Thermal flexibility of microporous titanosilicate with distorted pharmacosiderite structure

The framework flexibility of the nanosized rhombohedrally distorted titanosilicate analog of the mineral pharmacosiderite (RTS) has been in situ studied by powder X-ray diffraction at elevated temperatures. Between 30 and 175 °C the rhombohedral lattice showed tendency to shrink and open the angle of the axes. At 125 °C the cell distortion resulted in pseudo cubic cell metrics where the reflections (0 2 1), (0 1 −2), (2 1 1), (2 2 0), (3 0 1) and (3 1 1) have been reduced. After heating at 175 °C the recovery of the reduced reflections has not been completed and the lattice remained shrank at room temperature.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Framework distortion of rhombohedral titanosilicate with pharmacosiderite structure. ► Thermal control of the structural changes. ► Determination of the thermal limits of framework reversibility. ► Preservation of the framework changes at ambient conditions.