Growing Oriented Layers of Bi4Ti3O12 in Bi2O3/TiO2/SiO2/Nd2O3/ Al2O3 Glass-Ceramics by Melt Quenching

A glass melt with the composition 24Bi(2)O(3)/40TiO(2)/10SiO(2)/10Nd(2)O(3)/16 Al2O3 was prepared and rapidly quenched between two copper blocks (sample A). A part of this glass was subsequently crystallised at 800 degrees C for 8 h (sample B). For the preparation of another two samples, the melt was slowly cooled on a cooper plate (sample C) or cast into a graphite mould and subsequently thermally treated at 300 degrees C for 3 h (sample D). As shown by X-ray diffraction (XRD) and scanning electron microscopy (SEM) including energy dispersive X-ray spectroscopy (EDXS) and electron backscatter diffraction (EBSD) measurements, the rapidly cooled samples contained notable amounts of uncrystallised glassy phase next to the Aurivillius phase Bi4Ti3O12. The latter occurred in higher concentrations in all other samples and formed oriented layers. Minor concentrations of Bi(2)AI(4)O(9) and Al2O3 were also detected in the microstructure.