Structural properties and phase transformation of sol–gel prepared lanthanum tantalates
Perovskite lanthanum tantalate La 1/3 TaO 3 (LT) precursors were prepared by a new polymeric complex sol–gel method using Ta-citrate or -tartrate complexes in different solvents (ethanol or methanol) and calcination between 750 and 1050 °C. The structural properties of precursors were characterised...
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Published in | Journal of materials science Vol. 49; no. 24; pp. 8423 - 8435 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Boston
Springer US
01.12.2014
Springer Springer Nature B.V |
Subjects | |
Online Access | Get full text |
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Summary: | Perovskite lanthanum tantalate La
1/3
TaO
3
(LT) precursors were prepared by a new polymeric complex sol–gel method using Ta-citrate or -tartrate complexes in different solvents (ethanol or methanol) and calcination between 750 and 1050 °C. The structural properties of precursors were characterised by X-ray diffraction (XRD), differential scanning calorimetry
/
thermogravimetric analysis (DSC/TG), Fourier transform infrared (FTIR) and Raman spectroscopy, scanning and transmission electron microscopy (SEM, TEM). The fluorite orthorhombic tungsten bronze (TB) of La
4.67
Ta
22
O
62
and perovskite La
1/3
TaO
3
phases with a small amount of pyrochlore monoclinic LaTaO
4
phase were formed after calcination at 900–1050 °C respectively, irregardless of solvent. The particle morphology changed from larger agglomerates composed of spherical 5–20 nm amorphous clusters without visible crystallization at 750 °C to plate-like shaped of well-ordered LT nanoparticles (ethanol) or individual spherical clusters with the fine inner structure (methanol) at 1050 °C. The same effect of alcohol solvent on phase transformation during annealing was shown, whereas the effect of chelating agent was insignificant.
Graphical Abstract
Selected area electron diffraction (SAED) patterns of La
1/3
TaO
3
precursors after calcination at 900 °C (
a
) metastable fluorite La
4.67
Ta
22
O
62
, (
b
) perovskite La
1/3
TaO
3
and (
c
) LaTaO
4
phases and (
d
) multidomain structure of super cell of La
2/3
Ta
2
O
9
. |
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ISSN: | 0022-2461 1573-4803 |
DOI: | 10.1007/s10853-014-8552-1 |