Single crystals of lead barium borate, Ba8.35Pb0.65(B3O6)6, octabarium lead(II) hexa-kis-(triborate), have been obtained by spontaneous nucleation from a high-temperature melt. Its three-dimensional structure is constructed on the basis of a BaO9 polyhedron, a (Pb/Ba)O6 octa-hedron (occupancy ratio Pb:Ba = 0.216:0.784) and a condensed B3O6 ring anion. In the crystal, the planar B3O6 anions are ...

We describe and demonstrate a general strategy for engineering binary and ternary hybrid nanoparticles based on spontaneous epitaxial nucleation and growth of a second and third component onto seed nanoparticles in high-temperature organic solutions. Multifunctional hybrid nanoparticles that combine magnetic, plasmonic, and semiconducting properties and that are tunable in size and morphology c...

The probability of destruction of a metastable vacuum state by the field of a highly virtual particle with energy E is calculated for a (3+1) dimensional theory in the leading WKB approximation in the thin-wall limit. It is found that the induced nucleation rate of bubbles, capable of expansion, is exponentially small at any energy. The negative exponential power in the rate reaches its maximum...

We report the growth of self-assembled ErAs islands embedded in GaAs by molecular beam epitaxy. The nucleation of ErAs on GaAs occurs in an island growth mode leading to spontaneous formation of nanometer-sized islands. Several layers of ErAs islands separated by GaAs can be stacked on top of each other to form a superlattice. X-ray diffraction shows superlattice fringes from such samples. Pump...

The liquid crystal alignment method described here provides uniform orientation of otherwise difficult-to-align smectic-A liquid crystal materials lacking a nematic phase. The smectic-A phase is grown in the presence of a 10–20 K/mm temperature gradient from an air bubble located within a cell by a photolithographically defined channel in the cell substrates. We obtain uniform layer alignment i...

In a numerical experiment based on Gross-Pitaevskii formalism, we demonstrate unique topological quantum coherence in optically trapped Bose-Einstein condensates (BECs). Exploring the fact that vortices in rotating BEC can be pinned by a geometric arrangement of laser beams, we show the parameter range in which vortex-antivortex molecules or multiquantum vortices are formed as a consequence of ...

A gaseous Bose-Einstein condensate (BEC) offers an ideal testing ground for studying symmetry breaking, because a trapped BEC system is in a mesoscopic regime, and situations exist under which symmetry breaking may or may not occur. Investigating this problem can explain why mean-field theories have been so successful in elucidating gaseous BEC systems and when manybody effects play a significa...

Models undergoing a phase transition to an absorbing state weakly broken by the addition of a very low spontaneous nucleation rate are shown to exhibit hysteresis loops whose width Deltalambda depends algebraically on the ramp rate r . Analytical arguments and numerical simulations show that Deltalambda approximately r(kappa) with kappa=1(beta'+1) , where beta' is the critical exponent governin...

Ni-based superalloy single crystals were grown by different methods (gradient method and Bridgman technique with spontaneous nucleation and with seed). In all crystal growth experiments using the Bridgman technique, the temperature gradient along the vertical furnace axes was constant (G = 33.5 °C/cm). The obtained single crystals were cut, mechanical and chemical polished, and chemically etche...

We speculate about the spacetime description due to the presence of Lorentzian wormholes (handles in spacetime joining two distant regions or other universes) in quantum gravity. The semiclassical rate of production of these Lorentzian wormholes in Reissner Nordström spacetimes is calculated as a result of the spontaneous decay of vacuum due to a real tunneling configuration. In the magnetic ca...