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High‐Temperature Stability of Lead Zinc Niobate: In Situ X‐Ray Diffraction
Author(s) -
Shanahan James V.>,
Kisi Erich H.,
Forrester Jennifer S.,
Goodshaw Heather J.,
Zobec Jennifer S.,
Phelan David
Publication year - 2010
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2010.03962.x
Subject(s) - pyrochlore , materials science , zinc , rietveld refinement , thermal stability , analytical chemistry (journal) , phase (matter) , diffraction , x ray crystallography , scanning electron microscope , crystallography , mineralogy , crystal structure , chemistry , metallurgy , physics , organic chemistry , chromatography , optics , composite material
The thermal stability of the relaxor ferroelectric Pb(Zn 1/3 Nb 2/3 )O 3 (PZN) upon heating was studied using high‐temperature X‐ray diffraction (XRD) and scanning electron microscopy. It was found that single‐phase PZN is stable below 700°C, whereupon the first decomposition phase, the pyrochlore Pb 1.83 Nb 1.71 Zn 0.29 O 6.39 was observed. With the increasing temperature, the amount of pyrochlore increased until at 1100°C there is no PZN remaining. Pyrochlore formation was accompanied by the precipitation of ZnO above 800°C and after holding at 1100°C, the formation of Nb 2 ZnO 6 . Rietveld refinements based on the XRD patterns have allowed the relative phase proportions as well as the atomic site occupancies of the metal ions in PZN and the pyrochlore to be estimated. The Zn site occupancy within the perovskite PZN decreases upon heating in parallel with the pyrochlore formation. An elemental mass balance based on the XRD results shows that PZN decomposition is well under way before any Pb is lost from the sample. This indicates that Zn egress rather than Pb volatility is the determining factor in the instability of PZN, contrary to prior published work.