Growth and Solvent Effects of a Promising Nonlinear Optical Sodium Paranitrophenolate Dihydrate (NO_2-C_H_4-ONa·2H_2O) Single Crystal

Sodium paranitrophenolate dihydrate (NPNa·2H2O) is an excellent semiorganic nonlinear optical (NLO) material, crystallizes both in water and methanol with high degree of transparency. Good optical quality single crystals of dimension upto 18 mm×6 mm×3 mm are obtained by isothermal solvent evaporation technique. The solubility of the crystal in different solvents was measured gravimetrically. The single crystals of NPNa·2H2O show variation in physical properties and growth rate in different solvents. Methanol or ethanol solution yields crystals of bipyramidal shape with clear morphology. However, methanol grown crystal is exhibiting improved hardness parameters and possesses excellent thermal stability as compared to water grown crystals. The effects of solvent on hardness parameter along with thermal and optical properties of NPNa·2H2O was revealed in this paper.     

Necking Effect on the Growth of Bi2Sr2CaCu2O8+δ Single Crystal by TSFZ Method

High-quality Bi ₂ Sr ₂ CaCu ₂ O ₈₊ single crystals have been grown by a travelling solvent floating zone method with a necking technique using a single crystal seed. The full-width at half maximum of the X-ray rocking curves was improved from 120 arcsec to 70 arcsec by the necking technique. The topographic results show that the crystals grown using the necking technique have better crystallinity. Especially, this technique is very effective on the growth of the atomically substituted single crystals. It results not only in the improvement of crystallinity but also in the enhancement of the single crystal size, especially for the crystals substituted by other elements.     

Growth and Solvent Effects of a Promising Nonlinear Optical Sodium Paranitrophenolate Dihydrate (NO2-C6H4-ONa·2H2O) Single Crystal

Sodium paranitrophenolate dihydrate (NPNa·2H2O) is an excellent semiorganic nonlinear optical (NLO) material, crystallizes both in water and methanol with high degree of transparency. Good optical quality single crystals of dimension upto 18 mmx6 mmx3 mm are obtained by isothermal solvent evaporation technique. The solubility of the crystal in different solvents was measured gravimetrically. The single crystals of NPNa·2H2O show variation in physical properties and growth rate in different solvents. Methanol or ethanol solution yields crystals of bipyramidal shape with clear morphology. However, methanol grown crystal is exhibiting improved hardness parameters and possesses excellent thermal stability as compared to water grown crystals. The effects of solvent on hardness parameter along with thermal and optical properties of NPNa·2H2O was revealed in this paper.     

Dielectric behaviour of nano-crystalline spinel Ni0·2Ca0·8Fe2O4 and their nano-composite with polypyrrole

The spinel ferrite nano-particles of chemical composition Ni_0·2Ca_0·8Fe₂O₄ have been prepared by sol-gel method. Subsequently, the nanoparticles are encapsulated with the intrinsically conducting polymer shell of polypyrrole. The X-ray diffraction patterns confirm the single phase cubic spinel structure of the materials. To understand the dielectric properties of the materials, frequency-dependent dielectric measurement has been performed at 300 K in the range of 100 mHz to 2 MHz. On polymerization, both the dielectric strength as well the dielectric loss is significantly increased. Also, the dielectric conductivity, which arises from the electron hopping mechanism, is considerably increased on polymerization.     

Studies on the Structural,Morphological, Optical,and Magnetic Properties of α-Fe2O3 Nanostructures by a Simple One-Step Low Temperature Reflux Condensing Method

Uniform hematite (α-Fe₂O₃) nanoparticles have been successfully synthesized through a simple one-step low temperature reflux condensing method which requires no surfactants or templates. The crystallite size was calculated by using Debye–Sherrer formula, and it showed the range of 4–27 nm. The lattice parameters of the samples were measured by Rietveld analysis. The morphology of the products was studied by high resolution scanning electron microscopy (HR-SEM), and it was confirmed by high resolution transmission electron microscopy (HR-TEM). The HRTEM images exhibit the well defined lattice fringes of α-Fe₂O₃ particles that confirm their high crystallinity. The formation of pure α-Fe₂O₃ was further confirmed by using energy dispersive X-ray (EDX) analysis. The optical properties and the bandgap energy were measured by UV-Visible diffuse reflectance spectra (DRS) and photoluminescence (PL) spectra. The bandgap energy was measured by using Kubelka–Munk method, and the value was found to be 2.26 eV. Magnetic hysteresis (M–H) loops revealed that the as-prepared α-Fe₂O₃ samples displayed ferromagnetic behavior. These results show that the prepared hematite possess good magnetic properties.     

