R. N. Jadhav

Structural and mechanical properties of Sr+2-doped bismuth manganite thick films

Bismuth strontium manganites Bi1 − xSrxMnO3 (0.20 ≤ x ≤ 0.50) belonging to the orthorhombic structural family were prepared in furnace using a solid-state reaction technique. Thick films of Bi(1 − x)SrxMnO3 were prepared by simple screen printing route. X-ray diffraction data suggest that the synthesized materials have an orthorhombic structure. For synthesized materials, texture coefficient (TC), dislocation density (ρD), density of crystallites per unit area (ψ), and mechanical properties are reported along with the influence of x on the structure and mechanical properties of BiMnO3 thick films.

MICROWAVE ABSORPTION, CONDUCTIVITY AND COMPLEX PEMITTIVITY OF FRITLESS Ni(1-x)CuxMn2O4 (0â¤xâ¤1) CERAMIC THICK FILM:EFFECT OF COPPER

The effect of copper on the microwave absorption, conductivity and complex permittivity of fritless Ni(1−x)CuxMn2O4 (x = 0, 0.4, 0.8, 1) thick film on alumina have been investigated in the 8–18GHz frequency range. The structural changes have been identified by scanning electron microscope (SEM), FTIR and RAMAN scattering spectroscopy. The microwave conductivity and permittivity increase as copper content increases. The fritless Ni(1−x)CuxMn2O4 (0 ≤ x ≤ 1) thick film with x = 0.4 shows best absorption properties, though all the other compositions also show good absorption in a large frequency range. The microwave conductivity increases from 1S/cm to 951 S/cm due to copper and the dielectric constant (έ) increases from 7 to 19.5.

Dielectric spectroscopy and microwave conductivity of bismuth strontium manganites at high frequencies

Bismuth strontium manganites (BSM) with variation in strontium content have been synthesized by simple solid state reaction method. X-ray diffraction data show that the samples have orthorhombic structure with crystallite size ∼40 to 60 nm. SEM studies reveal morphology of micro-rods and micro-flakes. The dielectric constant (ɛ′) and the dielectric loss (tan δ) decreases with the strontium content and the applied frequency which has been attributed to Maxwell-Wagner polarization. The microwave conductivity of samples decreases from 8.9 S/cm to 2.29 S/cm at 8.2 GHz as strontium increases. The penetration depth has also been reported at microwave frequencies from 8–18 GHz.

Effect of Ca on microwave properties of strontium manganite synthesized by microwave processing

Nanostructured Sr1−xCaxMnO3 was prepared by oxalic precursor method and sintered using microwave process. The pervoskite structure was confirmed by x-ray diffraction. The complex permittivity and permeability with calcium concentration were measured by VSWR in the frequency range 8–12 GHz. We present the frequency dependence of microwave absorbing properties of Sr1−xCaxMnO3 (0 ≤ x ≤ 0.4) powders at room temperature which is correlated to the value of its complex permittivity and permeability. The composition dependent microwave absorption was observed and it increased with Ca concentration from 47% to 68% at 9.7 GHz. The excellent microwave absorption properties were attributed to a better electromagnetic impedance match and a higher electric resistivity.

Microwave Studies of Ferrite-Ferroelectric Composites Prepared through Self Propagating Auto Combustion Route

The structural and microwave properties of (y) Ni1ixCdx Fe2O4 and (1iy) Ba0:8Sr0:2TiO3 (x = 0:2, 0.4, 0.6 and y = 0:15, 0.30 and 0.45) composites synthesized by self propagating auto combustion route was studied. X-ray difiraction patterns reveal this method can produce two phases simultaneously. The porosity increases with increase in ferrite content in the composite. The SEM morphologies show the growth of cadmium substituted nickel ferrite grains which are well dispersed in barium strontium titanate (BST) matrix. The composite material shows microwave absorption of about 0.575 in a broad band from 8{12GHz. The permittivity varied from 7 to around 43 with increase in ferrite content. The microwave conductivity measurements reveal the loss of polaron conduction which supports the dielectric loss in the microwave region.

