Influence of dopant concentration on the structure and physical properties of NdimagePbimageMnOimage single crystals

The structure of NdimagePbimageMnOimage crystal for image is determined at room temperature by single-crystal X-ray diffraction. The structural refinement reveals that the crystal is tetragonal with space group image, image and image of 8.3image. The lattice parameters are image Å, image Å and image. The structural analysis is then extended to image. It is noticed that substitution of Pb at the Nd site results in structural phase change from tetragonal (image) to cubic (image). These changes are attributed to the progressive removal of inter-octahedral tilting and minimization of the octahedral distortion leading to a higher symmetry as doping concentration increases. While the unit cell volume of tetragonal structure (image) is comparable to that of parent NdMnOimage (image), the volume of cubic unit cell (image) is doubled. Electron diffraction patterns support these results and rule out the possibility of twinning. Changes in transport properties as a function of temperature at different doping levels are in accordance with the observed structural changes. It is observed that image and image increase with image.