Materials Literature
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Room-temperature visible luminescence from Pr3+ ions embedded in germaniumsulfide glass hosts is reported along with edge luminescence from these hosts. The important role of energy transfer processes between the host and Pr ions is demonstrated experimentally through the dependencies of photoluminescence on excitatio…
The influence of ultraviolet (UV) illumination on piezoelectric properties is investigated in lead zirconate titanate (PZT) thin films. It is found that the poling procedure is more effective when the film is exposed to a broadband UV light in the presence of a high electric field. Piezoelectric coefficients are incre…
We have determined the inclination angle of the backbone structure of polyimide with alkyl side-chains in rubbed films. Four different polyimides with the same backbone structure but different lengths of alkyl side-chains were used in this study. The inclination angle of the backbone structure increases with the numbe…
As reported earlier, the metal hydride ${\mathrm{YH}}_{x}$ reveals spectacular switchable optical properties. In this Letter we report on another remarkable property of the hydrogen deficient ${\mathrm{YH}}_{3\ensuremath{-}\ensuremath{\delta}}$ trihydride phase. A logarithmic temperature dependence of the electrical r…
High-resolution x-ray and neutron scattering studies on powder samples of pure and Zr-doped (5 at.%) show that mesoscopic compositional inhomogeneities exist in the doped compound which are unlikely to be revealed by conventional diffraction methods. Even if the structural refinement of the doped compound gives quite…
The configuration ions and have been incorporated in strontium fluorovanadate (SVAP) crystals grown using the Czochralski technique. Such crystals provide fourfold-coordinated sites for occupancy by the and ions, which are located near the centres of their respective tetrahedrally bonded molecular ions and . The optic…
We have demonstrated the 1.5 μm electroluminescence from implanted Er ions inside the SiO2 insulator of a silicon metal-oxide-semiconductor structure under forward bias. The Er ions are excited by the direct impact from electrons tunneling through the oxide at electric fields larger than 6 MV/cm. Under these condition…
A thin Er2O3 layer grown on a Si surface by vapor doping of Er exhibits intense photoluminescence in the green and red regions excited by laser beams in the 800 nm and 450–490 nm ranges. These intense light emissions take place via resonant two or one step photoexcitations of the 4f levels in Er3+ ions. Our sample fab…
An algorithm for the design of diffractive optical phase elements (kinoforms) that give rise to fan-out (i.e., spot) patterns was developed and tested. The algorithm is based on the Helmholtz-Kirchhoff rigorous scalar diffraction integral for the evaluation of the electric field behind the kinoform. The optimization o…
CdS films were grown by chemical bath deposition. The as-grown films had the cubic CdS crystalline structure. As-grown films were thermally annealed in a controlled atmosphere. The annealing temperature was varied from 200 to . The annealing process produces a gradual structural transition from cubic for the as-grown…
We fabricated a homeotropically aligned nematic liquid crystal display with positive dielectric anisotropy, whose on and off states are controlled by in-plane field. The rubbing-free device, dark in voltage-off state, reveals bright uniformity in all directions due to the dual domainlike director configuration in the…
The mechanism for cross slip of a screw dislocation in Cu is determined by atomistic simulations that only presume the initial and final states of the process. The dissociated dislocation constricts in the primary plane and redissociates into the cross-slip plane while still partly in the primary plane. The transition…
The pressure-induced variations of the anisotropic charge-transport and magnetic properties have been investigated for a bilayered manganite crystal, ${\mathrm{La}}_{2\ensuremath{-}2x}{\mathrm{Sr}}_{1+2x}{\mathrm{Mn}}_{2}{\mathrm{O}}_{7}$ ( $x\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.3$). The magnitude of t…
It is demonstrated theoretically that particle irradiation may lead to a destabilization of graphitic structures with respect to low-pressure growth of diamond. This is due to the large difference in the cross sections for irradiation-induced displacements of carbon atoms in diamond and graphite. A nonequilibrium phas…
Until now, it has been observed that a collective handling of uniform spheres could only lead to a random close packing of 0.64 maximum volume fraction. In this Letter, we show that denser crystalline arrangements can be obtained when beads are poured at low flow rates into a horizontally shaken container. A parallel…
The photoluminescence (PL) and electroluminescence (EL) properties of Ge-implanted SiO2 layers thermally grown on a Si substrate were investigated and compared to those of Si-implanted SiO2 films. The PL spectra from Ge-implanted SiO2 were recorded as a function of annealing temperature. It was found that the blue-vio…
Understanding the thermal conductivity and heat transfer processes in superlattice structures is critical for the development of thermoelectric materials and optoelectronic devices based on quantum structures. This letter reports modeling of the heat transfer and thermal conductivity of superlattice structures based o…
Silicon dioxide films grown by industrial thermal furnace, rapid thermal, and low-pressure thermal methods were measured by x-ray photoelectron spectroscopy, transmission electron microscopy (TEM), spectroscopic ellipsometry, and capacitance–voltage analysis. Based on TEM measurements, the photoelectron effective atte…
The development of the ordered channel array in the anodic porous alumina was initiated by the textured pattern of the surface made by the molding process, and growth of an almost defect-free channel array can be achieved throughout the textured area. The long-range-ordered channel array with dimensions on the order o…
Dynamics of coarsening of a statistically homogeneous fractal cluster, created by a morphological instability of diffusion-controlled growth, is investigated theoretically. An exact mathematical setting of the problem is presented that obeys a global conservation law. A statistical mean field theory is developed that…