Growth and characterization of l-asparagine thiourea monohydrate (LATM): A nonlinear optical single crystal

l-Asparagine thiourea monohydrate (LATM) single crystal has been successfully grown (size 15 × 10 × 3 mm³) by slow evaporation solution growth technique. To the best of our knowledge this is the first report to the literature. The grown crystal was characterized by powder X-ray diffraction (XRD) and Fourier transform infrared spectroscopic analysis. The UV-Vis transmittance spectrum shows that the material has wide optical transparency in the entire visible region. The relative second harmonic generation was confirmed by Kurtz powder technique. The mechanical properties have been studied using Vickers microhardness tester. The birefringence of the crystal was measured in the visible region and it was found to vary with the wavelength.     

Growth and characterization of the nonlinear optical single crystal: l-Lysinium trifluoroacetate

A novel organic nonlinear optical (NLO) crystal, l-lysinium trifluoroacetate (with the molecular formula as (H₃N)⁺CH₂CH₂CH₂CH₂CH(H₃N)⁺COO⁻CF₃COO⁻), was grown by the controlled evaporation of its aqueous solution. The X-ray powder diffraction was used to determine its cell parameters. The calculated results based on the diffraction data reveal that l-lysinium trifluoroacetate belongs to the monoclinic crystallographic system, space group P2₁, with cell parameters: a = 5.698(5), b = 23.542(8), c = 8.500(6) Å, β = 91.62(9)°, V = 1139.96 Å³. The grown crystals were characterized by the elemental analyses, Fourier transform infrared and Raman spectra. Experiments of thermogravimetric (TG) and differential thermal analysis (DTA) were carried out to study its thermal properties. The optical behaviours, including transmission spectrum and second harmonic generation (SHG), were investigated to study its linear and nonlinear optical properties. Optical nonlinearities were analyzed and discussed involved with its crystal structure.     

The growth of l-Glutamic acid hydrochloride crystals by Sankaranarayanan-Ramasamy (SR) method

An efficient semiorganic nonlinear optical crystal l-Glutamic acid hydrochloride has been grown by using the novel uniaxial crystal growth method of Sankaranarayanan and Ramasamy with a slight modification in the experimental setup. This method allows the crystals to grow in one specified axis with well developed facet. The grown crystal has a cylindrical morphology with good optical quality. The grown crystal has been characterized by powder X-ray diffraction and UV-Vis-NIR analyses. The NLO efficiency of the crystal has been confirmed by using the Kurtz powder technique.     

Growth and characterization of l-proline cadmium chloride monohydrate single crystals

A novel semi-organic material of l-proline cadmium chloride monohydrate (l-PCCM) has been successfully synthesized and single crystal was grown by slow evaporation solution growth technique at room temperature. The grown single crystals have been characterized by different instrumentation techniques like XRD, FTIR, UV-Vis-NIR and TG/DTA measurements. Its nonlinear optical property has been tested by Kurtz powder method. The mechanical properties of grown crystals have been studied using Vickers microhardness tester. Its relative SHG efficiency is two times higher than that of potassium dihydrogen phosphate (KDP) single crystal.     

l-lysine monohydrochloride dihydrate as novel elasto- and electrooptical materials

We have studied optical parametrical effects (electrooptical and elastooptical ones) at wavelength 1150 nm generated by continuous He-Ne laser. We have found that the maximal value of the effective electrooptics coefficient is equal to about 12.6 pm/V and of the elastooptical coefficient was 12 · 10¹⁴ m²/N and was achieved at temperature about 300 K. l-lysine monohydrochloride dihydrate (C₆H₁₄N₂O₂, HCl·2H₂O, LLMHCl), a semiorganic potential nonlinear optically active crystal belongs to noncentrosymmetry class P2₁. FTIR and FT Raman of this crystal have been studied at room temperature. The vibrational spectral characterization has been carried out for different Raman configurations and has been interpreted following existed crystal structural data and factor group analysis. Following the performed analysis it was discovered that the principal role in the observed electrooptics group plays the vibrational bands originating of the functional groups such as [NH₃]⁺, C=O, O-H, C-H, C-N, O-C=O, C-N-C-C ring, C-OH. For elastooptical effects the principal role belongs to the modes situated at 3500-1500 cm^− 1 originating from stretching vibrations of [NH₃]⁺, CH₂, C=O, COO⁻ and C-N groups.     

