Experimental and theoretical studies on bis(glycine) lithium nitrate (BGLiN): A physico-chemical approach

Good quality and bulk size single crystal (size: 20×13×8 mm³) of bis(glycine) lithium nitrate (BGLiN) was grown by a slow evaporation solution technique from the aqueous solutions at constant temperature i.e. 27 °C using synthesized materials. Crystal system and lattice parameters were determined by single crystals as well as powder X-ray diffraction analysis. The lattice parameters of the titled compound are a=10.0223 Å, b=5.0343 Å, c=17.0510 Å, and V=860.312 Å³ and it crystallized in an orthorhombic system with space group Pca2₁ obtained by single crystal XRD. Elemental composition was confirmed by energy dispersive X-ray spectroscopic analysis. Optical absorption spectrum was recorded and various optical parameters such as optical transmission (~60%), and optical band gap (4.998 eV) were calculated. Photoluminescence study shows that the grown crystal is free from major defects. Crystalline perfection of the grown crystal was assessed and found good. Ground state optimized geometry has been obtained by using DFT with 6-31G(d,p) basis set. HOMO and LUMO energy gap was found to be 6.01 eV and dipole moment was 1.65 D.     

Linear and nonlinear optical properties of N-(3-nitrophenyl) acetamide single crystals

Optically transparent nonlinear optical bulk single crystal of N-(3-nitrophenyl) acetamide (3NAA) of dimension 7 mm × 6 mm × 5 mm has been grown from its aqueous solution by slow solvent evaporation technique. The grown crystal was characterized by powder X-ray diffraction to confirm the crystal structure. Investigation has been carried out to assign the vibrational frequencies of the grown crystals by Fourier Transform Infrared Spectroscopy and FT-NMR technique. Thermal behaviour of the grown crystals was studied by thermogravimetric analysis. The second harmonic generation efficiency of 3NAA was determined by Kurtz and Perry powder technique. The optical absorption study confirms the suitability of the crystal for device applications. The mechanical properties of the grown crystals have been studied using Vickers microhardness tester. Dielectric, microhardness and photoconductivity studies also carried out for the grown sample.     

Growth,characterization and upconversion properties of erbium-doped potassium lithium tantalate niobate single crystals under 975 nm laser excitation

Potassium lithium tantalate niobate single crystals doped with erbium ions are grown by top-seeded solution growth method. The crystals are characterized by X-ray diffraction and differential thermal analysis. The refractive indices of the crystal are measured using ellipsometry method and fitted by Sellmeier equation. The as-grown crystals are tetragonal phase tungsten bronze-type structure with Curie temperature of 271.3 °C. Characteristic Er^3 + absorption bands are observed from 350 to 1100 nm in ultraviolet–visible-near infrared absorption spectra. These crystals emit brightly green and red upconversion fluorescence under 975 nm LD laser excitation, and the steady state upconversion spectra are obtained at room temperature. The red emission intensity increases as the erbium ions concentration increases in crystals. Processes of excited state absorption and energy transfer are responsible for upconversion luminescence. The emission intensities are quadratic dependences on pump power from pump power dependence analyses and deduction of transition rate equation model.     

LEED and STM studies of the stability of the MoO2(100) surface

Atomic scale images and low energy electron diffraction pattern of a MoO₂(100) single crystal surface are presented, which show different structural modifications depending on surface preparation. A short in-situ heat treatment of the as-grown single crystal results in an atomically ordered surface whose diffraction pattern and STM images are consistent with those expected from the bulk structure. The symmetry of the STM images suggests an oxygen termination of the surface. A significantly longer heat treatment causes a thermodynamically stable (4 × 1) reconstruction which is interpreted to be due to a loss of oxygen chains. The (4 × 1) reconstruction vanishes after Ar-ion-sputtering and subsequent annealing. Additional long sputtering cycles result in a (2 × 1) reconstruction. The observed surface reconstructions can be transformed into each other by heating or sputtering cycles.     

