Growth,structural, optical,DFT, thermal and dielectric studies of N-Benzyl-3-nitroaniline (B3NA): a promising nonlinear optical crystal

The non-linear optical material N-Benzyl-3-nitroaniline was synthesized and grown through an aqueous solution using a low temperature solution growth technique. This conforming monoclinic crystal structure with the P2₁ space group was established by the characterization study of single crystal X-ray diffraction. A powder X-ray diffraction analysis was performed to confirm crystalline nature. As one of the functioning groups of nitro-aniline revealed using the Fourier transform infrared spectrum and the prominent spectral band seen at 3404 cm^?1 is caused by stretching vibrations of the N–H group. The lower cut-off wavelength of the ultra violet-visible absorption and emission spectrum was found to be about 320 nm as the excitation of fluorescence and the emission of blue and red colors are expected at 459 nm and 688 nm. To determine the difference in energy between HOMO and LUMO by 9.6258, using the B3LYP/6-311G++ (d,p) method. The time-based DFT technique was used to calculate the first-order hyperpolarization (β)?=?1.214?×?10^–30 esu. Thermo gravimetric and differential thermal analysis measurements were used to determine the crystal’s moisturing toughness up to 282.87 °C. The relative dielectric constant changes with frequency. Kurtz Perry’s method confirmed 1.66 times the efficiency of second harmonic generation to this present crystal comparing KDP crystal. This data shows that there is a significant amount of promise that is used in optoelectronic materials.

     

Synthesis,growth, and two-photon absorption induced optical limiting action of cytosinium benzoate single crystal

Two-photon absorption induced optical limiting action was demonstrated in cytosinium benzoate (CB) under nanosecond laser (532 nm, 9 ns, and 10 Hz) excitation. Intensity dependent open aperture Z-scan experiment exposed the presence of reverse saturable absorption ascribed due to sequential two-photon absorption. Initially CB single crystals were grown at room temperature by slow evaporation solution technique. Single crystal XRD shows that CB belongs to monoclinic crystal system with P2₁/c space group. Fourier Transform Infrared spectrum was recorded to identify the presence of functional groups. Thermal studies shows that the crystal is stable upto 168 °C. Vickers microhardness studies confirm that the grown crystal was belongs to soft material category. Etching study shows linear rectangular etch patterns (5 s) and well defined stacking planes (10 s) for water etchant. Optical studies demonstrate that CB crystal possess lower cut-off (287 nm) and moderate linear transmittance in visible region. The optical energy band gap of CB crystal was estimated from photoluminescence studies as 3.1 eV. CB with higher two-photon absorption coefficient (1.26?×?10^–10 m/W) and lower onset limiting threshold (1.92?×?10¹² W/m²) can be a potential candidate for developing laser safety devices under nanosecond green laser excitation regime.

     

Crystal growth,structure, surface,optical, thermal,mechanical, magnetic,electrical investigations on cesium sulphate-doped 4-methoxyaniline: a single crystal for NLO and antimicrobial applications

A new single crystal of cesium sulphate-doped 4-methoxyaniline (CS-4MOA) was obtained by the solvent evaporation approach. XRD manifests that the CS-4MOA crystallizes in orthorhombic crystal structure. The existence of several functional groups in the CS-4MOA crystal is affirmed by FTIR analysis. SEM-EDAX analysis was performed to examine the surface morphology and the composition of CS-4MOA sample. Ultraviolet–visible spectral study validates the transparency of CS-4MOA in the region of 330–1100 nm. The thermal steadiness of the CS-4MOA crystal was examined using TG/DTA, which revealed that it was stable up to 88 °C. The mechanical stability of CS-4MOA crystal was assessed through Vickers microhardness analysis. VSM analysis was used to evaluate the magnetic behaviour of the CS-4MOA crystal. The electrical characteristics of the CS-4MOA were investigated by impedance study for various temperatures. The NLO parameters of CS-4MOA were computed by Z-scan technique. The existence of second order nonlinear optical susceptibility in CS-4MOA was confirmed by the SHG investigation. Additionally, antimicrobial activity of CS-4MOA was performed against bacterial strains and fungal pathogen for medicinal applications.