Synthesis, growth, and characterization of nonlinear optical material l-arginine iodate crystal

Single crystals of nonlinear optical l-arginine iodate (l-Arg·2HIO₃) (C₆H₁₄N₄O₂·2HIO₃), were successfully grown for the first time by the temperature-lowering method and also by the slow evaporation method at a constant temperature (30 °C) from its aqueous solution at pH value of 6. Crystals were of average dimensions 3 × 2.5 × 1.0 cm³ by optimizing the growth parameters. Initially, solubility studies were carried out for four different solvents such as water, water-methanol, water-ethanol, and water-acetone. Among the four solvents, the solubility of l-Arg·2HIO₃ was found to be the highest in water and hence crystallization of l-Arg·2HIO₃ was carried out from aqueous solution. Morphology studies reveal that the crystals grow with reasonable growth rate along the [100], [001], [110¯] and [011] direction. As-grown crystals were characterized by density measurement, X-ray powder diffraction studies, infrared spectrophotometer, UV-Vis spectrometer, laser induced damage threshold studies and nonlinear optical study.     

Crystallization and characterization of nonlinear optical material l-arginine formomaleate

The influence of mixed acids in the growth and characteristic properties of a new nonlinear optical material l-arginine formomaleate abbreviated as LAFM was examined. Single crystal X-ray diffraction analysis was used to calculate the lattice parameters of the crystals. Fourier transform infrared (FTIR) spectroscopy and thermal analysis (DTA, TGA) were performed to study the molecular vibrations and thermal behaviour of the crystals. UV-VIS spectral study shows that LAFM is transparent down to 315 nm and its second harmonic generation efficiency is 1.2 times that of KDP.     

Synthesis, spectral and thermal studies of new nonlinear optical crystal: l-valinium fumarate

An organic nonlinear optical material, l-valinium fumarate (abbreviated as LVF) has been successfully synthesized and good quality single crystals have been grown by low temperature solution growth method. The purified form of LVF is achieved by repeated crystallization. The cell parameters of LVF have been determined using single crystal X-ray diffraction technique and the crystal system is found as monoclinic. From the UV-Vis-NIR absorption spectrum, the good transparency is revealed from 300 nm to 1100 nm. The mode of vibration of different molecular groups present in LVF was identified by FT-IR spectral analysis. The thermogravimetric (TGA) and differential thermal analysis (DTA) studies show the thermal behavior and crystal was thermally stable up to 266 °C. Second harmonic generation (SHG) conversion test was made to explore the nonlinear optical behavior of this material using Kurtz and Perry method.     

Studies on lithium l-ascorbate dihydrate: An interesting chiral nonlinear optical crystal

Lithium l-Ascorbate dihydrate (LLA) is a new metal organic nonlinear optical crystal belonging to the saccharide family. Single crystals of LLA were grown from aqueous solution. Solubility of the crystal has a positive temperature coefficient facilitating growth by slow cooling. Rietveld refinement was used to confirm the phase formation. The crystal has prismatic habit with (010), (001) and (10−1) prominent faces. Thermal analysis shows that the crystal is stable up to 102 °C. Transmission spectrum of the crystal extends from 302 nm to 1600 nm. Dielectric spectroscopic analysis revealed Cole–Cole behaviour and prominent piezoelectric resonance peaks were observed in the range of 100–200 kHz. Second harmonic generation (SHG) conversion efficiency of up to 2.56 times that of a phase matched KDP crystal was achieved when the (010) plate of LLA single crystal was rotated about the +ve c axis, by 9.4° in the clockwise direction. We also observed SHG conical sections which were attributed to noncollinear phase matching. The observation of the third conical section suggests very high birefringence and large nonlinear coefficients. A detailed study of surface laser damage showed that the crystal has high multiple damage thresholds of 9.7 GW cm⁻² and 4.2 GW cm⁻² at 1064 nm and 532 nm radiation respectively.     

Crystal growth and characterization of new nonlinear optical single crystals of l-alaninium fumarate

Amino acid based crystals exhibit excellent nonlinear and electro optical properties. A new nonlinear optical single crystal l-alaninium fumarate (LAF) belonging to the amino acid group was grown by slow evaporation solution growth technique. Single crystal X-ray diffraction study showed that LAF belongs to orthorhombic crystal system. The UV-Vis-NIR spectrum of LAF showed very good transparency in the region from 300 nm to 1100 nm. Fourier transform infrared is used to confirm the presence of various functional groups in the grown crystal. Thermal properties of the LAF crystal were carried out by thermogravimetric analysis (TGA) and differential thermal analysis (DTA) techniques, which indicate that the material does not decompose before melting. The melting point of grown crystal was observed as 267.5 °C by melting point apparatus. The existence of nonlinear optical (NLO) property of LAF was confirmed by second harmonic generation test using Nd:YAG laser fundamental wavelength of 1064 nm.     

