A. V. Butashin

Ordered gold nanostructures on sapphire surfaces: Fabrication and optical investigations

The possibilities of obtaining ordered gold nanoarrays on sapphire surfaces with oriented nanorelief are demonstrated. The structures are morphologically described using atomic force microscopy data. A study of the angular dependence of the reflectivity in the visible range of electromagnetic waves has revealed some features which are likely to indicate surface plasmon-polariton excitation at the air-gold interface under exposure to p-polarized radiation. The experimental results are found to be in good agreement with the theoretical calculations.

New ferroelectrics in KTiOPO4 family

Abstract New compounds AMOXO4 (A = Na, K, Rb, Tl; M = Sb, Ta; X = Ge, Si) were prepared by solid state synthesis and as single crystals by the flux method. Their crystal structure and ferroelectric properties are similar to those of KTiOPO4, but optical nonlinearity is much lower. For TlSbOGeO4 an antiferroelectricity was supposed to exist in the interval between two phase transitions at Tc = 272 K and TN = 286 K. According to values of Curie-Weiss constant (C = 5·103) the phase transitions in TlSbOGeO4 have features of order-disorder transformation while in KTaOGeO4 the value C = 1.2·105 corresponds to displacive one. Special role of the monovalent cations in KTiOPO4-type compounds is discussed taking into consideration data on ferroelectric, nonlinear optical properties and structure.

Suppression of growth domains in epitaxial ZnO films on structured (0001) sapphire surface

Zinc oxide layers have been grown by magnetron sputtering in an oxygen atmosphere on structured sapphire surfaces. The formation of ZnO islands oriented in two directions (the so-called domains) was observed on (0001) Al2O3 surfaces with steps spaced by a distance from several thousands to several tens of thousands of nanometers. The islands formed along steps on (0001) Al2O3 surfaces with an ordered terrace-step structure (and, subsequently, ZnO films) have only one orientation. Another method is proposed for suppressing domains during ZnO growth on (0001) Al2O3 d.

Lasing and refractive indices of nanocrystalline ceramics of cubic Yttrium Oxide Y2O3 doped with Nd3+ and Yb3+ ions

A continuous-wave lasing at 1 μm was excited by the radiation of semiconductor laser diodes at room temperature in nanocrystalline ceramics Y2O3 doped with Nd3+ and Yb3+ ions. The refractive indices of the undoped nanocrystalline Y2O3 ceramics were measured in the wavelength range 0.4–9 μm.

Gd3Ga5O12:Nd3+ crystals for a continuous-wave diode-pumped laser operating in 4F3/2 → 4I11/2 and 4F3/2 → 4I13/2 channels

Garnet crystals of the composition Gd3Ga5O12:Nd3+ (concentration series CNd = 1–10 at. %) were grown from flux. In terms of spectroscopy, these crystals, unlike those grown from melts, form medium with a single activator center. For the first time, continuous-wave lasing was excited by diode pumping with the use of Gd3Ga5O12:Nd3+ crystals at the wavelengths λ3 = 1.3315 and λ4 = 1.3370 μm of the 4F3/2 → 4I13/2 channel and also the simultaneous generation at two wavelengths, λ1 = 1.0621 and λ2 = 1.0600 μm, of the 4F3/2 → 4I11/2 channel.

Nondestructive methods of controlling the surface nanorelief by the example of sapphire substrates

The paper deals with the study of the roughness parameters of sapphire substrates as studied by atomic force microscopy and X-ray dispersion. It is shown that the functions of the central power density of the roughness height calculated from data of both methods are in good agreement. A complex approach to the surface analysis enables the stable manufacturing of plates with the effective roughness height less than 0.2 nm, which is not inferior to data given in the specification of the producers outside Russia

New applications of sapphire crystals

1 Deutsches Elektronen-Synchrotron, Hamburg, Germany, 2 A.V. Shubnikov Institute of Crystallography, Moscow, Russia, 3 European Synchrotron Radiation Facility, Grenoble, France, 4 Institute for Photon Science and Synchrotron Radiation, KIT, Karlsruhe, Germany, 5 Jülich Centre for Neutron Science JCNS and Peter Grünberg Institute PGI, Forschungszentrum Jülich, Jülich, Germany, 6 Faculty of Sciences, University of Liège, Liège, Belgium