Properties of fritless Ni0.6Cu0.4FeyMn2−yO4 NTC ceramic thick films

This paper reports a study on the microstructure, electrical and microwave properties of fritless thick films of Ni0.6Cu0.4FeyMn2?yO4 negative temperature coefficient (NTC) ceramic. Substitution of Fe has an important effect on the lattice parameter, x-ray density, thermistor constant and microwave properties in the GHz frequency range. The x-ray density increased linearly and the lattice parameter decreased with iron concentration. The Raman intensity mode around 720?cm?1 increased and shifted towards lower frequency with an increase in Fe content. The room temperature electrical resistivity of these thick films decreased from 2.8 to 0.37?M??cm and the microwave permittivity as well as absorption increased as the iron content increased.

Structural and mechanical properties of Sr-doped barium niobate thick films

Polycrystalline strontium barium niobates SrxBa1 − xNb2O6 (SBN, 0.40 ≤ x ≤ 0.75) were prepared by standard solid state ceramic method at relatively at low temperatures. Thick SBN films prepared by simple, low-cost, screen printing route were characterized by XRD. Preliminary structural analysis exhibits the formation of tetragonal tungsten bronze crystal structure at room temperature. Texture coefficient [TC(hkl)], dislocation density (ρD), density of crystallites per unit surface area (Ψ), mechanical properties, and microwave behavior of synthesized materials are reported.

Microwave studies by perturbation of Ag thick film microstrip ring resonator using superstrate of bismuth strontium manganites

Purpose – The purpose of this paper was to determine the complex permittivity of bismuth strontium manganites (Bi1−xSrxMnO3) in the 8‐12 GHz range by using perturbation of Ag thick film microstrip ring resonator (MSRR) due to superstrate of both bulk and thick film.Design/methodology/approach – The BSM ceramics were synthesized by simple low cost solid state reaction method and their fritless thick films were fabricated by screen printing technique on alumina substrate. A comparison has been made between the X band response of Ag thick film microstrip ring resonator due to perturbation of bulk and thick film Bi1−xSrxMnO3 ceramic.Findings – The bulk and thick film superstrate decreases the resonance frequency of MSRR. In this technique even minor change in the properties of superstrate material changes the MSRR response. Variation of strontium content also influences microwave conductivity and penetration depth of bulk and thick films.Originality/value – The microwave complex permittivity decreases with in...

Combustion synthesis and electromagnetic properties of nanocrystalline Pb(Zr 0.52 Ti 0.48 )O 3

The properties of nanocrystalline lead zirconate titanate [PZT, Pb(Zr0.52Ti0.48)O3] thick films and pellets synthesized by self-propagating auto combustion route using sucrose as a fuel are reported. The X-ray diffraction reveals the formation of nanocrystalline tetragonal PZT having a particle size of 5.52 nm in thick films and 7.08 nm in bulk material. SEM images show the grain size of 300–400 nm with some agglomeration, as well as modified open grain boundaries and grain growth in the PZT thick film as compared to the bulk material. The DC electric resistivity of PZT shows semiconducting behavior. We also characterized the 8–18 GHz microwave insertion loss, absorption, complex permittivity, and microwave conductivity of synthesized materials. The real part of permittivity and dielectric loss were found to decrease with increasing frequency.

Response of Ag thick film microstrip straight resonator to perturbation of bulk and thick film Ni(1−x)CuxMn2O4 (0≤x≤1) ceramics

Purpose – The purpose of this paper is to describe the use of copper‐substituted nickel manganite thick film and bulk ceramic superstrate on Ag thick film microstrip straight resonator (MSR), to modify its response and measure complex permittivity as a function of copper.Design/methodology/approach – The glass frit free (fritless) copper‐substituted nickel manganite thick films were formulated on alumina substrate by screen printing technique from the powder synthesized by oxalic precursor method. A comparison has been made between the X band response of Ag thick film MSR due to perturbation of bulk and thick film Ni(1−x)CuxMn2O4 (0≤x≤1) ceramic. The shift has been used to measure the permittivity of the ceramic. The dielectric constants obtained by superstrate technique on Ag thick film microstrip component are comparable to those obtained from theoretical calculations.Findings – The resonance frequency of MSR shifts towards lower frequency due to the presence of Ni(1−x)CuxMn2O4 (0≤x≤1) ceramic as supers...