Growth and characterization of pure and doped bis thiourea zinc acetate: Semiorganic nonlinear optical single crystals

Metal–organic coordination complex single crystals bis thiourea zinc acetate (BTZA) and Cd²⁺ doped BTZA have been synthesized and grown successfully by slow-cooling technique from their aqueous solutions. Single crystals of pure and Cd²⁺ doped BTZA with dimensions of 35 × 4 × 2 mm³ and 10 × 5 × 6 mm³, respectively were obtained with well defined morphology. The as grown single crystals are characterized by single crystal XRD studies and melting point measurements which reveal the incorporation of metallic dopants has not changed the structure of the parent crystal. The powder X-ray diffractogram of the grown crystals has been recorded and the various planes of reflection identified shows shift in the peak positions. The metal coordination with thiourea through sulphur in pure and Cd²⁺ doped BTZA were ascertained by FTIR studies and optical absorption study to identify the UV cut-off range. The presence of metals in pure and Cd²⁺ doped BTZA crystal lattice were confirmed by atomic absorption spectroscopy (AAS). The thermal decomposition of pure and Cd²⁺ doped BTZA crystals were investigated by thermo gravimetric analyses (TGA) and differential thermal analysis (DTA) indicate that doped crystals are more stable than pure crystals. The dielectric response of the crystals were studied in the frequency range 100 Hz–5 MHz at different temperatures and the results are discussed. Second harmonic generation (SHG) measurement confirms that the pure and Cd²⁺ doped BTZA have nonlinear optical (NLO) property. Laser damage threshold value of 12.44 MW/cm² has been determined using Q-switched Nd:YAG laser operating at 1064 nm and with 8 ns pulses in single shot mode for pure BTZA single crystal is reported for the first time.     

X-ray photoelectron spectroscopy of LiM0.05Mn1.95O4 (M = Ni,Fe and Ti)

LiMn₂O₄ and LiM_0.05Mn_1.95O₄ (M = Ni, Fe and Ti) were synthesized by using solid-state reactions and their surface stoichiometries were confirmed by XPS data. The crystal and electronic structures were investigated by using X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). XRD data suggested that LiM_0.05Mn_1.95O₄ possesses nearly no any variations in lattice parameters compared with LiMn₂O₄ for slight substitution of Ni, Fe and Ti; the substituted Ni, Fe and Ti ions were located on the 16d octahedral sites in the spinel crystal lattice. The XPS results suggested that Fe and Ti ions were at + 3 and + 4 oxidation states, respectively; while Ni ions are mixed with + 2 and + 3 oxidation states. The normal oxidation state of Mn ions in the above four materials is almost the same and calculated as + 3.55 according to the splitting energies of Mn3s states.     

Crystal growth and structural properties of the spinel-type Li1 + xMn2 − xO4 (x = 0.10, 0.14)

Single crystals of the lithium-rich lithium manganese oxide spinels Li_1 + xMn_2 − xO₄ with x = 0.10 and 0.14 have been successfully synthesized in high-temperature molten chlorides at 1023 K. The single-crystal X-ray diffraction study confirmed the cubic Fd3¯m space group and the lattice parameters of a = 8.2401(9) Å for x = 0.10 and a = 8.2273(10) Å for x = 0.14 at 300 K, respectively. The crystal structures have been refined to the conventional values R = 3.7% for x = 0.10 and R = 3.1% for x = 0.14, respectively. Low-temperature single-crystal X-ray diffraction experiments revealed that these single crystal samples showed no phase transition between 100 and 300 K. The electron-density distribution images in these compounds by the single-crystal MEM analysis clearly showed strong covalent bonding features between the Mn and O atoms due to the Mn–3d and O–2p interaction.     

Thermal evolution of the crystal structure of the correlated 4d post-perovskite CaRhO3

Thermal effect on the orthorhombic crystal structure (Cmcm) of the correlated 4d post-perovskite CaRhO₃ was investigated by an X-ray powder diffraction method between 60 K and 300 K. Anisotropic thermal evolution of the structure was observed over the temperature range, and in addition, an anomalous change of the lattice parameters was detected at the antiferromagnetic transition temperature of 90 K, indicating possible correlations between the lattice and the magnetic order.     