     

Dielectric relaxation in complex perovskite Ba(Bi1/2Ta1/2)O3

A new lead-free perovskite Ba(Bi_1/2Ta_1/2)O₃ was prepared by conventional ceramic fabrication technique at 1,200 °C/4 h in air atmosphere. The crystal symmetry, space group and unit cell dimensions were determined from the experimental results using FullProf software. The crystallite size and lattice strain were estimated from Williamson-Hall approach. XRD analysis of the compound indicated the formation of a single-phase cubic structure with the space group Pm3m. EDAX and SEM studies were carried out in order to evaluate the quality and purity of the compound. Permittivity data showed a low temperature coefficient of capacitance (T _CC  < 4%) up to +125 °C. Complex impedance analyses suggested the dielectric relaxation to be of non-Debye type. Electric modulus studies supported the hopping type of conduction in Ba(Bi_1/2Ta_1/2)O₃.     

Synthesis,studies of 2-benzyl-amino-4-p-tolyl-6,7-di-hydro 5H-cyclo-penta–[b]pyridine-3 carbo-nitrile (BAPTDHCPCN) crystals for optical,photonic and mechano-electronic uses

2-benzyl-amino-4-P-tolyl-6,7-di-hydro 5H-cyclo-penta –[b]pyridine–3 carbo–nitrile—BAPTDHCPCAN crystal is grown by solution growth evaporation method and analysed for XRD, Unit Cell, Dielectric analysis, UV, Tauc’s plot and fluorescence and mechano studies. The single crystalline XRD data portrays the monoclinic nature of BAPTDHCPCAN with space group P2₁/c and a, b, c as 8.6828 Å, 17.7283 Å, 12.0403 Å with β as 94.254°. Chemical formula of crystal as C₂₃H₂₁N₃. The crystalline dimension is 14?×?12x7 mm³. The dielectric properties of the BAPTDHCPCAN have larger value at low range of frequencies. The phase matching effectiveness is analyzed and found to be 66 mV. The influx value of macro and thin film of BAPTDHCPCAN crystal is 4.2125 microns and 4.4336 microns as mid value before nano shaped influx. Absorption spectral two peaks centered at 248 nm at 325 nm, the band gap of crystal is calculated as 5.0 eV by photonic enhancement and the fluorescence represented emission for 399 nm. The BAPTDHCPCAN crystal is found to have represented –ve photoconductive nature. The BAPTDHCPCAN crystal specimen in of RISE [Reverse Indentation Size Effect] consequence with n greater than 2.

     

Dielectric characterization of gadolinium tartrate trihydrate crystals

Single crystals of gadolinium tartrate trihydrate have been grown by gel diffusion technique. Single crystal X-ray diffraction analysis shows that the crystals belong to the tetragonal system with non-centrosymmetric space group. The dielectric constant, dielectric loss and ac conductivity have been measured as a function of frequency in the range 1 kHz–5 MHz and temperature range 20–300 °C. The dielectric constant increases with temperature, attains a peak around 240 °C and then decreases as the temperature exceeds 240 °C. The dielectric anomaly at 240 °C is suggested to be due to phase transition brought about in the material, which is further supported by the thermal studies. The variation of ac conductivity with temperature has been measured and the material is suggested to show protonic conductivity.     

Synthesis of lanthanum titanate (La2Ti2O7) for high temperature sensor applications

Lanthanum titanate (La₂Ti₂O₇) with perovskite-like layered structure is a candidate material for high temperature sensor application due to its high curie temperature (T_c?=?1461 °C) and linearity of temperature vs. electrical resistance. La₂Ti₂O₇ (LTO) was synthesized by solid state reaction using constituent powders at 1250 °C for 2 h. The LTO samples prepared in the form of circular pellets were sintered in temperature ranges (1350 to 1400 °C for 2 h). The sintered density was found highest at 1400 °C for LTO samples (>?97.24% Th.). Moreover, the sintered LTO samples were characterized for their ferroelectric properties as well as DC electrical resistivity (ρ) measured in the temperature range of 100 to 900 °C. The electrical resistivity was decreased from 10¹³ to 10⁶ Ω cm linearly with the increase in temperature from 100 to 900 °C. Hence, LTO is a promising sensor material for high temperature applications.

