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Keramische Fasern auf der Basis von PMN oder PMNT und Verfahren zu deren Herstellung

Stable organic lead, magnesium and niobium sol with variable rheology, obtained from various starting materials - by dissolving hydrated lead carboxylate and/or oxide and magnesium and/or oxide in carboxylic acid or alcohol and adding niobium alkylate or solution, useful for making ceramic and electrostrictive thin film and fibres.
: Glaubitt, W.; Jahn, R.

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DE 1996-19635722 A3: 19960903
DE 1996-19635722 A3: 19960903
DE 1996-19654980 A: 19960903
DE 19654980 C2: 20010104
Patent, Elektronische Publikation
Fraunhofer ISC ()

An organic sol containing lead (Pb), magnesium (Mg) and niobium (Nb) ions is claimed. It is obtained by (i) preparing a solution (PM) containing Pb and Mg compounds by (a) (1) dissolving a hydrated Pb carboxylate of the formula Pb(O2CR)2 x mH2O and/or lead oxide (PbO) in solvent(s) (I) or (II), using not less than 2 moles (I)/mole PbO, giving solution (P); (2) dissolving Mg and/or magnesium oxide (MgO) in solvent(s) (I) or (II), giving solution (M); and (3) mixing these solutions, giving solution PM; or (b) dissolving Pb(O2CR)2 x mH2O and/or PbO and Mg and/or MgO in solvent(s) (I) or (II); in which X = oxygen (O), sulphur (S) or imino (NR5); R, R1, R2, R3, R5 = optionally substituted and/or unsaturated alkyl with 1-10 or more carbon (C) atoms or optionally substituted aryl; or R1 = R4 X; or R2R3 = a bridging group; n = 1 or 2; R6 = optionally substituted and/or unsaturated 1-10, preferably 1-4 C alkyl; and (ii) adding a Nb alkoxylate of the formula Nb(OR6)5, optionally as solution (N), such that at least one of the solutions contains a substituted carboxylic acid of formula (I; R1 = R4 X) or a substituted alcohol of formula (II) in at least the equimolar amount with respect to Nb. Also claimed are (1) methods for producing thin ceramic coatings and fibres based on PMN (Pb-Mg-niobate) or PMNT (Pb-Mg niobate-titanate) and coatings and fibres with electrostrictive properties; and (2) the ceramic and ceramic electrostrictive fibres per se. USE - The thin dielectric films are useful in microelectronics, e.g. for ferro-electric random access memory (FRAM), dynamic random access memory (DRAM) or capacitors in integrated semiconductor technology. ADVANTAGE - Known sols require critical conditions for preparation, including careful exclusion of water. The new sols are stable and are suitable for making a wider range of PMN and PMNT mouldings than usual. The can be prepared from various starting materials by a stable method and their rheological properties can be suited to th e production of PMN fibres with the required electrical properties.