STRUCTURE AND PROPERTIES OF THE NONCENTROSYMMETRIC OXIDE BORATE K2GA2O(BO3)(2)

Crystals of a new, noncentrosymmetric oxide, orthoborate have been gro wn, and the structure of the material has been determined by X-ray dif fraction techniques. The material crystallizes in the space group P321 . The structure consists of a continuous, three-dimensional gallium be rate framework with channels that run parallel to the [001] direction wherein the potassium atoms are located. The triangular orthoborate gr oups and the trigonal bases of the gallium-centered tetrahedra form tw o-dimensional layers through Ga-O-B linkages; these layers are paralle l to (001) planes. Ga-O-Ga linkages interconnect adjacent layers to co mplete the three-dimensional framework. Use as a nonlinear optical mat erial is unlikely because of nonoptimal alignment of the triangular or thoborate groups. (C) 1997 Elsevier Science Ltd.