Ferroelectric perovskites
AssigneeEtat Francais as represented by the Delegue General pour l 'Armement
InventorsLucien Eyraud, Michel M. Boisrayon, Paul A. Eyraud, Franck F. Eyraud, David D. Audigier
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Abstract
The invention relates to pulverulent ferroelectric perovskites having piezoelectric properties up to a temperature of approximately 300.degree. C. as well as their manufacturing processes. The processes include a step wherein fluorine ions are inserted into the perovskites at anionic sites and/or oxygen vacancies. The perovskites are used as raw materials for the production of piezoelectric ceramics which find application in a variety of fields, such as electroacoustic transducers, piezoelectric motors, welding and industrial cleaning.
Claims5
A process of making pulverulent ferroelectric perovskites having piezoelectric properties up to a temperature of approximately 300.degree. C., said process comprising substituting fluorine for oxygen in a perovskite lattice at locations including at least one of anionic sites and oxygen vacancies, wherein said process comprises the following steps:
- coprecipitating main cations which form the perovskite to form a deposit comprising the main cations, wherein the coprecipitating comprises:
- forming an aqueous solution comprising oxalic acid, titanium butylate, zirconium butylate, iron chloride and manganese acetate;
- adding at least one lead salt and at least one barium salt to the aqueous solution;
- adjusting a solution pH to about 9 by adding a material to the aqueous solution to form the deposit comprising the main cations;
- and
- separating the deposit comprising the main cations from the aqueous solution and drying the deposit comprising the main cations;
- mixing the deposit comprising the main cations with a lead fluoride to form a mixture;
- and
- thermally treating the mixture at approximately 600.degree. C.
Pulverulent ferroelectric perovskite comprising at least one of the elements Pb, Ba, Ti and Zr, and having piezoelectric properties up to a temperature of approximately 300.degree. C. and comprising fluorine ions within the perovskite lattice, wherein the perovskite has the following formula:
- PbX!Zr Ti Y!O.sub.3
- wherein X is a cation substituted for Pb, and Y is a cation substituted for Zr or Ti, and wherein X is selected from the group consisting of sodium and potassium, and Y is selected from the group consisting of iron, manganese and nickel.
Dependencies are inferred from the claim text.