Second harmonic generation in Na3Gd2(BO3)3 crystals

Na₃Gd₂(BO₃)₃ crystals with dimensions up to 22 × 20 × 5 mm³has been grown from NaBO₂ flux by the top‐seeded solution growth (TSSG) method for the first time. Differential scanning calorimetry (DSC) result shows that Na₃Gd₂(BO₃)₃ melts incongruently. The infrared spectrum indicates that Na₃Gd₂(BO₃)₃ contains characteristic triangular [BO₃]^3– groups responsible for the nonlinear optical effect. For the as‐grown crystal, the transmittance exceeds 80% in the wavelength range of 315 nm to 2670 nm, and the UV cutoff wavelength is 207 nm. The damage threshold is 0.47 GW cm^–2 at 1064 nm. Moreover, Na₃Gd₂(BO₃)₃ crystal exhibits an optical second harmonic generation effect which is 1.3 times as large as that of KH₂PO₄ (KDP). (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Crystallization of PbxSr1‐x(NO3)2 Solid Solutions from Aqueous Solutions

A series of Pb_xSr_1‐x(NO₃)₂ crystals have been grown from aqueous solutions and characterized by X‐ray powder diffraction. All diffraction data were well indexed according to the simple cubic structure. The variation of lattice constants with the concentrations of Pb²⁺ in the crystals accorded quite well to the Vegard's Law. The composition of the Sr(NO₃)₂ crystal doped with Pb²⁺ was studied by electron microprobe and it was found that Pb²⁺ was enriched in the 111 sectors. Equilibrium behavior in the Pb(NO₃)₂‐Sr(NO₃)₂‐H₂O system was analyzed by Lippmann's phase diagram and the equilibrium distribution coefficient D_Pb=133.6. This large value of D indicates that Pb²⁺ ion is preferentially distributed to the solid phase.     

Growth,structure, and superconducting properties of Bi2Sr2Ca2Cu3O10 and (Bi,Pb)2Sr2Ca2Cu3O10‐y crystals

Large and high‐quality single crystals of both Pb‐free and Pb‐doped high temperature superconducting compounds (Bi_1‐xPb_x)₂Sr₂Ca₂Cu₃O_10‐y (x = 0 and 0.3) were grown by means of a newly developed “Vapour‐Assisted Travelling Floating Zone” technique (VA‐TSFZ). This modified zone‐melting technique was realised in an image furnace and allowed for the first time to grow Pb‐doped crystals by compensating for the Pb losses occurring at high temperature. Crystals up to 3×2×0.1 mm³ were successfully grown. Post‐annealing under high pressure of O₂ (up to 10 MPa at T = 500°C) was undertaken to enhance T_c and improve the homogeneity of the crystals. Structural characterisation was performed by single‐crystal X‐ray diffraction (XRD) and the structure of the 3‐layer Bi‐based superconducting compound was refined for the first time. Structure refinement showed an incommensurate superlattice in the Pb‐free crystals. The space group is orthorhombic, A2aa, with cell parameters a = 27.105(4) Å, b = 5.4133(6) Å and c = 37.009(7) Å. Superconducting studies were carried out by A.C. and D.C. magnetic measurements. Very sharp superconducting transitions were obtained in both kinds of crystals (ΔT_c ≤ 1 K). In optimally doped Pb‐free crystals, critical temperatures up to 111 K were measured. Magnetic critical current densities of 2�10⁵ A/cm² were measured at T = 30 K and μ₀H = 0 T. A weak second peak in the magnetisation loops was observed in the temperature range 40‐50 K above which the vortex lattice becomes entangled. We have measured a portion of the irreversibility line (0.1‐5 Tesla) and fitted the expression for the melting of a vortex glass in a 2D fluctuation regime to the experimental data. Measurements of the lower critical field allowed to obtain the dependence of the penetration depth on temperature: the linear dependence of λ(T) for T < 30 K is consistent with d‐wave superconductivity in Bi‐2223. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Nonlinear optical properties of strontium tartrato‐antimonate(III) dihydrate,Sr[Sb2{(+)‐C4H2O6}2]·2H2O

