Effect of MnO2 addition on temperature-dependent properties of tetragonal (Bi,Na)TiO3–BaTiO3 thick films prepared on MgO ceramic substrates

Density functional theory calculations are conducted for tetragonal BiFeO3–BaTiO3 superlattices to investigate the influence of electronic structures on ferroelectric spontaneous polarization (Ps). When the number of the perovskite unit cell in one layer (N) is decreased below 10, the Ps starts to decrease from the volume-averaged one of 50.9 C/cm2 and eventually becomes half at N = 1. In the BiFeO3 cell (N = ∞) with a large Ps (73.3 C/cm2), a Bi-O covalent bond arising from a Bi_6p-O_2p orbital interaction is extended in an -O-Bi-O- network, and stereo-chemical lone-pair electrons of Bi are accommodated in the opposite direction of the c axis. In the superlattice with N = 1, the -O-Bi-O- bonding is interrupted by Ba and then the Bi-O bond becomes ionic. We show that the large Ps of the BiFeO3 cell originates from the Bi_6p-O_2p mixing superimposed on the stereo-chemical nature of lone-pair electrons of Bi.

Section: Discussionmentioning

confidence: 99%

Ferroelectric polarization of tetragonal BiFeO₃—an approach from DFT calculations for BiFeO₃–BaTiO₃ superlattices—

Noguchi

Matsuo

2022

“…Conversely, thick films are frequently fabricated through aerosol deposition, inkjet printing, and screen printing. [9][10][11][12][13][14] In these approaches, powders (from submicron to micron sizes) are deposited on substrates. Thus, the size of thick film deposition materials is three orders of magnitude larger than that of thin film deposition materials.…”

Section: Introductionmentioning

confidence: 99%

Preparation of Pb(Mg_1/3Nb_2/3)TiO₃–PbTiO₃ thick films with highly preferred orientation via screen printing

Sakai

Karaki

2023

Self Cite

Rhombohedral 0.75Pb(Mg1/3Nb2/3)TiO3–0.25PbTiO3 (PMN–25PT) and tetragonal 0.65Pb(Mg1/3Nb2/3)TiO3–0.35PbTiO3 (PMN–35PT) thick films with a highly preferred orientation were prepared via screen printing on MgO and YSZ ceramics substrates. The use of oriented BaTiO3 thick films as template layers was effective in forming the oriented PMN–25PT and PMN–35PT thick films. The orientation degrees of both thick films were over 0.85. The formation process of the thick films was examined using electron backscatter diffraction. PMN–25PT grains grew on the BaTiO3 template layers and aligned with the BaTiO3 orientation direction. Finally, the PMN–25PT and PMN–35PT thick films prepared on MgO had better electrical properties than the thick films fabricated on YSZ.

Hardening of (Ba_0.5Na_0.5)_0.85Ba_0.15TiO₃lead-free piezoelectric ceramics by adding (Bi_0.5Na_0.5)MnO₃

Doshida¹,

Hayakawa²,

Tamura³

et al. 2022

The hardening of (Bi0.5Na0.5)0.85Ba0.15TiO3 (BNBT15) piezoelectric ceramics was investigated by adding raw materials with Bi0.5Na0.5MnO3 (BNM). BNBT15-BNM exhibited a single phase of BNBT15. BNM acts as a sintering aid for BNBT15 to produce domain pinning, and produces tetragonality based on BaTiO3 for increased stability. BNBT15-BNM hardens piezoelectric material with low Mn content, increasing the coercive field and mechanical quality factor. The mechanical quality factor of BNBT15-BNM (0.75 wt%) exceeded 1200. In high-power conditions, BNBT15-BNM (0.75 wt%) exhibited a vibration velocity twice that of hard-PZT. The quality factor gradually decreased with a high vibration velocity. The equivalent stiffness slightly decreased with strain, and the mechanical nonlinearity was much less than that of hard-PZT. BNBT15-BNM (0.75 wt%) has superior high-power properties, and is expected to be a candidate material for use in lead-free piezoelectric ceramics in high-power applications.