X-ray powder diffraction and IR study of NaMg(H2O)2[BP2O8]·H2O and NH4Mg(H2O)2[BP2O8]·H2O

NaMg(H₂O)₂[BP₂O₈]·H₂O was prepared by hydrothermal synthesis and was characterized by X-ray powder difraction and IR method. The title compound was synthesized from MgCl₂·6H₂O, NaBO₃·4H₂O, and (NH₄)₂HPO₄ with variable molar ratios using hydrothermal method by heating at 165 °C for 3 days. The X-ray powder diffraction data was indexed in hexagonal system, the unit cell parameters were found to be as a = 9.428, c = 15.82 Å, Z = 4 and the space group is P6₁22. It is isostructural with M^lM^ll(H₂O)[BP₂O₈] type compounds where M^l = Na, K; M^ll = Mg, Mn, Fe, Co, Ni and Zn. In addition NH₄Mg(H₂O)₂[BP₂O₈]·H₂O was also synthesized the first time in this research. Its unit cell parameters and hkl values were in good agreement with the sodium magnesium compound. The unit cell parameters are a = 9.529, c = 15.736 Å. The indexed X-ray powder diffraction data of both compounds which were not reported in the literature is presented in this work. The IR data of NaMg(H₂O)₂[BP₂O₈]·H₂O is also reported.     

Effect of Sm+ Rare Earth Ion on the Structural,Thermal,Mechanical and Optical Properties of Potassium Hydrogen Phthalate Single Crystals简

Rare earth Sm~+ ion doped potassium hydrogen phthalate(KHP) single crystal was grown by slow evaporation technique.Single crystal and powder X-ray diffraction analyses confirm the crystalline perfection of Sm~+ ion doped KHP crystal.The functional groups of pure and Sm~+ ion doped KHP crystals were identified by Fourier transform infrared spectroscopy(FTIR) spectral studies.Thermogravimetric and differential thermal analyses were carried out to study the thermal behavior of the grown crystals.UV—Vis studies explored the optical transmittance of the grown crystals in the entire visible region.The mechanical strength and etching studies were performed to assess the perfection of the pure and Sm~+ ion doped KHP crystals.The refractive index and birefringence properties of the grown crystal were analyzed.The second harmonic generation efficiency of Sm~+ ion doped KHP crystals was observed by Kurtz—Perry powder test.     

Growth of YBa2Cu3O7 – δ Single Crystals in “Ba3Cu5O8”/Y2BaCuO5 and (“Ba3Cu5O8” + 0.2BaCuO2)/Y2BaCuO5 Diffusion Couples

YBa₂Cu₃O_{7 –} single crystals were grown in Ba₃Cu₅O₈/Y₂BaCuO₅ and (Ba₃Cu₅O₈ + 0.2BaCuO₂)/Y₂BaCuO₅ diffusion couples at temperatures between 1170 and 1270 K under optimized conditions. Copper nonstoichiometry was shown to have a significant effect on the superconducting properties of YBa₂Cu₃O_{7 –} crystals subjected to thermal cycling.     

Influence of temperature on structural and magnetic properties of Co0·5Mn0·5Fe2O4 ferrites

Co_0·5Mn_0·5Fe₂O₄ ferrites have been synthesized using a single-step sol-gel auto-combustion method in which the metal nitrate (MN)-to-citric acid (CA) ratio was adjusted to 0.5: 1 and pH to 7, respectively. The structural and magnetic properties of as-burnt and annealed samples were studied as a function of temperature. The inverse spinel structure was confirmed by X-ray diffraction (XRD) and crystallite size was estimated by the most intense peak (311) using Scherrer’s formula. Contrary to earlier studies reported in the literature, both as-burnt and annealed samples exhibit crystalline behaviour. Room temperature magnetic properties were studied using vibrating sample magnetometer (VSM) with field strengths up to ±10 kOe. Lattice constant and crystallite size increased as the annealing temperature was increased. However, the coercivity (H _c) initially increased and then decreased with the increase of crystallite size. The variation in coercivity is ascribed to the transition from a multi-domain to a single-domain configuration.     

