The effect of malonic acid on the physico-chemical characterisation of 4-hydroxy pyridine: A new third order NLO single crystal

Designed Metal-Free Quasi-1D Crystals with Giant Birefringence

Birefringence, a vital property of anisotropic crystals, is indispensable for advanced optical technologies. Quasi-1D structures, with their inherent structural anisotropy, offer fertile ground for discovering materials with exceptional optical anisotropy. In this work, we report four metal-free quasi-1D crystals-(C5H6NO)+(NO3)-(4HPN), (C5H6NO)+(HC2O4)-(4HPO), (C4N3H6)+(NO3)-(2APMN), and (C4N3H6)+(HC2O4)-·H2O (2APMO)-designed to feature pseudo-chain structures and grown as centimeter-scale crystals via a facile aqueous-solution method. These crystals display wide bandgaps (3.40-4.48 eV) and exceptional birefringence, with calculated values up to 0.555@546 nm and an experimental maximum of 0.597@546 nm for 4HPN. The giant birefringence stems from their quasi-1D architectures, high-spatial density, and optimal arrangement of the birefringence-active groups (BAGs). This study highlights the promise of metal-free quasi-1D materials for next-generation miniaturized polarization optics and laser-driven applications.

Theoretical insight on the optical centred electrical properties of guanidinium isophthalate NLO crystal for electro-optic Q switches

Guanidinium isophthalate single crystals with dimensions 16 × 4 x 2 mm3 were prepared by the low temperature solvent evaporation method and growth kinetics with interfacial tension was discussed to bring out the growth parameters of guanidinium isophthalate single crystals. The harvested single crystals were utilized for various characterization studies like powder X-ray diffraction, optical transmission, photoluminescence, laser damage study and optical limiting studies. The visualization of varying potential regions on the surfaces to quantify short contacts were generated by Hirshfeld surface analysis. 2D fingerprint plots were analyzed, in which H ….H contact was found to be the most significant with 54.1%. Growth kinetics of the crystalline material was studied to reveal the nucleation process. Crystal samples prepared with reference to the solubility data were found to be free of inclusions and cracks and had maximum transmittance in the complete visible region. The electronic disorder of the crystal sample was reported in the form of Urbach energy. The PL spectra with the emission intensity provide the emission characteristic of the title compound. The major fundamental optical limit for a crystal material is experimentally measured and presented in the picosecond regime. Thus the present work contributes to the understanding of growth, structural, optical and electronic characteristics of the title guanidinium isophthalate single crystals for the fabrication of electro-optic devices in photonic industry.