共查询到20条相似文献,搜索用时 31 毫秒
1.
R. Sathyalakshmi V. Kannan R. Bairava Ganesh P. Ramasamy 《Crystal Research and Technology》2007,42(1):78-83
L(+)Glutamic acid hydrochloride [HOOC (CH2)2CH(NH2) COOH·HCl], a monoamino dicarboxylic acid salt of L‐Glutamic acid was synthesized and the synthesis was confirmed by FTIR analysis. Solubility of the material in water was determined. Pure and Thiourea doped L‐Glutamic acid hydrochloride crystals were grown by low temperature solution growth using solvent evaporation technique. XRD, UV‐Vis‐NIR analyses were carried out for both pure and thiourea doped crystals. The crystals were qualitatively analyzed by EDAX analysis and the presence of thiourea was confirmed. The cell parameters of L‐Glutamic acid hydrochloride have been determined as a = 5.151 Å, b = 11.79 Å, c = 13.35 Å by X‐ray diffraction analysis and it crystallizes in orthorhombic space group P212121. UV‐Vis‐NIR spectra analysis showed good optical transmission in the entire visible region for both pure and doped crystals. Micro hardness of both pure and doped crystals has been determined using Vickers micro hardness tester. The SHG efficiencies of both pure and doped crystals were determined using Kurtz powder test and pure L‐Glutamic acid hydrochloride crystal was found to possess better efficiency than thiourea doped L‐Glutamic acid hydrochloride crystals. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
2.
Modified TGS single crystals have been grown by doping with Cobalt (II) Phosphate in ferroelectric phase. The effects of different amounts of doping entities on the growth habit and P‐E hysteresis loop have been investigated. The experimental results show that while the spontaneous polarization Ps measured on variously doped crystals remains virtually unchanged, the coercive field values differ in dependence on the growth conditions and grown pyramidal features. The highest values of the coercive field Ec have been found to fall in the interval 800‐900 V/cm. 相似文献
3.
Following the chemical reaction method pure and doped lead hydrogen phosphate single crystals were grown in silica gel using different gel density, various concentrations of phosphoric acid, and lead nitrate solutions. As the gel pH plays an important role in the formation of different H3PO4 species in the phosphoric acid system, the pH range in which HPO ions dominate, was considered which in turn in necessary for the growth of lead hydrogen phosphate crystals. Characteristics of these crystals were carried out by infrared spectral analysis and microhardness study. 相似文献
4.
J. Mary Linet S. Mary Navis Priya S. Dinakaran S. Jerome Das 《Crystal Research and Technology》2008,43(8):806-810
Single crystals of amino acid doped (L–citrulline, L‐ascorbic acid) triglycine sulphate were grown by slow evaporation technique. The lattice parameters and crystalline quality were confirmed by powder X‐ray diffraction studies. The presence of functional groups in the grown crystals was confirmed by Fourier transform infrared spectrum analysis. The dielectric studies were carried out to identify the phase transition temperature and the dielectric constant was found to be less for both the doped crystals than pure triglycine sulphate crystal. Micro hardness studies were carried out using Vickers pyramidal indentation technique at room temperature showed a decrease in hardness due to doping. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
5.
Mohd Anis G. G. Muley M. D. Shirsat S. S. Hussaini 《Crystal Research and Technology》2015,50(5):372-378
Optically transparent formic acid (FA) doped potassium dihydrogen phosphate (KDP) crystal of dimension 21×15×9 mm3 has been grown by slow evaporation solution technique (SEST). The X‐ray diffraction (XRD) technique was used to confirm the cell parameters and the shifts in peak positions of identified reflecting planes. The incorporation of FA in KDP has been qualitatively analyzed by fourier transform infrared analysis. The UV‐visible absorption spectrum of crystals has been recorded in the range of 200 to 900 nm and the doped KDP crystal is found to have improved optical parameters than pure KDP. The color centered photoluminescence emission spectrum of grown crystal has been illustrated in visible region. The mechanical behavior of pure and doped KDP crystal has been investigated using the Vicker's microhardness analyzer and hardness parameters have been calculated. The effect of FA on thermal stability of KDP crystal was examined by means of thermogravimetric and differential thermal analysis. The temperature dependent dielectric behavior of crystals was studied. 相似文献
6.
