Electrical, optical, and mechanical properties of modified Czochralski grown organic 4-nitrobenzaldehyde single crystal

Abstract

Growing large crystals of organic compounds with low melting points is a challenge but it was resolved by suitable modifications of the Czochralski (CZ) technique in the present study. A nonlinear optical single crystal of 4-nitrobenzaldehyde (4-NB) with a cylindrical shape, length of 2.5 cm, and diameter of 3 mm was successfully grown using an inexpensive modified CZ crystal growth technique at a temperature of 106 °C. The crystal structure and lattice parameters of the as-grown crystal were determined by single crystal and powder X-ray diffraction analyses. Intermolecular interactions were studied in the 4-NB crystal based on the Hirshfeld surface and two-dimensional fingerprint plot. The presence of various functional groups in the as-grown crystal was confirmed by Fourier transform infrared spectroscopy and nuclear magnetic resonance (1H and 13C) spectroscopy. The thermal behavior of the 4-NB crystal was analyzed by thermogravimetric analysis and differential thermal analysis. High transparency (75%) with an optical band gap of 3.34 eV and lower cut-off of 370 nm were confirmed by ultraviolet–visible–near infrared spectroscopy. The temperature-dependent dielectric behavior was determined for the 4-NB crystal at a constant frequency of 5 kHz. The mechanical properties of the 4-NB single crystal were analyzed based on the Vickers microhardness and void analysis, which confirmed the soft nature of the crystal. The modified CZ technique allowed us to obtain disk-shaped organic 4-NB crystals for use in optical applications.