Polarization and leakage current properties of high quality bismuth sodium titanate single crystals and polycrystalline ceramics

Abstract

Investigation to obtain the high quality (Bi,Na)TiO 3 (BNT) single crystals and polycrystalline ceramics and to reveal the polarization mechanism of rhombohedral BNT were performed. BNT single crystals were grown by the high-Po 2 flux method and their polarization and piezoelectric properties were investigated along [100] c , [110] c and [111] c , where "c" denote cubic notation used. Strain measurements of rhombohedral BNT crystals suggest that the polarization reversal along [111] c is achieved by non180°spontaneous polarization (P s ) rotation. The values of remanent polarization (P r ) obtained along these three directions provided a value of P s of 5560¯C/cm 2 at 25°C for rhombohedral BNT. The aerosol deposition (AD) method with use of heat treatment supplied fully dense self-supported BNT polycrystalline films detached from substrates. The annealed self-supported BNT polycrystalline films indicated a superior low leakage current density (J) of approximately 10 ¹8 A/cm 2 at 150 kV/cm, which was lower than that of sintered bulks. Also well-saturated hysteresis loops with a large P r of 40¯C/cm 2 were confirmed, which was near value of maxmum P r (4852¯C/cm 2 ) estimated from the P s of high quality BNT single crystals. The high-Po 2 flux method and use of the AD method have been demonstrated to be effective for the obtaining high quality BNT single crystals and polycrystalline ceramics.

Effect of starting powder morphology on film texture for bismuth layer-structured ferroelectrics prepared by aerosol deposition method

“…The aerosol deposition (AD) method based on roomtemperature impact consolidation (RTIC) phenomena attracts attention because it can form thick ceramic layers of simple or complex compositions at room temperature. [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] The use of this method has already been reported for the fabrication of Pb(Zr,Ti)O 3 (PZT) [22][23][24][25] and its application as a component in a piezoelectric actuator. 26) Also, this method was successfully used to enhance the dielectric properties of PbTiO 3 and (Pb 0.91 ,La 0.09 )(Zr 0.65 ,Ti 0.35 )O 3 (PLZT) in the THz range, 27) and the electro-optical properties of PLZT films.…”

“…30) For optical MEMS scanning devices without using Si, a wide optical scan angle at a high resonance frequency (applied voltage of less than 30 V) was achieved by using BTO thick films deposited on Pt=Ti=yttriumstabilized zirconia (YSZ) substrates with a high electric field applied to the BTO layer. 31,32) We obtained enhanced polarization properties for Bi based perovskite oxide ceramic films [SrBi 2 Ta 2 O 9 (SBTa) 33) and (Bi 0.5 Na 0.5 )TiO 3 (BNT) 34,35) where high quality single crystal growth was achieved 36,37) ] by using the AD method because of suppressed Bi vaporization due to low temperature treatment.…”

Bismuth sodium titanate lead‐free piezoelectric coatings by thermal spray process

“…The effective d 33 of BNT–10Bi thermal sprayed coating was very close to BNT bulk ceramic, which was reported to be 57‐64 pm/V, after taking into account the in‐plane substrate clamping effect for the sample of coating. Compared with other processing methods such as pulsed laser deposition (PLD), sol‐gel, and aerosol deposition (AD), thermal sprayed coatings in this work show significantly superior piezoelectric performance property. The d 33 value of the films with the same BNT composition as reported in the literature is only up to 25 pm/V, in which the film was produced by PLD in vacuum chamber, and d 33 was measured by PFM over a micro‐scale area.…”

Excellent Energy-Storage Performance in BNT-SST-LMN Lead-Free Relaxor Ferroelectric Ceramics with High Electrical Homogeneity

“…As one of the relaxor ferroelectric materials receiving the most attention, lead-free (Bi 0.5 Na 0.5 )­TiO 3 (BNT) ceramics have been studied a lot due to the large spontaneous polarization. − However, the low BDS of BNT-based ceramics is detrimental to obtain high W rec and η. To solve this problem, previous research works of BNT-based ceramics have been widely studied. − For example, Y. Lin et al modified Bi­(Mg 2/3 Nb 1/3 )­O 3 ceramic with (Bi 0.5 Na 0.5 ) 0.7 Sr 0.3 TiO 3 and realized W rec of 3.45 J/cm 3 and η of 88.01%.…”