Showing papers in "Crystal Research and Technology in 2006"
TL;DR: In this paper, the structural properties of ZnO thin films have been evaluated using X-ray diffraction, and the results showed that the films are transparent beyond 400 nm, while the intensity of the band edge emission peak increases.
Abstract: Zinc oxide thin films have been prepared on different substrates by the sol-gel method using 2-methoxyethanol solution of zinc acetate dihydrate stabilized by monoethanolamine. The photoluminescence spectra of the films show the band-edge and sub-band transitions. The intensity of the band edge emission peak increases, while the intensity of the deep level emission peak decreases in the films coated on sapphire substrate. Transmittance spectra show that the films are transparent beyond 400 nm. The structural property of the films has been evaluated using X-ray diffraction. The X-ray peak intensity of the film (002) grown on sapphire substrate is higher than the films grown on glass and quartz substrates. The AFM images show improvement in the surface of the annealed films as compared to the as-grown ZnO films coated on sapphire substrates. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
85 citations
TL;DR: In this paper, single crystals of organic nonlinear optical material, γ-glycine have been grown by gel method for the first time and the γ phase is confirmed by single crystal XRD.
Abstract: Single crystals of organic non-linear optical material, γ-glycine have been grown by gel method for the first time. The γ-phase is confirmed by single crystal XRD. The presence of various functional groups of γ-glycine are confirmed by FTIR. The UV-Vis-NIR spectrum reveals the high percentage of transmission of the sample in the entire visible region. The SHG of γ-glycine is confirmed by Kurtz powder technique. TGA-DTA studies indicate that the crystal is structurally stable upto 170 °C. Microhardness investigations are conducted on the grown crystals. The dielectric constant measurements are carried out and the nature of variation of dielectric constant e′ and dielectric loss D in the frequency range of 50 Hz to 5 MHz is studied and reported. Photoconductivity studies of γ-glycine crystals revealed the negative photoconducting nature. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
82 citations
TL;DR: A nonlinear optical crystal of L-lysine monohydrochloride dihydrate (L-LMHCl) was grown by slow evaporation solution growth technique using deionised water and mixed solvents of deionized water and ethanol as discussed by the authors.
Abstract: A nonlinear optical crystal of L-lysine monohydrochloride dihydrate (L-LMHCl) was grown by slow evaporation solution growth technique using deionised water and mixed solvents of deionised water and ethanol. The functional groups and vibrational frequencies were identified using FTIR and FT-RAMAN spectra analyses. Also, the presence of hydrogen and carbon atoms in the grown sample was confirmed using proton and carbon NMR spectra analyses. Using TG-DTA analyses, the decomposition temperature was obtained. Transmittance of the grown crystals was analysed using UV-visible spectrum. The mechanical strength of the grown crystals was found using Vicker's microhardness tester.
80 citations
TL;DR: In this article, the crystallinity of nanosized ZSM-5 zeolite from precursors mixtures containing different alumina sources, e.g. sodium aluminate, aluminum sulphate, aluminum hydroxide and alumina has been studied.
Abstract: Alumina sources can influence different aspects of ZSM-5 crystallization and it leads to change in the properties of the final product. The crystallinity of nanosized ZSM-5 zeolite from precursors mixtures containing different alumina sources, e.g. sodium aluminate, aluminum sulphate, aluminum hydroxide and alumina has been studied. The produced samples were investigated using XRD, SEM, FT- IR and BET surface area. The product obtained by sodium aluminate and aluminum sulphate was ZSM-5 phase. Whereas, the product obtained by aluminum hydroxide and alumina was the albit phase. As-synthesized ZSM-5 was prepared by sodium aluminate, as alumina source was the highest crystallinity. It was found that the average crystallite size increased in the following order; alumina
61 citations
TL;DR: In this article, the authors used FT-IR, TGA-DTA, and XRD studies to characterize ZnO nanofibers with diameters in the range of 100-200 nm.