Studies on the optical and mechanical properties of non-linear optical 3-aminophenol orthophosphoric acid (3-amphph) single crystal

Single crystals of semiorganic material 3-aminophenol orthophosphoric acid (denoted as 3-amphph) of size 29 × 17 × 4 mm³ have been grown by the slow evaporation of an aqueous solution of deionized water at 50 °C. The crystal belongs to orthorhombic system with the non centrosymmetric space group P2₁2₁2₁. The lattice parameter values of 3-amphph crystal are a = 4.481(2) Å, b = 9.782(4) Å and c = 18.326(4) Å. The grown crystals are subjected to single crystal XRD studies to identify its morphology and structure. Optical transmittance and second harmonic generation of the grown crystals have been studied by UV–Vis–NIR spectrum and Kurtz powder technique respectively. The transmittance of 3-amphph crystal has been used to calculate the refractive index n, the extinction coefficient k, reflectance R and both the real (?_r) and imaginary (?_i) components of the dielectric constant as a function of wavelength. The optical band gap of 3-amphph is 4.05 eV with direct transition. The anisotropic mechanical behavior of 3-amphph has been analyzed using Vickers microhardness test. The mechanism of growth is revealed by carrying out chemical etching using water as etchant.     

The local structure of Cs(I) and Cs(II) in a Cs2ZnCl4 single crystal studied by nuclear magnetic resonance

The rotation patterns of the ¹³³Cs (I=7/2) nuclear magnetic resonance (NMR) in a Cs₂ZnCl₄ single crystal grown by using the slow evaporation method were measured in two mutually perpendicular crystal planes. Two different groups of Cs resonances were recorded; this result points to the existence of two types of crystallographically inequivalent Cs(I) and Cs(II). The angular dependences of the NMR spectra led to different values for the quadrupole coupling constants and asymmetry parameters: e²qQ/h=148 kHz and η=0.11 for the Cs(I) ion, and e²qQ/h=274 kHz and η=0.66 for the Cs(II) ion. The EFG tensors of Cs(I) and Cs(II) are asymmetric, and the orientations of the principal axes of the EFG tensors do not coincide. Only, the principal Y-axes of the EFG tensors coincide for the Cs(I) and Cs(II) sites. The Cs(I) ion is surrounded by 11 chlorine ions, making it rather free and high in symmetry. The Cs(II) ion has only nine neighbors and seems to be more tight than the Cs(I) ion.     

h-BN on Rh(1 1 1): Persistence of a commensurate 13-on-12 superstructure up to high temperatures

We present a high-resolution surface X-ray diffraction study of hexagonal boron nitride (h-BN) on the surface of Rh(1 1 1). The previously observed commensurate 13-on-12 superstructure for this system is stable in the temperature range between room temperature and 830 °C. Surface X-ray diffraction measurements up to 830 °C on the superstructure show no sign of a shift towards a different superstructure, demonstrating the high thermal stability and strong bonding between film and substrate. At lower temperatures, an anomalous thermal expansion behaviour of the topmost surface region of rhodium is observed, where the rhodium in-plane lattice constant remains invariant. This can be explained by the (h-BN) single-layer being compressively strained, whereby the strong bonding to the substrate causes the latter to be tensile strained.     

Synthesis and characterization of a new nano lead(II) 0-D coordination supramolecular compound: A precursor to produce pure phase nano-sized lead(II) oxide

Nano-structure of a new 0D Pb(II) coordination supramolecular compound, [Pb₄(8-Quin)₆](ClO₄)₂(1), L = 8-HQuin = 8-hydroxyquinolin ligand has been synthesized by use of a sonochemical process and characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy (FTIR) and elemental analyses. The structure of compound 1 was determined by single-crystal X-ray diffraction. The single crystal X-ray data of compound 1 implies that the Pb⁺² ions are five coordinated. Each lead atom is coordinated to nitrogen and oxygen atoms of 8-hydroxyquinolin ligand. Topological analysis shows that the compound 1 is 1,2,3,4,4M12-1net. Nanoparticles of lead(II) oxide have been prepared by calcination of lead(II) coordination polymer at 500 °C that were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRPD) and IR spectroscopy.     

