N. Manopradha, S. Rama, S. Gowri, K. Kirubavathi and K. Selvaraju
This work illustrates the significance of kinetic parameters of nucleation and thermal decomposition for Pyridine-2-carboxylic acid crystals. In the interest of maximizing the growth condition for the production of single crystals, nucleation parameters such as interfacial energy (σ), volume free energy (ΔGv), critical energy barrier for nucleation (ΔG*), radius of the critical nucleus (r*) and nucleation rate (J) were determined from the classical nucleation theory of solubility-enthalpy relation. The optimized geometry of the compound was computed from the DFT-B3LYP gradient calculations employing 6-31G(d,p) basis set and its vibrational frequencies were evaluated. Based on the vibrational analysis, the thermodynamic parameters were obtained and the correlative equations between these thermodynamic properties and variation in temperatures were also reported.
S. Reena Devi, S. Suresh, S. Kalaiyarasi, M. Nizammohideen and R. Mohan Kumar
A novel 4-methylpyridinium 3-nitrophthalate (4MP3NP) was synthesized and the crystals were grown by using slow evaporation method. The structural data of the grown crystal was collected by single crystal X-ray diffraction. It revealed that the 4MP3NP crystal belongs to triclinic crystal system with a space group P1. Structure of the synthesized compound was established using SHELXL 97 program package. The crystalline nature and composition of the grown crystal was established using high resolution X-ray diffraction and FT-IR analyses. UV-Vis transmittance and photoluminescence studies revealed the optical transmission window and electronic transition mechanism of ions, respectively. The laser damage threshold of the grown crystal was estimated by Nd:YAG laser and these results were mutually related to specific heat capacity of the grown crystal. The third-order nonlinear optical susceptibility of the grown crystal was studied by Z-scan technique.
It is important to grow and characterize new bimetallic thiocyanate single crystals as they are expected to exhibit useful optical and electrical properties. In the present study, calcium cadmium thiocyanate CaCd(SCN)4 single crystals were grown by slow evaporation of solvent and were characterized chemically, structurally, thermally, optically and electrically. X-ray diffraction analysis indicates that the grown crystal belongs to the tetragonal crystal system with lattice parameters: a = b = 12.2491(7) Å and c = 15.1012(5) Å. EDAX spectral analysis confirms the expected chemical composition. Thermogravimetric (TG/DTA) measurement implies good thermal stability. Optical (UV-Vis-NIR absorption spectral and SHG efficiency) measurements suggest good optical absorption in the UV and blue regions and the SHG efficiency of 6.13 (in urea unit). The dielectric measurements carried out in the temperature range of 40 °C to 150 °C at five different frequencies, viz. 100 Hz, 1 kHz, 10 kHz, 100 kHz and 1 MHz indicate a normal dielectric behavior.
R. Vasanthakumar, W. Nirmala, R. Santhakumari, R. Meenakshi and A. Sinthiya
4-aminopyridinium adipate monohydrate (4APA) was grown by slow evaporation solution growth technique. The functional groups in the grown crystal were identified from FT-IR spectral evaluation. The optical properties together with transmittance of the grown crystal were obtained from UV-Vis spectroscopic study. The mechanical and thermal properties of the grown crystal were studied using Vickers microhardness and TGA/DTA analyses, respectively. Microhardness test revealed that 4-aminopyridinium adipate monohydrate crystal is a soft category material. The density functional method (DFT) was performed using B3LYP with the 6-311G (d,p) basis set. The electronic charge distribution, reactivity of the molecules and the molecular electrostatic potential (MEP) of the grown crystal were analyzed using the B3LYP method. The intermolecular interactions that exist in the crystal structure of the 4APA have also been investigated by Hirshfeld surface analysis. The nonlinear optical properties of the 4APA crystal were confirmed by Kurtz-Perry technique.