Abstract: Electrospun ZnO nanofibers were obtained by calcinating PVA/Zinc Acetate composite fibers at various temperatures. Atomic Force Microscopy (AFM) revealed that the ZnO fibers have diameters in the range of 100-200 nm. The fibers were characterized by FT- IR, TGA-DTA, and XRD studies. The XRD results showed that the crystal structure and the morphology of the fibers were largely dependent on the calcination temperature (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
57 citations
TL;DR: In this article, the potential organic NLO crystal of benzimidazole (BMZ) has been successfully grown by slow evaporation solution growth technique at room temperature, and the crystalline perfection has been verified by High resolution X-ray diffraction (HRXRD) analysis.
Abstract: The potential organic NLO crystal of benzimidazole (BMZ) has been successfully grown by slow evaporation solution growth technique at room temperature. The crystalline perfection has been verified by High resolution X-ray diffraction (HRXRD) analysis. The very low angle boundary obtained for this solution-grown specimen may be attributed to the segregation of solvent molecules (methanol), which were entrapped within the crystal during growth. The laser damage threshold has been measured by using high intensity Q-switched Nd:YAG laser. The observed value is greater than that of KDP and lesser than that of melt grown benzimidazole. The NLO efficiency has been determined and it is compared with the KDP crystal. The thermal behaviour has been assessed by TG/DTA analysis. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
54 citations
TL;DR: In this paper, the morphology of spherulitic needles, an amino acid constituent responsible for brain nutrition, was crystallized in a silica gel of pH 6.0 by single diffusion method in a period of 30 minutes.
Abstract: L-Phenylalanine (C9H11NO2), having the morphology of spherulitic needles, an amino acid constituent, responsible for brain nutrition is crystallized in silica gel of pH 6.0 by single diffusion method in a period of 30 minutes. The grown crystals were characterized by X-ray powder diffraction, Fourier Transform infrared spectroscopy and Visible Ultraviolet spectroscopy. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
52 citations
TL;DR: In this article, a single crystal of glycine lithium sulphate, a nonlinear optical material, was grown from aqua solution by temperature reduction method and the cell parameters of the grown crystal were estimated by single crystal X- ray diffraction analysis.
Abstract: Single crystal of glycine lithium sulphate, a nonlinear optical material, was grown from aqua solution by temperature reduction method. The solubility and metastable zonewidth of glycine lithium sulphate were estimated using aqueous solution. The cell parameters of the grown crystal were estimated by single crystal X- ray diffraction analysis. The presence of functional groups was identified from FTIR spectrum. Thermal analysis was performed to study the thermal stability of the grown crystal. The transmission and absorption spectra of this crystal show that the lower cut off wavelength lies at 330 nm. Powder Second Harmonic Generation efficiency of the grown crystal measured by Kurtz technique is 0.75 times that of potassium dihydrogen orthophosphate. Vickers microhardness study was carried out on the well developed (011) face of the grown crystal. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
51 citations
TL;DR: In this article, single crystals of BTZA have been grown by low temperature solution growth method using slow cooling process at an optimized pH of 3.5 and the grown crystals have been examined under an optical microscope to study its surface morphology.
Abstract: Single crystals of BTZA have been grown by low temperature solution growth method using slow cooling process at an optimized pH of 3.5. The grown crystals have been examined under an optical microscope to study its surface morphology. The morphological studies show that the growth takes place by spreading of growth layers. Formation of rectangular shaped etch pit on the as-grown crystal has been explained in relation to the growth conditions. Single crystal X-ray diffraction analysis has been carried out to confirm the monoclinic system. Transmission spectrum reveals that the crystal has a low UV cut off of 434.5 nm and has a transmittance of 100%. Dependence of micro hardness on load has been studied. Powder X-ray Diffraction and FT-IR have been carried out to characterize the grown crystals. BTZA forms metal – sulfur bond and has good optical transmission in the entire visible region, which is the essential requirement for a non-linear crystal. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
49 citations
TL;DR: The thermal behavior of the bovine bone mineral and synthetic stoichiometric hydroxyapatite was investigated by X-ray diffraction as discussed by the authors, showing that the growth of biogenic apatite is non-monotonic and multi-staged.
