A series of tin oxide $\rm{(SnO_{2})}$/polyaniline (PANI) nanocomposites with loading of different wt% of PANI were synthesised using a solution-based processing method for improving the structural and physical properties of tin oxide. The effect of PANI loading on the gross structure, surface morphology, optical properties and electrical properties of $\rm{(SnO_{2})}$/PANI nanocomposites was investigated. The scanning electron micrographs (SEM) show congruent dispersal of PANI in the tin oxide matrix where the gross/average structure is unchanged as revealed by powder X-ray diffraction (PXRD). A slight change in the lattice parameter of the pristine rutile crystalline structure $\rm{(SnO_{2})}$and its nanocomposites has been recorded. However, the crystallite size has been found to decrease from 60 to 40 nm with different wt% loading of PANI. The presence of characteristic Fourier transform infrared (FT-IR) peaks dovetail to $\rm{C–H, C=C, NH_{2}, C–C}$ and the energy-dispersive analysis of X-rays (EDAX) confirm the development of the PANI nanocomposite. Photoluminescence (PL) spectroscopic study shows the gradual decrement in the intensity of the emission peak at 611 nm due to the disappearance of surface defects associated with oxygen vacancies. The uniform dispersion of PANI at the nanoscale significantly enhanced the electrical properties, e.g. four orders of magnitude changes in electrical conductivity and carrier mobility.

In this article, we have studied the solutions of Einstein–Maxwell field equations for compact objects in the presence of net electric charge. Interior physical 3-space is defined by Vaidya–Tikekar metric in spheroidal geometry. The metric is characterised by two parameters, namely, spheroidal parameter K and curvature parameter R. The nature of the interior fluid is considered to be anisotropic. Assuming strange matter equation of state (EOS)in the MIT Bag model for the interior matter content, namely, p = $\frac{1}{3}$(ρ − 4 B), where B is the Bag constant, we determine various physical properties of the charged compact star. We have taken the value of surface density ρs(= 4 B) as a probe to evaluate the mass–radius relation for the compact star in the presence of net electric charge and using the range of B necessary for possible stable strange matter. It is interesting to note that in this model thereexist a maximum radius of a star which depends on B. We further note that compactness of the star corresponding to the maximum radius always lies below the Buchdahl limit ($\le$$\frac{4}{9}$) for the maximum allowed value of the pressure anisotropy and electromagnetic field. Energy and causality conditions hold good throughout the star in the presence of charge also. Prediction of mass of the strange stars is possible in the present model. We have determined mass, radius, surface red-shift and other relevant physical parameters of the compact objects.