Dielectric and Electromechanical Properties of BaTiO₃ Ceramics Prepared by Hot Isostatic Pressing

Abstract

Lead-free piezoelectric barium titanate (BaTiO₃ or BT) ceramics with various grain sizes were prepared by hot isostatic pressing (HIP) and post-annealing. The dielectric, ferroelectric and electromechanical properties were investigated. The average grain sizes of the ceramics were controlled by changing the post-annealing temperature. The BT ceramics obtained by HIP at 800°C without post-annealing with the average grain size 0.48 μm exhibited ferroelectric behaviors as shown by polarization and electromechanical measurements and the piezoelectric response corresponding to the d₃₃ coefficient of 46 pC/N. The polarization hysteresis loops became more saturated with increasing grain sizes. The remanent polarization and the unipolar strain/field of the BT ceramics prepared by HIP at 800°C under 200 MPa and annealed at 1400°C in air for 12 h were 9.4 μC/cm² and 380 pm/V, respectively.

Keywords:

• Hot isostatic pressing
• BaTiO₃
• lead-free
• piezoelectrics
• grain sizes