The growth and spectral analysis of mixed crystal of Yb‐doped Lu0.5Y0.5PO4 mixed crystals

A new kind of 5 at% Yb‐doped Lu_0.5Y_0.5PO₄ crystals were firstly grown by spontaneously nucleated high‐temperature solution method using lead pyrophosphate (Pb₂P₂O₇) as the solvent. The X‐ray powder diffraction (XRPD) patterns recorded at room temperature showed the crystals possessed tetragonal xenotime structure. The polarized absorption spectra and the fluorescence spectra of Yb:Lu_xY_1‐xPO₄ were measured at room temperature, respectively. The results show that Yb:Lu_xY_1‐xPO₄ mixed crystal will be a promising laser material if the crystal size and quality is further improved.     

Heat‐treatment influence on the microstructure and magnetic properties of rare‐earth substituted SrFe12O19

Rare‐earth substituted strontium ferrite nanopowders SrFe_12‐xR_xO₁₉ (R = La, Gd and Er; x = 0.2, 0.5 and 1) were prepared by sol‐gel‐autocombustion method and subsequent heat treatments. Structural and magnetic properties of SrFe_12‐xR_xO₁₉ powders heat treated at 800, 900 and 1000⁰C, for various times, were characterized with an X‐ray diffractometer, a vibrating sample magnetometer and a scanning electron microscope. The results of X‐ray diffraction measurements showed the M‐type hexagonal structure formation by heat treatments. Magnetic properties, such as specific saturation magnetization σ_s, specific remanent magnetization σ_r and coercivity H_c, as well as microstructure depend on the heat treatment conditions (temperature and time). The coercivity H_c exhibits a great increase after a critical heat treatment time. When the heat treatment time increases, one obtains an increase in H_c after a shorter heat treatment time. This jump of H_c was explained by a transition from the superparamagnetic state to normal state of the single domain nanoparticles. The occurrence of an agglomerated structure composed of magnetically interacting ultrafine crystallites also contributes to the increase of H_c.The heat treatment determines a reduced grain growth due to the internal stress generated by R ions. With increasing R content the σ_s and σ_r decrease due to the dissolution of R ions into the hexaferrite lattice. We believe that by selecting the time and temperature of the heat treatment, microstructure and magnetic properties suitable for magnetic recording media application can be obtained. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Inversion of conductivity type of III‐V compound layers in experiments with LPE growth from rare‐earth containing melts

Rare‐earth (RE) elements present in the growth melt of the LPE process are known to have a purifying effect on the grown layers of III‐V compounds. The RE atoms exhibit high chemical affinity preferentially to shallow donors, forming insoluble aggregates that remain in the melt and do not, ordinarily, enter the solid phase. The aim of the paper is to simulate the situation, sometimes observed experimentally, where the gradual gettering of donor impurity, consequent upon increasing the RE content in the melt, leads to an inversion of the electrical conductivity type of the grown layer from n to p. Usefulness of the approach is demonstrated by interpreting results of an experimental work. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Influence of the preparation route on the optical properties of dosimetric phosphors based on rare‐earth doped polycrystalline strontium borates

Most of commercial dosimetric phosphors consist of suitably doped polycrystalline compounds. Whereas the activation issue has been usually addressed, less attention has been paid to the influence of host preparation in the final perfomance of the products. In this paper different routes have been followed to synthesise phosphors based on rare‐earth doped strontium borates. The structural and optical properties of the materials have been given special consideration. Finally, thermoluminescence glow curves have been recorded in order to assess which of the preparation routes yields the most efficient compound. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Cobalt phthalocyanine nanowires: Growth,crystal structure,and optical properties

Cobalt phthalocyanine nanowires with new crystal structure and broad optical absorption spectra were fabricated by using organic vapor phase deposition method. The morphology, crystal structure and optical properties of CoPc nanowires were characterized by SEM, X‐ray diffraction, Fourier transform infrared and UV‐visible spectroscopies. Analyses of X‐ray diffraction patterns and Fourier transform infrared spectra indicate that the crystal structure of CoPc nanowires represents a new polymorph, which is designated J‐CoPc. These J‐CoPc nanowires with high directionality (average diameter ∼50 nm) surprisingly possess much broader optical absorption spectra in the visible spectral region than those of the α‐ and β‐phase CoPc, enabling high potential for practical applications in novel molecular electronic/optical devices.     

