Structural peculiarities and electrical properties of multicomponent oxide crystals. Alkali ion conductors

Electrical and dielectric properties of anisotropic, “pure” and rare earth doped, K₅Bi(MoO₄)₄ (KBMO), β-BaB₂O₄ (BBO), and CsLiB₆O₁₀ (CLBO) single crystals are studied. Cationic conductivity by alkali ions is found in these crystals. Anisotropy of their electrical and dielectric properties is examined. Relations between the structure and transport mechanisms are discussed. Published in Russian in Elektrokhimiya, 2009, Vol. 45, No. 6, pp. 679–686. The article is published in the original. Published by report at IX Conference “Fundamental Problems of Solid State Ionics”, Chernogolovka, 2008.     

Growth of high quality large size LBO crystals for high energy second harmonic generation

Using the method of heat field symmetry control [5], large high quality LBO crystals of more than 1.3 kg have been grown. In accordance with the so-called Curie principle, rhombic LBO crystals were grown in the heat field of the same symmetry. Elements of excellent optical homogeneity with diameters up to 50 mm were used for frequency doubling of high energy 1053 nm laser beam. Second-harmonic energies up to 115 J [1] were produced and conversion efficiencies up to 90% were measured.     

Convection in a Horizontal Layer in a Rotating Heat Field

An asymptotic laminar-convection pattern in a plane horizontal liquid layer with a radially nonuniform temperature gradient on its boundaries is investigated. The problem arises in applications connected with modified Czochralski crystal growth technology using the heat field rotation method. An analytical model of the flow is compared with the results of experiments, specially carried out using model fluids and a technological melt. The conditions of adequacy of the model are analyzed and the restrictions on the parameter values and fluid thermophysical properties that ensure the validity of the model are found. The range of variation of the heat field rotation velocity for which the mixing of the melt in the crucible is maximum is determined.     

Growth of GaSe and GaS single crystals

The paper describes principal manipulations to prepare single crystals of GaSe and GaS. A new simple method of synthesis with single‐zone heating furnace is proposed. Growth of crystals was performed by modified Bridgman method with the use of rotating heat field. Raman and optical depth spectra show high structural and optical quality of obtained crystals. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Change of symmetry and rotation of thermal field as a new method of control of heat and mass transfer in crystal growth (by example of β-BaB<Subscript>2</Subscript>O<Subscript>4</Subscript>)

It is suggested to change the symmetry and rotation of thermal field as a method of contact-free control of the heat and mass transfer in crystal growth. By the example of growth of the low-temperature barium borate (β-BaB₂O₄) phase, a technically important crystal with nonlinear-optical properties, it is shown that the use of the suggested method allows one to grow larger crystals of a higher quality.     

Phase equilibria in BaB2O4–LiF system and β–BaB2O4 bulk crystals growth

Solid state synthesis, differencial thermal analysis and visual polythermal analysis were applied to study the phase equilibria in BaB₂O₄–LiF system. A phase diagram BaB₂O₄–LiF has been plotted for the first time. The system has proved applicable for growing β–BaB₂O₄ bulk crystals.     

Highly efficient deep ultraviolet generation by sum-frequency mixing in a BBO crystal pair

Generation of deep ultraviolet radiation at 210 nm by Type-I third harmonic generation is achieved in a pair of BBO crystals with conversion efficiency as high as 36%. The fundamental source is the dye laser radiation pumped by the second harmonic of a Q-switched Nd: YAG laser. A walk-off compensated configuration with the BBO crystal pair has enabled us to realize such a high conversion efficiency in the interaction.     

Search for compounds of the NaBaR(BO3)2 family (R = La, Nd, Gd, and Yb) and the new NaBaYb(BO3)2 orthoborate

A search for compounds of the NaBaR(BO₃)₂ composition (where R = La³⁺, Nd³⁺, Gd³⁺, or Yb³⁺) is performed by solid state synthesis and spontaneous crystallization. A new compound, NaBaYb(BO₃)₂, is found in this series. It crystallizes in space group $R\bar 3$ and belongs to the family of sublayer complex orthoborates with isolated BO₃ groups NaBaR(BO₃)₂ (R = Y, Sc, and Yb). Theoretical X-ray powder diffraction patterns of NaBaY(BO₃)₂, NaBaSc(BO₃)₂, and NaBaYb(BO₃)₂ are calculated based on single-crystal data.     

Effect of mechanical activation on the properties of the working mixture for BaB2O4 and Ba2Na3[B3O6]2F crystal growth

A comparative study is made regarding the effect of the mechanical activation of carbonate acidic (BaCO₃-HBO₂/H₃BO₃)₂ and carbonate-acidic fluoride (BaCO₃-Na₂CO₃-NaF-(HBO₂/H₃BO₃)₂) systems on the thermal synthesis of barium metaborate β-BaB₂O₄ and fluoroborate Ba₂Na₃[B₃O₆]₂F.