Growth and characterization studies of ferroelectric diglycine nitrate (DGN) single crystals

Single crystals of diglycine nitrate [(NH2CH2COOH)2HNO3] (DGN), a ferroelectric material with Curie temperature 206 K, were grown in silica gel at room temperature by the solubility reduction method at room temperature (39 °C). Bulk crystals of dimension 21 mm × 18 mm × 11 mm have been grown by optimizing the growth conditions. The grown crystals have been characterized by structural, optical and mechanical characterization studies. Fourier transform infrared (FTIR) spectral analysis reveals that the crystal consists of all functional vibrational groups. FT-Raman spectrum, which is complement to FTIR studies, has also been recorded. Surface analysis by SEM reveals that the crystal absorbs water from the moisture. The optical transparency range and the lower cut-off of UV transmission were identified from the recorded UV–vis spectrum of DGN. The UV cut-off wavelength of DGN is 286 nm. Thermal analysis of the crystalline sample was performed by TGA and DTA methods. The crystal is thermally stable up to 217 °C. The Vicker's microhardness value of DGN crystal is decreases with increase of load. The work hardening coefficient (n) of diglycine nitrate was determined using the least squares fit method and found to be 1.5.