-probe method. The magnetic measurement was carried out using a vibrating sample magnetometer. Microwave absorption was studied in the 8-18 GHz frequency range by using the vector network analyzer (N5230A). The permittivity in the 8-18 GHz frequency range was measured by using voltage standing wave ratio slotted section method.
Findings
The formation of two individual ferrite–ferroelectric phases in composite thick films was confirmed by the X-ray diffraction patterns. The scanning electron microscope morphologies show the growth of cobalt-substituted nickel cadmium ferrite grains which are well dispersed in lead zirconium titanate matrix. The DC electrical resistivity increases with increase in ferrite content and decreases with increase in temperature. The present ferrite shows ferromagnetic nature and it increases saturation magnetization and coercivity of the composite thick films. Tuning properties are observed in the Ku-band and broadband X-band microwave absorption is observed in the composite thick films. The imaginary part of permittivity increases with an increase in ferrite content, which increases microwave absorption. The real part of microwave permittivity varied from 17 to around 22 with an increase in ferrite content and it decreases with frequency. The microwave conductivity, which increases with an increase in ferrite content, reveals the loss of polaron conduction, which supports the dielectric loss in the microwave region.
Originality/value
Electric, magnetic and microwave properties of screen-printed y(Ni0.4Co0.2Cd0.4Fe2O4) + (1 − y)Pb(Zr0.52Ti0.48)O3 (y = 0.0, 0.15, 0.30, 0.45, 1.0) composite thick films on alumina substrate is reported for the first time.
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The aim of this paper is to investigate microwave Ku band absorbance, complex permittivity, and permeability of SrFe12O19 thick films by a simple and novel waveguide technique.
Abstract
Purpose
The aim of this paper is to investigate microwave Ku band absorbance, complex permittivity, and permeability of SrFe12O19 thick films by a simple and novel waveguide technique.
Design/methodology/approach
The glass frit free or fritless strontium hexaferrite thick films were formulated on alumina by screen printing technique from the powder synthesized by chemical co precipitation method for pH 11 adjusted during the reaction. The 13‐18 GHz frequency band microwave absorbance of the SrFe12O19 thick films by a simple waveguide method. The complex permittivity and permeability of strontium hexaferrite thick films was measured by voltage standing wave ratio technique.
Findings
SrFe12O19 thick films show high ∼80 percent absorbance in the whole 13‐18 GHz frequency band. The thickness dependant microwave properties of strontium hexaferrite thick films were observed. The real permittivity ε′ lies in between eight and 35 with the variation in thickness of the thick film SrFe12O19. The real microwave permeability μ′ of strontium hexaferrite thick films lies in the range 1.12‐6.41. The resonance type behavior was observed at frequency 14.3 GHz. The SrFe12O19 thick film of thickness 30 μm could be a wide band (∼5,000 MHz) absorber with absorbance ∼87 percent for the whole 13‐18 GHz frequency band.
Originality/value
The complex permeability of strontium hexaferrite thick films was measured by simple novel waveguide method. The high absorbance (∼87 percent) of thick film SrFe12O19 over a broad band ∼5,000 MHz will be useful in achieving RAM coatings required for 13‐18 GHz frequency band.
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MANY who realise the implications of White's book on The Organisation Man have probably closed it with the self‐satisfied reflection that ‘it can't happen here.’ That is the…
Abstract
MANY who realise the implications of White's book on The Organisation Man have probably closed it with the self‐satisfied reflection that ‘it can't happen here.’ That is the anodyne we generally swallow to protect us from disagreeable fears.