Schott Corporation

Schott Ag

Keith Gregory Rozenburg

Eric Hector Urruti

Martin Letz

Albrecht Seidl

Ulrike Stoehr

The invention relates to a polycrystalline IR transparent material produced by sintering chalcogenide powder, e.g., ZnS powder, using hot uniaxial pressing followed by hot isostatic pressing. The microstructure of the material described in this disclosure is much finer than that found in material produced using the state of the art process. By using a powder with a particle size fine enough to improve sintering behavior but coarse enough to prevent a lowering of the wurtzite-sphalerite transition temperature, a highly transparent material with improved strength is created without degrading the optical properties. A high degree of transparency is achieved during hot pressing by applying pressure after the part has reached a desired temperature. This allows some degree of plastic deformation and prevents rapid grain growth which can entrap porosity. The crystallographic twins created during this process further inhibit grain growth during hot isostatic pressing.

Polycrystalline chalcogenide ceramic material

An optical converter is provided that has both a stable colour even at highest luminous powers and a high luminous efficiency. The optical converter includes a ceramic element that is fluorescent so that light of a first wavelength is absorbed in the ceramic element and fluorescent having longer wavelength light is emitted. The ceramic element includes pores spatially irregularly distributed within the ceramic element. The distribution of the pores within the ceramic element is inhomogeneous so that the radial distribution function of the pore locations deviates from unity and has a maximum at a characteristic distance, the maximum having a value of at least 1.2.

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Factoryville, PA, United States of America

Keith Gregory Rozenburg