Monoclinic distortion, polarization rotation and piezoelectricity in the ferroelectric NaBiTiO.

The relationship between crystal structure and physical properties in the ferroelectric NaBiTiO (NBT) has been of interest for the last two decades. Originally, the average structure was held to be of rhombohedral (3) symmetry with a fixed polarization direction. This has undergone a series of revisions, however, based on high-resolution X-ray diffraction, total neutron scattering, and optical and electron microscopy.