Motorola Corporation

Cts Corporation

Donald W Forst

Xunhu Dai

James R Phillips

Dean Lawrence Cook

Hugh Robert Malone

Deborah Sue Dendy

Harold W Mech

Dale G Hall

Gary L Vaughn

Low loss piezoelectric ceramic compositions cofirable with silver at a reduced sintering temperature and methods for producing the such compositions are provided. The compositions are binary piezoelectric ceramic compositions having a first component which is characterized by about 95.0 to about 99.5 weight percent of a system represented by a general formula Pb(Zr,Ti,)O,&plus;y wt % MnO,in which x and y represent weight percentages and wherein x is within a range from 0.0 to about 1.0, and y is within a range from about 0.1 to about 1.0. The compositions also have 0.5 to 5.0 wt % of a second component represented by the general formula w wt % Bi,O,&minus;z wt % CdO in which w and z represent weight percentages and wherein w is within a range from about 0.1 to about 1.0, and z is within a range from about 0.1 to about 2.0. The piezoelectric ceramic compositions are non-reactive with a silver electrode layer when cofired therewith at sintering temperatures of about 900&deg; C. and may be employed to produce piezoelectric transformers having a voltage breakdown of about 50 kv/cm or more.

Piezoelectric ceramic compositions and methods for production thereof

An array (100) of voltage variable capacitors (110) is provided in which voltage variable capacitors (110) are fabricated with piezoelectric displacement devices (150). Voltage variable capacitors (110) have first plates (120) which are coupled to displacement devices (150). First plates (120) are dielectrically coupled to second plates (130). Displacement device (150) has a stack of metallic layers (154), voltage variable material blocks (152), and voltage supply terminals (170) and (180). Voltage differences are established across voltage variable material blocks (152) using voltage supply terminals (170) and (180). A voltage difference causes a voltage variable material layer to change thickness, and this causes first plate (120) to move relative to second plate (130). Voltage variable material is selected from a group of piezoelectric ceramics, which can include lead-titanate (PbTiO.sub.3), lead-zirconate (PbZrO.sub.3), barium-titanate (BaTiO.sub.3), and lead-zirconate-titanate (PbZr.sub.x Ti.sub.1-x O.sub.3), where x varies from zero to one.

Voltage variable capacitor array and method of manufacture thereof

A piezoelectric transformer with voltage feedback is disclosed. The transformer comprises a piezoelectric plate of predetermined length, width and height with a driving section formed by alternately stacking a plurality of piezoelectric ceramic layers having internal interdigitated electrode layers. A driven section including an unpolarized dielectric section, a voltage feedback section in the form of a multilayer electrode structure or an outer strip, and a normally polarized dielectric section is also disclosed. The transformer generates an output voltage at an output terminal by the piezoelectric vibration transmitted from the driving section. A feedback control circuit is connected to the voltage feedback section. The isolated voltage feedback provides feedback control to keep the transformer operating at the proper resonant frequency even as there is a change in output load of the transformer.

Piezoelectric transformer with voltage feedback

A low loss piezoelectric ceramic composition cofirable with silver at a reduced sintering temperature and a process for producing the same is provided. The composition is a binary piezoelectric ceramic composition consisting of a main composition which is characterized by 95.0 to 99.5 weight percent of a system represented by a general formula Pb(Zr.sub.x Ti.sub.1-x)O.sub.3 +yMnO.sub.2 in which 0.ltoreq.x.ltoreq.1.0 and 0.1.ltoreq.y.ltoreq.1.0 wt. % The composition also contains 0.5 to 5.0 weight percent of an additive represented by a general formula wB.sub.2 O.sub.3 -xBi.sub.2 O.sub.3 -yMeO-zCuO wherein w,x,y, and z are weight percentages of the respective components and w+x+y+z=1. In the composition, Me is one of the metals selected from a group consisting of Ca, Sr, Ba, Zn, and 0.01.ltoreq.w.ltoreq.0.15, 0.ltoreq.x.ltoreq.0.80, 0.ltoreq.y.ltoreq.0.60 and 0.ltoreq.z.ltoreq.0.55. Significantly, the piezoelectric ceramic composition is non-reactive with a silver electrode layer when cofired therewith at sintering temperatures of about 900.degree. C.

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Albuquerque, NM, United States of America

Donald W Forst