THERMAL AND CRYSTALLOGRAPHIC PROPERTIES OF A NEW NLO MATERIAL, UREA-(D)TARTARIC ACID SINGLE-CRYSTAL

The crystallographic and thermal properties including thermal expansio n coefficients and specific heat as well as differential scanning calo rimeter (DSC), thermogravimetric analysis (TG) curves for a single cry stal of a new organic nonlinear optical material, urea-(d)tartaric aci d (UDT) are reported. It is orthorhombic and belongs to the D-2 point group and P2(1)2(1)2, space group, a = 17.229(6) Angstrom, b = 9.824(3 ) Angstrom, c = 5.056(2) Angstrom, V = 855.77 Angstrom(3), Z = 4 and D -m = 1.63 g/cm(3) The second harmonic generation (SHG) of UDT, based o n powder measurement, is three times higher than that of KDP. Its tran sparency range is from 240 to 1395 nm. (C) 1998 Elsevier Science B.V.