The tensor of nonlinear optical susceptibility for second harmonic generation [d^SHG _ijk ] of hexagonal (point group 6) strontium tartrato‐antimonate(III) dihydrate, Sr[Sb₂{(+)‐C₄H₂O₆}₂]·2H₂O, was determined using the Maker fringes method and a Nd:YAG laser with a wavelength of 1064 nm. The largest component of the tensor d^SHG ₃₃₃ amounts two times d^SHG ₁₁₁ of α‐quartz. Effective nonlinear optical susceptibility d^SHG _eff is given for phase matching type I for several wavelengths (for type II d^SHG _eff is nearly zero). The thermal stability of crystals of Sr[Sb₂{(+)‐C₄H₂O₆}₂]·2H₂O was determined in the temperature range from 153 K to 573 K by means of thermal expansion measurements and thermogravimetry. The temperature dependence of thermal expansion coefficients is given in the range from 153 K to 293 K. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Real Structure of LiB3O5 (LBO) Crystals Grown in Li2O‐B2O3‐MoO3 System

The liquidus surface structure and field of LiB₃O₅ (LBO) primary crystallization have been revealed in Li₂O‐B₂O₃ ‐MoO₃ ternary system. The optimization of charge composition and growth conditions results in large volume optical quality LBO single crystals yielding. Crystallographic properties and real defect structure of grown LBO single crystals have been investigated by X‐ray powder diffraction method and X‐ray reflection topography. The volume of the crystals is partly free of any structural imperfections.     

Re‐determination of the pseudobinary system Li2O – MoO3

The quasi‐binary phase diagram lithium oxide – molybdenum(VI) oxide was investigated by differential scanning calorimetry and X‐ray diffraction. The four intermediate phases Li₄MoO₅, Li₂MoO₄, Li₄Mo₅O₁₇, and Li₂Mo₄O₁₃ show incongruent melting. The system has one eutectic point at 50.5 mol% MoO₃ and 49.5 mol% LiO_0.5 with a eutectic temperature of 524.6°C. At this point the melt is in equilibrium with Li₂MoO₄ and Li₄Mo₅O₁₇. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Phase Formation and Structure of (RE,M)2Ca0.5Sr0.5Cu2O6+δ (RE=La,Pr, M=Ca,Sr)

The samples of (RE,M)₂Ca_0.5Sr_0.5Cu₂O_6+d are prepared by solid state reaction method. The single phase boundary of RE and M in (RE,M)₂Ca_0.5Sr_0.5Cu₂O_6+d is 1.0 ∼2.0 and 0 ∼1.0 respectively. In (Pr,M)₂Ca_0.5Sr_0.5Cu₂O_6+d, the phase boundary of Sr is 0 ∼1.0. The structure of (RE,M)₂Ca_0.5Sr_0.5Cu₂O_6+d belongs to the structure type of 212 cuprate superconductors with space group I4/mmm.     

Thermal expansion and structural properties of (CuAlTe2)1–x(CuAlSe2)x solid solutions

Investigations of the thermal expansion of (CuAlTe₂)_1–x(CuAlSe₂)_x solid solutions in the temperature range from 100 to 800 K have been carried out for the first time. It has been demonstrated that the thermal expansion coefficient α_L grows considerably in the temperature range from 100 to 300 K, whereas the temperature dependence above 300 K is rather weak. The isotherms of composition dependence of the thermal expansion coefficient α_L for 100, 293, 500 and 800 K were constructed, and it was found that linear relations could express them. The Debye temperatures θ_D , the average mean‐square dynamic displacements , the average root‐mean‐square amplitudes of thermal vibration RMS , the anion position parameter u using S. C. Abrahams & J. L. Bernstein (u_AB ) and J. E. Jaffe & A. Zunger (u_JZ ) models were calculated. The composition dependence of microhardness H using the phenomenological theory was also calculated, and it was discovered that this dependence has a non‐linear character with a maximum of 383 kg/mm² at x=0.67. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Preparation and investigation of (CuInSe2)x(2ZnSe)1‐x and (CuInTe2)x(2ZnTe)1‐x solid solution crystals

