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NBT based lead-free piezoelectric materials for high power applications

a piezoelectric material and lead-free technology, applied in piezoelectric/electrostrictive/magnetostrictive devices, basic electric elements, electric apparatus, etc., can solve the problems of limited use range, low mechanical quality factor q of knn-type lead-free compounds, and limit their utility. , to achieve the effect of high mechanical quality factor, wide temperature usage range, and high internal bias field

Active Publication Date: 2017-06-20
PENN STATE RES FOUND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The NBT-based materials demonstrate improved 'hardening' effects, high acoustic velocities, and environmental friendliness, making them suitable for high-power applications like ultrasonic transducers and motors, while maintaining performance comparable to PZT materials.

Problems solved by technology

However, the lead content in PZT type ceramics is an environmental concern in electronic devices.
), show low piezoelectric activity, multiple polymorphic phase transitions as well as depolarization temperature which limit their utility.
NBT-KBT, NBT-KBT-BT, and NBT-KBT-LBT, however, exhibit a nonpolar antiferroelectric phase transition temperature that occurs below their TC that limits their temperature range of use.
However, these KNN type lead-free compounds exhibit low mechanical quality factor Q and a shift in the orthorhombic-tetragonal polymorphic phase transition temperature from about 200° C. to about room temperature.
This polymorphic phase transition significantly limits their utility due to property variations.

Method used

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  • NBT based lead-free piezoelectric materials for high power applications
  • NBT based lead-free piezoelectric materials for high power applications
  • NBT based lead-free piezoelectric materials for high power applications

Examples

Experimental program
Comparison scheme
Effect test

example 1a

Manufacture of an Undoped Piezoelectric Compound of the Formula xNa0.5Bi0.5TiO3-yK0.5Bi0.5TiO3-pBaTiO3 where x is 0.79, y is 0.14, and p is 0.07, Hereinafter Referred to as BNBK79

[0060]0.64 gms K2CO3, 2.77 gms Na2CO3, 10.57 gms TiO2, 14.19 gms Bi2O3 and 1.83 gms BaCO3 are blended to yield a mixture. The mixture is calcined in air at 880° C. for 2 hrs to yield a calcined composition. The calcined composition then is vibration milled in anhydrous ethanol to produce a milled material that has a particle size of 1 micron. The milled material then is mixed with 2 wt. % Rhoplex binder from Rohm and Haas where the amount of binder is based on the weight of milled material. The resulting milled material-binder composition is compressed at 5000 PSI to yield a preform in the form of a disk that measures 12 mm diameter by 1 mm thick.

[0061]The preform is heated in air to 550° C. to burn out the binder and to yield a green preform. The green preform then is sintered in air at 1100° C. for 2 hrs ...

example 1b

Manufacture of Piezoelectric Compound that has the Formula ((xNa0.5Bi0.5TiO3-yK0.5Bi0.5TiO3-pBaTiO3)-0.5Mn) where x is 0.79, y is 0.14, and p is 0.07, Hereinafter Referred to as BNBK 79-0.5 wt % MnO2

[0062]0.64 gms K2CO3, 2.77 gms Na2CO3, 10.57 gms TiO2 and 14.19 gms Bi2O3 and 1.83 gms BaCO3 are blended to yield a mixture. The mixture then is calcined in air at 880° C. for 2 hours to yield a calcined composition. The calcined composition then is mixed with 0.14 gms MnO2 (0.5 wt % MnO2 based on the weight of the calcined composition) to yield a doped mixture. The doped mixture is vibration milled in anhydrous ethanol to produce a milled material that has a particle size of 1 micron. The milled material is mixed with 2 wt. % Rhoplex binder from Rohm and Haas where the amount of binder is based on the weight of milled material. The resulting milled material-binder composition is compressed at 5000 PSI to yield a preform in the form of a disk that measures 12 mm diameter by 1 mm thick. ...

example 1c

Manufacture of Piezoelectric of the Formula (xNa0.5Bi0.5TiO3-yK0.5Bi0.5TiO3-pBaTiO3)-0.7Mn where x is 0.79, y is 0.14, and p is 0.07 Hereinafter Referred to as BNBK 79-0.7 wt % MnO2

[0063]The procedure of example 1B is followed except that 0.2 gms. MnO2 is employed.

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Abstract

Piezoelectric compounds of the formula xNamBinTiO3-yKmBinTiO3-zLimBinTiO3-pBaTiO3 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.

Description

[0001]This application claims priority to U.S. provisional patent application 61 / 194,461 filed Sep. 26, 2008.FIELD OF THE INVENTION[0002]The disclosed invention relates to hard lead free piezoelectric materials.BACKGROUND OF THE INVENTION[0003]Hard PZT ferroelectric materials such as PZT4 and PZT8 have been the mainstay in last half century for high power applications. However, the lead content in PZT type ceramics is an environmental concern in electronic devices. For example, the European Union is proposing directives on waste from electrical and electronic equipment as well restrictions on hazardous substances and end-of life vehicles. The USA and Japan are expected to issue similar environmental regulations. It therefore is desirable to develop lead-free piezoelectric ceramics to replace lead-based materials.[0004]Lead-free ceramic compounds may be categorized into three primary types, all of which have the ABO3 perovskite formulation: (1) BaTiO3 (“BT”), (2) K0.5Na0.5NbO3 (“KNN”...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): H01L41/187C04B35/626H01L41/43C04B35/468C04B35/475H01L41/107H10N30/85H10N30/853H10N30/01H10N30/093H10N30/097H10N30/20H10N30/40
CPCC04B35/4682C04B35/475C04B35/6262C04B35/62675C04B2235/3201C04B2235/3203C04B2235/3215C04B2235/3217C04B2235/3224C04B2235/3234C04B2235/3236C04B2235/3262C04B2235/3267C04B2235/3272C04B2235/3275C04B2235/3277C04B2235/3279C04B2235/3298C04B2235/445C04B2235/5436C04B2235/604C04B2235/72C04B2235/77H10N30/40H10N30/8542H10N30/097
Inventor ZHANG, SHUJUNLEE, HYEONG JAESHROUT, THOMAS R
Owner PENN STATE RES FOUND