Investigation on mechanical properties of some thiourea complex crystals: Important nonlinear optical materials

In this work the authors have grown good quality single crystals of zinc thiourea sulphate, bis thiourea cadmium acetate, bis zinc thiourea acetate and bis thiourea zinc chloride were grown from slow evaporation solution growth method at ambient temperature and studied their mechanical properties. The crystal system and lattice parameters were confirmed by powder X-ray diffraction analysis. Vickers microhardness of the grown crystals was investigated by using Leitz-Wetzlar (Miniload 2) hardness tester up to an applied load of 120 g. It was observed that, upto 40 g applied load the hardness of the grown crystals increases with increasing the load and thereafter it is practically independent of the indentation load. Meyer's law and Hays–Kendall's law fail to explain the observed load variations. But the variation could be satisfactorily explained by PSR model proposed by Li and Bradt. Classification of cracks and their transition from Palmqvist to median types is explained. The average value of fracture toughness, brittleness index, Young's modulus and yield strength were calculated using expressions for Palmqvist and median types of cracks. Anisotropic nature of the grown crystals was studied using Knoop indentation technique.     

Preparation for exchange-coupled permanent magnetic composite between α-Fe (soft) and Nd2Fe14B (hard)

Soft magnetic α-Fe nanoparticles were prepared by a coprecipitation route and hard magnetic Nd₁₅Fe₇₇B₈ nanoparticles were prepared by ball milling for 20 h by using a shaker mill. A mechanical ball-mill technique was applied to build up exchange-coupled nanoparticles. A mixture of Nd₂Fe₁₄B and α-Fe nanoparticles in a stainless steel boat was milled for 2 h and annealed in a vacuum furnace under vacuum (∼10⁻⁵ Torr) at 650 °C for 30 min. The crystal structure of the nanoparticles was confirmed by using X-ray powder diffraction (XRD). The surface morphology was identified by FE-SEM. The magnetization curve was measured with a vibrating-sample magnetometer (VSM). Thermogravimetry using a microbalance with magnetic field gradient positioned below the sample was used for the measurement of a thermomagnetic analysis (TMA) curve showing the downward magnetic force versus temperature.     

Structure of V thin films on Al(100) using XPD,LEED, and LEIS

We have used X-ray photoelectron diffraction (XPD), low energy electron diffraction (LEED), and low energy ion scattering (LEIS) to determine the atomic structure of V thin films grown on the Al(100) single crystal surface. For V film thicknesses ranging from 0.75 ML–7 ML, the LEED patterns show no significant changes from the p(1 × 1) symmetry of a clean Al(100) surface, other than becoming more diffuse for higher V coverage. XPD and LEIS spectra indicate that during the initial deposition (1–3 ML) V atoms diffuse into the Al lattice, and tend to accumulate at the surface during subsequent deposition. Strain associated with the lattice mismatch for V and Al is likely relieved by the formation of a surface alloy during the first few ML's of V deposition. For 7 ML V coverage, XPD and LEED showed that an ordered V structure is stabilized on the Al(100) surface. Due to the close resemblance of the V and Al XPD polar scans, we conclude that V and Al are occupying similar lattice sites in tetragonally distorted bcc lattice, although the specific lattice location of the V and Al atoms is not clear.     

