NBT based lead-free piezoelectric materials for high power applications

Patent metadata

Field	Value
Publication number	US-RE46445-E
Application number	US-201514819216-A
Country	US
Kind code	E1
Filing date	Aug 5, 2015
Priority date	Sep 26, 2008
Publication date	Jun 20, 2017
Grant date	Jun 20, 2017

Abstract

Piezoelectric compounds of the formula xNa m Bi n TiO 3 -yK m Bi n TiO 3 -zLi m Bi n TiO 3 -pBaTiO 3 where (0<x≦1), (0≦y≦1), (0≦z≦1), (0.3≦m≦0.7), (0.3≦n≦0.7), (0<p≦1) (0.9≦m/n≦1.1) as well as to doped variations thereof are disclosed. The material is suitable for high power applications.

First claim

The invention claimed is:

1. A piezoelectric compound having the formula xNa m Bi n TiO 3 -yK m Bi n TiO 3 -zLi m Bi n TiO 3 -pBaTiO 3 where (0<x≦1), (0≦y≦1), (0≦z≦1), (0<p<1, (0<x≦0.85), (0<y<1) (0<z<1), (0<p<1), (x+y+z+p=1), (0.3≦m≦0.7), (0.3≦n≦0.7), and (0.9≦m/n≦1.1).

2. A piezoelectric compound having the formula ((xNa m Bi n TiO 3 -yK m Bi n TiO 3 -zLi m Bi n TiO 3 -pBaTiO 3 )-rM) where (0<x≦1), (0≦y≦1), (0<z≦1), (0<p<1), (0<x≦0.85), (0<y<1), (0<z<1), (0<p<1), (x+y+z+p=1), (0.3≦m≦0.7), (0.3≦n≦0.7), (0.9≦m/n≦1.1) and (0 wt %<r≦5 wt %) where r is based on the weight of a compound within the scope of formula xNa m Bi n TiO 3 -yK m Bi n TiO 3 -zLi m Bi n TiO 3 -pBaTiO 3 and M is a dopant selected from the group consisting of Al 2 O 3 , CoO, Re 2 O 3 where Re is a rare earth element, NiO, MnO 2 , Fe 2 O 3 , and mixtures thereof.

3. A piezoelectric compound having the formula
(xNa m Bi n TiO 3 -yLi m Bi n TiO 3 -zBaTiO 3 )   (III)

where (0<x≦1), (0<y≦1), (0<z≦1), (0<x<1), (0.2≦y<1), (0<z<1), (x+y+z=1), (0.3≦m≦0.7), (0.3≦n≦0.7), (0.9<m+n<1.1) and (0.9≦m/n≦1.1).

4. A piezoelectric compound having the formula ((xNa m Bi n TiO 3 -yLi m Bi n TiO 3 -zBaTiO 3 )-wN) where (0<x≦1), (0<y≦1), (0<z≦1), (0<x<1), (0<y<1), (0<z<1), (x+y+z=1), (0.3≦m≦0.7), (0.3≦n≦0.7), (0.9<m+n<1.1), (0.9<m/n<1.1) and (0<w≦5 wt %) where w is based on the weight of a compound within the scope of the formula xNa m Bi n TiO 3 -yLi m Bi n TiO 3 -zBaTiO 3 and where N is a dopant selected from the group consisting of Al 2 O 3 , CoO, Re 2 O 3 where Re is a rare earth element, NiO, MnO 2 , Fe 2 O 3 , and mixtures thereof.

5. A piezoelectric compound having the formula ((xNa m Bi n TiO 3 -yK m Bi n TiO 3 -zLi m Bi n TiO 3 -pBaTiO 3 )-rM) where (0<x≦1), (0≦y≦1), (0<p<1), (0<x<1), (0<y<1), (0<p<1), (0<z≦0.2) (x+y+z+p=1), (0.3≦m≦0.7), (0.3≦n≦0.7), (0.9≦m/n≦1.1) and (0 wt %<r≦5 wt %) where r is based on the weight of a compound within the scope of formula xNa m Bi n TiO 3 -yK m Bi n TiO 3 -zLi m Bi n TiO 3 -pBaTiO 3 and M is a dopant selected from the group consisting of Al 2 O 3 , CoO, Re 2 O 3 where Re is a rare earth element, NiO, MnO 2 , Fe 2 O 3 and mixtures thereof.

