Electronic structure and ferroelectricity in SrBi2Ta2O9

The electronic structure of SrBi2Ta2O9 is investigated from first-principles, within the local density approximation, using the full-potential linearized augmented plane wave (LAPW) method. The results show that, besides the large Ta(5d)-O(2p) hybridization which is a common feature of the ferroelectric perovskites, there is an important hybridization between bismuth and oxygen states. The underlying static potential for the ferroelectric distortion and the primary source for ferroelectricity is investigated by a lattice-dynamics study using the Frozen Phonon approach.Comment: 17 pages, 7 figures. Phys. Rev. B, in pres

Optical filters by the pyrolysis of metal-organics

Optical coatings and filters have enormous applications in every branch of modern optics. Traditionally optical films are deposited by evaporation, sputtering, and by chemical methods. Using these above mentioned techniques it is very difficult to obtain excellent quality films ; that is, films with extremely low values of scattering, absorption and film stress and high corrosion resistance to humidity. Recently developed Ion-Assisted Deposition techniques produce high performance films but suffer with high cost and their difficulty to coat odd shaped objects