Centre National De La Recherche Scientifique

France Telecom

Compagnie D'electronique Et De Piezo-electricite C.e.p.e.

Etat Francais, Represente Par Le Ministre Des Ptt (centre National

Compagnie D'electronique Et De Peizo-electricite Cepe

Etienne Philippot

Aline Goiffon

Yves Toudic

Jacques Detaint

Jacquie Schwartzel

Albert Zarka

Maurice Maurin

Bernard Capelle

Alain Ibanez

Olivier Cambon

Roger Arnaud

Jean-Claude Jumas

Jean-Pierre Aubry

Bernard Cappelle

Xavier Buisson

Yun L Zheng

Jean-Claude Doukhan

Daniele Cachau Hereillat

A method of obtaining a crystal by crystal growth in the liquid phase from a seed in the form of a plate taken from a primary crystal, which method comprises at least two steps constituted firstly by forming first crystal growth to obtain a secondary crystal from a first seed taken from said primary crystal in a first growth zone, and secondly in performing second crystal growth from a second seed taken from said secondary crystal in a second growth zone, said first and second seeds being selected so that few of the dislocations that they contain propagate respectively into the second zone of the secondary crystal or into the first growth zone of the resulting crystal. According to the invention said first and second crystal growth steps are performed in different growth directions. Application to monocrystals of quartz, or of materials that are isomorphs of quartz, such as berlinite, and that are intended for use in making electronic components, in particular oscillators and filters.

Method of obtaining a crystal by crystal growth in the liquid phase from

Quartz sections having a surface condition as polished as possible are prepared by controlled dissolution by placing said quartz sections in a bath of a quartz solvent or a mixture of solvents, wherein the bath is basic and comprises an alkaline hydroxide or fluoride, or ammonium hydroxide, or a mixture of these compounds; and conducting controlled dissolution of the quartz sections at atmospheric pressure.

Controlled dissolution of quartz

The present invention relates to a process for increasing the dimensions of quartz crystals and of quartz-isomorphic materials, which can be produced by hydrothermal growth from seed, in which a seed obtained by assembly of several crystalline plates is used, wherein there are assembled at least two plates of strictly identical lengths and/or widths and of similar thicknesses, cut in at least one crystal and having, on at least three faces crystalline orientations, the deviations from which remain, between the plates, smaller than about 10' of arc, and wherein said plates are brought together on a support by guidance elements, thus ensuring their alignment on the aforementioned three faces while maintaining crystalline orientation deviations smaller than about 10' of arc, one face per plate being left free for growth of the assembled seeds, leading to the production of a single crystal exhibiting at least one dimension greater than that corresponding to the original crystalline plate. The subject of this invention is also to the crystals obtained by this process.

Process for increasing the dimensions of crystals which can be produced

Process for dissolution of a crystalline material

The invention relates to a process for the preparation of berlinite crystals AlPO.sub.4, with a high Q factor, from seeds or crystalline flakes of AlPO.sub.4, by a hydrothermal method. It is characterized in that the crystallization solution is a sulfuric solution of AlPO.sub.4. The invention also relates to the berlinite monocrystals obtained by this process.

Process for the preparation of berlinite crystals with high Q factor

Growing community of inventors

Saint Mathieu de Treviers, France

Etienne Philippot