The (CuInSe₂)_x(2ZnSe)_1‐x and (CuInTe₂)_x(2ZnTe)_1‐x solid solution crystals prepared by Bridgman method and chemical vapor transport have been studied. The nature of the crystalline phases, the local structure homogeneity and composition of these materials have been investigated by X‐ray diffraction (XRD) and Electron Probe Microanalysis (EPMA) methods. The analysis revealed the presence of chalcopyrite‐sphalerite phase transition between 0.6 ≤ X ≤ 0.7. Lattice constants, value of σ position parameter and bond length between atoms were also calculated. It was found that the lattice parameters exhibit a linear dependence versus composition. The transmission spectra of solid solution crystals in the region of the main absorption edge were studied. It was established that the optical band gap of these materials changes non‐linearly with the X composition. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Linear Optical Properties of the Nonlinear Optical Calcium and Strontium Tartrato-Antimonates (III), Ca[Sb2 {(+) - C4H2O6}2] x2H2O and Sr[Sb2{(+) - C4H2O6}2 ] x2H2O

The study of nonlinear optical properties of crystals requires a thorough knowledge of the linear optical properties: knowledge of the transparency range is necessary, some information about the optical activity is useful. Above all, high quality refractive indices (with errors less than 10^-4) and their dispersion are the most important basic data, as they enable a detailed analysis of phase-matching conditions of nonlinear optical processes and an estimation of the nonlinear optical potential of a new non-centrosymmetric crystal. Such high quality refractive indices are also necessary in other areas of nonlinear optics, for example for the evaluation of nonlinear optical measurements like measurements of Maker fringes. In this short communication we present the linear optical basis for nonlinear optical investigations of the title compounds. The Sr compound has been known for a long time; its morphological crystallography is already presented in the famous Chemische Krystallographie by Paul Groth (1910). The Ca salt was first synthesized 1983 by one of us (L.B.).     

Crystal growth and investigation of CuAlxGa1−xTe2 solid solutions

Alloys of the CuGaTe₂‐CuAlTe₂ system have been synthesized by the one‐temperature method and homogenized by annealing. It was established for the first time by X‐ray and DTA methods that a continuous row of solid solutions is formed in the system. Large block crystals of CuAl_xGa_1−xTe₂ solid solutions have been grown by the Bridgman method (horizontal version). Measurements of density, microhardness and thermal expansion have been carried out on the grown crystals. It has been established, that the density and thermal expansion coefficients are changed linearly with composition, microhardness has a maximum at x = 0.6. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Crystal Structure of (Cr,Cu)(Sr,La)2(La,A)Cu2O8‐δ (1212‐type) and (Cr,Cu)Sr2(Y,Ce)2Cu2O10‐δ (1222‐type) Phases

Conditions of the synthesis, crystal structures, mechanical properties, electrical resistivities and magnetizations of cuprates with the general formula (Cr,Cu)(Sr,La)₂(La,A)Cu₂O_8‐δ where A=Ca or Sr of 1212‐type and (Cr,Cu)Sr₂(Y,Ce)₂Cu₂O_10‐δ of 1222‐type were investigated. The compositions of the cuprates and an amount of the impurity phases in the samples were determined. Rietveld refinement of the structure was carried out. It was found that the formal charges of Cu (FC_Cu) calculated from the electroneutrality of refined phase compositions do not achieve value optimal for the appearence of superconducting phases.     

