Processing method for grain-oriented lead-free piezoelectric Na0.5Bi0.5TiO3—BaTiO3 ceramics exhibiting giant performance

Patent metadata

Field	Value
Publication number	US-9773967-B2
Application number	US-201314068687-A
Country	US
Kind code	B2
Filing date	Oct 31, 2013
Priority date	Dec 17, 2012
Publication date	Sep 26, 2017
Grant date	Sep 26, 2017

Abstract

Textured ceramic compositions having improved piezoelectric characteristics as compared with their random counterparts are provided. Methods of making the compositions and devices using them are also included. More particularly, compositions comprising textured ceramic Na 0.5 Bi 0.5 TiO 3 —BaTiO 3 (NBT-BT) materials synthesized from high aspect ratio NBT seeds exhibit improved characteristics, including an increased longitudinal piezoelectric constant (d 33 ) and magnetoelectric coupling coefficient over randomly oriented NBT-BT. Additionally provided are compositions comprising of nanostructured Na 0.5 B 0.5 TiO 3 —BaTiO 3 ferroelectric whiskers having a high aspect ratio. Nanostructured whiskers can be used to improve the piezoelectric properties of the bulk ceramics. The inventive materials are useful in microelectronic devices, with some finding particular application as multilayer actuators and transducers.

First claim

The invention claimed is:

1. A composition comprising a NBT-BT ceramic with NBT seeds oriented within the ceramic to a desired degree, wherein the NBT seeds have an aspect ratio of greater than 1, and wherein the composition has a degree of grain orientation that is greater than 90%.

2. The composition of claim 1 , wherein the NBT seeds have an aspect ratio of 2-20.

3. The composition of claim 1 , wherein the NBT-BT ceramic is formed from an NBT-BT matrix comprising an NBT:BT ratio of from 80:20 to 99:1.

4. The composition of claim 3 , wherein the NBT is present in the matrix at about 93% and the BT in the matrix is present at about 7%.

5. The composition of claim 1 , wherein the composition has a degree of grain orientation of about 92-99%.

6. The composition of claim 1 , wherein the composition has a degree of grain orientation of about 93-98%.

7. The composition of claim 1 , wherein the composition has a degree of grain orientation of about 94-96%.

8. The composition of claim 1 , wherein the composition has a d 33 value of about 300-500.

9. The composition of claim 1 , wherein the composition has a d 33 value of about 350-450.

10. The composition of claim 1 , wherein the NBT seeds have an aspect ratio in the range of 2 to 50.

11. The composition of claim 1 , wherein the NBT seeds have an aspect ratio in the range of 2 to 10.

12. The composition of claim 1 , wherein the NBT seeds have an aspect ratio in the range of 5 to 20.

13. The composition of claim 1 , wherein the aspect ratio is in the range of greater than 1 to 60.

14. The composition of claim 1 , wherein the aspect ratio is in the range of 5 to 10.

15. The composition of claim 1 , wherein the NBT-BT ceramic has the formula (Na 0.5 Bi 0.5 TiO3) (1-x) —(BaTiO 3 ) x where x is 0.05, 0.6, 0.7, or 0.08.

Assignees

• Virginia Tech Intellectual Properties Inc

Inventors

• Maurya Deepam
• Priya Shashank

Classifications

• Y10T428/325

  Magnetic layer next to second metal compound-containing layer · CPC title

• C04B2235/3298

  Bismuth oxides, bismuthates or oxide forming salts thereof, e.g. zinc bismuthate · CPC title

• C04B35/462 Primary

  based on titanates · CPC title

• C04B2235/787

  Oriented grains · CPC title

• C04B2235/5276

  Whiskers, spindles, needles or pins · CPC title