Experimental and theoretical investigations of propyl para-hydroxybenzoate crystal for optical applications

Propyl para-hydroxybenzoate (PHB) known as Propylparaben is an organic family that single crystal is grown by solvent evaporation process with a solvent like methanol. The value of unit cell geometry and the crystalline system with space group nature are estimated from the single-crystal XRD study. From the optical spectra, the lower absorption wavelength edge is measured using the visible optical spectrum of range 200–1200 nm. From the absorption edge value, different optical parameters such as band gap, extinction coefficient with absorption, optical and electrical conductivity, Urbach energy, and susceptibility values are measured. Also, the grown PHB crystals’ different dispersion parameters and strength of oscillator are also evaluated by using Wemple Di-Domenico single oscillator method. Third-order nonlinear parameters such as refractive index, nonlinear absorption coefficient, and nonlinear susceptibility are evaluated as 5.99 × 10−9cm2/W, 3.41 × 10−4 cm/W, and 5.76 × 10−6 esu by using the z-scan method. The microhardness analysis and different mechanical properties such as elastic stiffness constant, yield strength, fracture toughness, and Brittleness index are also estimated. The basic important solid-state properties such as the energy of plasma, Penn, and Fermi gap and the value of molecular electronic polarizability are measured and compared from various methods as the coupled dipole method, Clausius–Mossotti relation, and Lorentz equation. The intermolecular interaction of the PHB molecule is confirmed by the Hirshfeld surface study, and their percentage is evaluated by using a fingerprint plot.