Microwave dielectric properties of (1‐x)La(Mg0.5Sn0.5)O3‐x(Sr0.8Ca0.2)3Ti2O7 ceramic system with a near zero temperature coefficient of resonant frequency

In this study, the microwave dielectric properties of (1‐x)La(Mg_0.5Sn_0.5)O₃‐x(Sr_0.8Ca_0.2)₃Ti₂O₇ ceramic system prepared by the conventional solid‐state method have been investigated for application in mobile communication. It was found that the diffraction peaks of (1‐x)La(Mg_0.5Sn_0.5)O₃‐x(Sr_0.8Ca_0.2)₃Ti₂O₇ ceramic system shift to higher angles as x increases from 0.2 to 0.4. It was also found that the X‐ray diffraction patterns of the 0.8La(Mg_0.5Sn_0.5)O₃‐0.2(Sr_0.8Ca_0.2)₃Ti₂O₇ ceramics exhibited no significant phase difference at different sintering temperatures. The average grain size of the (1‐x)La(Mg_0.5Sn_0.5)O₃‐x(Sr_0.8Ca_0.2)₃Ti₂O₇ ceramic system decreased from 6.4 to 4.3 μm as the value of x increased from 0.2 to 0.4 sintered at 1550 °C for 4 h. The dielectric constant increased from 26.6 to 35.9 and the quality factor (Q×f) decreased from 31,600 to 23,300 GHz for (1‐x)La(Mg_0.5Sn_0.5)O₃‐x(Sr_0.8Ca_0.2)₃Ti₂O₇ ceramic system as the x value increases from 0.2 to 0.4 sintered at 1550 °C for 4 h. The average value of temperature coefficient of resonant frequency (τ_f) increased from ‐18 to +8 ppm/ K as the x value increases from 0.2 to 0.4. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Thermal analysis,powder diffraction and spectroscopic investigation of the solid phases of 1‐chloro‐2,2‐dimethylpropane

By the substitution of one methyl group in Neopentane C(CH₃)₄ with a methylchlorid group the globular sphere is expanded in 1‐chloro‐2,2‐dimethylpropane (CH₃)₃C(CH₂Cl). With the aid of DSC measurements, X‐ray powder diffraction, ¹H NMR and ³⁵Cl NQR measurements two orientationally disordered (plastic) phases were established. The low temperature structure was solved and a structural model of phase II is proposed. A mechanism to describe the reorientation in the different phases is given as well as a connectivity scheme between the phases is discussed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Thermal “order‐disorder” behaviour in (Na1‐xKx)4B8O14 solid solutions investigated by X‐ray powder diffraction

In the potassium‐rich part of the binary system Na₄B₈O₁₄‐K₄B₈O₁₄ solid solutions have been found that can be described with the formula (Na_1‐xK_x)₄B₈O₁₄ with 0.45 ≤ x < 1.0. The crystal structures of (Na_0.25K_0.75)₄B₈O₁₄ and (Na_0.45K_0.55)₄B₈O₁₄ were refined at room temperature by the Rietveld method. The solid solutions crystallize like K₄B₈O₁₄ in the triclinic crystal system, space group P ‐1, with K partially substituted for Na. An ordered distribution of the alkali atoms over the four cation sites at room temperature has been discovered. The structure of (Na_0.25K_0.75)₄B₈O₁₄ was also refined for data collected at 300 and 500 °C. The refinements show that sodium and potassium atoms are less ordered at higher temperatures. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth and magnetic‐optical properties of Sr3Gd(BO3)3 and Sr3TbxGd1‐x(BO3)3 single crystals

Single crystals of Sr₃Gd(BO₃)₃ (SGB) and Sr₃Tb_xGd_1‐x(BO₃)₃ (TSGB) with dimension Ø 20 mm×20 mm have been grown by Czochralski method. The grown crystals were characterized by X‐ray powder diffraction analysis which showed the crystals belong to hexagonal structure with lattice parameters of a=b=1.254 nm, c=0.926 nm (SGB) and a=b=1.253 nm, c=0.925 nm (TSGB). In TSGB, x=17.7% was obtained by X‐ray fluorometry which showed the segregation coefficient of Tb is closed to 1. The transmission spectrum was measured, which indicated the crystals have high transmittance in 400‐1100 nm region. The Faraday rotation of single crystals at 532 nm wavelength was measured at room temperature. Finally, the Verdet constants were investigated, (SGB) V=17.9 degcm^‐1T^‐1 and (TSGB) V=21.3 degcm^‐1T^‐1. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Photoelectric and photothermal investigations of Zn1‐x‐yBexMnySe solid solutions

