Microstructural, dielectric, impedance and electric modulus studies on vanadium—doped and pure strontium bismuth niobate (SrBi2Nb2O9)(SrBi_2Nb_2O_9) ceramics

$SrBi_2Nb_2O_9$ (SBN) and $SrBi_2(Nb_{0.9}V_{0.1})_2O_9$ (SBVN) ceramics were fabricated from the powders consisting of $\mu m$ sized grains, obtained via the solid state reaction route. $V_2O_5$ was found to be an effective microstructure modifier and grain growth truncator for SBN ceramics. X-ray structural studies carried out on SBVN ceramics confirmed the existence of preferential orientation (c-planes) of the grains. $V_2O_5$ addition has substantially improved the sinterability of SBN and enabled to achieve high density (95%) which was otherwise difficult in the case of pure SBN. The dielectric properties of SBN ceramics were significantly enhanced by the partial replacement of Nb ions by pentavalent vanadium ions. The complex impedance diagrams of dense SBVN ceramics exhibited only one semicircle indicating a significant contribution from the grains. In contrast, the impedance plots for the porous (density 88%) SBN ceramics show an additional low-frequency semicircle which was attributed to the blocker (pore) size effects. The dielectric behavior of SBN and SBVN ceramics was rationalized using the impedance and modulus data

Microstructural, dielectric, impedance and electric modulus studies on vanadium-doped and pure strontium bismuth niobate (SrBi2Nb2O9)(SrBi_{2}Nb_{2}O_{9}) ceramics

$(SrBi_{2}Nb_{2}O_{9})$ (SBN) and $SrBi_{2}(Nb_{0.9}V_{0.1})_{2}O_{9}$ (SBVN) ceramics were fabricated from the powders consisting of \mu m sized grains, obtained via the solid state reaction route. $V_{2}O_{5}$ was found to be an effective microstructure modifier and grain growth truncator for SBN ceramics.X-ray structural studies carried out on SBVN ceramics confirmed the existence of preferential orientation (c-planes) of the grains. $V_{2}O_{5}$ addition has substantially improved the sinterability of SBN and enabled to achieve high density (95%) which was otherwise difficult in the case of pure SBN. The dielectric properties of SBN ceramics were significantly enhanced by the partial replacement of Nb ions by pentavalent vanadium ions. The complex impedance diagrams of dense SBVN ceramics exhibited only one semicircle indicating a significant contribution from the grains. In contrast, the impedance plots for the porous (density 88%) SBN ceramics show an additional low-frequency semicircle which was attributed to the blocker (pore) size effects. The dielectric behavior of SBN and SBVN ceramics was rationalized using the impedance and modulus data

Grain orientation and anisotropy in the physical properties of SrBi2(Nb1−xVx)2O9SrBi_2(Nb_{1-x}V_x )_2O_9 (0≤x≤0.3)(0 \leq x \leq 0.3) ceramics

$SrBi_2(Nb_{1-x}V_x)_2O_9$ ($0 \leq x \leq 0.3$ in molar ratio) ceramics have been fabricated via conventional sintering at elevated temperatures. Interestingly sintering the pellets in the 1320–1470 K temperature range yielded partially grain oriented ceramics. The orientation factor (f) monitored via X-ray powder diffraction studies was found to increase with increasing $V_2O_5$ content and reached 83% for x = 0.3. The increment in (f) was not that significant with increase in sintering temperature and its duration. The microstructural studies suggest that $V_2O_5$ has a truncating effect on the abnormal platy growth of SBN grains. The dielectric constant $(\epsilon_{r})$ and loss (D) measurements as functions of both temperature and $V_2O_5$ content have been carried out along the directions parallel $(\epsilon_{rp})$ and perpendicular $(\epsilon_{rn})$ to the cold pressing axis of the pellet. The anisotropy $(\epsilon_{rn}/\epsilon_{rp})$ associated with $\epsilon_{r}$ was found to be 1.11 at 300 K and 2.1 at the Curie temperature, (T c) respectively. Different dielectric mixture formulae that were employed to analyze the effective dielectric constants of these samples with varying porosity confirmed that the experimental value of $\epsilon_{r}$ was comparable with that obtained using Wiener's formula. Impedance spectroscopy was employed to rationalize the electrical behavior of these ceramics. The pyroelectric coefficients along the directions parallel and perpendicular to the pressing axis of the grain oriented (83%) SBN ceramic at 300 K were 0.13145 $mC/m^2K$ and 0.26291 $mC/m^2K$ respectively. The ferroelectric properties of these grain-oriented ceramics were better in the direction perpendicular to the pressing axis than those in the parallel direction

Modeling the effects of pharmaceutical marketing

Effects of pharmaceutical marketing, Drug price elasticity, Marketing model building,