Influence of hydrothermal synthesis conditions on the composition of the pyrochlore phase in the Bi2O3–Fe2O3–WO3 system
https://doi.org/10.17586/2220-8054-2020-11-2-246-251
Abstract
The paper deals with a study of the effect which the hydrothermal fluid pH has on the formation of a pyrochlore-structured phase in the Bi2O3– Fe2O3–WO3 system. It was shown that at pH of 1 and 8, the formation of pyrochlore-structured phase particles with crystallite sizes of 38 and 118 nm, respectively, is accompanied by the formation of the Bi2WO6 compound with the Aurivillius phase structure. At pH values from 2 to 7, only pyrochlore-structured nanocrystalline particles with a variable composition are formed. Under these conditions, the dependence of the average size of crystallites of the pyrochlore-structured phase particles on pH is extreme, as the size increases from ∼ 67 nm at pH 2 up to ∼ 126 nm at pH 5 and then decreases to ∼ 102 nm at pH 7. The samples obtained at pH 3–4 have a composition that is the closest to that specified for the synthesis.
When pH increases up to 10, there forms a non-single-phase product that contains the Bi2WO6 phase and δ-Bi2O3-based phase.
Supporting agencies: XRD studies, SEM and EDXMA of samples were performed employing the equipment of the Engineering Center of the St. Petersburg State Institute of Technology.
About the Authors
M. S. Lomakin
Ioffe Institute; St. Petersburg State Institute of Technology
Russian Federation
Russian Federation
26, Politekhnicheskaya St., 194021, St. Petersburg
26, Moskovsky pr, 190013, St. Petersburg
O. V. Proskurina
Ioffe Institute; St. Petersburg State Institute of Technology
Russian Federation
Russian Federation
26, Politekhnicheskaya St., 194021, St. Petersburg
26, Moskovsky pr, 190013, St. Petersburg
V. V. Gusarov
Ioffe Institute
Russian Federation
Russian Federation
26, Politekhnicheskaya St., 194021, St. Petersburg
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Review
For citations:
Lomakin M.S., Proskurina O.V., Gusarov V.V. Influence of hydrothermal synthesis conditions on the composition of the pyrochlore phase in the Bi2O3–Fe2O3–WO3 system. Nanosystems: Physics, Chemistry, Mathematics. 2020;11(2):246–251. https://doi.org/10.17586/2220-8054-2020-11-2-246-251
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