Zn_1‐x‐yBe_xMn_ySe solid solutions were grown from the melt by the high pressure Bridgman method. Optical, luminescence, photoelectric and photothermal properties of this material were investigated. Interpretation of the piezoelectrically detected photoacoustic spectra was performed using Jackson and Amer theory. From the spectral dependence of the amplitude and phase of photoacoustic signal as well as from photoluminescence spectra the variation of energy gap with composition was determined. The values of thermal diffusivity were derived from the dependence of photoacoustic signal on modulation frequency of the laser radiation illuminating the sample. The photoluminescence‐excitation spectra and photoconductivity spectra were measured. The origin of luminescence in Zn_1‐x‐yBe_xMn_ySe was discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Infrared optical properties of (CuGe2P3)1−x(6 Ge)x solid solutions

Infrared reflectivity spectra of (CuGe₂P₃)_1−x(6 Ge)_x mixed crystals with compositions in the range x = 0.07–0.33 are measured at room temperature in the wavenumber range from 180 to 4000 cm⁻¹. An analysis of the spectra reveals six vibrational modes. The composition dependence of the mode frequencies and of the free carrier concentration and mobility is given and compared with infrared optical data for CuGe₂P₃.     

Crystal structure,spectroscopic studies and non‐linear optical properties of 2‐amino‐3‐nitropyridinium trichloroacetate

A new quadratic nonlinear optical crystal, 2‐amino‐3‐nitropyridinium trichloroacetate (2A3NPTCA), was synthesized and the single crystals were grown by slow evaporation method at room temperature. Single crystal X‐ray diffraction and powder X‐ray diffraction experiments were carried out in order to confirm the structure and crystalline nature of 2A3NPTCA crystal. The chemical bonding and various functional groups present in the 2A3NPTCA were identified from FT‐IR spectrum. The UV–visible–NIR transmission spectrum shows that it is suitable for frequency‐converting in the wavelength region of 431–1200 nm. Thermogravimetric (TG) and differential thermal analysis (DTA) were carried out to characterize the thermal behaviors of the grown crystals. Kurtz and Perry powder method for second harmonic generation (SHG) measurements demonstrate that 2A3NPTCA is a phase matching material and its nonlinear optical efficiency is two times that of KDP. All the above results suggest that 2A3NPTCA is a potential candidate of NLO material.     

Crystal and Molecular Structure of Bis{2,6‐bis(hydroxymethyl)pyridine‐O,O,N}{μ‐bis(2‐hydroxymethylpyridyl)methanolate‐O,N}dicopper(II)di(propionate). First example of non‐coordinate propionate anoins

Bis{2,6‐bis (hydroxymethyl) pyridine‐O,O,N} {μ‐bis(2‐hydroxymethylpyridyl) methanolate‐O,N} dicopper(II) di(propionate) (CCDC 143763) has been prepared and studied by single‐crystal X‐ray diffraction methods at 293(2) K. The crystal structure consists of dimeric complex cation, [Cu₂(μ‐bhmp)₂(bhmpH)₂]⁺² and propionate anions (bhmp ‐ 2,6‐bis(hydroxymethyl) pyridine; bhmpH ‐ 2‐(6‐hydroxymethylpyridyl) methanolate ) and propionate anions. The complex cation contains two neutral and two monodeprotonated bhmp molecules, each coordinate to one Cu(II) atom in a tridentate chelating manner, via two O atoms and N atom. The monodeprotonated bmph molecules are also tridentate coordinate via N atom and only one O atom, which serve as bridge between two CuO₄N₂ moieties. The propionate anions are “ fixed” to the complex by the hydrogen bonds.