Abstract: The thermal behavior of the bovine bone mineral and synthetic stoichiometric hydroxyapatite was investigated by X-ray diffraction. The bone samples in solid (planar oriented pieces) and in powder form were examined to elucidate how the microstructural and textural properties of bone mineral are modified under heating. As could be expected, the thermal behavior of the bone mineral depends not only on the structural distortions, but also on the crystal habit, texture and ordering of biocrystals in tissue. The temperature growth of biogenic apatite crystals, unlike synthetic hydroxyapatite, is seen to be nonmonotonic and multi-staged. At 600 to 700°C the biomineral crystallites grow rapidly due to disappearance of the mosaic structure as the lattice imperfections are annealed. After heating between 700°C and 900°C the bone mineral appears to be composed of roughly equidimensional ≥200 nm crystals. The further growth of the crystals in the range from 900 to 1300°C occurs by the mass transport mechanism, supporting the idea that the bone mineral is not a discrete aggregation of crystals, but rather a continuous mineral phase with direct crystal-crystal bonding. Estimates are presented to show the important role of the surface mass transport mechanism in the growth of apatite crystals. The material obtained by heating a cortical bone fragment between 900°C and 1300°C turns out to be composed of two crystal types: crystals oriented along the bone axis (major morphology) and those of differing shape and orientation (minor morphology). The heating-induced variations in the longitudinal and transverse dimensions of differing-morphology crystals are found to be coherent. Small amounts of CaO, MgO and other crystalline phases are seen to be formed in the bone mineral under heating. © 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
48 citations
TL;DR: In this paper, a new single crystal for ultraviolet light filter, KCNSH (Potassium Cobalt Nickel Sulfate Hexahydrate) was designed and its crystal structure was studied using X-ray diffraction.
Abstract: A new single crystal for ultraviolet light filter, KCNSH (Potassium Cobalt Nickel Sulfate Hexahydrate) was designed and its crystal structure was studied using X-ray diffraction in this paper. The empirical of the title compound is K2Co0.1Ni0.9(SO4)2.6H2O with formula weight 437.15. KCNSH crystal belongs to the monoclinic space group P2(1)/c, a=6.1390(3)A, b=12.1839(6)A, c=9.0095(4)A, α=γ=90°, β=105.060(2)°, V=650.74(5)A3, Z=2, Dc=2.231g/cm3. Using the cooling solution method, we have grown a deep green KCNSH crystal with dimension of 12×12×40mm3. The transmission spectrum of KCNSH in the range from UV to near IR wavelengths, its thermal properties, and the relationship between the structure and optical transmission properties are also studied and further discussed in this paper. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this paper, the influence of La3+ ions in KDP crystals is studied and the incorporation of La in the crystal was confirmed by EDAX analysis and the HRXRD analysis showed reduced structural defects in the La added KDP in the (100) plane than pure KDP.
Abstract: Single crystals of pure and Lanthanum added KDP crystals were grown from aqueous solution. The influence of La3+ ions in KDP crystals is studied. Isolated centers are formed by La3+ ions in KDP structure along (100) plane. La3+ ions incorporated into superficial crystal growth layer and slightly affect the growth process as they generate weak lattice stresses. The creation of these weak lattice stress is confirmed by Vickers's micro hardness test. The HRXRD analysis showed reduced structural defects in the La added KDP in the (100) plane than pure KDP. The incorporation of La in the crystal was confirmed by EDAX analysis. The Kurtz's powder SHG efficiency was found to be 1.5 times that of pure KDP. The UV-Vis transmission spectra of La added KDP showed excellent transmittance from 1100 nm to 340 nm and did not show any change in lower cutoff wavelength with respect to pure KDP. Laser damage threshold value has been determined using Q-switched Nd:YAG laser operating at 1064 nm and with 65 ns pulses in single shot mode. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this article, single crystals of calcium tungstate and strontium tungstane have been grown by double decomposition flux reaction technique using lithium chloride as flux, the effect of primary and secondary flux density in the growth charge has been studied.
Abstract: Single crystals of calcium tungstate and strontium tungstate have been grown by double decomposition flux reaction technique using lithium chloride as flux. Growth conditions are optimized to synthesize well faceted crystals. Effect of primary and secondary flux density in the growth charge has been studied. Thermogravimetric study reveals that the grown crystals are highly stable in the temperature range 25 – 1000°C. Analysis of optical absorption normal to the ab-plane in the spectral range of 200 – 800 nm reveals the true absorption edge, the nature of transition being the allowed indirect one at 4.60 eV and 4.56 eV respectively for CaWO4 and SrWO4. The crystals have been characterized by determining useful pertinent optical and dielectric parameters. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this article, chemical method has been used in synthesis of CdS nanoparticles and thiophenol was used as capping agent, and X-ray diffraction studies of both samples were done.
