Structural solution of a new mesoporous Rb3Ta5O14 phase

Introduction In exploring the Ca-Rb-Ta-O phase diagram and attempting to grow new four layered members of the technologically interesting Rb2Ca2Ta4O13 perovskite family, a new structural phase was encountered. Initial XRF and EDAX analyses indicated only Rb and Ta components. Single crystal synchrotron X-ray data using BL-14A [1] was measured for the new compound at 0.85Å wavelength, chosen to avoid the 0.81Å Rb absorption edge [2]. Our use of the synchrotron was essential because only a few crystals smaller than 0.05 mm were of suitable quality for study. The Diff14A Software [3] was used to drive the horizontal-type 4circle diffractometer and an eight channel avalanche photodiode detector was used for photon counting [4]. The Rb3Ta5O14 structure was solved from a half sphere of reflection data using SHELXS97 [5]. Subsequent refinement was done with Xtal3.7 [6]. Absorption coefficients [2] and anomalous dispersion coefficients [7] were taken from the tables of Sasaki. The results have been published [8].