Crystal growth,structure and spectroscopic studies of a novel organic single crystal: L‐lysine p‐nitrophenolate monohydrate (LLNP)

A novel organic crystal, L‐lysine p‐nitrophenolate monohydrate (LLNP) has been grown successfully from an aqueous solution by the slow cooling method. Transparent single crystal of dimensions 22 × 12 × 12 mm³ has been obtained. The single crystal X‐ray diffraction has shown that LLNP belongs to the orthorhombic crystallographic system with space group P2₁2₁2₁. The functional groups and vibrational frequencies of the crystal have been identified using IR and Raman spectra. The proton and carbon configurations have been confirmed through ¹H‐NMR and ¹³C‐NMR spectra analyses. The UV‐Vis‐NIR transmittance spectrum for LLNP crystal has been recorded in the range from 200 to 2500 nm. The second harmonic generation (SHG) intensity of LLNP has been measured by powder SHG method and found to be as 4.2 times as that of KDP. The thermal properties have been studied by using thermo gravimetric (TG) and differential thermal analysis (DTA).     

The crystal structure of hexaammonium diacetyl‐octa‐molybdate tetrahydrate

The crystal structure of hexaammonium diacetyl‐octa‐molybdate tetrahydrate, (NH₄)₄₂[Mo₁₃₂O₃₇₂ (CH₃COO)₃₀(H₂O)₇₂] is documented. The crystals are triclinic, space group P‐1, with a=8.1018(16) Å, b=10.334(2) Å, c=12.238(2) Å, α=68.20(3)°, β=74.98(3)°, γ=67.25(3)°, V=869.3(3) ų, Z=1. The structure was solved by direct methods and refined by least squares methods to a Final R1 = 0.0374 and wR2 = 0.1074 for 3805 observed reflections with I > 2σ(I). The structure contains ammonium cations and isolated acetyl octamolybdate(6‐) anions, [Mo₈O₂₈(CH₃CO)₂]^6‐. The crystallographic data of the structure was deposited with the Cambridge Data Center as No. CCDC 249565. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

New nonlinear‐laser effects in GdVO4 – host‐crystal for Ln3+ lasants

We discovered several new nonlinear‐laser χ⁽³⁾‐properties in tetragonal GdVO₄ vanadate, which is host‐crystal for lanthanide lasant ions, and attractive gain media for Raman laser converters. We hope that observed many‐phonon SRS, almost two‐octave Stokes and anti‐Stokes lasing comb, cascaded self‐frequency “tripling” and self‐sum‐frequency generation in the blue and UV spectral range could significantly enriche funcional laser potential of this crystal. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis,characterization and crystal structure of a 3‐D supramolecular Cu/Mn complex with pydc

A supramolecular compound, {[CuMn(pydc)₂(H₂O)₅]·2H₂O} ( 1 ) (pydc = pyridine‐2,6‐dicarboxylate dianion), has been synthesized and characterized by single‐crystal X‐ray diffraction. Single‐crystal X‐ray analysis reveals that it crystallizes in the triclinic space group P‐1, a = 8.4763(17) Å, b = 9.7715(19) Å, c = 13.909(3) Å, α =101.234(3)°, β =102.520(3)°, γ= 97.375(4)°. Two mixed‐metal ions exhibit similar coordinated geometries with octahedron. 1 possesses a 3‐D unusual supramolecular network featuring 1D water tape. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis,characterization and crystal structure of a novel 3‐D copper(II) polymer with bent N‐containing ligand

