ISSN:
1551-2916
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
Formation of lead niobate pyrochlores by the reaction of PbO with Nb2O5 in various molar ratios and at various temperatures has been investigated. It has been shown that for a PbO/Nb2O5 molar ratio between 1.5 and 3.0, a pyrochlore solid solution having cubic symmetry is formed at low temperatures (∼500-600°C). X-ray diffraction data show evidence for the existence of compositional inhomogeneity for this phase which contains part of the Pb in the Nb site leading to the formula Pb1.5+x(Nb2-yPby)O7-delta (0.0 〈 x 〈 0.5; 0.0 〈 y 〈 0.5). A phase-pure Pb-deficient pyrochlore (Pb1.5Nb2O6.5) and Pb-excess pyrochlores (Pb2.5Nb2-O8, Pb3Nb2O8) are formed by the decomposition of this cubic solid solution and subsequent reaction at high temperatures. These results indicate that the mechanism of the structural transformation from the low-temperature (LT) cubic solid solution to the corresponding high-temperature (HT) phases is reconstructive.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1151-2916.1999.tb01877.x
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