STRUCTURAL AND DIELECTRIC PROPERTIES OF Ba₂Sr₃SmTi₃V₇O₃₀

Abstract

The polycrystalline sample of Ba 2 Sr 3 SmTi 3 V 7 O 30, a member of the tungsten bronze structural family, was prepared by a high-temperature solid-state reaction technique. Preliminary X-ray diffraction analysis suggests the formation of a single-phase compound with orthorhombic structure. Detailed studies of the dielectric constant and tangent loss as a function of frequency (100 Hz to 1 MHz) and temperature (32°–500°C) show that this compound has a diffused-type of ferroelectric phase transition at 230°C. Study of the surface morphology by SEM showed uniform grain distribution on the surface of the sample with less porosity. The activation energy, calculated from the plot of temperature dependence of AC conductivity, of the compound was found to be 0.11 eV and 0.14 eV at 500 kHz and 1 MHz respectively. The nature of the variation of conductivity and value of activation energy suggest that the conduction process is of a mixed-type.

Impedance spectroscopy of Ba3Sr2DyTi3V7O30 ceramic

“…On the basis of the best agreement (based on least-squares refinement) between observed (obs) and calculated (cal) interplaner distance d (i.e. ∑(d obs -d cal ) = minimum), an orthorhombic unit cell was selected with lattice parameters: a = 12⋅2719(39) Å, b = 8⋅9715(39) Å, c = 19⋅7812(39) Å (estimated standard deviation in parenthesis) which are consistent with the reported ones (Ranga Raju and Choudhary 2003;Sahoo et al 2008a). The coherently scattered crystallite size (D) of the compound was determined using Scherrer's equation: D = 0⋅89λ/(β 1/2 cosθ hkl ), where λ = 1⋅5405 Å and β 1/2 = peak width of the reflection at half maxima (Klug 1974).…”

Dielectric properties of Ba3Sr2DyTi3V7O30 ceramics

“…The least-squares refined lattice parameters are: a = 12.2719(39) Å, b = 8.9715(39) Å, and c = 19.7812(39) Å (the number in parentheses is the estimated standard deviation). These parameters are in good agreement with those previously reported [11,12]. The crystallite size of the calcined powder was roughly estimated from the broadening of reflection peaks using Scherrer's equation: D = 0.89λ / (β 1/2 cosθ ) [13,14], where λ = 1.5405 Å and β 1/2 = peak width of reflections at half-maximum intensity.…”

Effect of strontium concentration on structural, dielectric and electrical properties of Ba5−xSrxDyTi3V7O30 (x=0–5) ceramics

“…The contributions of strain, instrumental and other unknown factors in the broadening have not been taken into account in the crystallite size calculation. The cell parameters are consistent and comparable to other compounds of this family [16,17]. Some of structural characteristic features of the BSDTV (x = 0-5) compounds are observed as (i) the position of the strongest peak in all the compounds is in the range of 20-35 • , (ii) for x = 0, the strongest peak has maximum intensity than other compounds, (iii) the lattice parameters get slightly changed with change in rare earth and Sr ion-concentration but do not exhibit any definite relationship between them, (iv) when Sr is substituted at the Ba site, a small variation in lattice parameters, volume and the particle size is observed, which may be due to the difference in the ionic radius of Sr and Ba and (v) some additional peaks with different intensities are also observed with slightly different (h k l) values in the XRD patterns of the compounds containing both Ba and Sr for x = 1-4.…”