Abstract: A method is disclosed for producing magnetic or piezoelectric particles consisting of dried microorganisms which contain fixed magnetic or piezoelectric powder. The microorganisms are cultured in a nutrient medium containing the magnetic or piezoelectric powder which is then fixed or ingested by the microorganism. The microorganisms containing the magnetic or piezoelectric powder are then extracted from the nutrient medium and dehydrated to obtain dry particles. The dry particles may be compacted or inserted into a matrix to form a composite material.

Abstract: The invention relates to the areas of piezoelectricity and magnetism, and relates in particular to a composite material having piezoelectric or magnetic properties and a method for manufacturing the same. The composite material can be used, for example, in piezosensitive sensors or in magnetic sensors. The method according to the invention includes culturing microorganisms in a nutrient medium in the presence of a piezoelectric powder or magnetic powder. The microorganisms fix or ingest the powder, and are subsequently extracted from the nutrient medium and dehydrated to obtain dry particles. The dry particles are then compacted or inserted into a matrix to constitute the composite material. The microorganisms can optionally be separated from the particles prior to compaction of the particles or insertion of the particles into the matrix.

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.