Abstract: II-VI semiconductor nanoparticles have recently attracted a lot of attention due to the possibility of their application in various devices. In the present study, chemical method has been used in synthesis of CdS nanoparticles and thiophenol was used as capping agent. X-ray diffraction studies of both samples were done. The dc conductivity of CdS increases at a lower rate or is approximately constant upto 500K and thereafter the conductivity increases at a rapid rate. Beyond Tc it is seen that the portion of the σdc versus 1000/T is almost a straight line showing an Arrehenious behaviour. The dielectric constant of nanoparticles of CdS is found to be larger than the corresponding values of CdS crystals. It is clearly observed that at lower wavelengths nanocrystalline samples show a blue-shift. The three peaks of sample (S2), A, Band C can be ascribed to the transition from Cd-O complex donor formed by adsorbed oxygen to the valance band, Cd - excess acceptor and the surface states, respectively. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: The effect of the type of solvent on the solid liquid interfacial energy was determined by performing induction time measurements of paracetamol in methanol, 1-propanol, acetone and water at a constant supersaturation temperature of 30 °C and different levels of supersaturation (a/a*) ranging from 1.03 to 1.24 as mentioned in this paper.
Abstract: The effect of the type of solvent on the solid liquid interfacial energy was determined by performing induction time measurements of paracetamol in methanol, 1-propanol, acetone and water at a constant supersaturation temperature of 30 °C and different levels of supersaturation (a/a*) ranging from 1.03 to 1.24. At equal supersaturation level and temperature the induction time increases with decreasing solubility whereas the solid liquid interfacial energy decreases with increasing solubility. The interfacial energy has a minimum value of 1.45 mJ/m2 in the solvent where paracetamol has a maximum solubility (methanol) whereas it has its maximum value of 2.91 mJ/m2 in the solvent with minimum solubility. The interfacial energy is a function of the solubility has been established. The critical radius for homogeneous nucleation was found to be minimum in the solvent of highest solubility. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this article, aqueous solution containing different concentrations and different molecular weight of polyethylene glycol (PEG) was analyzed by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD).
Abstract: Calcium Carbonate has been precipitated from aqueous solutions containing different concentrations and different molecular weight of Polyethylene Glycol (PEG). The precipitations were analyzed by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The results demonstrated that PEG has profound influence on the nucleation and crystal growth of CaCO3, under condition of low PEG6000 (refer to PEG MW=6000) concentration, it favored the formation of calcite, while high PEG6000 concentration promoted vaterite formation. Additionally, low molecular weight PEG can stabilize vaterite phase. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: The nonlinear optical single crystals of L-Lysine monohydrochloride dihydrate (L-LMHCl) have been grown and examined by high-resolution X-ray diffraction and etching studies for their perfection as mentioned in this paper.
Abstract: The nonlinear optical single crystals of L-Lysine monohydrochloride dihydrate (L-LMHCl) have been grown and examined by High-resolution X-ray diffraction and etching studies for their perfection. The vibrational frequencies have been identified by the micro-Raman studies and the dielectric behaviour has been studied and the results are presented in detail. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this article, three metal complexes of thiourea (ZTC, ZTS and Bisthiourea Cadmium Chloride) were grown from aqueous solution by slow evaporation technique.
Abstract: In the present study three crystals of thiourea family viz. Zinc Thiourea Chloride (ZTC), Zinc Thiourea Sulfate (ZTS) and Bisthiourea Cadmium Chloride (BTCC) were grown from aqueous solution by slow evaporation technique. The grown crystals were studied by powder XRD, FT-IR and UV-visible. The dielectric study of grown crystals was carried out in X-band using transmission line wave guide method. It was found that the BTCC has lowest dielectric constant among three metal complexes of thiourea crystals (ZTC, ZTS and BTCC), therefore it can be used for high speed electro-optic modulation. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this paper, a single crystal tetrakis thiourea nickel chloride (NTC) was grown using silica gel and the properties of the NTC were investigated.