Single crystals of potassium acid phthalate (KAP) and amino acid (DL‐Alanine, L‐Methionine) doped KAP were grown from aqueous solutions by slow cooling method. The grown crystals were characterized using powder X Ray diffraction (XRD) and Fourier Transform Infrared (FTIR) analysis. The thermal stability of KAP in the presence of dopants was analysed using Thermogravimetric and Differential Scanning caloriemetric (TGA/ DSC) studies and the maximum temperature for non linear optical application of this compound in the presence of dopants was found out. The transmittance of KAP was found to increase in the presence of dopants. Etch pits were observed for all the crystals using different etchants. Vickers microhardness tests were performed to study the mechanical stability of the crystals. The hardness of DL‐alanine doped KAP is more than that of L‐alanine doped KAP crystal. The dielectric constant and loss were determined as a function of temperature. Frequency response of the dielectric constant and dielectric loss factor have been studied over the frequency range of 50Hz – 5MHz. Second harmonic generation (SHG) was confirmed in all the crystals using the Kurtz and Perry powder technique. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
7.
R. K. Choubey B. Q. Khattak S. Kar P. Ramshankar P. Sen K. S. Bartwal 《Crystal Research and Technology》2007,42(7):718-722
Undoped, Cr doped and Mg, Cr codoped LiNbO3 crystals were grown by conventional Czochralski technique. Comparative study was carried out using Fourier transform infrared (FTIR) and UV‐Visible spectroscopy. Infrared optical absorption for OH– ion has been used to study the effect of dopants on the crystals. The peak position of OH– shift to 3535 cm‐1 for Mg, Cr codoped crystals compared to 3484 cm‐1 for undoped and Cr doped crystals. Prominent absorption bands are found in the visible region centered at 480 nm (20833 cm‐1) and 653 nm (15313 cm‐1) in Cr doped crystals. Whereas in Mg, Cr codoped crystals these broad absorption bands are red shifted to 517 nm (19342 cm‐1) and 678 nm (14749 cm‐1). UV cutoff in Cr doped crystals shift towards higher wavelength compared to undoped LiNbO3 crystals. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
8.
Hui Shen Jiayue Xu Anhua Wu Jinxing Yu Yan Liu Liqing Luo 《Crystal Research and Technology》2007,42(10):943-947
The floating zone growth of magneto‐optical crystal YFeO3 has been investigated. The polycrystalline feed rod was prepared by a pressure of 250MPa and sintering at about 1500°C. A crack‐ free YFeO3 single crystal has been successfully grown. The crystal preferred to crystallize along <100> direction with about 10° deviation. The X‐ray rocking curve of the crystal has a FWHM of 24 arcsec, confirming the high crystal quality of the sample. The (100) plane was etched by hot phosphoric acid and the dislocation density was about 104/cm2. A thin outer layer with Y2O3‐rich composition was found at the periphery of as‐grown crystals, which was attributed to the Fe2O3 evaporation during growth. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
9.
S. Natarajan G. P. Chitra S. A. Martin Britto Dhas S. Athimoolam 《Crystal Research and Technology》2008,43(7):713-719
A new semiorganic crystal, L‐glutamic acid hydrobromide, C5H10NO4Br (GHB) has been grown from aqueous solution. The single crystal X‐ray analysis of the crystal showed that it belongs to the non‐centrosymmetric P212121 space group with protonated glutamic acid as cation and bromine as anion. The back‐bone conformations of the amino acid are in cis and trans form. The side‐chain conformations are observed to be in gauche I / trans / cis / trans forms. The characteristic ‘head‐to‐tail’ hydrogen bonding interaction is observed through a chain C(5) motif. Further, the crystal structure is stabilized by an intricate three‐dimensional hydrogen bonding network. TGA/DTA showed that the grown crystals are thermally stable upto 219 °C without any phase transition. The functional groups responsible for the various modes of vibrations were identified by using FTIR spectroscopy. UV‐Vis‐NIR spectra showed that the crystals have excellent transparency in the visible and infrared regions. The second harmonic generation (SHG) conversion efficiency was investigated to explore the NLO characteristics of the material. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
10.
