Abstract

This paper describes a cold sintering process for Pb(Zr,Ti)O3 ceramics and the associated processing-property relations. Pb(Zr,Ti)O3 has a very small, incongruent solubility that is a challenge during cold sintering. To circumvent this, a Pb(NO3)2 solution was used as the transient liquid phase. A bimodal lead zirconate titanate powder was densified to a relative density of 89% by cold sintering at 300 °C and 500 MPa. After the cold sintering step, the permittivity was 200, and the dielectric loss was 2.0%. A second heat-treatment involving a 3 h anneal at 900 °C increased the relative density to 99%; the resulting relative dielectric permittivity was 1300 at room temperature and 100 kHz. The samples showed well-defined ferroelectric hysteresis loops, having a remanent polarization of 28 μC/cm2. On poling, the piezoelectric coefficient d33 was ∼200 pC/N. With a 700 °C 3 h post-annealing, samples show a lower room temperature relative permittivity (950 at 100 kHz), but a 24 h hold time at 700 °C produces ceramics where there is an improved relative dielectric constant (1050 at 100 kHz).

Highlights

  • Lead Zirconate Titanate (PZT) piezoelectric ceramics are widely employed in ultrasound transducers,[1] precise positioning actuators,[2] sensors, and energy harvesters.[3]

  • In the case of BaTiO3, the use of water as a liquid phase promotes leaching of Ba2+ with subsequent formation of BaCO3 and passivation of the powder surfaces with an unreactive hydrated titanium-rich surface layer that prevents densification.[18]

  • Sintering temperature reduces the amount of lead loss, which may decrease the number of point defects in PZT, and leads to less pollution

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Summary

Introduction

Lead Zirconate Titanate (PZT) piezoelectric ceramics are widely employed in ultrasound transducers,[1] precise positioning actuators,[2] sensors, and energy harvesters.[3]. (Received 12 September 2017; accepted 5 December 2017; published online 2 January 2018) Some of the cold sintered PZT pellets underwent a post-annealing step at 700 ◦C for 3 h, 700 ◦C for 24 h, or 900 ◦C for 3 h.

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