     

Elucidation of structural,optical, mechanical,dielectric, DFT and nonlinear optical response of 2-amino-1-methyl-5H-imidazol-4-one single crystal

A single crystal of 2-Amino-1-methyl-5H-imidazol-4-one (AMH) with chemical formula C₄H₇N₃O were synthesized using slow evaporation solution growth approach and analyzed its structural and optical features. Single crystal X-ray diffraction (SXRD) examination is used for measuring crystallinity as well as lattice characteristics of generated single crystals. AMH crystal has monoclinic structure and shows the space group P2₁/n, according to the result. The computed structural parameters were compared with the experimental observations and the presence of intramolecular charge transfer interactions were analyzed by Natural Bond Orbital analysis. Hirshfeld surface analysis has been used for visualizing various intermolecular interactions that exist within the synthesized material. The functional group in association with formed compound as well as absorption peaks and bands have been investigated and designated using FTIR spectroscopy. Using Vicker’s microhardness, we can assessed the mechanical strength and determined the work hardening coefficient as 3.1, which confirming the compound’s soft nature. UV–Visible absorbance spectral analysis have been utilized for examining the optical characteristics of the material, which shows the lower cut-off wavelength and optical bandgap as 300 nm and 3.9 eV, respectively. Frontier molecular orbital analysis is performed for explaining charge transfer exists within AMH and the material’s energy gap is estimated as 4.1 eV. The effective charge transfer interactions (ICT) are visualized by MEP plots. By the use of Gaussian ‘09 software package and Kurtz Perry powder technique, the compound’s nonlinear optical behaviour is verified in both theoretical and experimental modes. The dielectric behaviour of the synthesized material was interpreted and analyzed.

     

Exploring the electrical transport properties of La0.67Ca0.33MnO3 at different sintering temperatures

The La_0.67Ca_0.33MnO₃ polycrystalline ceramics were prepared by the co-precipitation method with ammonium carbonate as the precipitant and the influence of the sintering temperature on the electrical transport properties of the ceramics were investigated. XRD results show that the ceramic structures obtained are all perovskite structures, which belong to the Pnma space group. Scanning electron microscopy (SEM) photographs demonstrated that the average size of the grains with the sinter temperature increased from 5.78 μm at 1300 °C to 24.04 μm at 1475 °C. Meanwhile, when the sintering temperature reached 1450 °C, the TCR reached the maximal value (32.3%·K^?1), which was much larger r than the TCR at 1350 °C. The theoretical model analysis of the data leads to the conclusion that the conductive mechanism of the low-temperature metallic region and the high-temperature insulating region is dominated by the grain boundary scattering effect and the small-polariton hopping (SPH), respectively.

     

Growth and characterization of a new semi-organic nonlinear optical sodium paranitrophenolate paranitrophenol dihydrate single crystal

A new semi-organic nonlinear optical sodium paranitrophenolate paranitrophenol dihydrate single crystal is grown successfully using methanol as solvent by slow evaporation technique to dimensions of 14 × 5 × 4 mm³ in a period of 7 days. The grown crystal is characterized by X-ray diffractometry and UV-Visible spectral analysis. X-ray diffraction data reveals that the crystal belongs to monoclinic system with space group C2. Optical absorption studies illustrate low absorption in the entire UV and Visible region. The second harmonic generation (SHG) efficiency of the crystal measured by Kurtz's powder technique infers that the crystal has NLO coefficient 5 times greater than that of KDP crystal. Remarkable mechanical strength with the work hardening coefficient less than 2 and thermal stability up to 120 °C of the grown crystal is reported.     

