Saint-gobain Cristaux Et Detecteurs

Alain Iltis

Vladimir Ouspenski

Dominique Richaud

The invention relates to a process for manufacturing a single crystal comprising a rare-earth halide, having improved machining or cleavage behavior, comprising heat treatment in a furnace, the atmosphere of which is brought, for at least 1 hour, to between 0.70 times Tand 0.995 times Tof a single crystal comprising a rare-earth halide, Trepresenting the melting point of said single crystal, the temperature gradient at any point in the atmosphere of the furnace being less than 15 K/cm for said heat treatment. After carrying out the treatment according to the invention, the single crystals may be machined or cleaved without uncontrolled fracture. The single crystals may be used in a medical imaging device, especially a positron emission tomography system or a gamma camera or a CT scanner, for crude oil exploration, for detection and identification of fissile or radioactive materials, for nuclear and high-energy physics, for astrophysics or for industrial control.

Annealing of single crystals

The invention relates to a method of preparing a polycrystalline block of a halide of formula ALnXin which Ln represents one or more rare earths, X represents one or more halogen atoms selected from the group consisting of Cl, Br and I, and A represents one or more alkali metals selected from the group consisting of K, Li, Na, Rb and Cs, e, which may be zero, being less than or equal to 3f, and f being greater than or equal to 1, having a low water and oxyhalide content, in which the method comprises heating a mixture of, on the one hand, at least one compound having at least one Ln&#x2014;X bond and, on the other hand, a sufficient amount of NHX in order to obtain the oxyhalide content, resulting in a molten mass comprising the rare-earth halide, the heating being followed by cooling, and the heating, after having reached 300&#xb0; C., never going below 200&#xb0; C. before the molten mass has been obtained. The blocks thus produced allow very pure single crystals having remarkable scintillation properties to be grown.

Rare-earth halide single crystals

Preparation of rare-earth halide blocks

The invention relates to a method of preparing a polycrystalline block of a halide of formula ALnXin which Ln represents one or more rare earths, X represents one or more halogen atoms selected from the group consisting of Cl, Br and I, and A represents one or more alkali metals selected from the group consisting of K, Li, Na, Rb and Cs, e, which may be zero, being less than or equal to 3, andbeing greater than or equal to 1, having a low water and oxyhalide content, in which the method comprises heating a mixture of, on the one hand, at least one compound having at least one Ln&#x2014;X bond and, on the other hand, a sufficient amount of NHX in order to obtain the oxyhalide content, resulting in a molten mass comprising the rare-earth halide, the heating being followed by cooling, and the heating, after having reached 300&#xb0; C., never going below 200&#xb0; C. before the molten mass has been obtained. The blocks thus produced allow very pure single crystals having remarkable scintillation properties to be grown.

Method for preparing rare-earth halide blocks

Inorganic scintillator material of formula ALnXin which has a very low nuclear background noise and is particularly suitable as a detector scintillator for coating weight or thickness measurements, in the fields of nuclear medicine, physics, chemistry and oil exploration, and for the detection of dangerous or illicit materials.

Scintillator material based on rare earth with a reduced nuclear background

The invention relates to the handling of a composition comprising a rare-earth halide, especially within the context of the growth of crystals from said composition, said crystals generally being of formula ALnXin which Ln represents one or more rare earths, X represents one or more halogen atoms chosen from Cl, Br or I, and A represents one or more alkaline metals such as K, Li, Na, Rb or Cs, e and f representing values such that e, which may be zero, is less than or equal to 2f and f is greater than or equal to 1. It is possible in this way to grow single crystals exhibiting remarkable scintillation properties.

Growing community of inventors

Montigny-Sur-Loing, France

Alain Iltis