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AssigneeFraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
InventorsChristian Thieme, Christian Ruessel
Estimating the term…
Ceramics and glass-ceramics have low and/or negative coefficients of thermal expansion. Crystalline phases of the formula AM2Si2-yGeyO7 (A=Sr and Ba and M=Zn, Mg, Ni, Co, Fe, Cu, Mn, with Sr, Ba and Zn necessarily having to be present) can be produced by conventional ceramic processes or by crystallization from glasses. The compositions form solid solutions, where the elements indicated as component M can be replaced by one another in virtually any concentration but the concentration of Zn must always be at least 50% of the sum of all components indicated under M. The stoichiometry of these silicates and also their structure can differ to a greater or lesser extent.
A material based on a crystal phase of composition Ba1-xSrxM2Si2-yGeyO7 with 0.1<x<1 and 0≤y≤2, where M comprises Zn as a constituent such that the material has a negative coefficient of thermal expansion or a coefficient of linear thermal expansion of <1·10−6K−1.
A material based on a crystal phase of composition Ba1-xSrxM2Si2-yGeyO7 with 0.1<x<1 and 0≤y≤2, where M comprises Zn as a constituent such that the material has a negative coefficient of thermal expansion or a coefficient of linear thermal expansion of <1·10−6 K−1 and M further contains at least one further constituent selected from the group consisting of Mg, Mn, Co, Ni, Fe and Cu, wherein the crystal phase is present in a volume concentration of >50% and other phases present being other crystal phases or one or more glass phases of a different chemical composition, and a sum of concentration(s) of the at least one further constituent does not exceed the concentration of Zn.
Dependencies are inferred from the claim text.