Crystal growth and electric‐property change by rubidium or cesium doping on potassium‐sodium‐niobate
Hideo Kimura Rumi Tanahashi Hongyang Zhao Koji Maiwa 《Crystal Research and Technology》2011,46(1):37-40
Alkali metals (Na, Rb or Cs) co‐doped with fiber‐ and bulk‐shaped KNbO3 single crystals were grown using two original methods by means of doping together of small ionic Na and large ionic Rb or Cs into KNbO3. Single‐phase crystals could be grown with an orthorhombic system at room temperature as well as pure KNbO3. Piezoelectric and ferroelectric property changes by the co‐doping of Rb or Cs with Na were estimated using d33 values and a polarization‐electric field hysteresis curve in fiber‐ and bulk‐shaped crystals. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
11.
Crack‐free, rod‐shaped single crystals of undoped and 0.5, 0.7 and 1.0 mol% ZrO2‐doped LiNbO3 with a near‐stoichiometric composition were grown by the micro‐pulling down (μ‐PD) method. The structural properties of the grown crystals were examined by powder X‐ray diffraction (XRD). Electron probe micro analysis (EPMA) of the near‐stoichiometric LiNbO3 single crystals revealed the homogeneous incorporation of Zr ions. The change in the refractive index and IR transmission spectra of the grown crystals were examined as a function of the Zr concentration. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
12.
In the dihydrate process to produce phosphoric acid, phosphate ore [Ca10F2(PO4)6] is leached with sulfuric and weak phosphoric acids to produce phosphoric acid and gypsum as a by‐product. Crystallization of gypsum occurs as the leaching is taking place. The effect of organic and inorganic additives on the structure and spectrum of gypsum crystals under simulated conditions of phosphoric acid production is studied using x‐ray diffraction and infrared spectroscopy. Structure and spectrum of formed gypsum crystals in the absence of additives are slightly different from the standard gypsum crystals (card No. 6‐0046), which reflect the effect of preparation medium on the crystal structure of gypsum crystals. Presence of additives such as cetyl trimethyl ammonium bromide and 1,2‐dihydroxybenzene‐3,5‐disulfonic acid, Al3+ and Mg2+ increase the crystallinity of gypsum, while presence of additives such as citric acid and sodium dodecyl sulfate decrease the crystallinity of gypsum. Presence of Al3+ and Mg2+ as additives lead to the formation of calcium sulfate hemihydrate beside calcium sulfate dihydrate. Presence of sodium dodecyl sulfate as an additive inhibits the crystallization of gypsum and leads to the formation of anhydrite and calcium sulfate hemihydrate. 相似文献
13.
Gallium orthophosphate (GaPO4) single crystals were grown by the reverse temperature gradient method from phosphoric acid solutions under hydrothermal conditions. Twins after (110) were studied by etching faces having been cut perpendicular to one of the twofold axes. Based on the determination of the twin boundary position as well as on the knowledge of the growth rates of different crystallographic forms, a few faces have been chosen to be quite promising for growing high‐quality GaPO4 single crystals if they are offered at the referring seed crystal. From the characterization of the grown crystals conditions have been found, which may lead to the reduction of the inversion twin number during the growth process. 相似文献
14.
V. I. Ivanenko I. V. Zatovsky N. S. Slobodyanik P. G. Nagornyi V. N. Baumer 《Crystal Research and Technology》2008,43(4):355-361
Zirconium‐doped KTiOPO4 (KTP) crystals were grown using a high temperature flux method in the K2O‐P2O5‐TiO2‐ZrF4 system. The dopant content in the single crystals with general composition KTi1‐xZrxOPO4 (where x = 0 – 0.026) strongly depends on zirconium concentration in the homogeneous melts. AES‐ICP method and X‐ray fluorescence analysis were used to determine the composition of the obtained crystals. Phase analyses of the products were performed using the powder XRD. The structures of KTiOPO4 containing different quantities of Zr were refined on the basis of single crystal XRD data. Applying ZrF4 precursor for zirconium injection into the flux allowed growing the zirconium‐doped KTP crystals at 930–750°C. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
15.