Abstract: Thiourea has a large dipole moment and has an ability to form extensive network of hydrogen bonds. In the course of our studies on new semiorganic NLO materials, thiourea is selected to combine with nickel chloride. Single crystals of tetrakis thiourea nickel chloride are grown using silica gel. Green transparent crystals of NTC (nickel thiourea chloride) of dimension 8x4x3 mm3 are grown in a period of 45 days. Single crystal XRD shows that the crystal belongs to body centered tetragonal symmetry class I4. The UV-Vis-NIR spectrum establishes the transmission range to be 300 nm to 2500 nm, with a sharp absorption peak at the red end of the visible region, which is due to the colour of the crystal. Photoconductivity and dielectric studies are also carried out. The mechanical strength of the crystal is estimated by Vickers hardness test. The crystal starts decomposing after about 200°C. Thus, we confirm from our present investigation that NTC is a suitable candidate for NLO applications. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: The dependence of photoluminescence (PL) and transmittance properties of aluminum-doped zinc oxide (AZO) thin films were deposited on sapphire and glass substrates by two different sputtering techniques radio frequency magnetron cosputtering of AZO and ZnO targets and sputtering of an AZO target as discussed by the authors.
Abstract: Aluminum-doped zinc oxide (AZO) thin films were deposited on sapphire (002) and glass substrates by two different sputtering techniques radio frequency magnetron cosputtering of AZO and ZnO targets and sputtering of an AZO target The dependence of the photoluminescence (PL) and transmittance properties of the AZO films deposited by cosputtering and sputtering on the AZO/ZnO target power ratio, R and the O2/Ar flow ratio, r were investigated, respectively Only a deep level emission peak appears in the PL spectra of cosputtered AZO films whereas both UV emission and deep level emission peaks are observed in the PL spectra of sputtered AZO films The absorption edges in the transmittance spectra of the AZO films shift to the lower wavelength region as R and r increase Also effects of crystallinity, surface roughness, PL on the transmittance of the AZO films were explained using the X-ray diffraction (XRD), atomic force microscopy (AFM), and PL analysis results (© 2006 WILEY-VCH Verlag GmbH & Co KGaA, Weinheim)
TL;DR: In this article, the alpha-and beta-methionine was crystallized in silica gel under suitable pH conditions by a single diffusion method and the grown crystals were characterized by density measurement and single crystal Xray diffraction.
Abstract: DL-Methionine C5H11NO2S] is one of the essential amino acids in humans. It has two crystalline forms, viz., alpha- and beta- methionine. In the present study, beta- form is crystallized in silica gel under suitable pH conditions by single diffusion method. The grown crystals were characterized by density measurement and single crystal Xray diffraction. Fourier transform infrared (FTIR) spectroscopic studies, thermal analysis and scanning electron microscopic (SEM) studies were also made as part of the structural studies. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
TL;DR: In this paper, the use of variants to analyze fcc/bcc orientation relationships is demonstrated by EBSD data and it is shown that pole figures of higher indexed lattice planes more reliably reflect the character of the orientation relationship since no overlapping of poles occurs.
Abstract: The use of variants to analyze fcc/bcc orientation relationships is demonstrated by EBSD data. Because of multiply occupied poles in the stereographic projections low indexed pole figures are not always suitable. This is mostly caused by the convolution of all scattered individual orientation data as the single poles cannot resolved in the pole figure. Pole figures of higher indexed lattice planes more reliably reflect the character of the orientation relationship since no overlapping of poles occurs. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this article, the effects of substrate temperature and atmosphere on the electrical and optical properties of Ga-doped ZnO thin films deposited by rf magnetron sputtering were investigated.
Abstract: Effects of substrate temperature and atmosphere on the electrical and optical properties of Ga-doped ZnO thin films deposited by rf magnetron sputtering were investigated. The electrical resistivity of Ga-doped ZnO (GZO) films decreases as the substrate temperature increases from room temperature to 300°C. A minimum resistivity of 3.3 × 10–4 Ω cm is obtained at 300°C and then the resistivity increases with a further increase in the substrate temperature to 400°C. This change in resistivity with the substrate temperature is related to the crystallinity of the GZO film. The resistivity nearly does not change with the O2/Ar flow ratio, R for R 0.25. This change in resistivity with R is also related to crystallinity. The crystallinity is enhanced as R increases, but if the oxygen partial pressure is higher than a certain level (R = 0.25 ± 0.10) gallium oxides precipitate at grain boundaries, which decrease both carrier concentration and mobility. Optical transmittance increases as R increases for R < 0.75. This change in transmittance with R is related to changes in oxygen vacancy concentration and surface roughness with R. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this article, the influence of the dopants on the optical, chemical, structural, mechanical and other properties of the KAP crystals was analyzed, which indicated better efficiency for doped crystals.
