Influence of dopant concentration on the structure and physical properties of Nd1-xPbxMnO3 single crystals

Ghosh, Nilotpal ; Elizabeth, Suja ; Bhat, H. L. ; Nalini, G. ; Muktha, B. ; Guru Row, T. N. (2005) Influence of dopant concentration on the structure and physical properties of Nd1-xPbxMnO3 single crystals Journal of Solid State Chemistry, 178 (1). pp. 120-127. ISSN 0022-4596

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Official URL: http://linkinghub.elsevier.com/retrieve/pii/S00224...

Related URL: http://dx.doi.org/10.1016/j.jssc.2004.07.016

Abstract

The structure of Nd1-xPbxMnO3 crystal for x=0.25 is determined at room temperature by single-crystal X-ray diffraction. The structural refinement reveals that the crystal is tetragonal with space group P4/mmm, Z=4 and R of 8.3%. The lattice parameters are a=7.7652(1) Å, c=3.884(1) Å and α =β =γ =90°. The structural analysis is then extended to x=0.38. It is noticed that substitution of Pb at the Nd site results in structural phase change from tetragonal (x=0.25) to cubic (x=0.38). 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 (P4/mmm) is comparable to that of parent NdMnO3 (Pnma), the volume of cubic unit cell (Pm3-m) 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 Tθ and TMI increase with x. Packing diagram of Nd0.75Pb0.25MnO2.76 along b-direction for tetragonal structure.

Item Type:Article
Source:Copyright of this article belongs to Elsevier Science.
Keywords:Manganites; Perovskite; Crystal Structure; Superlattice; MI Transition; Ferromagnetism; Tθ; TMI
ID Code:11795
Deposited On:13 Nov 2010 13:53
Last Modified:16 May 2016 21:12

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