Optical, thermal, dielectric and ferroelectric behaviour of sodium acid phthalate (SAP) single crystals

Sodium acid phthalate (SAP), an efficient semi-organic crystal having dimensions 17×8×2 mm³ has been grown from aqueous solution by slow evaporation technique at room temperature within the period of 2 weeks. The lattice parameters of the grown crystals were determined using single-crystal X-ray diffraction analysis. The presence of functional groups was estimated qualitatively by Fourier transform infrared (FTIR) analysis. The band gap energy was determined using optical absorption studies. The TG/DTA analysis reveals that the SAP crystal is thermally stable up to 141.6 °C. The dielectric constant and dielectric loss was studied as a function of frequency and the corresponding activation energy (E_a) has been calculated for the grown crystal. Scanning electron microscope studies enunciate the ferroelectric domain patterns of the SAP crystal. Ferroelectric property of the grown crystal was confirmed by hysteresis loop studies.     

Thermal, mechanical, electrical, linear and nonlinear optical properties of a nonlinear optical l-ornithine monohydrochloride single crystal

Optically transparent semiorganic nonlinear optical bulk single crystal of l-ornithine monohydrochloride (LOMHCL) of dimension 11×3×2 mm³ 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 technique. Thermal behavior of the grown crystals was studied by thermogravimetric analysis. The second harmonic generation (SHG) efficiency of LOMHCL 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 and photoconductivity studies are also carried out for the grown samples.     

Growth and characterization of two new NLO materials from the amino acid family: l-Histidine nitrate and l-Cysteine tartrate monohydrate

Single crystals of organic nonlinear optical (NLO) materials l-Histidine nitrate (C₆H₁₀N₃O₂)⁺ · (NO₃)⁻ and l-Cysteine tartrate monohydrate (C₃H₈NO₂S)⁺ · (C₄H₅O₆)⁻ · H₂O were grown by submerged seed solution method. Characterization of the crystals was made using single crystal X-ray diffraction. Fourier transform infrared (FTIR) spectroscopic studies, optical behaviour such as UV-visible-NIR absorption spectra and second harmonic generation (SHG) conversion efficiency were investigated to explore the NLO characteristics of the above materials. Microhardness measurements and dielectric studies of the compounds were also carried out.     

Comparison of physical properties of pure and doped new metal organic crystal Bisthiourea sodium nitrate (BTSN)

Single crystals of pure and Na⁺ doped Bisthiourea Sodium Nitrate (BTSN), semi organic crystal were grown by slow evaporation technique. The grown crystals were subjected to various studies such as single crystal X-ray diffraction (XRD), UV–vis studies, Fourier transform infrared (FTIR), TG–DTA, and Vickers's microhardness were also measured. Single crystal X-ray diffraction studies reveal the crystals belong to orthorhombic crystallographic system. The mechanical property of the grown crystal was determined by microhardness studies.     

Growth and characterization of L-histidinium fumarate fumaric acid monohydrate single crystal: A promising second and third order nonlinear optical material

L-histidinium Fumarate Fumaric acid Monohydrate (LHFFAM), an organic nonlinear optical single crystal[C₁₄H₁₉N₃O₁₁], has been synthesized and grown using aqueous solution by slow evaporation technique at room temperature. Crystal structure details were obtained from single crystal XRD. The coordination of functional groups was identified in the grown crystal by FTIR analysis. The UV-absorption studies evince the transparent nature of the crystal is in the visible region and the optical band gap energy E_g was evaluated. The TG/DSC analyses confirm the thermal stability for the as-grown crystal. The Vickers microhardness test was carried out on the grown crystals and there by Vickers hardness number (H_v), work hardening coefficient (n), yield strength (σ_y), stiffness constant C₁₁ were evaluated. The dielectric behaviour of LHFFAM has been determined in the frequency range 50 Hz to 5 MHz at various temperatures. Kurtz-Perry and Z-scan techniques were performed for the acentric crystal LHFFAM which highlighted good nonlinear response and hence proves it appropriate for frequency conversion process and photonic device fabrications.     

