Electromagnetic characterization of microwave sintered Sr1-xCaxMnO3 (0.0 ≤ x ≤ 0.4) thick films

Electromagnetic characteristics of microwave sintered strontium calcium manganites thick film with variation in calcium content have been investigated. The X-ray diffraction analysis reveals tetragonal perovskite structure for all the compositions. The grain size increases with the increase in calcium content. The microwave absorption, complex permittivity, permeability and conductivity are reported in the frequency range of 8.2–18 GHz. The absorption loss is larger in Ku band while insertion loss is larger in X band. The permittivity, permeability and microwave conductivity decreases from X-band to Ku-band. The almost identical values of real part of permittivity and permeability indicate possible application as materials for impedance matching

Response of thin film Al₂O₃ optical waveguide to moisture in paper

549-551The response to paper moisture of thin film Al2O3 optical waveguide has been studied. The changes in the transmission of thin film optical waveguide due to changes in relative humidity of paper used as in touch overlay have been reported in this paper. The output decreases due to the overlay of paper. The transmission of the waveguide depends on the moisture content, texture and colour of the paper. Higher moisture content in paper tends to saturate the waveguide output. The sensitivity to moisture changes and type of paper is more for lower moisture content. Hysteresis is observed due to all the papers studied. The larger sensitivity in the lower moisture range may provide a means for detecting and controlling moisture in paper for packing, printing and other applications, as this overlay method requires only a small piece of paper

Study of lead free ferroelectrics using overlay technique on thick film microstrip ring resonator

The lead free ferroelectrics, strontium barium niobates, were synthesized via the low cost solid state reaction method and their fritless thick films were fabricated by screen printing technique on alumina substrate. The X band response (complex permittivity at very high frequencies) of Ag thick film microstrip ring resonator perturbed with strontium barium niobates (SrxBa1-xNb2O6) in form of bulk and thick film was measured. A new approach for determination of complex permittivity (ε′ and ε′′) in the frequency range 8–12 GHz, using perturbation of Ag thick film microstrip ring resonator (MSRR), was applied for both bulk and thick film of strontium barium niobates (SrxBa1-xNb2O6). The microwave conductivity of the bulk and thick film lie in the range from 1.779 S/cm to 2.874 S/cm and 1.364 S/cm to 2.296 S/cm, respectively. The penetration depth of microwave in strontium barium niobates is also reported

Structural, dielectric and magnetic properties of nickel substituted cobalt ferrite nanoparticles: Effect of nickel concentration

Nickel substituted cobalt ferrite nanoparticles with composition Co1−xNixFe2O4 (0.0 ≤ x ≤ 1.0) was synthesized using simple, low temperature auto combustion method. The X-ray diffraction patterns reveal the formation of cubic phase spinel structure. The crystallite size varies from 30-44 nm with the nickel content. Porous and agglomerated morphology of the bulk sample was displayed in the scanning electron microscopy. Micro Raman spectroscopy reveals continuous shift of Eg and Eg(2) stokes line up to 0.8 Ni substitution. The dispersion behavior of the dielectric constant with frequency and the semicircle nature of the impedance spectra show the cobalt nickel ferrite to have high resistance. The ferromagnetic nature is observed in all the samples, however, the maximum saturation magnetization was achieved by the 0.4 Ni substituted cobalt ferrite, which is up to the 92.87 emu/gm at 30K