TY - JOUR
T1 - Composition-induced structural phase transitions in the (Ba
1-x
La
x
)
2
In
2
O
5+x
(0≤x≤0.6) system
AU - Tenailleau, C.
AU - Pring, A.
AU - Moussa, S. M.
AU - Liu, Y.
AU - Withers, R. L.
AU - Tarantino, S.
AU - Zhang, M.
AU - Carpenter, M. A.
PY - 2005/3/1
Y1 - 2005/3/1
N2 -
Composition-induced structural phase changes across the high temperature, fast oxide ion conducting (Ba
1-x
La
x
)
2
In
2
O
5+x
, 0≤x≤0.6, system have been carefully analysed using hard mode infrared (IR) powder absorption spectroscopy, X-ray powder diffraction and electron diffraction. An orthorhombic brownmillerite to three-dimensionally disordered cubic perovskite phase transition in this system is signalled by a drastic change in slope of both wavenumber and average line widths of IR spectra as a function of composition. Some evidence is found for the existence of an intermediate tetragonal phase (previously reported to exist from electron diffraction data) around x∼0.2. The new spectroscopic data have been used to compare microscopic and macroscopic strain parameters arising from variation in composition. The strain and spectroscopic data are consistent with first-order character for the tetragonal→orthorhombic transition, while the cubic→tetragonal transition could be continuous. Differences between the variation with composition of spectral parameters and of macroscopic strain parameters are consistent with a substantial order/disorder component for the transitions. There is also evidence for precursor effects within the cubic structure before symmetry is broken.
AB -
Composition-induced structural phase changes across the high temperature, fast oxide ion conducting (Ba
1-x
La
x
)
2
In
2
O
5+x
, 0≤x≤0.6, system have been carefully analysed using hard mode infrared (IR) powder absorption spectroscopy, X-ray powder diffraction and electron diffraction. An orthorhombic brownmillerite to three-dimensionally disordered cubic perovskite phase transition in this system is signalled by a drastic change in slope of both wavenumber and average line widths of IR spectra as a function of composition. Some evidence is found for the existence of an intermediate tetragonal phase (previously reported to exist from electron diffraction data) around x∼0.2. The new spectroscopic data have been used to compare microscopic and macroscopic strain parameters arising from variation in composition. The strain and spectroscopic data are consistent with first-order character for the tetragonal→orthorhombic transition, while the cubic→tetragonal transition could be continuous. Differences between the variation with composition of spectral parameters and of macroscopic strain parameters are consistent with a substantial order/disorder component for the transitions. There is also evidence for precursor effects within the cubic structure before symmetry is broken.
KW - (Ba La ) In O solid solution
KW - Autocorrelation analysis
KW - Electron diffraction
KW - IR powder absorption spectroscopy
KW - Perovskites
KW - Phase transition
KW - Strains
UR - http://www.scopus.com/inward/record.url?scp=17744361857&partnerID=8YFLogxK
U2 - 10.1016/j.jssc.2005.01.004
DO - 10.1016/j.jssc.2005.01.004
M3 - Article
AN - SCOPUS:17744361857
VL - 178
SP - 882
EP - 891
JO - Journal of Solid State Chemistry
JF - Journal of Solid State Chemistry
SN - 0022-4596
IS - 3
ER -