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Masafumi Kobune,Hisashi Oshima,Akihiro Tamura,Kazuki Imagawa,Yusuke Daiko,Atsushi Mineshige,Tetsuo Yazawa,Hitoshi Morioka,Keisuke Saito,Hideshi Yamaguchi,Koichiro Honda 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.31
a- and b-axis-oriented (Bi_(3.25)Nd_(0.75))Ti_3O_(12) films, 3.0 mm thick, were fabricated on conductive IrO_2(101)/Al_2O_3(012) and Nb:TiO_2(101) [Nb = 0, 0.05 and 0.79 mass%] substrates by high-temperature sputtering. A BNT film grown on an IrO_2(101)/Al_2O_3(012) substrate had a low crystallinity (2.83˚), a low degree of a- and b-axis orientations [a_((h00/0k0)) = 49.2%] and a dense microstructure that a- and b-axis-oriented crystals existed locally in the film, while a BNT film grown on Nb:TiO_2(101) substrate with 0.79 mass% Nb showed a high crystallinity (0.57˚), a high a_((h00/0k0)) (99.9%) and a porous microstructure that was comprised of many nanoplate-like crystals. It is shown that the BNT film grew with a heteroepitaxial relationship to the underlying Nb:TiO_2 substrate has a symmetric loop shape, with a remanent polarization (2P_r) of 29 mC/cm^2 and a coercive field (2E_c) of 297 kV/cm.
Akihiro Tamura,Masafumi Kobune,Kazuki Imagawa,Hisashi Oshima,Yusuke Daiko,Atsushi Mineshige,Tetsuo Yazawa,Hiroshi Nishioka,Hironori Fujisawa,Masaru Shimizu,Hideshi Yamaguchi,Koichiro Honda 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.31
3.0-mm-thick a- and b-axis-oriented (Bi_(3.25)Nd_(0.75))Ti_3O_(12) (BNT-0.75) films were fabricated on conductive Nb:TiO_2(101) (Nb = 0, 0.048, 0.46, 0.79 mass%) single crystal substrates by high-temperature sputtering. A BNT films grown on undoped TiO_2 substrates have no orientation, whereas BNT films deposited on Nb:TiO_2 substrates with 0.46-0.79 mass% Nb show strong (h00/0k0) diffractions and grow with a heteroepitaxial relationship to the underlying Nb:TiO_2 substrates. The BNT-0.75 film deposited on Nb:TiO_2(101) substrate with 0.79 mass% Nb was indicated the peculiar shape of approximately 100-150-nm-thick nanoplates. We speculate that the driving force for producing a plate-like structure for BNT films is attributed to the large anisotropy of linear expansion coefficients for Bi_4Ti_3O12, and the comparatively small lattice matching between Nb:TiO_2 substrate and BNT film.
Jiro Abe,Masafumi Kobune,Tetsuo Yazawa 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.46 No.1
High-density (Bi0:5Na0:5TiO3)0:94(BaTiO3)0:06 (BNBT-6) ceramics were fabricated under varying oxygen partial pressure conditions to develop useful lead-free piezoelectric materials with high mechanical quality factors (Qm). In uence of oxygen partial pressure-controlled sintering on physical properties of BNBT-6 ceramics was investigated. A liquid phase occurred in the sample sintered under logP(O2) = 3.50 atm because part of the Bi, a highly volatile element, evaporated from the sample surface during sintering. The mechanical quality factor, Qm, for the radial vibration mode exhibited a maximum (= 270) at logP(O2) = 3.50 atm that was 1.4 times as large as that of the sample sintered at logP(O2) = 0.12 atm. The temperature coecients of resonant and antiresonant frequencies (TCFfr1 and TCFfa1) of the BNBT-6 sample sintered under logP(O2) = 3.50 atm were almost constant: TCFfr1 = 465 ppm/C for the fundamental resonant frequency and TCFfa1 = 381 ppm/C for the fundamental antiresonant frequency. The current technology produces a substantial improvement in Qm characteristics without lowering other piezoelectric parameters, such as relative permittivity, "r, and electromechanical coupling factors, kp and kt, and can be expected to extend the selectivity of electrode materials used in multilayer ceramic actuators.