Abstract: Potassium hydrogen phthalate (KAP) single crystals were grown by slow evaporation and slow cooling techniques. The growth procedure like temperature cooling rate, evaporation rate, solution pH, concentration of the solute, supersaturation ratio etc., has been varied to have optically transparent crystals. Efforts were made to dope the KAP crystals with rubidium, sodium and lithium ions. The dopant concentration has been varied from 0.01 to 10 mole percent. Good quality single crystals were grown with different concentrations of dopants in the mother phase. Depending on the concentration of the dopants and the solution pH value, there is modification of habit. Rubidium ions very much improve the growth on the prismatic faces. The transparency of the crystals is improved with rubidium and sodium doping. The role of the dopants on the non-linear optical performance of KAP indicates better efficiency for doped crystals. The grown crystals were characterized with XRD, FT-IR, chemical etching, Vickers microhardness and SHG measurements. The influence of the dopants on the optical, chemical, structural, mechanical and other properties of the KAP crystals was analysed. © 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
TL;DR: In this article, Cadmium Magnesium Tetra Thiocyanate (CdMg(SCN)4) was grown by solution growth technique at room temperature.
Abstract: Cadmium Magnesium Tetra Thiocyanate, CdMg(SCN)4, [CMTC] belongs to bimetallic thiocyanate complexes. CMTC crystals has been grown by solution growth technique at room temperature. The morphologies of the grown crystals are identified by single crystal analysis. Also the Powder X-ray Diffractogram of the crystal has been recorded and the various planes of reflection are identified. The title compound crystallizes under triclinic structure with lattice parameters a = 10.0976 A, b = 7.5015 A, c = 5.7720 A and β = 90.2135°. The presence of magnesium and cadmium in the grown crystals were confirmed through Atomic Absorption Spectroscopy. The grown crystals are analysed qualitatively by Fourier Transform Infrared (FTIR) and Fourier Transform Raman spectral measurements. The transmittance spectrum of the crystal in the UV-Visible region has been recorded and analysed. The dielectric measurements for the crystals were carried out in the microwave region. The thermal stabilities of the crystals were studied by using different thermal analyses like Thermo Gravimetric Analysis (TGA), Differential Thermal Analysis (DTA) and Differential Scanning Calorimetry (DSC). (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this article, ZnSe hollow spheres aggregated from nanoparticles with size of 60∼100 nm have been successfully synthesized via simple hydrothermal routes using NaOH and cetyltrimethyl ammonium bromide (CTAB) to control the shape and size, respectively.
Abstract: ZnSe hollow spheres aggregated from nanoparticles with size of 60∼100 nm have been successfully synthesized via simple hydrothermal routes. NaOH and cetyltrimethyl ammonium bromide (CTAB) were used to control the shape and size, respectively. The as-prepared microspheres were characterized with powder X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-vis spectroscopy. The results indicate that the products are well dispersed and uniform. The effect of two additives was discussed. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this paper, high quality GaAs layers have been grown by low pressure MOVPE on Ge(001) and GaAs(001), 9° off oriented in [110] direction by using a thin low temperature (LT) GaAs layer.
Abstract: High quality GaAs layers have been grown by low pressure MOVPE on Ge(001) and Ge(001) 9° off oriented in [110] direction by using a thin low temperature (LT) GaAs layer Investigations of the initial growth step were performed at different V/III ratios and temperatures To show the good buffer layer quality solar cell structures were grown on off oriented n-Ge(001) and n-GaAs(001) substrates The surface morphology was studied by atomic force microscopy which showed the step-flow growth mode on 12 µm thick GaAs/Ge structures The crystalline qualities of this structures and the smooth surface morphology were investigated by double crystal X-ray diffraction (XRD) and atomic force microscopy (AFM) (© 2006 WILEY-VCH Verlag GmbH & Co KGaA, Weinheim)
TL;DR: In this paper, the title compound N-[2-hydroxy-1-naphthylidene]2,5-dichloroaniline is nearly planar.
