Synchrotron radiation topography studies of twinning in NdP5O14 crystals

An investigation of twin structures in NdP5O14 single crystals has been undertaken using white-beam synchrotron x-ray topography. The so-called a-type twins along the a axis are clearly revealed in the topographs. The displacements of the images that arise from the twins are directly measured in different topographs. With the measured values, the monoclinic distortion angle δ(δ=β−90°) is calculated, which is in good agreement with the unit cell parameters. A fine-beam Laue diffraction pattern of the twin has also been taken which is well consistent with its simulation. From these results, the twin structures of NdP5O14 are discussed.