NEUTRON DIFFRACTION OF KTiOPO₄ AND ISOMORPHS. Jenni Almgren, Goran Svensson, Jorgen Albertsson, Dept of Inorganic Chemistry, Chalmers University of Technology, S-412 96 Goteborg, Sweden (jean@inoc.chalmers.se)

This neutron diffraction study on potassium titanyl phosphate (KTiOPO₄, KTP) and its analogues RbTiOAsO₄ (RTA) and CsTiOAsO₄ (CTA) was made at the Studsvik Neutron Research Laboratory (Uppsala, Sweden). Data from powder samples have been collected in the range 0< 2[[theta]] <129deg., with a step size of 0.08deg. at a temperature of 295 K. Neutron diffraction has been used to retrieve a better understanding of structure and property relationships such as accurate metal to oxygen distances. Refinement of the data sets by the Rietveld method is in progress.

Crystallographic studies of the KTP isomorphic family are part of a project at our department engaged in producing the materials and then investigating physical and chemical properties. The obstacles for technological use of RTA and CTA are the difficult and expensive growth techniques needed to produce these crystals. We have built two four-zone furnaces to accomodate top seeded solution growth of single crystals of CTA and RTA from self fluxes. Our objective is to obtain single crystals of optical quality and improved size by optimizing growth parameters.

KTP has non-linear optical (NLO) properties and is commercially used as waveguides in integrated optical devices. The active site in the crystal structure, for second harmonic generation, is the slightly deformed octahedron of oxygen atoms around titanium. Arsenate isomorphs of KTP such as RTA and CTA have different NLO-properties compared to KTP and the arsenate analogues give frequency conversion in a broader wavelength region. The development of blue light generating solid state laser is needed to further increase information storage and transmission. The isomorphs RTA and CTA can be used in LIDAR technology, optical parametric oscillation devices and tunable lasers.