Research output: Contribution to journal › Article › peer-review
Demixion of the K2NiF4 type aluminate LaCaAlO4 : Precursor role of the local ordering of lanthanum and calcium. / Zvereva, I.; Smirnov, Yr; Choisnet, J.
In: Materials Chemistry and Physics, Vol. 60, No. 1, 15.07.1999, p. 63-69.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Demixion of the K2NiF4 type aluminate LaCaAlO4
T2 - Precursor role of the local ordering of lanthanum and calcium
AU - Zvereva, I.
AU - Smirnov, Yr
AU - Choisnet, J.
N1 - Funding Information: We are grateful to the Russian Fund of Basic Research for its financial support (Grant 97-03-33115).
PY - 1999/7/15
Y1 - 1999/7/15
N2 - The modeling of the modulation of the X-ray diffuse scattering background is applied to get evidence of local ordering phenomena of La3+ and Ca2+ in the K2NiF4 type aluminate LaCaAlO4. Such short range ordering phenomena play a precursor role in the demixion of the intergrowth structure of LaCaAlO4 in LaAlO3 and CaO, the perovskite and rock-salt type parent oxides, respectively. As the first stage of formation of twinned LaAlO3 precipitates with the matrix, a La3+ enrichment occurs in the {113} planes of the tetragonal cell of LaCaAlO4. The tendency to get simultaneously a short range ordering of the first nine neighbours and a clustering of the 8 second neighbours of Ca2+ accounts well for the formation of `LaO3' compact planes, ensuring the progressive coming out of the perovskite structure. In comparison with LaCaAlO4, no local ordering is detected in the stable aluminate NdCaAlO4, as in YCaAlO4 a slight tendency to get a short range ordering of both the first and second neighbouts results in the formation of mixed `Y,CaO3' compact planes. The local ordering phenomena prove not to be contradictory to the overall randomness of the cationic distribution which is the usual crystal-chemical property of the A3+A′2+AlO4 aluminates.
AB - The modeling of the modulation of the X-ray diffuse scattering background is applied to get evidence of local ordering phenomena of La3+ and Ca2+ in the K2NiF4 type aluminate LaCaAlO4. Such short range ordering phenomena play a precursor role in the demixion of the intergrowth structure of LaCaAlO4 in LaAlO3 and CaO, the perovskite and rock-salt type parent oxides, respectively. As the first stage of formation of twinned LaAlO3 precipitates with the matrix, a La3+ enrichment occurs in the {113} planes of the tetragonal cell of LaCaAlO4. The tendency to get simultaneously a short range ordering of the first nine neighbours and a clustering of the 8 second neighbours of Ca2+ accounts well for the formation of `LaO3' compact planes, ensuring the progressive coming out of the perovskite structure. In comparison with LaCaAlO4, no local ordering is detected in the stable aluminate NdCaAlO4, as in YCaAlO4 a slight tendency to get a short range ordering of both the first and second neighbouts results in the formation of mixed `Y,CaO3' compact planes. The local ordering phenomena prove not to be contradictory to the overall randomness of the cationic distribution which is the usual crystal-chemical property of the A3+A′2+AlO4 aluminates.
UR - http://www.scopus.com/inward/record.url?scp=0032649441&partnerID=8YFLogxK
U2 - 10.1016/S0254-0584(99)00072-3
DO - 10.1016/S0254-0584(99)00072-3
M3 - Article
AN - SCOPUS:0032649441
VL - 60
SP - 63
EP - 69
JO - Materials Chemistry and Physics
JF - Materials Chemistry and Physics
SN - 0254-0584
IS - 1
ER -
ID: 88614251