Hisashi Oshima,Masafumi Kobune,Hideto Tada,Koji Fukushima,Hideshi Yamaguchi,Koichiro Honda 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.2
The formation mechanism of the perovskite structure, the structural properties, and the ferroelectric properties of bismuth lanthanoid nickel titanate (Bi1−xLnx)(Ni0.5Ti0.5)O3 (BLNT, Ln:La, Nd, or Sm, x = 0 − 0.9) thin films deposited on Pt(100)/MgO(100) substrates by sputtering have been investigated using X-ray diffraction and transmission electron microscopy. The present (Bi1−xLax)(Ni0.5Ti0.5)O3 (BLNT, x ≥0.3), (Bi1−xNdx)(Ni0.5Ti0.5)O3 (BNNT, x 0.4), and (Bi1−xSmx)(Ni0.5Ti0.5)O3 (BSNT, x≥0.6) films were confirmed to have been grown heteroepitaxially and to have had a single-phase perovskite structure. It is shown that of the three, the La-substituted BLNT (x = 0.5) film exhibits the best hysteresis loop shape with a remanent polarization of 12 μC/cm2. The formation mechanism of the perovskite structure, the structural properties, and the ferroelectric properties of bismuth lanthanoid nickel titanate (Bi1−xLnx)(Ni0.5Ti0.5)O3 (BLNT, Ln:La, Nd, or Sm, x = 0 − 0.9) thin films deposited on Pt(100)/MgO(100) substrates by sputtering have been investigated using X-ray diffraction and transmission electron microscopy. The present (Bi1−xLax)(Ni0.5Ti0.5)O3 (BLNT, x ≥0.3), (Bi1−xNdx)(Ni0.5Ti0.5)O3 (BNNT, x 0.4), and (Bi1−xSmx)(Ni0.5Ti0.5)O3 (BSNT, x≥0.6) films were confirmed to have been grown heteroepitaxially and to have had a single-phase perovskite structure. It is shown that of the three, the La-substituted BLNT (x = 0.5) film exhibits the best hysteresis loop shape with a remanent polarization of 12 μC/cm2.
Hideto Tada,Masafumi Kobune,Koji Fukushima,Hisashi Oshima,Daisuke Horit,Akihiro Tamura,Yusuke Daiko,Atsushi Mineshige,Tetsuo Yazawa,Hironori Fujisawa,Masaru Shimizu,Hideshi Yamaguchi,Koichiro Honda 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.2
The structural characteristics, the mechanism of crystal growth, and the ferroelectric properties of partially Sm-substituted perovskite bismuth-samarium-nickel-titanate [(Bi1−xSmx)(Ni0.5Ti0.5)- O3; BSNT, x = 0− 0.9] thin films deposited on Pt(100)/MgO(100) substrates by rf sputtering have been investigated using X-ray diffraction, transmission electron microscope, and polarization - electric field hysteresis loop measurements. The fabricated BSNT samples with x≥0.6 were confirmed to have a single-phase perovskite structure. Of the four samples (x = 0.6 0.7, 0.8, and 0.9) with a single-phase perovskite structure, the c-axis-oriented epitaxial BSNT film with x = 0.9 exhibited the best hysteresis loop, with a remanent polarization of 2 μC/cm2 and a coercive field of 100 kV/cm. The structural characteristics, the mechanism of crystal growth, and the ferroelectric properties of partially Sm-substituted perovskite bismuth-samarium-nickel-titanate [(Bi1−xSmx)(Ni0.5Ti0.5)- O3; BSNT, x = 0− 0.9] thin films deposited on Pt(100)/MgO(100) substrates by rf sputtering have been investigated using X-ray diffraction, transmission electron microscope, and polarization - electric field hysteresis loop measurements. The fabricated BSNT samples with x≥0.6 were confirmed to have a single-phase perovskite structure. Of the four samples (x = 0.6 0.7, 0.8, and 0.9) with a single-phase perovskite structure, the c-axis-oriented epitaxial BSNT film with x = 0.9 exhibited the best hysteresis loop, with a remanent polarization of 2 μC/cm2 and a coercive field of 100 kV/cm.