Structural, Morphological and Optical Properties of ZnO Thin Films Grown on γ-LiA1O_2 Substrate by Pulsed Laser Deposition

ZnO thin films were deposited on the substrates of (100) γ-LiAIO2 at 400, 550 and 700℃using pulsed laser deposition (PLD) with the fixed oxygen pressure of 20 Pa, respectively. When the substrate temperature is 400℃, the grain size of the film is less than 1μm observed by Leitz microscope and measured by X-ray diffraction (XRD). As the substrate temperature increases to 550℃, highly-preferred c-orientation and high-quality ZnO film can be attained. While the substrate temperature rises to 700℃, more defects appears on the surface of film and the ZnO films become polycrystalline again possibly because more Li of the substrate diffused into the ZnO film at high substrate temperature. The photoluminescence (PL) spectra of ZnO films at room temperature show the blue emission peaks centered at 430 nm. We suggest that the blue emission corresponds to the electron transition from the level of interstitial Zn to the valence band. Meanwhile, the films grown on 7-LiAIO2 (LAO) exhibit green emission centered at 540 nm, which seemed to be ascribed to excess zinc and/or oxygen vacancy in the ZnO films caused by diffusion of Li from the substrates into the films during the deposition.     

Model of the (PuO2)2SiO4·2H2O Crystal Structure,Based on Powder X-ray Diffraction Data

Plutonyl orthosilicate dihydrate (PuO₂)₂SiO₄·2H₂O was prepared by a hydrothermal procedure at 180°C. Its powder diffraction pattern (Guinier camera, CuK ₁ radiation) was indexed in the tetragonal crystal system: a 6.912(3), c 18.563(3) Å, space group I4₁/amd. The structure of (PuO₂)₂SiO₄·2H₂O is similar to the known structures of (UO₂)₂SiO₄·2H₂O and (UO₂)₂GeO₄·2H₂O, but differs in the mutual orientation of the chains of coordination polyhedra of actinide atoms (pentagonal bipyramids) sharing common equatorial edges.     

Synthesis,Characterization, and X-ray Structure of Tetraaminoguanidinium Diuranyl Tetraoxalate Monohydrate (HAgun)4[(UO2)2(C2O4)4]·H2O

Radiochemistry - A new uranyl oxalate complex containing aminoguanidinium cation was isolated from an aqueous solution containing uranyl nitrate hexahydrate, oxalic acid dihydrate, and...     

Conductivity of (NH_4)_3[CrMo_6O_(24)H_6]·7H_2O Treated by Nd Chemistry-Heated Diffused Permeation

1.IntroductionDue to special constructions,POMs(polyoxometa-lates)have received much attention recently in materialchemistry[1~3].However,the property of conductivity re-duces with increasing temperature[4~6],which limits itsapplication greatly.In this paper,rare earth co-permeation[5]was usedto treat(NH4)3[CrMo6O24H6]·7H2O with Nd.The com-position was determined by chemical analysis,TG-DTA,XRF and XRD.The XRD results indicate that the com-pound has Anderson structure.The product,…     

Crystal Structure of An(VI) Complexes with Succinate Anions, [PuO2(C4H4O4)(H2O)] and Cs2[(AnO2)2(C4H4O4)3]·H2O (An = U,Np, Pu)

Radiochemistry - Actinide(VI) complexes with succinate anions [PuO2(succ)(H2O)] and Cs2[(AnO2)2(succ)3]·H2O (An = U, Np, Pu), where succ = [C4H4O4]2 ?, were synthesized and studied by...     

Growth of Mixed Rare Earth Tartrate Crystals (Y(1-x)Sm_x)_2(C_4H_4O_6)_3·zH_2O from Silica Gels

Experiments performed on the grwth of mixed crystals of rare earth tartrates (Y1-xSmx)2 (C4H4O6)3.zH2O (0≤x≤1) from silica gels at 35~40℃ and 25~30℃ employing single-diffusion technique. are discussed. The crystals maintain spherulitic morphology, irrespective of the value of x, concentration of upper and lower reactants, gel pH, gel age and gel temperature. Formation Of Liesegang rings in this system is a temperature dependent phenomenon. It is shown that with the increase of the value of x the system passes from Liesegangring phenomenon to singlezone phenomenon. Operative mechanism of crystallization in the higher (35~40℃) and lower temperature ranges (25~30℃) is explained. Seeded growth experiments indicate the possibility of increasing the size of the spherulites in the gel medium     

Synthesis,characterization and crystal structure of a novel Strandberg-type polyoxoselenomolybdate Rb4[Se2Mo5O21]·2H2O

An inorganic compound formulated as Rb₄[Se₂Mo₅O₂₁]·2H₂O (1) has been isolated by conventional solution method and structurally characterized by single-crystal X-ray diffraction methods, scanning electron microscopy (SEM), powder XRD, IR, UV–vis spectra, and cyclic voltammetry measurements. This compound crystallizes in the monoclinic system, space group C2 with unit a = 19.701 (3) Å, b = 10.296 (2) Å, c = 12.134 (4) Å, β = 106.96 (2)° and Z = 4. The crystal structure of (1) is built up from a Strandberg clusters connected through hydrogen-bonding interactions into a three-dimensional supramolecular network.     

