Rhone-poulenc Industries

Rhone-poulenc Specialites Chimiques

Patrick Dougier

Claude Fouassier

Claude Magnier

Bertrand Latourrette

Regis Poisson

Jean-Francois Colombet

Jean-Philippe Browaeys

Alex Chamard

Jean-Bruno Monteil

Bernadette Saubat

Jean-Phillippe Browaeys

Finely divided powders of alkaline earth metal titanates, well suited for the fabrication of, e.g., ceramic resistors and condensers, are facilely prepared by (i) admixing a solution of an alkaline earth metal nitrate with a titanium sol having a pH ranging from 0.8 to 2.5 and which comprises elementary crystallites of TiO.sub.2 having particle sizes ranging from 10 to 100 .ANG., agglomerated into submicronic masses having particle sizes ranging from 200 to 1000 .ANG., (ii) next drying the suspension which results, (iii) calcining said dried suspension at a temperature ranging from 700.degree. to 1300.degree. C. for from 30 minutes to 24 hours, under a NO.sub.x partial pressure decreasing from 1 to 0, and then (iv) optionally grinding the powder resulting from said step (iii).

Process of making finely divided powders of alkaline earth metal

New luminescent substances are disclosed. They have a monoclinic crystalline structure and are formed of a double borate of magnesium and rare earths having the general formula Ln.sub.1-x Tb.sub.x MgB.sub.5 O.sub.10 in which Ln represents at least one element selected from the group consisting of the lanthanides and yttrium and in which 0&lt;x.ltoreq.1. The luminescent substances can be used in screens or tubes, for example, in low-pressure mercury vapor discharge lamps and plasma panels.

Luminescent substances having a base of double borate of magnesium and

Highly coercive, cobalt-doped ferrimagnetic iron oxide particulates comprised of ferrous iron and well-adapted for the manufacture of various magnetic recording media, are prepared by (i) thermally decomposing a .beta.-diketone/cobalt complex onto fluidized iron oxide particles having the formula (FeO).sub.x Fe.sub.2 O.sub.3, wherein 0.ltoreq.x.ltoreq.1.5, (ii) next annealing the particulates which result at a temperature ranging from about 300.degree. to 500.degree. and then (iii) permitting the same to cool, while at the same time sweeping the cooling zone with an inert gas, and then (iv) controlledly re-oxidizing the annealed/cooled particles.

High coercivity, cobalt-doped ferrimagnetic iron oxide particulates

Hydrated strontium fluosilicates activated with divalent europium, having the formula:

Novel black light emitting luminophors

Growing community of inventors

Andresy, France

Patrick Dougier