Structure of the mixed oxides La
0.6
Pb
0.4
Mn
1-y
Ti
y
O
3z
(0 y 0.4) via Rietveld refinements
G. Nalini, M. Sahana, M.S. Hegde, T.N. Guru Row*
Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012, India
(Refereed)
Received 3 May 2000; accepted 22 May 2000
Abstract
The crystal structure of several compositions in the system La
0.6
Pb
0.4
Mn
1-y
Ti
y
O
3
(0 y 0.4)
have been investigated by powder X-ray diffraction using the Rietveld refinement technique. The solid
solutions of compositions y = 0.1, 0.2, and 0.3 crystallize in the rhombohedral structure (space group
R3 c), while for the composition corresponding to y = 0.4, the crystal structure transforms from
rhombohedral to orthorhombic system (space group Imma). Profile refinements on all these compo-
sitions reveal that the MnO
6
octahedra are distorted and rotated from their ideal positions. The doping
at the B-site results in the formation of the orthorhombic phase Imma at room temperature. The
structural implications on the magnetic properties also correlate with previous observations. © 2001
Elsevier Science Ltd. All rights reserved.
Keywords: A. Oxides; B. Chemical synthesis; C. X-ray diffraction; D. Crystal structure
1. Introduction
A large number of perovskite systems belonging to La
(1-x)
A
x
Mn
(1-y)
B
y
O
3
have been a
subject of interest due to their wide-ranging physical properties. Various perovskites com-
pounds in these series where the A- and the B-sites are occupied by two cation species have
been synthesized and their crystal structures have been determined.
The crystallographic and magnetic structures of the series of perovskite type compounds
La
1-x
Ba
x
Mn
1-y
Ti
y
O
3
have been determined by neutron powder diffraction [1]. These
* Corresponding author. Tel.: +91-80-309-2796; fax: +91-80-360-1310.
E-mail address: ssctng@sscu.iisc.ernet.in (T.N. Guru Row).
Pergamon Materials Research Bulletin 36 (2001) 307–314
0025-5408/01/$ – see front matter © 2001 Elsevier Science Ltd. All rights reserved.
PII: S0025-5408(00)00474-8