Optical, thermal, mechanical and dielectric studies of NLO active unidirectional grown l-alanine lithium chloride single crystal by SR method

Abstract

The bulk single crystal of l-alanine lithium chloride (LAL), an efficient semiorganic nonlinear optical (NLO) material of size 60mm in length, 15mm in diameter was grown successfully in unidirectional by Sankaranarayanan Ramasamy (SR) method. Single crystal X-ray diffraction study reveals that LAL crystallizes into orthorhombic system with the space group Pna21. The unidirectional growth along the plane (101) was confirmed from the powder XRD pattern with the sharp peak having maximum intensity. Optical absorption spectrum shows that LAL has highly transparent in the entire visible region with a wide band gap of 3.55eV for large photon absorption. Thermal studies brings forth that the crystal is stable up to 84.2°C. Photoconductivity measurements carried out on the grown crystal reveals positive photoconductivity. Photoluminescence study establishes that LAL exhibit green emission in the wavelength region 525nm. The Vicker's microhardness test is used for the assessment of fracture toughness, brittleness index and yield strength for the synthesized crystal. Dielectric constant and dielectric loss were calculated by varying frequency at different temperatures. The SHG efficiency of the crystal is also examined by Kurtz's powder test using Nd:YAG Laser.