Crystal structures of RbTiOAsO₄, KTiO(P_0.58,As_0.42)O₄, RbTiOPO₄ and (Rb_0.465,K_0.535)TiOPO₄, and analysis of pseudosymmetry in crystals of the KTiOPO₄ family

Abstract

The crystal structures of RbTiOAsO4, KTiO(Po.58,-AS0.42)O4, RbTiOPO4 and (Rbo.465,Ko.535)TiOPO4, all of which are orthorhombic (space group Pna2~)and isostructural with KTiOPO4, have been determined from single-crystal X-ray diffraction data and refined to R factors between 0.027 and 0.040. The results are used for an analysis of structural trends in crystals of the KTiOPO4 family by comparison of the room-temperature structures with that proposed for the high-temperature prototypic phase (space group Pnan). RbTiOAsO4, KTiO(Po.ss,Aso.42)O4, RbTiOPO4 AND (Rbo.465,Ko.535)TiOPO4 Crystal colour, shape and size Linear absorption coefficient (cm ') Diffractometer Radiation Scan Lattice parameters (A) Ranges of tl. k. 1

Investigation of the Cs x Rb1−x TiOAsO4 Series. I. Crystal Structure Analysis and Pseudo-symmetry

“…The distribution of Rb and Cs over the M(1) and M(2) sites shows that Cs atoms have a clear preference for the larger M(2) site, which is consistent with previous studies of mixed cation isomorphs (Thomas et al, 1994;Thomas et al, 1992;Northrup et al, 1994). Furthermore, the M(1) and M(2) cages increase in size as more Cs is incorporated.…”

“…Pisarev et al (1990) showed for TlTiOPO 4 (TTP) that the phase transition was characterized by a soft mode associated with displacements of Tl along c coupled with the TiO 6 vibrational modes. This has focused considerable attention upon the role of the monovalent cations in the structural phase transition and, in general, the heavier the cation in a particular framework, the smaller its displacement from the highsymmetry position and the lower T c (Thomas et al, 1992). From the static picture of displacements revealed by the room-temperature structure determinations, a linear relationship for the phase transition temperature T c has been found: T c = GÁD 2 + C, where ÁD 2 is the square of the shift of the M cation relative to the TiO 6 /AsO 4 framework and G and C take the values 840 (96) K A Ê À2 and 988 (21) K, respectively .…”

Trimethyloxosulfonium Salts. IX. Study of some Mixed Compounds, (CH3)3SOCdCl3−xBrx

“…No papers in the literature seem to deal with this subject for the CI-Br couple. We have only found some reports about cationic substitution (Nord, 1983;Thomas, Mayo & Watts, 1992 (1996). C52, 812-817 Trimethyloxosulfonium Salts.…”

Femtosecond-Laser Microstructuring of Ribs on Active (Yb,Nb):RTP/RTP Planar Waveguides

“…It crystallizes in the orthorhombic space group [1]. Because of its non-linear optical properties, RTP can be used for frequency doubling the light emitted by Yb and Nd lasers with a wavelength close to 1 m [2].…”