Rhodia Electronics & Catalysis

Rhodia Electronics & Catalysts

Centre National De La Recherche Scientifique

Thierry Le Mercier

Jean-Yves Chane-Ching

Valérie Buissette

Olivier Le Roux

Claude Fouassier

Benjamin Delespierre

Cédric Froidefond

Wilfried Blanc

Claude Ceintrey

The invention concerns a colloidal dispersion of a vanadate or a phosphovanadate of at least a rare earth comprising either a complex-forming agent having a pK higher than 2.5, or an anion of a monovalent acid, soluble in water and having a pKa ranging between 2.5 and 5. The dispersion is obtained by contacting a colloidal dispersion or a dispersion of initial complexes comprising at least a rare earth compound and at least a complex-forming agent or an anion of said monovalent acid and whereof the pH has been adjusted to a value of at least 7, with vanadate ions, then, in adjusting the pH of the resulting medium to a value of at least 9 and heating.

Colloidal dispersion of particles of a rare-earth vanadate or phosphovanadate

The invention relates to alkaline-earth or rare-earth metal aluminate precursor compounds, to their method of preparation and to their use in particular as phosphor precursors. These alkaline-earth or rare-earth metal aluminate precursor compounds are essentially crystallized in the form of a transition alumina and in the form of substantially spherical and chemically homogeneous particles including pores whose mean diameter is of at least 10 nm.

Precursor compounds of alkaline earth metal or rare earth metal aluminates method production and use thereof particularly as precursors for luminophores

The invention concerns a light transforming material, in particular for greenhouse walls, comprising as additive a barium and magnesium silicate of formula BaEuMgMnSiO, wherein 0&#x3c;x&#x2266;0.3 and 0&#x3c;y&#x2266;0.3and 0&#x3c;y=0.3. The material is capable of transforming solar energy of UV range into a red light. The material can also be used in paints and cosmetics.

Light-converting material comprising a barium magnesium silicate as additive

The invention relates to a compound based on at least one element A chosen from alkaline-earth metals, on at least one element B chosen from aluminium, gallium and indium, on sulphur and on a dopant capable of giving the compound luminescence properties, which is characterized in that it is in the form of a mixture of predominantly an ABS-type crystallographic phase and a BS-type crystallographic phase. This compound is prepared by a method in which a solution or suspension comprising salts or sols of the elements A, B and of the dopant is formed in a proportion such that the B/(A+dopant) atomic ratio is at least 2.06; the solution or suspension is spray-dried; the product thus obtained is sulphurized. This compound may be used as a phosphor, especially in cathodoluminescence.

Compound based on an alkaline-earth metal, sulphur and aluminium, gallium or indium, its method of preparation and its use as a phosphor

The invention relates to a compound based on at least one element A chosen from alkaline-earth metals, on at least one element B chosen from aluminium, gallium and indium, on sulphur and on a dopant capable of giving the compound luminescence properties, which is characterized in that it is in the form of a mixture of predominantly an AB S -type crystallographic phase and a B S -type crystallographic phase. This compound is prepared by a method in which a solution or suspension comprising salts or sols of the elements A, B and of the dopant is formed in a proportion such that the B/(A&plus;dopant) atomic ratio is at least 2.06; the solution or suspension is spray-dried; the product thus obtained is sulphurized. This compound may be used as a phosphor, especially in cathodoluminescence.

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Paris, France

Thierry Le Mercier