Growth and characterization of pure and doped L-Lysine monohydrochloride dihydrate (L-LMHCl) nonlinear optical single crystals

Semi-organic nonlinear optical single crystals of pure, Ni²⁺ and Cd²⁺ doped L-Lysine monohydrochloride dihydrate (L-LMHCl) were grown from aqueous solution by slow evaporation technique. Single crystal X-ray diffraction analysis reveal that the pure and doped L-LMHCl crystals belong to monoclinic system with the space group P2₁. The presence of functional groups present in the pure and doped crystals was determined qualitatively by using Fourier Transform Infrared (FTIR) spectroscopy. Optical absorption studies reveal very low absorption for the doped crystal than that of the pure crystal. Dielectric studies have been carried out for the grown crystals and the results were discussed in detail.     

Growth and comparison of physicochemical properties of pure,Ca and Sr doped NH4Sb3F10 single crystals for electro optic applications

Single crystals of pure, Ca²⁺ and Sr²⁺ doped NH₄Sb₃F₁₀ are grown by slow evaporation technique. The effect of dopants on the growth and physicochemical properties also have been investigated and reported for the first time. The grown crystals are characterized with the aid of single crystal X-ray diffractometry to confirm the crystal structure. EDAX studies are done to confirm the presence of dopants in the crystal lattice. The vibrational frequencies of various group ligands in the crystals have been derived from the Fourier transform infrared (FT-IR) spectrum. From the optical absorption spectrum the band gap energy was calculated and it was found to be 5.76, 6.29 and 6.35 eV for pure, Ca²⁺ and Sr²⁺ doped NH₄Sb₃F₁₀ crystals respectively. Thermal stability of the sample has been analysed using TG-DTA analysis. The activation energy of pure, Ca²⁺ and Sr²⁺ doped NH₄Sb₃F₁₀ crystals were calculated from the dc conductivity measurements and it is found to be 0.2728, 0.2816 and 0.3622 eV Experimental results shows improved physicochemical properties when the dopant is added to the pure material.     

Synthesis,crystal growth and characterisation of 2-aminomethylpyridinium picrate (2-ampp)-a charge transfer molecular complex and organic nonlinear optical material

Single crystals of 2-aminomethylpyridinium picrate (2-AMPP) were grown by slow evaporation-solution growth technique at room temperature. The cell and structural parameters of the grown crystal were determined by single crystal X-ray diffraction analysis. The characteristic functional groups in the compound were identified from Fourier transform infrared spectroscopy. The transmission and absorption spectra of this crystal show that the lower cut-off wavelength lies at 360 nm. Thermal analysis was performed to study the thermal stability of the grown crystal. The powder second harmonic generation efficiency of the grown crystal measured by Kurtz technique is 2 times efficient than potassium dihydrogen orthophosphate (KDP). Vicker's microhardness test showed that the hardness value increases with increasing the applied load up to 50 g. The dielectric measurements of the compound in the frequency region from 50 Hz to 5 MHz showed that the material has lesser defects and can be used for optical application.     

Effect of pressure on electrical properties of SnS x Se1−x single crystals

The single crystals of tin monosulphoselenides in the form of a series SnS _x Se_1?x (where x?=?0, 0.25, 0.50,0.75 and 1) have been grown using the direct vapor transport technique (DVT). The analysis of the X-ray diffraction patterns reveals that all crystals belong to the orthorhombic crystal structure. Hall effect measurements were carried out on grown crystals at room temperature. The optical absorption measurements at room temperature have been carried out for all crystals. The values of the band gap were determined at atmospheric pressure and also calculated at high-pressure. Simultaneous thermoelectric power (TEP) and a.c. resistance measurements up to 8?GPa were carried out. The results of the effect of high-pressure on the electrical resistance of the grown crystals are reported in this paper.     