High-temperature mechanical behavior of cordierite-based porous ceramics prepared by modified cassava starch thermogelation

In this study, the high-temperature mechanical response of a cordierite-based porous material prepared by direct starch consolidation was evaluated. Disks were prepared by the thermogelation (85 °C, 4 h) of an aqueous suspension (29.6 vol. %) of a cordierite precursor mixture (talc, kaolin, and alumina) with the addition of a commercial modified cassava starch (11.7 vol.%), drying (50 °C, 24 h), firing (650 °C, 2 h), and reaction sintering (1330 °C, 4 h). The porous microstructures were characterized by Archimedes method (bulk density and apparent porosity measurements), SEM with image analysis (pore cavity sizes), and mercury porosimetry (pore throat sizes). Mechanical behavior was evaluated in diametral compression using a servohydraulic testing machine at room temperature, 800, 1000, and 1100 °C. Apparent stress–strain relationships were obtained from load–displacement curves, and mechanical parameters, such as fracture strength (σ_F), fracture strain (ε_F), and apparent Young modulus (E _a) were determined. Moreover, crack patterns and fracture surface were also evaluated. The obtained results were analyzed as a function of the developed microstructures, considering the presence of a silicate glassy phase and a complex porosity, and the testing temperature. From these results, the operative fracture mechanism was proposed. Finally, the obtained results were compared with those reported by the authors for cordierite porous materials prepared using other types of native starches, determining that the best mechanical response, in particular at high temperature, was obtained using modified cassava starch.     

Effect of α-lath size on the mechanical properties of Ti–6Al–4V using core time hydrogen heat treatment

ABSTRACT

When hydrogen is dissolved, brittleness occurs in the material. However, in the case of titanium and titanium alloy, hydrogen can be temporarily dissolved and removed, thereby improving the mechanical properties of titanium and titanium alloy. In this study, Core time Hydrogen Heat treatment (CHH) applies to Ti–6Al–4V alloy to improve mechanical properties. CHH was performed at 800°C and 1000°C for 2?h. Thereafter, dehydrogenation was performed for 2 h at 700°C in vacuum atmosphere to remove residual hydrogen. After the CHH at 800°C, it was found that the α-lath size in the Ti–6Al–4V was narrowed; thereby increasing the Vickers hardness and tensile strength without decreasing in elongation.     

Facile synthesis of hexagonal boron nitride fibers and flowers

Hexagonal boron nitride (h-BN) fibers and flowers were synthesized with a facile synthesis route. The precursor was obtained as an intermediate material by the reaction of KBH₄ and NH₄Cl at 120 °C for 48 h. h-BN was obtained by heating the intermediate material at 1250 °C for 10 h. The sample obtained was characterized by X-ray powder diffraction (XRD), Fourier transformation infrared spectroscopy (FT-IR), thermogravimetry (TG/DTA) and environment scanning electron microscopy (ESEM), which matched with h-BN. ESEM image indicated that the diameter of the BN fibers is mainly in the range of 1–2 μm.     

Mechanical testing of cordierite porous ceramics using high temperature diametral compression

In this study, the high temperature mechanical behavior of cordierite porous disks prepared by the starch consolidation forming method was evaluated. In this method, due to the swelling and gelatinization properties of starch in aqueous suspension at a temperature between 55 and 85 °C, the starch granules perform as both consolidator/binder of the green body and pore former at high temperature. Aqueous suspensions (29.6 vol.%) of a cordierite precursor mixture (talc, kaolin, and alumina) with the addition of potato or cassava starches (11.5 vol.%) were prepared by intensive mechanical mixing, homogenization, and vacuum degasification. Green disks were formed by thermogelling of the aqueous suspensions at 85 °C for 4 h followed by additional drying at 50 °C for 24 h. They were characterized by bulk density and apparent porosity measurements, and microstructural analysis by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Porous cordierite materials were obtained by calcination at 650 °C for 2 h and reaction-sintering at 1330 °C for 4 h, employing specific, controlled heating schedules in both treatments. Cordierite disks were characterized by bulk density and apparent porosity measurements, and microstructural analysis by SEM. Mechanical behavior was evaluated in diametral compression using a servohydraulic testing machine at room temperature (RT), 800, 1000, and 1100 °C. Apparent stress–strain relationships were obtained from load–displacement curves, and mechanical parameters, such as fracture strength (σ_F), apparent Young modulus (E _a), and yield stress (σ_Y), were determined. Moreover, crack patterns were also evaluated. The obtained results were analyzed in function of the developed microstructures, considering the presence of a silicate glassy phase and a complex porosity, and the testing temperature.     

