Using an analytical electron microscope, the distribution of phases an
d order-disorder phenomena in the Pb(Fe1/2Nb1/2)O3-Pb(Fe2/3W1/3)O3 Pb(
Zn1/3Nb2/3)03(PFN-PFW-PZN) perovskite system were examined. It was fou
nd that after sintering the solid solution, small cubic pyrochlore par
ticles with chemical composition close to Pb(Fe0.28Zn0.01 Nb0.50W0.21)
O3.4 and a(o) = 1.05 nm were present in the 0.8 mol % Pb2WO5-0.2 mol %
PbO liquid phase. In samples fired at 1000-degrees-C, several 1 0 nm
sized ordered areas with faint F spots in the selected-area electron d
iffraction pattern and (h + 1/2 k + 1/2 I + 1/2) lattice fringes were
found. Similar features were found in the PZN perovskite monocrystal,
leading to the conclusion that local 1:1 ordering of cations (presumab
ly Zn2+ and Nb5+) in the PFN- PFW PZN system caused partial decomposit
ion of the perovskite phase at firing temperatures equal to or higher
than 850-degrees-C.