Abstract: The title compound has been synthesised by the reaction of 2-hydroxy-1-naphthaldehyde with 2,5-dichloroaniline. The compound was characterized by elemental analysis, IR and UV-Visible techniques. The UV-Visible spectra of the Schiff base with OH group in ortho position to the imino group was studied in polar and nonpolar solvents in acidic and basic media. The structure of compound has been examined cyrstallographically. It crystallizes in the orthorhombic space group P212121 with a = 6.059(1), b = 12.105(2) c = 20.006(2) A, V = 1467.4(3) A3, Dx = 1.431 g.cm-3 and Z = 4. The crystal structure was solved by direct methods and refined by full-matrix least squares. Molecule of the title compound N-[2-hydroxy-1-naphthylidene]2,5-dichloroaniline is nearly planar. The molecule contains a strong intramolecular N…H-O hydrogen bond between the imine and hydroxyl group [O1 and N1 = 2.540(4) A]. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
TL;DR: In this paper, the first attempt to grow high quality anthracene crystals by solution technique adopting slow evaporation method in different solvents like CS2 and CCl4 was made.
Abstract: In recent years considerable effort has gone into the preparation and characterisation of high purity anthracene crystals, since anthracene is used as a model organic molecular crystal in studies of solid-state properties. Studies of organic molecular crystals and their applications in optics and electronics have been increasing attractive interest. Several attempts have been made to grow single crystals of anthracene. This is the first attempt to grow high quality anthracene crystals by solution technique adopting slow evaporation method in different solvents like CS2 and CCl4. The harvested crystals were subjected to various characterization studies. The results of characterisation studies support the purity of solution grown anthracene crystals. The solubility of anthracene in various solvents like CS2 and CCI4 was determined. The crystals of anthracene were grown by systematic method of slow evaporation technique in various solvents. Different morphology is noted with varying solvents. The crystal was subjected to XRD studies, FTIR studies and thermal studies. © 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
TL;DR: In this paper, the temperature dependent structural phase transition from the tetragonal chalcopyrite structure to the cubic sphalerite like structure in CuInSe 2 was investigated by in-situ high temperature synchrotron radiation X-ray diffraction.
Abstract: The temperature dependent structural phase transition from the tetragonal chalcopyrite like structure to the cubic sphalerite like structure in CuInSe 2 was investigated by in-situ high temperature synchrotron radiation X-ray diffraction. The data were collected in 1K steps during heating and cooling cycles (rate 38 K/h). The Rietveld analysis of the diffractograms led us to determine the temperature dependence of the lattice parameters, including the tetragonal deformation, |1-η|, and distortion |u-1/4| (η=c/2a, a and c are the tetragonal lattice constant; u is the anion x-coordinate). The thermal expansion coefficients α a and α c of the tetragonal lattice constant which are related to the linear thermal expansion coefficient α L were obtained, as were α a of the cubic lattice constant, also α u and α η . The transition temperature is clearly identified via a strong anomaly in α L . The temperature dependence of the anion position parameter was found to be rather weak, nearly α u ∼0, whereas α η increases slightly. However, both increase strongly when approaching to within 10 K of the transition temperature (the critical region) and |1-η| as well as |u-1/4| go to zero with IT-T trans | 0.2 approaching the phase transition. The cation occupancy values, derived from the Rietveld analysis, remain constant below the critical region. Close to the transition temperature, the number of electrons at the Cu site increases with a dercrease in the number of electrons at the In site with increasing temperature, indicating a Cu-In anti site occupancy, which is assumed to be the driving force of the phase transition. At the transition temperature 67% of Cu + were found to occupy the Mel site with a corresponding 67% of In 3+ at the Me2 site. Although full disorder is reached with 50%, this level seems to be high enough that the phase transition takes place. The order parameter of the phase transition, goes with |T-T trans | β to zero with the critical exponent β=0.35(7) which is in good agreement to the critical exponent β=0.332 calculated for order-disorder transitions according to the Ising model.