Laser damage threshold,antimicrobial efficacy and physicochemical properties of an organometallic L-proline lithium chloride monohydrate single crystal for NLO application and optoelectronic device fabrication

The potential metalorganic L-proline lithium chloride monohydrate single crystal was grown by slow evaporation method for evaluating optoelectronic device fabrication. From the single crystal XRD studies, the grown crystal was confirmed the molecular packing in monoclinic crystal lattice. The powder XRD data confirm the phase purity of the grown crystal. Vibrational absorption band assignments were recognized by FTIR and FT-Raman spectrum and they confirmed the presence of multiple functional groups in the grown crystal structure. Optical properties of the grown crystal were studied by using transmittance and absorption spectrum of UV–Vis–NIR analysis. The dielectric response of the grown crystal was studied in the frequency range between 50 Hz and 2 MHz for four temperature gradients. From the microhardness study, some mechanical parameters such as fracture toughness, brittleness index and yield strength were calculated. The photoluminescence activity of the grown crystal was deliberate in terms of optical peaks. The amino group participation over the optical scattering nodal regions for generating radiation absorption process to fascinate optical endurance was studied. TG/DTA curve shows that the LPLCM crystal was thermally stable up to 132 °C. The laser damage threshold value of the grown crystal was measured using multishot mode and it was found to be 7.78 GW/cm². The fractionation of the etching time prevents lattice from over etching and degradation of the mechanical properties of the grown crystal. LPLCM crystal showed higher antibacterial activity against one gram positive and one gram negative bacterial species. Second order nonlinear optical efficiency of the LPLCM crystal was studied at 1064 nm generated by a nanosecond pulsed Nd:YAG laser source.

     

Hot deformation of ultrafine-grained Al6063/Al2O3 nanocomposites

Ultrafine-grained (UFG) Al6063 alloy reinforced with 0.8 vol% nanometric alumina particles (25 nm) was prepared by reactive mechanical alloying and direct powder extrusion. Transmission electron microscopy and electron backscatter diffraction analysis showed that the grain structure of the nanocomposite composed of nanosize grains (<0.1 μm), ultrafine grains (0.1–1 μm) and micronsize grains (>1 μm) with random orientations. Mechanical properties of the material were examined at room and high temperatures by compression test. It was found that the yield strength of the UFG composite material is mainly controlled by the Orowan mechanism rather than the grain boundaries. The deformation activation energy at temperature ranges of T < 300 °C and 300 °C ≤ T < 450 °C was determined to be 74 and 264 kJ mol⁻¹, respectively. This observation indicated a change in the deformation mechanism at around 300 °C. At the higher temperatures, significant deformation softening was observed due to dynamic recrystallization of non-equilibrium grain boundaries. The reinforcement nanoparticles, however, renders the high strength of the material at the elevated temperatures mainly by dislocation pinning.     

Crystal structure refinement of A-type carbonate apatite by X-ray powder diffraction

Complete carbonate substitution at A-sites (OH) of low-crystallinity hydroxyapatite with near stoichiometric composition (i.e. Ca/P ratio of 1.65) was achieved by heating in a dry carbon dioxide flow at 1173 K for 64 h. The carbonate content was analysed by thermogravimetry and infrared absorption spectrometry; the chemical composition was determined to be Ca_9.9±0.1(PO₄)_6.00±0.1(CO₃)_0.9±0.1. The crystal structure and atomic configuration of the carbonate ion were determined by Rietveld refinement using X-ray powder diffraction data. This analysis revealed that the space group was monoclinic Pb with a = 0.9571(1), b = 1.9085(2), c = 0.68755(3) nm and γ = 119.847(7)°. The triangular planes of the carbonate ions were oriented parallel to the c- and a-axes, though there were two independent carbonate sites with occupancy factors of 0.56(1) and 0.34(1), where the triangles were oppositely rotated about the corresponding carbon atoms by 23° and −18°, respectively. The arrangement of the ions was disordered, which explains the lack of a thermal phase transition below 623 K.     

