So Yon Lee has completed her Bachelor’s degree at Chung-Ang Univeristy and is currently on her Master’s degree at Chung-Ang University. She is advised by Prof. Kang Min Ok in the inorganic chemistry labratory. So, she is working on the synthesis and characterization of new noncentrosymmetric materials.
Materials crystallizing in noncentrosymmetric (NCS) structures may show certain properties such as pyroelectricity, piezoelectricity, ferroelectricity and nonlinear properties. To achieve a macroscopic NCS structure, bismuth, tellurium and NO3- were used in the synthesis as constituents. Since the lone pairs on bismuth and tellurium are stereochemically active, they can exhibit asymmetric environment. The π-conjugated electron in the NO3 group can also facilitate the nonlinear optical property. The hydrothermally synthesized material reveals a layered nonpolar structure with a weak hydrogen bond interaction. The compound crystallizes in the orthorhombic space group, P-21-21-21. Two types of existing telluriums, Te4+ and Te6+ show see-saw and octahedral coordination environment with oxide ligands, respectively. Bi3+ cations are linked to oxygen atoms and form BiO9 and BiO10 polyhedra. NO3- is connected to the bismuth atoms. Powder second-harmonic generation(SHG) measurements indicate that the NCS material has a SHG efficiency of 20 times that of α-SiO2