P
USRE46445EActiveUtilityPatentIndex 51

NBT based lead-free piezoelectric materials for high power applications

Assignee: PENN STATE RES FOUNDPriority: Sep 26, 2008Filed: Aug 5, 2015Granted: Jun 20, 2017
Est. expirySep 26, 2028(~2.2 yrs left)· nominal 20-yr term from priority
Inventors:ZHANG SHUJUNLEE HYEONG JAESHROUT THOMAS R
C04B 2235/3215C04B 2235/3277C04B 2235/3236C04B 2235/3272C04B 2235/3267C04B 2235/3224C04B 35/4682C04B 2235/5436H01L 41/43C04B 2235/3201H01L 41/107C04B 2235/77C04B 35/6262C04B 2235/3234C04B 2235/72C04B 2235/3203H01L 41/1873C04B 2235/3275C04B 2235/3217C04B 2235/3298C04B 35/475C04B 2235/604C04B 35/62675C04B 2235/3262C04B 2235/445C04B 2235/3279H10N 30/097H10N 30/8542H10N 30/40
51
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Claims

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.

Claims

exact text as granted — not AI-modified
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 880° C.  
     
     
       23. The process of claim 22 wherein the sintering is performed at 1100° C.  
     
     
       24. The process of claim 23 wherein the sintering is performed for 2 hrs.  
     
     
       25. The product of the process of claim 24.  
     
     
       26. The compound of claim 1 wherein (0.2≦y<1).  
     
     
       27. The compound of claim 4 wherein (0.2≦y<1).

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