Growth and characterization of a new NLO material: l-Glutamic acid hydro bromide [l-GluHBr]

l-(+)-Glutamic acid hydro bromide, an isomorphic salt of l-glutamic acid hydrochloride, was synthesized and the synthesis was confirmed using Fourier transform infrared analysis. Solubility of the material in water was determined. l-Glutamic acid hydro bromide crystals were grown by low temperature solution growth using the solvent evaporation technique. Single crystal X-ray diffraction studies were carried out and the cell parameters, atomic co-ordinates, bond lengths and bond angles were reported. High-resolution X-ray diffraction studies were carried out and good crystallinity for the grown crystal was observed from the diffraction curve. The grown crystals were subjected to dielectric studies. Ultraviolet-visible-near infrared spectral analysis shows good optical transmission in the visible and infrared region of the grown crystals. The second harmonic generation efficiency of l-glutamic acid hydro bromide crystal was determined using the Kurtz powder test and it was found that it had efficiency comparable with that of the potassium di-hydrogen phosphate crystal.     

Investigation on the nucleation kinetics of antiferroelectric ADP admixtured ferroelectric TGS crystals

Induction period and interfacial energy have been determined for the aqueous solution growth of ammonium dihydrogen orthophosphate admixtured triglycine sulphate. It is observed that the induction period decreases exponentially with supersaturation and hence the nucleation rate increases with the increase of supersaturation. The solubility of synthesized ADPTGS has been estimated at different temperatures. ADPTGS has a positive temperature coefficient of solubility. Nucleation parameters such as radius of the critical nucleus, number of molecules in the critical nucleus and critical free energy change have also been investigated.     

Growth and characterization of an organic nonlinear optical material: l-alanine alaninium nitrate

l-alanine alaninium nitrate (LAAN), an organic nonlinear optical material was grown by slow evaporation technique at room temperature from its aqueous solution at pH value of 2.5. As grown single crystals were characterized for its spectral, thermal, linear and second order nonlinear optical properties. LAAN crystallizes in monoclinic system with space group P₂₁ and cell parameters a = 7.846 Å, b = 5.431 Å, c = 12.806 Å and β = 94.65°. The mode of vibrations of different molecular groups present in LAAN were identified by FTIR studies. The thermal behaviour of the crystals has been investigated using thermogravimetry (TG) and differential thermal analysis (DTA), which indicates that the material does not decompose before melting. Transmittance spectrum reveals that the crystal has a low UV cut-off of 320 nm and has a good transmittance in the entire visible region. NLO property of the crystal was confirmed by Kurtz SHG powder technique.     

Growth and characterization of l-phenylalanine nitric acid, a new organic nonlinear optical material

A new organic nonlinear optical material L-phenylalanine nitric acid [2C₉H₁₁NO₂.H⁺. NO₃⁻] (LPN), was synthesized in mixed solvent of deionised water and methanol and single crystals of LPN was grown by slow evaporation method. Transparent crystals upto 2.9 × 0.3 × 0.05 cm³ were obtained. The grown crystals have been subjected to powder X-ray diffraction studies to identify the crystalline nature. Single crystal X-ray diffractometer was utilized to measure unit cell parameters and to confirm the crystal structure. The modes of vibration of different molecular groups present in LPN were identified by FTIR spectral analysis. Transmission spectra reveals that the crystal has low UV cutoff of 295 nm and has a good transmittance in the entire visible region enabling its use in optical applications. Thermal properties of the crystals have been investigated using thermogravimetric (TG) and differential thermal analyses (DTA), which indicate that the material does not decompose before melting. The existence of second harmonic generation signals was observed using Nd:YAG laser with fundamental wavelength of 1064 nm.     

Nucleation studies and surface SHG analysis of l-arginine phosphate monohydrate (LAP) family crystals

The metastable zone width and the nucleation parameters, such as interfacial tension, radius of the critical nucleus and critical free energy change have been estimated for pure l-arginine phosphate (LAP), potassium thiocynate (KSCN) mixed LAP (LAP:KSCN) and sodium sulfite (Na₂SO₃) mixed LAP LAP:Na₂SO₃ single crystals. Pure and additive mixed LAP single crystals are grown by slow cooling technique. The surface second harmonic generation (SHG) analysis is done on (100) face of the grown crystals. The SHG intensity on (100) face of the crystals are measured.     