Piezoelectric Properties of High-temperature-Poled Pb(Mn1/3Nb2/3)O3−PbZrO3−PbTiO3 Solid Solutions
Mizuyo Yamaguchi,Masafumi Kobune,Haruka Okuda,Takeyuki Kikuchi 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.4
The piezoelectric properties of high-temperature-poled high-density solid solutions with compositionsof xPb(Mn1/3Nb2/3)O3−yPbZrO3−zPbTiO3 (xPMnN−yPZ−zPT; PMnNZT) with x =0.020 − 0.180, y = 0.420 − 0.580, and z = 0.400 − 0.560 were investigated by using the resonantantiresonantfrequency method. The two optimal compositions that exhibited large values ofd33 · Qm(p), where d33 is the piezoelectric coefficient (longitudinal length mode) and Qm(p) is themechanical quality factor (radial mode) for high-power piezoelectric applications were x = 0.040, y= 0.540, and z = 0.420 in the rhombohedral and the morphotropic phase boundary (MPB) regionsand x = 0.095, y = 0.435, and z = 0.470 in the MPB and the tetragonal regions. By comparingthe maxima in d33 · Qm(p) for high-temperature (HT)-poled PMnNZT samples with the maximain d33 · Qm(p) for room-temperature (RT)-poled PMnNZT samples that had been previously reported,the ratio of d33 · Qm(p)HT /d33 · Qm(p)RT was approximately 1.8, exhibiting a significantimprovement due to HT-poling treatments.
Hirokazu Matsumato,Masafumi Kobune,Takeyuki Kikuchi 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.12
High-density solid solutions with compositions of (1−x)(Bi1/2Na1/2)TiO3−xBa(Mn1/3Nb2/3)O3(BNT-BMN), with x = 0 − 0.06, were prepared by using the conventional ceramic fabricationprocess. The optimal composition that yielded the best piezoelectric properties for high-powerpiezoelectric applications was investigated. X-ray diffraction (XRD) analyses of BNT-BMN withx = 0 − 0.06 suggested that the rhombohedral-pseudocubic morphotropic phase boundary (MPB)for this material system is in the compositional region 0.035 x 0.04 at room temperature. Ahard-mode BNT-BMN with x = 0.03, which lay on the rhombohedral side near the MPB region,exhibited excellent piezo- and ferroelectric properties.
Ryo Kishimoto,Masafumi Kobune,Hiroshi Nishioka,Takeyuki Kikuchi,Hajime Kishi,Hironori Fujisawa,Seiji Nakashima,Masaru Shimizu,Satoshi Kimura 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.7
<EM>a-</EM> and <I>b</I>-axis-oriented Bi<SUB>3.25</SUB>Nd<SUB>0.75</SUB>Ti<SUB>3</SUB>O<SUB>12</SUB> (BNT) nanoplates, 3.0 mm thick, were fabricated on conductive Nb:TiO<SUB>2</SUB>(101) substrates with 0.79 mass% Nb at 650C by high-temperature sputtering. Successively, the fabrication of inorganic-organic composites was carried out by introducing an epoxy resin to the spaces between BNT nanoplates. The fourier transform infrared spectroscopy (FT-IR) and energy dispersive X-ray (EDX) elemental mapping results confirmed that the fabricated composite was an inorganic-organic hybridized material which introduced the cured epoxy resin into the spaces between BNT nanoplates. Based on polarization reversal measurements of the fabricated BNT-epoxy resin composites by piezoresponse force microscopy (PFM), it is shown that the composites have potential as ferroelectric microelement materials.
Jiro Abe,Hiroshi Masumoto,Kazuya Kitada,Masafumi Kobune,Takashi Goto,Tetsuo Yazawa 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.51 No.2I
High-density (1.x)(Na0.5K0.5)NbO3-xLiTaO3 [(1.x)NKN.xLT] ceramics with x = 0 . 0.2 were successfully fabricated by spark-plasma sintering (SPS). The effect of SPS on the microstructure and the piezoelectric properties of the fabricated NKN-LT ceramics are discussed and compared with those of the same NKN-LT ceramics prepared by conventional mixed-oxide ceramic processing. The morphotropic phase boundary (MPB) between the orthorhombic and tetragonal phases for the NKN-LT series was found to be in the vicinity of x = 0.06 . 0.08. The MPB was shifted to the slightly LT-rich side of that previously reported by excess addition of 2.5 mol% K2CO3. The dielectric, ferroelectric and piezoelectric properties of the NKN-LT ceramics fabricated by using the SPS process were excellent compared to those for the conventionally prepared sample. The values of "T 33/"0, kp and Pr were 1.9, 1.4 and 2.3 times larger than the values for the conventionally prepared sample, respectively. These improvements in the ferroelectric and piezoelectric properties of the present ceramics are shown to originate from both the slight excess addition of K2CO3 and the particle orientation imparted by SPS.