Effect of plasma CVD operating temperature on nanomechanical properties of TiC nanostructured coating investigated by atomic force microscopy

The structure, composition, and mechanical properties of nanostructured titanium carbide (TiC) coatings deposited on H₁₁ hot-working tool steel by pulsed-DC plasma assisted chemical vapor deposition at three different temperatures are investigated. Nanoindentation and nanoscratch tests are carried out by atomic force microscopy to determine the mechanical properties such as hardness, elastic modulus, surface roughness, and friction coefficient. The nanostructured TiC coatings prepared at 490 °C exhibit lower friction coefficient (0.23) than the ones deposited at 470 and 510 °C. Increasing the deposition temperature reduces the Young's modulus and hardness. The overall superior mechanical properties such as higher hardness and lower friction coefficient render the coatings deposited at 490 °C suitable for wear resistant applications.     

A study on the <Emphasis Type="SmallCaps">l</Emphasis>-lysine-iodic acid: semi organic non linear optical single crystals for electro-optic applications

Non linear optical single crystals of l-lysine-iodic acid (LLI) of dimensions upto 24?×?14?×?5 mm³ have been grown successfully by slow evaporation technique from aqueous solution. The crystal structure of the grown material was solved by single crystal X-ray diffraction analysis and it was found that the LLI crystal belongs to monocinic system with space group P2₁. Functional groups of the grown crystal were identified by Fourier Transform Infrared (FTIR) spectral analysis. The UV–Vis spectral analysis was carried out to measure the transparent range of the LLI crystal which is nearly 85% and the band gap energy is found to be 5.51 eV. Thermal stability and decomposition temperature of LLI crystal was found by means of TGA and DTA analyses. The mechanical behavior of the grown crystal has been employed using Vicker’s micro hardness technique. The Second Harmonic Generation (SHG) efficiency of the crystal was investigated and it was found to be 3.2 times of KDP. The particle size dependent SHG studies of LLI crystals were performed using Nd:YAG laser. The laser damage threshold value of LLI crystal is found to be 8.54 GW/cm². Dielectric study indicates the reasonable dielectric constant and low dielectric loss of LLI crystal which are essential properties to develop optoelectronic devices. The ac and dc electrical conductivity measurements were carried out at various temperatures. Photoconductivity study exhibits the negative photoconductivity nature of the LLI crystal and the results are discussed for the first time.     

Silica ceramic nanofiber membrane with ultra-softness and high temperature insulation

Silica ceramic nanofiber (SCNF) membranes with ultra-softness were fabricated by electrospinning and precursor derived ceramic technology. Firstly, the precursor fiber membrane was obtained by electrospinning from spinnable precursor sol, which was prepared by using silica sol as raw material and polyvinyl alcohol (PVA) as spinning aid, and after heat treatment, it was converted into the SCNF membrane composed of pure inorganic components, which had the ultra-softness to restore the original shape after arbitrary folding. Then the effects of different PVA dosages and heat treatment temperatures on the fiber morphology, thermal stability, mechanical properties, and thermal conductivity of SCNF membranes were investigated. Among all the membranes, the SCNF membrane that was made with a precursor sol of 5% PVA and sintered at 900 °C (Ss?+?PVA 5%-900 °C) showed the smoothest as well as the most uniform fiber morphology, with an average fiber diameter of 285.19 nm, a density of 0.106 g cm^?3, the best mechanical properties (tensile strength of 4.145 MPa), and it also had the lowest thermal conductivity of 0.05285 Wm^?1 K^?1. The Ss?+?PVA 5%-900 °C SCNF membrane still maintained intact fiber morphology after being treated at 1200 °C. These excellent properties make the SCNF membrane have a potential application prospect as an insulation material in ultra-high temperature environments.