ZnO-activated formation of phase pure perovskite Pb(In1/2Nb1/2)O3-Pb(Zn1/3Nb2/3)O3-PbTiO3 powder |
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| Authors: | Michael J. Brova Beecher H. Watson III Elizabeth R. Kupp Mark A. Fanton Richard J. Meyer Jr Gary L. Messing |
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| Affiliation: | 1. Department of Materials Science and Engineering and Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania;2. Applied Research Laboratory, The Pennsylvania State University, State College, Pennsylvania |
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| Abstract: | This paper reports on the phase formation of perovskite Pb(In1/2Nb1/2)O3-Pb(Zn1/3Nb2/3)O3-PbTiO3 (PIN-PZN-PT) powder when doped with 0.04 to 0.83 mol% ZnO. Air calcination of undoped powder mixtures for 4 hours at 800°C resulted in a mixture of Pb2Zn0.29Nb1.71O6.565 pyrochlore, PIN-PZN-PT perovskite, and In2O3. ZnO dopant concentrations as low as 0.04 mol% increased the rate of perovskite formation and resulted in near phase pure perovskite powder of 0.5 μm particle size when heated at 800°C in air. In all cases PbTiO3 and Pb(In1/2Nb1/2)O3 formed prior to PIN-PZN-PT formation. ZnO doping promotes perovskite phase formation by increasing the reactivity of the intermediate pyrochlore phase by substituting Zn2+ on Nb5+ sites and forming oxygen vacancies when heated in air. Heating in high  resulted in an incomplete reaction and a mixture of perovskite and pyrochlore whereas low  resulted in phase separation into a mixture of rhombohedral perovskite, tetragonal perovskite, and pyrochlore. The  sensitivity clearly shows that oxygen vacancies due to ZnO-doping are critical for synthesis of phase pure PIN-PZN-PT powder. |
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