Fabrication and properties of reduction-resistant lead-free NaNbO₃–BaTiO₃ piezoelectric ceramics

Abstract

Lead-free NaNbO 3 -BaTiO 3 piezoelectric ceramics were fabricated under a low oxygen partial pressure, which enables co-sintering with base metal Ni electrodes. The reducing atmosphere was accurately controlled by adopting a suitable mixture of Ar, H 2 , and CO 2 gases. By adding MnCO 3 , ZrO 2 , and Li 2 CO 3 , resultant NaNbO 3 -BaTiO 3 ceramics sintered in a reducing atmosphere have high resistivities, maintain high sintering densities, and exhibit piezoelectric constants equivalent or superior to samples prepared in air. The Curie temperatures of the prepared reductionresistant NaNbO 3 -BaTiO 3 samples depend on the amount of BaTiO 3 ; they can be maintained at approximately 200 °C or higher by setting the BaTiO 3 content to 10 mol%. Particularly, 5 mol% MnCO 3 , 2 mol% ZrO 2 , and 1 mol% Li 2 CO 3 -added (Na 0.9 Ba 0.1 )(Nb 0.9 Ti 0.1 )O 3 ceramics sintered under a low oxygen partial pressure (PO 2 = 10 -8 atm at 1250 °C) showed a piezoelectric constant (d 33 ) of 135 pC N −1 and an electromechanical coupling coefficient (k p ) of approximately 25%. © 2021 The Japan Society of Applied Physics 2. Experimental methods 2.1. Fabrication of NaNbO 3 -BaTiO 3 ceramics in air or a reducing atmosphere Samples were prepared by the solid-state reaction process. NaNbO 3 (Kojundo Chemical), BaTiO 3 (Sakai Chemical

NaNbO3‐Based Multilayer Ceramic Capacitors with Ultrahigh Energy Storage Performance

“…[ 17 ] Meanwhile, it is reported that NaNbO 3 ‐based ceramics can be co‐fired with base metal Ni electrodes in a reducing atmosphere, taking advantage of the stable valence state of Nb 5+ . [ 18 ] Considering its exceptional energy storage characteristics and adaptability to various preparation environments, NN emerges as a highly suitable material for developing lead‐free MLCCs intended for actual applications. However, there has been limited research on NN‐based MLCCs, and the existing related investigations primarily focus on materials showing the AFE features.…”

Similarities and differences in the ordering at short and long ranges in a NaNbO3 based Pb-free smart system: a key to functional properties

“…Although barium titanate-based materials have several advantageous properties, their lowtemperature stability of piezoelectric properties has hindered their widespread use in technology. The study of the solid solution of Sodium niobate and Barium Titanate has been an area of significant interest [27][28][29][30][31][32][33].…”

Young’s modulus and ferroelectric property of BaTiO3 films formed by aerosol deposition in consideration of residual stress and film thickness

“…However, piezoelectric materials implemented to date relied on lead zirconate titanate (PZT), which is regulated in Europe. Although lead-free piezoelectric materials are being developed, [15][16][17][18] their output power remained low compared to those of PZTs.…”