6. The compound of claim 5 wherein m=0.5 and n=0.495.

7. The compound of claim 2 wherein a source of M is Co 2 O 3 , x is 0.80, y is 0.102, z is 0.03, p is 0.068 and r is 1.5%.

8. The compound of claim 7 wherein m=0.5 and n=0.495.

9. A piezoelectric compound having the formula xNa 0.5 Bi 0.5 TiO 3 -yLi 0.5 Bi 0.5 TiO 3 -zBaTiO 3 where (0.3≦x≦0.95), (0<y≦0.7), (0.2≦y≦0.7), (0<z≦0.2) and (x+y+z=1).

10. A method of manufacture of a piezoelectric compound of the formula xNa 0.5 Bi 0.5 TiO 3 -yK 0.5 Bi 0.5 TiO 3 -zBaTiO 3 where (0<x≦1), (0<y≦1), (0<z≦1) (0<x<1), (0.7<y<1), (0<z<1), and (x+y+z=1) comprising, forming a mixture of K 2 CO 3 , Na 2 CO 3 , BaCO 3 , Bi 2 O 3 or and TiO 2 starting materials in amounts suitable for yielding a compound within formula xNa 0.5 Bi 0.5 TiO 3 -yK 0.5 Bi 0.5 TiO 3 -zBaTiO 3 , calcining the mixture at about 800° C. to about 950° C. for about 0.5 hrs to about 2 hrs to yield a calcined mixture, milling the calcined mixture to a particle size of about 0.5 microns to about 2 microns to produce a calcined milled mixture, compressing the calcined milled mixture at about 3000 PSI to about 10000 PSI to yield a preform, heating the preform to a temperature of about 500° C. to about 600° C. to yield a green preform, sintering the green preform at about 1060° C. to about 1220° C. for about 0.5 hrs to about 2 hrs to yield a piezoelectric compound of the formula xNa 0.5 Bi 0.5 TiO 3 -yK 0.5 Bi 0.5 TiO 3 -zBaTiO 3 where (0<x≦1), (0<y≦1), (0<z≦1) (0<x<1), (0.7<y<1), (0<z<1), and (x+y+z=1).

11. A method of manufacture of a piezoelectric compound of the formula (xNa 0.5 Bi 0.5 TiO 3 -yK 0.5 Bi 0.5 TiO 3 -zBaTiO 3 )-rM where (0<x≦1), (0<y≦1), (0<z≦1), (0<x<1), (0<y<1), 0<z<1), (x+y+z=1), (0<r≦5 wt %) where r is based on the weight of a compound within formula xNa 0.5 Bi 0.5 TiO 3 -yK 0.5 Bi 0.5 TiO 3 -zBaTiO 3 and M is a dopant comprising, wherein the method comprises forming a mixture of K 2 CO 3 , Na 2 CO 3 , BaCO 3 , Bi 2 O 3 or and TiO 2 starting materials in amounts suitable for yielding a compound within the formula xNa 0.5 Bi 0.5 TiO 3 -yK 0.5 Bi 0.5 TiO 3 -zBaTiO 3 where (0<x≦1), (0<y≦1), (0<z≦1), (0<x<1), (0<y<1), 0<z<1), (x+y+z=1), calcining the mixture at about 800° C. to about 950° C. for about 0.5 hrs to about 2 hrs to yield a calcined mixture, blending a source of dopant M wherein the source is selected from the group consisting of Al 2 O 3 , CoO, Co 2 O 3 , Re 2 O 3 where Re is rare earth element, NiCO 3 , MnO 2 , MnCO 3 , Fe 2 O 3 , and mixtures thereof with the calcined mixture to produce a doped mixture,
milling the doped mixture to a particle size of about 0.5 microns to about 2 microns to produce a calcined milled mixture, compressing the calcined milled mixture at about 3000 PSI to about 10000 PSI to yield a preform, heating the preform to a temperature of about 500° C. to about 600° C. to yield a green preform, and sintering the green preform at about 1060° C. to about 1220° C. for about 0.5 hrs to about 2 hrs to yield a piezoelectric compound of the formula (xNa 0.5 Bi 0.5 TiO 3 -yK 0.5 Bi 0.5 TiO 3 -zBaTiO 3 )-rM where (0<x≦1), (0<y≦1), (0<z≦1), (0<x<1), (0<y<1), 0<z<1), (x+y+z=1), (0<r≦5 wt %).

