SYNCHROTRON-RADIATION TOPOGRAPHY STUDIES OF TWINNING IN NDP5O14 CRYSTALS

An investigation of twin structures in NdP5O14 single crystals has bee n undertaken using white-beam synchrotron x-ray topography. The so-cal led a-type twins along the a axis are clearly revealed in the topograp hs. The displacements of the images that arise from the twins are dire ctly measured in different topographs. With the measured values, the m onoclinic distortion angle delta(delta = beta-90-degrees) is calculate d, which is in good agreement with the unit cell parameters. A fine-be am Laue diffraction pattern of the twin has also been taken which is w ell consistent with its simulation. From these results, the twin struc tures of NdP5O14 are discussed.