Sonochemical synthesis of two new nano structure zinc(II) 1,10-phenanthroline coordination supramolecular compounds: New precursors to produce nano-sized zinc(II) oxide

Nanoparticles of two zinc(II) coordination supramolecule compounds (CSCs), [Zn(L)Cl2] (1) and [Zn(L)Br2] (2) L = 1,10-phen = 1,10-phenanthroline ligand, have been synthesized by use of a sonochemical process and characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRPD), Fourier transform infrared (FTIR) spectroscopy and elemental analyses. The single crystal X-ray data of compounds 1 and 2 imply that the Zn⁺² ions are four coordinated. Topological analysis shows that the compound 1 and 2 are new topology for net: 1,3M4-1. Nanoparticles of zinc(II) oxide have been prepared by calcination of two different zinc(II) CPs at 500 °C that were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and IR spectroscopy.     

Structure and electrochemical performance of Y(III) and Al(III) codoped amorphous nickel hydroxide

Amorphous nickel hydroxide codoped with rare earths Y(III) and Al(III) has been synthesized by the chemical precipitation method combined with the rapid freezing technique. The microstructure and morphology of the prepared sample were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Raman spectra. The electrochemical performance of the sample was characterized by the charge/discharge test and cyclic voltammetry. The results show that this amorphous nickel hydroxide codoped with Y(III) and Al(III) has many structural defects and therefore results in a relatively high specific capacity (351.83 mA h g^?1 at a charge/discharge rate of 0.2 C) and good electrochemical reversibility.     

Structural,optical and mechanical property analysis of magnesium sulphate admixtured l-Threonine: A novel optoelectronic material

l-Threonine is an important amino acid and famous due to their property of frequency conversion and electro optic modulation. Single crystals of magnesium sulphate admixtured l-Threonine was grown by slow evaporation technique. Good quality single crystal with dimension 58 × 5 × 10 mm³ was harvested after 60 days. The powder X-ray diffraction pattern of the grown crystal has been indexed. The optical transmission spectrum shows that the magnesium sulphate admixtured l-Threonine possess good optical transparency in the entire visible region with Ultra Violet cut-off wavelength at 250 nm. The presence of fundamental functional groups was identified by Fourier Transform Infra Red spectral analysis. The structure of the grown crystal was established using Fourier Transform-Nuclear Magnetic Resonance spectral analysis. The thermal behaviour of the crystal has been discussed by Thermal Gravimetric Analysis and Differential Thermal Analysis. Magnesium sulphate admixtured l-Threonine was characterized by Energy dispersive analysis of X-ray. The second harmonic generation efficiency of magnesium sulphate admixtured l-Threonine crystal is found to be same as that of potassium dihydrogen phosphate crystal.     

Synthesis,crystal growth and characterization of a semiorganic material: Calcium dibromide bis(glycine) tetrahydrate

Single crystals of semiorganic material calcium dibromide bis(glycine) tetrahydrate were grown from aqueous solution. The crystal belongs to monoclinic system, with a = 13.261(5) Å, b = 6.792(2) Å, c = 15.671(9) Å and β = 91.68(4)°. The presence of the elements in the title compound was confirmed by energy dispersive X-ray analysis. The solubility and metastable zone width were found. The grown crystals were tested by powder XRD, FTIR, Thermo Gravimetric and Differential Thermal Analysis, UV–vis–NIR analysis, dielectrical and mechanical studies. The transmittance of calcium dibromide bis(glycine) tetrahydrate crystal has been used to calculate the refractive index n, the extinction coefficient K and both the real ɛ_r and imaginary ɛ_i components of the dielectric constant as functions of wavelength. The optical band gap of calcium dibromide bis(glycine) tetrahydrate is 3.23 eV.     

Morphological modifications and surface amorphization in ZnO sonochemically treated nanoparticles

Application of nanoscale materials in photovoltaic and photocatalysis devices and photosensors are dramatically affected by surface morphology of nanoparticles, which plays a fundamental role in the understanding of the physical and chemical properties of nanoscale materials. Zinc oxide nanoparticles with an average size of 20 nm were obtained by the use of a sonochemical technique. X-ray diffraction (XRD) associated to Rietveld refinements and transmission electron microscopy (TEM) were used to study structural and morphological characteristics of the samples. An amorphous shell approximately 10 nm thick was observed in the ultrasonically treated sample, and a large reduction in particle size and changes in the lattice parameters were also observed.