Growth of epitaxial γ-Al2O3 films on rigid single-crystal ceramic substrates and flexible,single-crystal-like metallic substrates by pulsed laser deposition

Epitaxial γ-Al₂O₃ thin films were grown on diverse substrates using pulsed laser deposition. The high quality of epitaxial growth and cubic structure of γ-Al₂O₃ films was confirmed by X-ray diffraction. SrTiO₃ and MgO single crystal substrates were used to optimize the growth conditions for epitaxial γ-Al₂O₃ film. Under the optimized conditions, epitaxial γ-Al₂O₃ thin films were grown on flexible, single-crystal-like, metallic templates. These included untextured Hastelloy substrates with a biaxially textured MgO layer deposited using ion-beam-assisted-deposition and biaxially textured Ni-W metallic tapes with epitaxially grown and a biaxially textured, MgO buffer layer. These biaxially textured, γ-Al₂O₃ films on flexible, single-crystal-like substrates are promising for subsequent epitaxial growth of various complex oxide films used for electrical, magnetic and electronic device applications.     

Optical absorption,electrical conductivity and spectral response measurements on the system CdGa2S4(1−x)Se4x

The compounds CdGa₂S₄ and CdGa₂Se₄ belong to the defect chalcopyrite (space group 1 ¯4) family. A series of compounds CdGa₂S_4(1–xSe_4x has been prepared and their single crystals grown by the chemical transport reaction method. Optical absorption, spectral response, electrical conductivity and thermoelectric power measurements have been made. The optical absorption spectra revealed that the fundamental absorption edge varies with composition, from 2.2 to 3.25 eV. The plots (w)² versus w revealed that these compounds are direct band gap materials, but plots of (w)^1/2 versus w did not give convincing support to the presence of indirect transitions. The values of energy gaps were also deduced from spectral response (max) measurements and found to be in agreement with those deduced from optical absorption measurements. D.c. resistivity versus temperature studies revealed that, in spite of their large band gaps, these compounds exhibit intrinsic semiconduction above 250° C. The energy gap values matched with those obtained from other measurements. All samples were n-type and had a constant thermoelectric power 300 V° C^–1 in the temperature range 250 to 350° C. However, the thermal dependence of electrical conductivity and thermoelectric power indicated strong irreversibility with the thermal heating and cooling cycle. Such behaviour has been attributed to the diffusion of contact materials such Ga and In.     

Crystal structure of mixed-valent Np(IV)/Np(V) chloride, [Np(NpO2)6(H2O)8(OH)Cl9]·H2O

A new mixed-valent Np(IV)/Np(V) chloride, [Np(NpO₂)₆(H₂O)₈(OH)Cl₉]·H₂O, was synthesized, and its crystal structure was determined. The crystals consist of NpO ₂ ⁺ and Np⁴⁺ cations, of Cl^? and OH^? anions, of coordination-bonded water molecules, and of water molecules of crystallization. The Np(V) atom, Np(1), has pentagonal bipyramidal coordination surrounding with O atoms in the apical position and with the equatorial plane formed by three Cl^? anions, O atom of the adjacent NpO ₂ ⁺ cation, and O atom of water molecule. The mutual coordination of the neptunyl(V) ions, cation-cation (CC) interaction, links the Np(1) coordination polyhedra via common vertices into rings around sixfold axes, with the Np(V)?Np(V) distance in these fragments of 4.276 Å. The ring fragments are linked with each other via common equatorial edges of the bipyramids into layers perpendicular to c-axis. The Np(IV) atom, Np(2), has coordination surrounding in the form of tricapped trigonal prism (CN 9) with the tetragonal lateral faces formed by the O atoms of the NpO ₂ ⁺ cations and the capping positions occupied by the O atoms of two water molecules and one hydroxy group. The Np(2) atoms act in CC interactions as coordination center for six NpO ₂ ⁺ ions, with the Np(IV)?Np(V) distance of 4.183 Å. The Np(2) polyhedra are arranged in the crystal between layers of the Np(1) coordination polyhedra, linking them with each other.