Relaxor ferroelectric single crystals for ultrasound transducers

• US 5,998,910 A
• Filed: 01/27/1998
• Issued: 12/07/1999
• Est. Priority Date: 01/28/1997
• Status: Expired due to Term

• Current Assignee: Penn State Research Foundation (Pennsylvania State University)
• Original Assignee: Penn State Research Foundation (Pennsylvania State University)
• Inventors: Lopath, Patrick D., Park, Seung-Eek, Shrout, Thomas R.
• Primary Examiner(s): Ramirez, Nestor
• Assistant Examiner(s): MEDLEY, PETER M
• Application Number:
  US09/013,746
• Time in Patent Office: 679 Days
• Field of Search: 310/358, 252/62.9 PZ
• US Class Current: 310/358
• CPC Class Codes: H10N 30/85 Piezoelectric or electrostrictive active materials
• CPC Class Codes: H10N 30/852 Composite materials, e.g. having 1-3 or 2-2 type connectivity
• CPC Class Codes: H10N 30/8548 Lead-based oxides

Abstract

<001>oriented crystals of lead zinc niobate--lead titanate solid solution (0 to 5 mole % lead titanate) have high electromechanical coupling>85% and exhibit electric field induced phase transition at electric field levels>10×Ec (where Ec is the coercive field), resulting in increased transducer driving voltages, decreased fabrication degradation, and high sensitivity/large bandwidth transducer characteristics due to high electromechanical couplings, up to 92%. <001>oriented crystals of lead magnesium niobate--lead titanate solid solution (20 to 50 mole % lead titanate) also exhibit high electromechanical couplings>85% and up to 94%, and thereby can be formed into transducers which exhibit both high sensitivity and large bandwidth.

Claims

1. A transducer comprising single crystals of a lead zinc niobate--lead titanate solid solution and exhibiting at least an 85% longitudinal coupling, wherein said single crystals of lead zinc niobate--lead titanate solid solution have a composition represented by the formulae:

space="preserve" listing-type="equation">Pb(Zn.sub.1/e Nb.sub.2/3).sub.l-x Ti.sub.x O.sub.3

where;

x is within the following limits;

0.02<

x<

0.05.

2. The transducer as recited in claim 1, wherein said single crystals are oriented along their respective pseudocubic <

001>

direction.

3. A transducer comprising single crystals of lead magnesium niobate--lead titanate, wherein said single crystals of lead magnesium niobate--lead titanate solid solution have composition represented by the formulae:

space="preserve" listing-type="equation">Pb(Mg.sub.1/3 Nb.sub.2/3).sub.l-y Ti.sub.y O.sub.3

where y is within the following limits;

0.20<

y<

0.50.

4. The transducer as recited in claim 3, wherein y is within the following limits:

0.20<

y<

0.35.

5. The transducer as recited in claim 3, wherein y is within the following limits:

0.35<

y<

0.50.

6. The transducer as recited in claim 3, wherein y is within the following limits:

0.25<

y<

0.33.

7. The transducer as recited in claim 3, wherein said single crystals are oriented along their respective pseudocubic <

001>

direction.