piezoelectric ceramics压电陶瓷 2

Crystal structure

<130℃

The cell of the perovskite form elongates along an edge

<0℃

The cube elongates along a face diagonal rather than an edge

<-90℃

The rhombohedral cell elongates along a body diagonal

Chemistry The solid state reactionTiO2 TiO2 TiO2 BaCO3 BaTiO Ba BaTiO 3 2TiO 3 3 TiO2 TiO2 BaCO3

BaCO3 BaTiO Ba BaTiO 3 2TiO 3 3

BaTiO3TiO2

BaCO3

TiO2

BaCO Ba BaTiO 3 BaTiO 2TiO 3 3 3

TiO2 TiO BaTiO 2 3 BaCO3

BaCO3 BaTiO Ba BaTiO 3 2TiO 3 3 TiO2

TiO2

BaCO3 3 BaTiO TiO2

BaTiO BaCO Ba BaTiO 3 3 2TiO 3 3

BaTiO3BaCO3

BaTiO3BaCO3

TiO2

BaCO3

BaTiO3

TiO BaTiO 3 2

BaTiO BaCO Ba BaTiO 33 2TiO 3 3

BaTiO BaCO Ba BaTiO 33 2TiO 3 3

The co-precipitation methods

Higher purity products More costly and do not give stronger piezoelectric properties

Microstructure and domain

Polyercrystalline BaTiO3 after polishing and etching

Electron micrograph of BaTiO3 ceramic showing 180o domain walls

Dielectric properties

Relative dielectric constant

Dielectric constant

Loss tangent

Temperature ℃Relative dielectric constant and

Relative dielectric constant

Relative porosity

Relative dielectric constant and loss tangent for unpoled ceramic BaTiO3, measured at 3 GHz and 1 kHz loss tangent for unpoled ceramic BaTiO3, measured at 3 GHz and 1 kHz

Effect of electric field DC field poling The application of a field while the ceramic is cooling through the Curie point causes maximum alignment, since the dipoles are most easily aligned as they appear spontaneously.

Temperature, ℃

Temperature and bias field dependence of kp and k31 for poled BaTiO3

k31

kp

Alternating fields

Hysteresis loops for (100) crystal plate and for high-quality BaTiO3 ceramics, drawn to same scale

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