L‐histidine tetrafluoroborate (L‐HFB), a semiorganic nonlinear optical (NLO) material has been synthesized and characterized by elemental analysis and FT–NMR spectroscopic studies. Solubility of L‐HFB has been determined in water and ethanol. The single crystals with dimensions 15 x 12 x 3 mm3 were grown by slow evaporation technique under two different pH conditions. The effect of pH on the morphology of the crystals have been studied. The grown crystals of both pH values has been subjected to single crystal X‐ray diffraction to determine the unit cell dimensions and morphology. The thermal stability has been analyzed by TGA and DTA. The microhardness test was carried out in (001) plane and the hardness coefficient was calculated. The birefringence values (Δn) were determined in the wavelength region 5540–6460 Å. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
16.
Lithium tetraborate crystals have great demand due to its non‐critical phase matching at 90°. Transparent and good optical quality single crystals of undoped and Mn doped Li2B4O7 were grown by Czochralski technique in air atmosphere. The crystalline phase was determined by X‐ray diffraction. Doping of Mn in the grown crystals was confirmed by energy dispersive analysis of X‐rays (EDAX) technique. Transmission spectra show that the crystal is transparent in the visible region. Birefringence interferograms were recorded to qualitatively analyse the optical homogeneity of the grown crystals and to quantify the birefringence of the samples in desired crystal direction. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
17.
In:Zn:LiNbO3 crystals doped with different indium concentrations were grown by Czochralski technique. The optical damage threshold value and ultraviolet‐visible absorption spectra of the In:Zn:LiNbO3 crystals were measured. The In:Zn:LiNbO3 crystals were made into optical waveguide substrates using hexanedioic acid as proton exchange agent. The optical damage resistant ability of those optical waveguide substrates was investigated by the m‐line method. The optical damage threshold values of In(2mol.%):Zn(3mol.%):LiNbO3 crystal and optical waveguide substrate are two orders of magnitude higher than those of pure LiNbO3. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
18.
Gallium orthophosphate (GaPO4) single crystals have been grown from phosphoric acid solutions under hydrothermal conditions. The crystals have been studied in terms of twinning because of the strong effect of this structural defect on the piezoelectric properties. The growth rates of individual faces have been compared to each other by considering the dipyramidal habit of the grown crystals. 相似文献
19.
Growth of undoped and Cr doped (0.1, 0.25 and 0.5 mol % Cr2O3) congruently‐ melting‐composition LiNbO3 single crystals by Czochralski technique is reported. Chromium doping was optimised to get crystals with potential for an integrated, broadband, tunable laser in the 700‐1100 nm spectral range. Typical sizes of the grown crystals are 25‐30 mm in diameter and 30‐40 mm in length. Symmetrical and sharp conoscopy pictures confirm the optical homogeneity of the crystals. Optical transmission was recorded for both undoped and doped crystals. 70% transmittance was observed. The grown crystals have reasonably good laser damage threshold. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
20.
L‐arginine hydrochloride monohydrate (LAHCl.H2O) has been synthesized and single crystals have been grown from its aqueous solution by slow evaporation and slow cooling methods. The solubility of the material was measured at various temperatures and bulk crystals of size 26×13×11 mm3 have been grown by optimizing the growth parameters. The grown crystals have been subjected to single crystal XRD studies to confirm the structure and to estimate the lattice parameters. FTIR analysis indicate the mode of vibrations of different molecular groups present in LAHCl and confirm the protonation of guanidyl, amino groups and deprotonation of COO‐ groups. UV‐Vis transmission spectrum revealed the linear optical properties of the grown crystals with a transparency of 65% over the entire visible range upto 300 nm. Thermal behavior of the grown crystal was investigated from DTA and TGA measurements. Dielectric studies have been carried out on the grown crystals. Kurtz and Perry powder SHG technique confirms the NLO property of the grown crystal. The SHG efficiency of LAHCl was found to be 0.38 with respect to KDP. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献