Electronic Optical Band Gap Research Articles

Crystal growth and investigation of novel semi organic single crystal: l-malic acid sodium nitrate for photonic applications

l-Malic acid sodium nitrate, a novel semi organic nonlinear optical crystal was grown from aqueous solution by slow evaporation method at room temperature. The cell parameters for the grown crystal were determined by using single crystal X-ray diffraction method. The different functional groups with different modes of vibrations were confirmed by FTIR spectral analysis. The optical absorption studies show that the crystal has wide optical transparency in the entire visible region. From UV absorption profile, the electronic optical band gap and Urbach energy is calculated as 5.0 eV and 0.1401 eV. The photoluminescence spectra exhibit different peaks to indicate the single transitional band structure and high purity of the grown crystal. The EDAX and SEM study shows the presence of elements in the grown crystal and growth of second layer over the surface. The second harmonic generation efficiency was confirmed by the Kurtz powder method using Nd:YAG laser with fundamental wavelength of 1064 nm. DSC study shows that the grown crystal was thermally stable up to 273 °C. The dielectric behavior of the grown crystal was measured in the frequency range 50 Hz–5 MHz at different temperatures. The Vickers micro hardness studies were carried out on the grown crystals and there by Vickers hardness number (Hv) and work hardening coefficient (n) were calculated.

Growth, spectral and optical characterization of a novel nonlinear optical organic material: d-Alanine dl-Mandelic acid single crystal

An organic nonlinear optical single crystal, d-alanine dl-mandelic acid was synthesized and successfully grown by slow evaporation solution growth technique at ambient temperature using solvent of aqueous solution. The unit cell parameters were assessed from single crystal X-ray diffraction analysis. The presence of diverse functional groups and vibrational modes were identified using Fourier Transform Infra Red and Fourier Transform Raman spectral analyses. The chemical structure of grown crystal has been identified by Nuclear Magnetic Resonance spectroscopic study. Ultraviolet–visible spectral analysis reveal that the crystal has lower cut-off wavelength down to 259 nm, is a key factor to exhibit second harmonic generation signal. The electronic optical band gap and Urbach energy is calculated as 5.31 eV and 0.2425 eV respectively from the UV absorption profile. The diverse optical properties such as, extinction coefficient, reflectance, linear refractive index, optical conductivity was calculated using UV–visible data. The relative second harmonic efficiency of the compound is found to be 0.81 times greater than that of KH2PO4 (KDP). The thermal stability of the grown crystal was studied by thermogravimetric analysis and differential thermal analysis techniques. The luminescence spectrum exhibited two peaks (520 nm, 564 nm) due to the donation of protons from carboxylic acid to amino group. The Vickers microhardness test was carried out employing one of the as-grown hard crystal and there by hardness number (Hv), Meyer's index (n), yield strength (σy), elastic stiffness constant (C11) and Knoop hardness number (HK) were assessed. The dielectric behaviour of the as-grown crystal was analyzed for different temperatures (313 K, 333 K, 353 K, and 373 K) at different frequencies.