Theoretical investigations of optical properties of l-arginine trifluoroacetate crystal

In order to determine the molecular dipole moment (μ), polarizability (α), and first hyperpolarizability (β) of l-arginine trifluoroacetate (LATF) crystals, a series of basis sets including polarized and diffuse functions have been employed at the framework of Hartree–Fock and second order Möller–Plesset perturbation theory methods. The MP2/6-311++G(d,p) model predicts for the converged value of in-crystal dipole moment, polarizability and first hyperpolarizability are 21.2 D, 20.0 × 10⁻²⁴ esu and 50.0 × 10⁻³¹ esu, respectively. The calculated HOMO and LUMO energies show that charge transfer occur within the molecule. Electronic excitation properties are discussed within the framework of the two-level model on the basis of an orbital analysis. The coupled perturbed Hartree–Fock (CPHF) procedure yields information on the dispersion behavior of first hyperpolarizability terms. The magnitudes of the various hyperpolarizability terms which describe the various second-order nonlinear processes show the following trend: β(−2ω;ω,ω) > β(0;ω,−ω) > β(0,0,0). By using the molecular structures and the molecular first hyperpolarizability, the components of second harmonic tensor coefficient d of the crystals were evaluated by the oriented-gas model.     

Studies on the growth and physical properties of nonlinear optical crystal: 2-Amino-5-nitropyridinium-toluenesulfonate

Single crystals of 2-amino-5-nitropyridinium-toluenesulfonate (2A5NPT) were grown by the slow cooling method. The unit cell dimensions were determined from single crystal X-ray diffraction studies. The thermal parameters - thermal diffusivity (α), thermal effusivity (e), thermal conductivity (K) and heat capacity (C_p) of 2A5NPT were measured by an improved photopyroelectric technique at room temperature. Single and multiple shot experiments performed on the grown crystals for the second harmonic of pulsed Nd:YAG laser (532 nm) show that it exhibits a high laser damage threshold which is a favorable property for nonlinear optical applications. Dielectric constant and dielectric loss of the grown crystal were evaluated for the frequency range 1 kHz-1 MHz in the temperature region 40-130 °C. Hardness values were measured using Vickers hardness measurement.     

Synthesis, growth, structural, optical, photoconductivity and dielectric studies on potassium p-nitrophenolate dihydrate: A new semiorganic nonlinear optical material

Potassium p-nitrophenolate dihydrate, a potential semiorganic nonlinear optical material, has been synthesized and grown by slow evaporation technique at room temperature. Single crystal X-ray analysis presents an unprecedented bonding between ions in the crystal with acentric structure. In the new structural investigation, p-nitrophenolate instead of producing bond between phenolic O⁻ and K⁺, it seems to put nitro group in bonding with the metal ion. Optical absorption shows excellent transmission in the entire visible and near-infrared region. Room temperature photocurrent, transport properties are carried out in order to enhance the application for second harmonic generation and opto-electronic devices. Dielectric constant is found to be independent at higher frequencies. The crystal possesses prominent positive photoconduction in the presence of photoactive centers formed with trap energy level. The nonlinear optical activity is confirmed by Kurtz powder test.     

Mechanical,thermal and laser damage threshold analyses of II group metal complexes of thiourea

Single crystals of thiourea metal complexes with selected Group II metal ions, Zinc and Cadmium, have been grown by solvent evaporation technique. The crystals grown are bisthiourea zinc chloride (BTZC) and bisthiourea cadmium chloride (BTCC). Following an improved photopyroelectric technique, the thermal transport properties have been determined. It is found that BTCC has a higher heat capacity (304.09 J kg⁻¹ K⁻¹) than BTZC (255.24 J kg⁻¹ K⁻¹), and hence BTCC has better thermal stability. Vicker's microhardness measurements reveal that these materials have reverse indentation size effect and belong to the category of soft materials. Elastic stiffness is found to be higher for BTCC (1.57 GPa) than BTZC (0.76 GPa). The roles of the Group II metal ions in improving the mechanical and thermal stability of the metal complexes are discussed. Multi-shot laser damage studies on these materials reveal that BTCC has a higher laser damage threshold (15 GW cm⁻²) than BTZC (6 GW cm⁻²).     

Crystal structure and characterization of a novel organic optical crystal: 2-Aminopyridinium trichloroacetate

2-Aminopyridinium trichloroacetate, a novel organic optical material has been synthesized and crystals were grown from aqueous solution employing the technique of controlled evaporation. 2-Aminopyridinium trichloroacetate crystallizes in monoclinic system with space group P2₁/c and the lattice parameters are a = 8.598(5) Å, b = 11.336(2) Å, c = 11.023(2) Å, β = 102.83(1)° and volume = 1047.5(3) Å³. High-resolution X-ray diffraction measurements were performed to analyze the structural perfection of the grown crystals. Thermal analysis shows a sharp endothermic peak at 124 °C due to melting reaction of 2-aminopyridinium trichloroacetate. UV-vis-NIR studies reveal that 2-aminopyridinium trichloroacetate has UV cutoff wavelength at 354 nm. Dielectric studies show that dielectric constant and dielectric loss decreases with increasing frequency and finally it becomes almost a constant at higher frequencies for all temperatures. The negative nonlinear optical parameters of 2-aminopyridinium trichloroacetate were derived by the Z-scan technique.