Nanocluster crystals of lacunary polyoxometalates as structure-design-flexible, inorganic nonlinear materials

Lacunary polyoxometalates, large inorganic, structure-design-flexible, nano cluster crystals are found to have higher optical nonlinearity than KH2PO4 by the powder second-harmonic-generation method. Moreover, the capability o f generating ultraviolet radiation down to around 300 nm is found. The basi c criteria to design the high nonlinearity are also discovered by the reduc tion of the molecular symmetry. (C) 2001 American Institute of Physics.