Verfahren zur Herstellung von Dickschichten aus ferroelektrischen Keramiken

DE 19817482 A UPAB: 19991215 NOVELTY - Thick ferroelectric ceramic layers are produced by applying a pure organometallic sol-gel solution, heating, applying a ferroelectric ceramic powder dispersion in the sol-gel solution, and then sintering. DETAILED DESCRIPTION - Thick ferroelectric ceramic layers are produced using a dispersion of more than 90 wt.% ferroelectric ceramic powder, comprising PbTiO3-PbZrO3-lead complex perovskite or a mixture of lead complex perovskites optionally with PbTiO3, in an organometallic sol-gel solution. Substrates are coated by initially applying the pure sol-gel solution, heating, applying the dispersion, and then sintering the layers. USE - For producing thick ferroelectric ceramic layers on e.g. silicon, alumina, zirconia or special steel substrates, useful as actuators, sensors, capacitors, vibrators or storage elements, or for ferroelectric printing processes. ADVANTAGE - The process produces crack-free thick layers of about 100 microns thickness, which have good adhesion even on silicon substrates

Verwendung eines ferroelektrischen keramischen Werkstoffs für die Informationsspeicherung bei elektrostatischen Druckverfahren: Ferroelektrischer keramischer Werkstoff (A1)

A novel ferroelectric ceramic material comprises a ceramic perovskite solid soln. contg. one or more group 1 and 2 components, the group 1 components being: PbTiO3 (PT), BaTiO3 (BT), Pb(Fe1/2Nb1/2)O3 (PFN) and Pb(Zn1/3Nb2/3)O3 (PZN); and the group 2 components being: Pb(Mg1/3Nb2/3)O3 (PMN), Pb(Ni1/3Nb2/3)O3 (PNN), Pb(Fe2/3W1/3)O3 (PFW) and Pb(Mn1/2Nb1/2)O3 (PMnN). The amounts of the components of the two groups in the solid soln. are given by the mathematical equation: ((j) sigma (i = 1)) xi multiplied by Tci = TcM; where Xi = molar fraction of the 'i'th component; Tci = Curie point of the 'i'th component; and TcM = Curie point of the solid soln. (50 - 100 deg.C). USE - E.g. as a printing roller surface layer for information storage in electrostatic printing processes. ADVANTAGE - The material has high remanent polarisation combined with appearance of surface charges, easy polarisability esp. at 50 Hz (Pr is greater than 13muC / cm2 at 50 Hz), an almost rectangular hysteresis loop, a h igh insulation resistance of more than 1010 ohm cm, low variation of coupling factor and a coercive field strength of less than 200 V / mm

PZT thick films for microsystems applications

The preparation of PZT thick films on various substrates with thicknesses between 5 micron and 150 micron has been an area of active research for the last 15 years. Sintering of such films is difficult due to constrained sintering conditions, decomposition by PbO loss and possible reaction with the substrate material. The authors investigated into dense PZT thick films by combining PZT-PMN powder with a low melting point glass and the eutectic forming oxides Bi2O3 and ZnO. Densification is due to transient liquid phase jormation with additional incorporation of cations into the growing PZT grains during sintering. PZT thick films prepared by this method show excellent dielectric, ferroelectric and piezoelectric properties. They have been applied on various substrates, like Al2O3, ZrO2, low temperature co-fired ceramics (LTCC) and silicon wafers which are basis materials for microsystems technology. The influence of the substrate material on the PZT thick film properties and the role of buffer layers will be discussed. PZT thick films are of great interest as sensors and actuators for microsystems, optical and smart structure applications like for example piezoelectric pressure sensors, ultrasonic transducers, ferroelectric printing forms and deformable mirrors. Entnommen aus TEMA</a