Growth and characterization of an organic NLO material ammonium malate

Second harmonic generation organic material, ammonium malate (AM), has been synthesized and grown as quality single crystals by the slow evaporation technique. As-grown crystals were characterized by X-ray powder diffraction (XRPD) and Fourier transforms – nuclear magnetic resonance (FT-NMR). The optical band gap was estimated for AM crystal using UV–vis study. Measuring transmittance of AM permitted the calculation of the refractive index n; the extinction coefficient K and both the real ε_r and imaginary ε_i components of the dielectric permittivity as functions of photon energy. Density functional theory at the HF/3-21 G (d, p) level has been used to calculate the first-order hyperpolarizability of AM. The second harmonic conversion efficiency of AM was determined using Kurtz powder technique; it was observed to be greater than that of KDP. The mechanical anisotropy property of the grown crystals was studied using Vickers microhardness tester at different planes. The photoluminescence study is also analyzed. The growth features were analyzed by wet chemical etching studies. The factor group analysis was carried out for AM which predicts that there are 132 vibrational optical modes.     

Structural, dielectric and piezoelectric properties of nonlinear optical γ-glycine single crystals

Gamma glycine was synthesized and the single crystals were grown by the slow evaporation method in the presence of lithium nitrate. Structure and crystalline nature of the grown γ-glycine crystal was confirmed by X-ray diffraction technique. It was found to crystallize in the trigonal system with space group P3₁. The chemical composition was determined by NMR. Fourier transform infrared studies revealed the functional groups present in the grown crystal and UV-vis-NIR spectra revealed the transmission properties of the crystal specimen. Surface morphology of the grown crystal was studied by scanning electron microscopy (SEM) and elemental composition was confirmed by energy-dispersive spectrometry (EDS). The second-order nonlinear optical property of the material was investigated by Kurtz powder technique and the relative second harmonic efficiency of γ-glycine was estimated to be higher than that of KDP. The dielectric measurement was carried out as a function of frequencies at room temperature and the results were discussed. The samples have shown piezoelectric behavior with a fairly good piezoelectric charge coefficient (d₃₃) of 7.37 pC/N. Photoluminescence studies showed emission peak around 350 nm. Thermo gravimetric and differential thermal analyses were employed to understand the thermal and physio-chemical stability of the synthesized compound.     

Growth and characterization of new semi-organic l-proline strontium chloride monohydrate single crystals

The present communication deals with the synthesis, single crystal growth and characterization of a new nonlinear optical material l-proline strontium chloride monohydrate (l-PSCM). Single crystals have been grown using the slow solvent evaporation technique. Single crystal XRD analysis confirmed that the crystal belongs to the orthorhombic structure with lattice parameter a=6.6966(3) Å, b=12.4530(5) Å, c=15.2432(5) Å and space group P2₁2₁2₁. Presence of various functional groups in l-PSCM and protonation of the ions were confirmed by Fourier transform infrared spectroscopy (FT-IR) analysis. The melting point of the single crystal was found to be 126 °C using DSC. Ultraviolet-visible spectral analyses showed that the crystal has low UV cut-off at 226 nm combined with very good transparency of 90% in a wide range. The optical band gap was estimated to be 5.82 eV. Capacitance and dielectric-loss measurements were carried out at different temperatures in the frequency range 1 kHz-2 MHz. The dielectric constant and loss factor were found to be 21 and 0.03 at 1 kHz at room temperature, respectively. Microhardness mechanical studies show that hardness number (H_v) increases with load for l-PSCM single crystals the by Vickers microhardness method. Second harmonic generation (SHG) efficiency was found to be 0.078 times the value of KDP.     