12. An ultrasonic transducer comprising the piezoelectric of claim 2 .

13. The transducer of claim 12 wherein the transducer is a high intensity focused ultrasound (HIFU) transducer.

14. An ultrasonic motor comprising a piezoelectric compound of claim 2 .

15. A piezoelectric transformer comprising a piezoelectric compound of claim 2 .

16. A piezoelectric compound according to claim 1 wherein (0<x≦0.85), (0<y<1), (0<z<0.2), (0<p<0.1), (x+y+z+p=1), (0.3≦m≦0.7), (0.3≦n≦0.7), and (0.9≦m/n≦1.1).

17. A Co-doped xNa m Bi n TiO 3 -yK m Bi n TiO 3 -zLi m Bi n TiO 3 -pBaTiO 3 piezoelectric compound where (0<x<1), (0<y<1), (0<z<1), (0<p<1), (x+y+z+p=1), (0.3≦m≦0.7), (0.3≦n≦0.7), (0.9≦m/n≦1.1), wherein Co 2 O 3 is a source of Co dopant.

18. A Co-doped piezoelectric compound according to claim 17 where the Co dopant is present in an amount of 1.5 wt % based on the weight of xNa m Bi n TiO 3 -yK m Bi n TiO 3 -zLi m Bi n TiO 3 -pBaTiO 3 piezoelectric compound.

19. A Co-doped piezoelectric compound according to claim 18 where 0.80≦x≦0.85, 0.072≦y≦0.102, z=0.03, and 0.048≦p≦0.068.

20. The compound of claim 19 where x is 0.80, y is 0.102, z is 0.03, and p is 0.068.

21. Process for manufacture of Co doped xNa 0.5 Bi 0.5 TiO 3 -yK 0.5 Bi 0.5 TiO 3 -zLi 0.5 Bi 0.5 TiO 3 -pBaTiO 3 piezoelectric compound where 0.80≦x≦0.85, 0.072≦y≦0.102, z=0.03, and 0.048≦p≦0.068 comprising,
forming a mixture of K 2 CO 3 , Na 2 CO 3 , Li 2 CO 3 , BaCO 3 , TiO 2 and Bi 2 O 3 , calcining the mixture to form a calcined composition,
mixing the calcined composition with Co 2 O 3 to form a doped composition, and sintering the doped composition to form Co doped xNa 0.5 Bi 0.5 TiO 3 -yK 0.5 Bi 0.5 TiO 3 -zLi 0.5 Bi 0.5 TiO 3 -pBaTiO 3 where 0.80≦x≦0.85, 0.072≦y≦0.102, z is 0.03, 0.048≦p≦0.068 and (x+y+z+p=1).

22. The process of claim 21 wherein the mixture comprises 1.09 wt. %-1.54 wt. % K 2 CO 3 , 9.32 wt. %-9.98 wt. % Na 2 CO 3 , 0.243 wt. %-0.244 wt. % Li 2 CO 3 , 4.17 wt. %-5.89 wt. % BaCO 3 , 35.22 wt. %-35.42 wt. % TiO 2 , and 47.77-49.09 wt. % Bi 2 O 3 , where all amounts are based on total weight of the mixture, and wherein the calcining is performed at

Assignees

• Penn State Res Found

Inventors

• Zhang Shujun
• Lee Hyeong Jae
• Shrout Thomas R

Classifications

• C04B2235/3215

  Barium oxides or oxide-forming salts thereof · CPC title

• C04B2235/3277

  Co3O4 · CPC title

• C04B2235/3236

  Alkaline earth titanates · CPC title

• C04B2235/3272

  Iron oxides or oxide forming salts thereof, e.g. hematite, magnetite · CPC title

• C04B2235/3267

  MnO2 · CPC title