An exploration of the mixed‐ligand system under hydrothermal condition, has led to the isolation of a 3‐D novel framework {[Cu₂(mp)L₂)(H₂O)₂]·6H₂O}_n ( 1 ) (mp = benzene‐1,2,4,5‐ tetracarboxylate tetraanion, L = 4‐(5‐(pyridin‐4‐yl)‐1,3,4‐thiadiazol‐2yl)pyridine). Single‐crystal X‐ray analyses reveal that it crystallizes in the triclinic space group P‐1, a = 8.807(4) Å, b =11.139(6) Å, c = 11.291(5) Å, α=75.337(7), β = 73.584(5), γ= 66.795(5)°. The Cu^II ions are linked into an extended 2‐D grid net via mp molecules. Further these layers are united together through the bridging L to form a 3‐D structure, which exhibits a new 4‐connected topological network. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis and characterization of phosphates in the pseudo‐ternary melted systems Cs2O‐P2O5‐MIIO (MII – alkaline earth)

The crystallization of alkali‐earth phosphates in the melts of Cs₂O‐P₂O₅‐M^IIO (M^II – Ca, Sr, Ba) pseudo‐ternary systems have been investigated at various Cs/P molar ratios and at fixed value of M^II/P equal to 0.15. Type of the phosphate which crystallizes in melts depends on the Cs/P initial ratio. Crystallization fields of CsM^IIP₃O₉, M^II₂P₂O₇ and Cs₂M^IIP₂O₇ were briefly investigated and characterized. The new diphosphate Cs₂CaP₂O₇ has been obtained and investigated by the single crystal and powder X‐ray diffraction and FTIR‐ spectroscopy. It crystallizes in C 2/m space group, with the following parameters of the monoclinic cell: a = 10.261(2), b = 5.9316(12), c = 7.2404(14) Å, β = 118.54(3)°. The architecture of [CaP₂O₇]^2‐ anionic sublattice, which is built up from [CaO₆] octahedra and [P₂O₇] bitetrahedra, interlinked via the common oxygen vertices, gives rise to formation of hexagonal tunnels along crystallographic direction b, where caesium atoms are located. One of the most remarkable features of the structure is specific positional disorder of the diphosphate group, which is connected with the existence of two equiprobable half‐occupied sites of the bridging oxygen. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Crystal structure,thermal behavior and IR investigation of 1,6‐diammonium hexan dihydrogenodiphosphate dihydrate

Physicochemical properties of (C₆H₁₈N₂)H₂P₂O₇·2H₂O denoted DHDP are discussed on the basis of X‐ray crystal structure investigation. The compound crystallises in the triclinic system with P space group. Its unit cell dimensions are a = 13.719(1) Å, b = 14.188(3) Å, c = 9.177(1) Å, α = 108.50(1)°, β = 91.11(1)°, γ = 115.47(1)°, V = 1503.8(4) ų and Z = 4. The structure has been solved using direct methods and refined to a reliability R factor 0.0401 for 4778 reflections. The main feature of the atomic arrangement of DHDP is the existence of infinite rows, parallel to the c direction of the unit cell, composed of H₂P₂O₇ groups. These phosphoric rows are organised to create, with the help of the organic cation, large rectangular channels in which the unstable water molecule are located since they have high thermal parameters. Phosphoric anions and organic cations have no internal symmetry. DSC and TG‐DTA show that dehydration occurs in one step. Such dehydration process may be related to the similar environments on the water molecules residing in the channel. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Crystal structure of cis,cis,cis‐1,2‐epoxy‐3,5‐dibromo‐4‐hydroxy tetralin

The title compound, C₁₀H₈Br₂O₂, consists of a tetrahydronaphthalene skeleton composed of a six‐membered ring A with arene oxide, monobromo and monohydroxy atoms in cis,cis,cis configuration held in a boat conformation and a six‐membered planar ring B, where the ring B carries monobromo atom. The repulsive interactions between the Br and OH atoms affect the topology of the tetrahydronaphthalene moieties.     

