Recently, nanotechnology has emerged as a tool for the development in the biological synthesis of noble metal nanoparticles. Among other conventional synthesis methods, biological synthesis methods have received great significance due to cost-effective and less hazardous nature which is due to the presence of plentiful as well as diversified biomolecules acting as capping and reducing agents. Biosynthesized silver nanoparticles (Ag NPs) manifest potential applications in several fields because of its safe and environment friendliness. Reported researches on the green synthesis of Ag NPs using different parts of stem, fruits, and seeds has been summarized along with the impact on the morphological properties. This review is important to find a way toward the cheaper, environmentally friendly and controlled synthesis of Ag NPs hence is of special concern.

An introduction to perovskites along with their structure and properties are discussed. Lanthanum Aluminate (LaAlO₃) compound, its phase transition from cubic to rhombohedral, chemical bonding, the electronic structure and the optical properties are argued in this review. The generalized gradient approximation by using the full potential linearized augmented plane wave is discussed. Other analysis methods are also discussed. The analysis of the bond population and the electronic density profile gives the nature of both ionic and covalent bonds. Moreover, dielectric function which is calculated is in full agreement with the experimental data. The spectrum of electron energy-loss, refractive index, conductivity, absorption spectrum and the reflectivity are easily obtained from a calculated dielectric function. The 6.1 eV optical band gap is exhibited by the absorption spectrum which agrees with some other experimental calculations. Importance of a perovskite type compounds cannot be denied. Different applications are also described in this paper.