Studies on the structural,optical, dielectric and mechanical properties of non-linear optical manganese mercury Tetrathiocyanate glycol mono methyl ether (MMTG) single crystal

Non-linear optical manganese mercury teterathiocyanate glycol monomethyl ether [MnHg(SCN)₄(C₃H₈O₂)] compound was synthesized and single crystals were grown from water-glycol monomethyl ether (1:1) mixed solvent by slow cooling method. Structure and crystallinity of the grown crystal were confirmed by both single crystal and powder X-ray diffraction analysis. Presence of functional groups and coordination of glycol monomethyl ether and thiocyanate in MMTG were confirmed by FT-IR analysis. Optical transmittance and second harmonic generation of the grown crystal were studied by UV–Vis spectrum and Kurtz powder technique. A dielectric study was performed on the MMTG single crystal to study the power dissipation of the material in the presence of alternating electric field. Mechanical behaviour was analysed using Vicker’s microhardness test. Optical surface damage measurement was carried out to confirm the suitability of MMTG crystal for NLO applications.     

Growth and optimization of optical traits of copper sulphate crystal exploiting L-ascorbic acid for photonic device applications

In current investigation organic ligand of _L-ascorbic acid (LAA) has been firstly exploited to tune the optical properties of copper sulphate (CuS) single crystal. The pure and LAA influenced CuS crystal has been grown from aqueous solution by slow evaporation process. The powder X-ray diffraction technique has been employed to identify the crystal planes and evaluate the structural parameters of grown crystals. The functional groups of LAA influenced CuS (LAA-CuS) crystal has been recognized by Fourier transform infrared analysis. The impact of LAA on optical transmittance of CuS crystal has been examined within 200-900 nm by means of UV-visible spectral analysis. The Z-scan technique has been employed to examine the third order nonlinear optical (TONLO) properties of pure and LAA-CuS crystal. The eye-catching effect of LAA in switching the nonlinear refraction behavior of CuS crystal from self-focusing to self-defocusing has been explored. The magnitude of TONLO refractive index (n₂), absorption coefficient (β) and susceptibility (χ³) of pristine and LAA-CuS crystal has been comparatively evaluated using the Z-scan transmittance data.     

Synthesis,growth, vibrational,optical and thermal studies of potassium diboro oxalate single crystals

Single crystals of novel semiorganic material, potassium diboro-oxalate (PDO) have been grown from aqueous solution by slow evaporation technique. The lattice parameters for the grown crystals were determined by the single crystal X-ray diffraction analysis and the crystallinity of the grown crystal was confirmed by powder X-ray diffraction analysis. The presence of functional groups was estimated qualitatively by using Fourier transform infrared (FTIR) analysis. The optical absorption spectrum shows that the UV cut-off wavelength for the grown crystal is at 240 nm and the band gap was calculated. The thermal stability of the grown crystal was studied by using TG/DTA analysis. The second harmonic generation and the phase-matchable tests were performed by Kurtz powder technique. The crystal perfection was analyzed by SEM photographs.     

Attainment of growth stability through the widening of Ostwold–Mier's zone width: A novel technique

A novel method has been found to enhance the metastable zone width of solutions in their supersaturated region in order to grow large size crystals at a faster rate under stabilized conditions. In which, the incorporation of a small quantity of ethylinediamine tetra acetic acid (EDTA) and hydrogen peroxide (H₂O₂) a well-known chelating agents, enhances Ostwold–Mier's metastable zone width significantly due to their chelating action. Also this incorporation reduces the secondary nucleation rate and enhances the growth rate of the crystal. Powder X-ray diffraction, Fourier transform infrared (FTIR), UV–visible–NIR studies for the grown crystal reveal that EDTA and H₂O₂ addition do not affect the crystalline quality. This concept has been realized with barium nitrate Ba(NO₃)₂, a potential SRS crystal. The complexation also promotes the growth rate leading to a rapid growth with high crystalline quality.     