Crystal and molecular structure of 3‐phenyl‐4‐(p‐chlorobenzylamino)‐4,5‐dihydro‐1‐H‐1,2,4‐triazol‐5‐on

The structure of the title compound, C₁₅H₁₃N₄OCl was determined by single crystal X‐ray diffraction technique. The structure consists of a p‐chlorobenzylamino moiety and triazol and phenyl rings. The title compound crystallizes in the monoclinic space group P2₁/c with a = 14.368(3), b = 6.255(3), c = 17.631(3) Å, β = 113.24(3)°, Z = 4, V = 1455.8(8) ų and D_x = 1.372 gcm^‐3. The structure was solved by direct methods and refined by full‐matrix least‐squares method (R=0.0477). The dihedral angle between the triazole moiety and the phenyl ring is 28.8(3)°. The molecular packing is stabilized by N‐H…N and N‐H…O types of inter molecular hydrogen bonds. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A novel metal‐organic coordination complex crystal: tri‐allylthiourea zinc chloride (ATZC)

A new metal‐organic coordination nonlinear optical crystal, tri‐allylthiourea zinc chloride (ZnCl₂(AT)₃, where AT is CH₂=CHCH₂NHCSNH₂, abbreviated as ATZC), is reported. It was synthesized in water and recrystallized in ethanol. For the crystal structure, optical and thermal characterization were determined by elemental analyses, X‐ray diffraction, infrared spectroscopy, differential scanning calorimeter, thermogravimetric analysis, and powder SHG efficiency meansurement. It belongs to the trigonal system, space group R3, with a = 11.0498(4) Å, c = 16.0416(11) Å, z = 3 and V = 1696.24(15) ų. It exhibits powder SHG efficiency the same order as Urea crystal. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Crystal structure and characterization of a novel organic optical crystal: 4‐chloro‐3‐nitrobenzophenone

Single crystals of a novel organic material, 4‐Chloro‐3‐Nitrobenzophenone (4C3N) were grown from acetone solution employing the technique of controlled evaporation. 4C3N belongs to the Orthorhombic system, with a = 12.9665(11) Å, b = 7.4388(6) Å, c = 24.336(2) Å, α = β = γ = 90°. FT‐IR study has been performed to identify the functional groups. The transmittance of 4C3N has been used to calculate the refractive index n; the extinction coefficient K and both the real ε_r and imaginary ε_i components of the dielectric constant as functions of photon energy. The optical band gap of 4C3N is 2.7 eV. Thermo gravimetric analysis and differential thermal analysis have also been carried out, and the thermal behavior of 4C3N crystal has been studied. The mechanical properties have been investigated. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth and crystal structure of the layered compound TlGaSe2

The semiconducting compound TlGaSe₂ was grown by solid state reaction technique. The crystal structure of this material was confirmed by single‐crystal X‐ray diffraction. TlGaSe₂ crystallizes in the monoclinic system with space group C2/c (No. 15), Z = 16 and unit cell parameters a = 10.779(2) Å, b = 10.776(1) Å, c = 15.663(5) Å, β = 99.993(6)°. The structural refinement converged to R(F) = 0.0719, R(F²) = 0.0652 and S = 1.17. The structure consists of a three‐dimensional arrangement of distorted TlSe₈ and GaSe₄ polyhedrons. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Hydrothermal synthesis and crystal structure of a three‐dimensional polyoxovanadate

A three‐dimensional polyoxovanadate formulated as HV₃O₈·H₂O has been synthesized by hydrothermal method. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

XRD,IR, and Raman investigations of structural properties of Dy2‐xHox O3 prepared by sol gel procedure

The Rare earth mixed oxides Dy_2‐xHo_x O₃ (0.0 ≤ x ≤ 2.0) solid solution was synthesized by a sol–gel process. X‐ray diffraction (XRD) data were collected and crystal structure and microstructure analyses were performed applying Rietveld refinement method. Infrared and Raman spectroscopy were used to define the microstructure and to locally probe the structure of the samples. The cationic distribution over the two non‐equivalent sites 8b and 24d of the space group Ia3 is found to be randomly. The crystallite size and microstrain as well as Raman modes positions are influenced by Ho³⁺ concentration. The apparent size is isotropic but significant anisotropy is found for the microstrain with its largest value along the crystallographic direction [h00]. Inspite the single phase solid solution confirmed by Rietveld analysis for all samples, Raman spectra detected the coexistence of two phases; cubic and distorted monoclinic of too small amount or highly disordered, i.e. amorphous like, to be detected by XRD. The result indicates the ability of Raman spectroscopy to detect minor phases in solid solutions. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)