A plate periodically bonded with piezoelectric patches on its surfaces is considered. The differential quadrature element method is used to solve the wave motion equation for the two-dimensional periodic structure. The method is very simple and easy to implement. Based on the method, band structures for in-plane wave propagating in the periodic piezoelectric plate are studied, from which the fr...

Reactive sputtering was used to grow thin films of ScxGa1-xN with scandium concentrations of 20%70% on quartz substrates at temperatures of 300-675 K. X-ray diffraction (XRD) of the films showed either weak or no structure, suggesting the films are amorphous or microcrystalline. Optical absorption spectra were taken of each sample and the optical band gap was determined. The band gap varied lin...

We examine band-structure engineering in extremely tetragonal ferroelectric perovskites (ABO3) to make these materials suitable for photovoltaic applications. Using first-principles calculations, we study how B-site ordering, lattice strain, cation identity, and oxygen octahedral cage tilts affect the energies and the compositions of the valence and conduction bands. We find that extreme tetrag...

Conducting polymers have infiltrated our day to day life with a wide range of products extending from the most common consumer goods to highly specialized applications in space, aeronautics and electronics. In this article, current efforts to design novel conducting polymers with the desired conduction properties are reviewed. Some recent results on the electronic structure and conduction prope...

Semiconductor nanocrystals are tiny light-emitting particles on the nanometer scale. Researchers have studied these particles intensely and have developed them for broad applications in solar energy conversion, optoelectronic devices, molecular and cellular imaging, and ultrasensitive detection. A major feature of semiconductor nanocrystals is the quantum confinement effect, which leads to spat...

O. Gülseren, T. Yildirim, S. Ciraci, and Ç. Kılıç* NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104 Department of Physics, Bilkent University, Ankara 06533, Turkey ~Received 18 April 2001; revised manuscript received 11 Decem...

A theoretical investigation is made of the dispersion characteristics of plasmons in a twodimensional periodic system of semiconductor (dielectric) cylinders embedded in a dielectric (semiconductor) background. We consider both square and hexagonal arrangements and calculate extensive band structures for plasmons using a plane-wave method within the framework of a local theory. It is found that...

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It has been experimentally observed that Ti doping of bulk ZrO(2) induces a large red-shift of the optical absorption edge of the material from 5.3 to 4.0 eV [Livraghi et al., J. Phys. Chem. C, 2010, 114, 18553-18558]. In this work, density functional calculations based on the hybrid functional B3LYP show that Ti dopants in the substitutional position to Zr in the tetragonal lattice cause the f...

We report the experimental observation and theoretical explanation of an unconventional interplay between divalent Co and trivalent Y dopants, both of which incur oxygen vacancies in the CeO2 host that has predominantly tetravalent Ce cations. The Co dopant atoms were experimentally found to act as a switch that turns on the dormant effect of Y-modulated band-gap reduction. As revealed by densi...