Synthesis,growth and studies of undoped and sodium chloride-doped Zinc Tris-thiourea Sulphate (ZTS) single crystals

Single crystals of undoped (pure) and sodium chloride (NaCl)-doped Zinc Tris-thiourea Sulphate (ZTS) were grown from aqueous solutions by slow evaporation technique. Morphological alterations have been observed when NaCl is doped into ZTS crystals. Density of the grown crystals was measured by floatation method. The values of unit cell parameters from single crystal X-ray diffraction (XRD) studies show that pure and sodium chloride-doped ZTS crystals are in orthorhombic structure. Impurity concentration in the doped crystals was estimated by using an atomic absorption spectrometer. Second Harmonic Generation (SHG) test for the undoped and NaCl-doped ZTS crystals was performed by the powder technique of Kurtz and Perry using a pulsed Nd:YAG laser. Microhardness studies show that hardness number (H_v) increases with load for all the grown crystals of this work. From the values of work hardening coefficients, it is concluded that pure and sodium chloride-doped ZTS crystals belong to the category of soft materials. UV–vis–NIR spectra show that the grown crystals have wide optical transparency in the entire visible region. Birefringence studies of the grown samples have been performed by channelled spectrum method. The thermal stability of the materials is found to be increasing with the doping concentration of sodium chloride (NaCl) in the lattice of ZTS crystals.     

Effect of magnetic field in the microhardness studies on calcium hydrogen phosphate crystals

Calcium hydrogen phosphate dihydrate (CaHPO₄·2H₂O, brushite) crystals are grown in gel medium at physiological pH by single diffusion method in the presence of different magnetic field strengths, namely 0, 0.1 and 0.2 Tesla. The results indicate that in the presence of magnetic field, the number of brushite crystals formed at the gel-solution interface reduces and the average size of the crystals increases. This shows that the growth of brushite crystal was favored by magnetism. Vickers and Knoop microhardness studies were carried out on the crystals grown at various magnetic fields. The Vickers (H_V) and Knoop (H_K) microhardness numbers were found to increase with increasing load. The values of Meyer’s index number (n) decrease while the magnetic field strength increases. Nevertheless the n values are greater than 1.6, which shows that the brushite crystals grown under magnetic fields still fall in the soft material category. The brittle index (Bi), yield strength (σ_y) and elastic stiffness constant (c₁₁) were calculated. The Young’s Modulus was calculated using the Knoop hardness value and found to decrease in higher magnetic field strengths.     

Growth and characterization of organic nonlinear optical material: 5-Nitroindole (5NI) for optical applications

Single crystals of organic nonlinear optical material 5-Nitroindole (5NI) has been grown by slow cooling solution growth technique using methanol as a solvent. The grown crystal was subjected to single crystal X-ray diffraction technique to determine the lattice parameters. Fourier transform infrared spectrum (FTIR) was recorded to identify the presence of functional groups. The optical properties such as the optical band gap, extinction coefficient (k), refractive index (n) and optical conductivity (σ) were calculated. The optical band gap of 5NI is 2.33 eV. The melting point and thermal stability of the crystal was analyzed from TG/DTA studies. Dielectric studies were carried out at different temperatures and frequencies.     

Growth, Characterization and Theoretical Study of a Novel Organometallic Nonlinear Optical Crystal: CdHg(SCN)4(C2H5NO)2

A novel potentially useful second harmonic generation (SHG) organometallic nonlinear optical (NLO) crystal: cadmium mercury thiocyanate bis(N-methylformamide), CdHg(SCN)₄(C₂H₅NO)₂ (CMTN), has been prepared, and large high-optical-quality single crystals with dimensions up to 30 ×27×9 mm³ have been grown by the temperature-lowering method. Its structural, physicochemical and optical properties are characterized by elemental analyses, X-ray powder diffraction, Fourier transform infrared and Raman spectroscopy, thermal analysis, powder SHG measurements and UV/Vis/NIR transmission. The specific heat has been determined to be 515.5 J?mol^?1?K^?1 at 300 K. CMTN possesses good physicochemical stability up to 128.5^°C, exhibits powder SHG efficiencies 0.8 times that of urea and its UV transparency cutoff is 358 nm. By the use of the DFT/B3LYP/6-31G(d) method, the microscopic second order NLO behavior of CMTN has been investigated by computing the first-order hyperpolarizability together with that of CdHg(SCN)₄ (CMTC) and CdHg(SCN)₄(C₃H₈O₂) (CMTG) crystals. The results have been explained based on their crystal structures.