Abstract: Inorganic scintillator material of formula AnLnpX(3p+n) in 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.

Abstract: The invention relates to a process for manufacturing a single crystal comprising a rare-earth halide, having improved machining or cleavage behaviour, comprising heat treatment in a furnace, the atmosphere of which is brought, for at least 1 hour, to between 0.70 times Tm and 0.995 times Tm of a single crystal comprising a rare-earth halide, Tm representing 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.

Abstract: 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 AeLnfX(3f+e) in 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.

Abstract: The invention relates to an inorganic scintillator material of formula AnLnpX(3p+n) in which Ln represents one or more rare earths, X represents one or more halogen atoms, chosen from F, Cl, Br or I, and A represents one or more alkali metals, such as K, Li, Na, Rb or Cs, n and p representing values such that n, which may be zero, is less than or equal to 2p, and that p is greater than or equal to 1, its content of daughter elements of uranium and thorium being low enough for the activity resulting from the alpha radiation from these elements to be less than 0.7 Bq/cc. This material 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.

Abstract: The invention relates to a method of preparing a polycrystalline block of a halide of formula AeLnfX(3f+e) in 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—X bond and, on the other hand, a sufficient amount of NH4X 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° C., never going below 200° C. before the molten mass has been obtained.

Abstract: 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 AeLnfX(3f+e) in 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.

Abstract: The rare earth borides, e.g., the tetraborides and hexaborides of lanthanum, cerium and praseodymium, are directly prepared by heating/reacting a mixture of at least one rare earth chloride and elemental boron at an elevated temperature, e.g., a temperature ranging from 1,200.degree. to 1,500.degree. C.

Abstract: The rare earth borides are prepared at relatively low temperatures by reacting a rare earth halide with elemental boron in the presence of a reducing amount of aluminum metal.

Abstract: Particulates, e.g., powders, of the rare earth borides are well suited for the effective abrasion/polishing of a variety of characteristically hard substrate face surfaces, e.g., hard ceramic surfaces.

Abstract: Novel compositions containing finely divided barium titanate particulates homogeneously dispersed in a solid organic matrix material, the barium titanate particles having a mean diameter of at least 1 micron, are well adopted for the production of electromagnetic wave absorbers, e.g., seals for microwave ovens.