| Abstract
| - To search for new ferroelectric materials exhibiting an Aurivillius structural type, thesyntheses of the solid solution Bi2Mo1-xWxO6 has been undertaken. A phase with a largehomogeneity range exists for 0.5 < x ≤ 1.0. The thermal behavior of mechanochemicallyassisted precursor powders has been studied, showing that the consecutive crystallizationof fluorite and Aurivillius-type phases arrives before a ferro-paraelectric transition occurs.TEM studies of the representative mechanoactivated 1:0.25:0.75 Bi2O3:MoO3:WO3 mixtureindicates that mechanosynthesis of a Bi2Mo0.25W0.75O6 amorphous phase takes place. Theferroelectric properties of Bi2Mo0.25W0.75O6 well-densified ceramic material have beenmeasured. The crystal structure of Bi2Mo0.25W0.75O6 has been refined using X-ray and neutronpowder diffraction combined with Rietveld analysis. This oxide is isostructural with bothγ(L) Bi2MoO6 and Bi2WO6 belonging to the orthorhombic system, space group Pca21, a =5.44547(7) Å, b = 16.3731(2) Å, and c = 5.46659(7) Å, V = 487.40(1) Å3, Z = 4, and ρcal =9.21 g·cm-3. The structure keeps the Aurivillius-type framework with alternating [Bi2O2]and [Mo/WO4] layers. The structural characteristics of Bi2Mo0.25W0.75O6 can be consideredintermediate between those of γ(L) Bi2MoO6 and Bi2WO6.
- The Bi2Mo1-xWxO6 solid solution (0.5 < x ≤ 1.0) has been prepared by both solid-state reaction and mechanochemically assisted methods. TEM studies show that the mechanosynthesis of the representative Bi2Mo0.25W0.75O6 phase takes place at room temperature. This compound turns out to be a ferroelectric material, isostructural with both γ(L) Bi2MoO6 and Bi2WO6 undoped phases.
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