• Title/Summary/Keyword: bismuth titanate

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[100]-Texturing of Barium Titanate Ceramics Using Sodium Bismuth Titanate Templates: Challenges and Insights

  • Nu-Ri Ko;Temesgen Tadeyos Zate;Wook Jo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.37 no.3
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    • pp.328-331
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    • 2024
  • This research explores the development of [100]-textured barium titanate (BaTiO3, BT) ceramics using sodium bismuth titanate (Na0.5Bi4.5Ti4O15, NBiT) templates, aimed at leveraging the inherent high dielectric property of BT. However, the attempted texturing was unsuccessful, primarily due to bismuth diffusion from the NBiT templates into the BT matrix below the sintering temperature, at 1,000℃. Systematical exploration about the cause of the failure is involved and alternative approaches are proposed in detail to overcome the challenge. These findings contribute to the understanding of techniques and conditions for textured ceramic fabrication and highlight the need for further research in this area.

Effect of Surface Charging on the SIMS Depth Profile of Bismuth Titanate Thin Film (SIMS 분석조건이 Bismuth Titanate 박막의 깊이방향 조성 해석에 미치는 영향)

  • Kim, Jae Nam;Lee, Sang Up;Kwun, Hyug Dae;Shin, Kwang Soo;Chon, Uong;Park, Byung Ok;Cho, Sang Hi
    • Analytical Science and Technology
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    • v.14 no.6
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    • pp.486-493
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    • 2001
  • The effect of SIMS analysis conditions such as mesh grid, offset voltage and ion species on the in-depth profile for bismuth titanate thin film was examined in terms of charging effect and detection limit. The results shows that the use of offset voltage -40 V reduces the charging effect and the detection limit. The employment of mesh grid in sample preparation leads to the reduction of the charging effect in small amount, but deteriorate the detection limit. Utilization of primary $O^-$ ion for SIMS analysis of bismuth titanate thin film showed almost the same effect as using offset voltage -40 V. However, it takes approximately triple acquisition time than using $O_2{^+}$ ion due to the poor beam current of the source in the experiment.

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Improvement of Fatigue Properties in Ferroelectric Dy-Doped Bismuth Titanate(BDT) Thin Films Deposited by Liquid Delivery MOCVD System (Liquid Delivery MOCVD로 증착된 강유전체 BDT 박막의 피로 특성 향상)

  • Kang, Dong-Kyun;Park, Won-Tae;Kim, Byong-Ho
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2007.06a
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    • pp.171-171
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    • 2007
  • Dysprosium-doped bismuth titanate (BDT) thin films were successfully deposited on Pt(111)/Ti/$SiO_2$/Si(100) substrates by liquid delivery MOCVD process and their structural and ferroelectric properties were characterized. Fabricated BDT thin films were found to be random orientations, which were confirmed by X-ray diffraction experiment and scanning electron microscope analysis. The crystallinity of the BDT films was improved and the average grain size increased as the crystallization temperature increased from 600 to $720^{\circ}C$ at an interval of $40^{\circ}C$. The BDT thin film annealed at $720^{\circ}C$ showed a large remanent polarization (2Pr) of $52.27\;{\mu}C/cm^2$ at an applied voltage of 5V. The BDT thin film exhibits a good fatigue resistance up to $1.0{\times}10^{11}$ switching cycles at a frequency of 1 MHz with applied pulse of ${\pm}5\;V$. These results indicate that the randomly oriented BDT thin film is a promising candidate among ferroelectric materials useti비 in lead-free nonvolatile ferroelectric random access memory applications.

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Direct Determination of Cationic Disordering in Sodium Bismuth Titanate

  • Choi, Si-Young;Ikuhara, Yuichi
    • Applied Microscopy
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    • v.42 no.3
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    • pp.164-173
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    • 2012
  • The relaxor ferroelectric feature in lead-free perovskite oxides, where the dipoles are randomly oriented and they can be feasibly aligned parallel to the external bias, is attracting lots of attention in the field of piezoelectric materials science, since it is one of candidates to replace the toxic lead-based materials that are still being commercially used. However, the origin of relaxor characteristic and its related atomic structure are still ambiguous. In this study, $Na_{1/2}Bi_{1/2}TiO_3$, chosen as a model relaxor system, was found to exhibit a cationic-disordered atomic structure; and furthermore the nonpolar atomic structure and its related oxygen tilting were ascertained via annular bright field imaging skill. We also found that this cationic disordering gives rise to the local formation of atomic vacancies.

Fabrication of barium titanate-bismuth ferrite fibers using electrospinning

  • Baji, Avinash;Abtahi, Mojtaba
    • Advances in nano research
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    • v.1 no.4
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    • pp.183-192
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    • 2013
  • One-dimensional multiferroic nanostructured composites have drawn increasing interest as they show tremendous potential for multifunctional devices and applications. Herein, we report the synthesis, structural and dielectric characterization of barium titanate ($BaTiO_3$)-bismuth ferrite ($BiFeO_3$) composite fibers that were obtained using a novel sol-gel based electrospinning technique. The microstructure of the fibers was investigated using scanning electron microscopy and transmission electron microscopy. The fibers had an average diameter of 120 nm and were composed of nanoparticles. X-ray diffraction (XRD) study of the composite fibers demonstrated that the fibers are composed of perovskite cubic $BaTiO_3$-$BiFeO_3$ crystallites. The magnetic hysteresis loops of the resultant fibers demonstrated that the fibers were ferromagnetic with magnetic coercivity of 1500 Oe and saturation magnetization of 1.55 emu/g at room temperature (300 K). Additionally, the dielectric response of the composite fibers was characterized as a function of frequency. Their dielectric permittivity was found to be 140 and their dielectric loss was low in the frequency range from 1000 Hz to $10^7$ Hz.

The ferroelectric and fatigue properties in Gd-modified bismuth titanate (BGT) thin films deposited by liquid delivery MOCVD

  • Kang Dong-Kyun;Park Won-Tae;Kim Byong-Ho
    • Proceedings of the Korean Society Of Semiconductor Equipment Technology
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    • 2006.05a
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    • pp.190-193
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    • 2006
  • Gadolinium-substituted bismuth titanate, $Bi_{3.3}Gd_{0.7}Ti_{3}O_{12}$, thin films were successfully fabricated on Pt(111)/Ti/$SiO_2$/Si(100) substrates by a MOCVD process. Fabricated BGT thin films were found to be random oriental ions, which were confirmed by X-ray diffraction and scanning electron microscope analysis. The remanent polarization value ($2P_r$) of the BGT thin film annealed at $720^{\circ}C$ was $45.13{\mu}C/cm^2$, at an applied voltage of 5 V. The BGT thin film exhibits a good fatigue resistance up to $1{\times}10^{11}$ switching cycles at a frequency of 1 MHz with applied voltage of 5 V. These results indicate that the randomly oriented BGT thin film is a promising candidate among ferroelectric materials useful in lead-free nonvolatile ferroelectric random access memory applications.

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Deposition mechanism of $Bi_4Ti_3O_{12}$ films on Si by MOCVD and property improvement by pulse injection method (MOCVD $Bi_4Ti_3O_{12}$ 박막의 실리콘 위에서의 증착기구 및 유기 금속원료의 펄스주입법에 의한 박막 특성 개선)

  • 이석규;김준형;최두현;황민욱;엄명윤;김윤해;김진용;김형준
    • Journal of the Korean Vacuum Society
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    • v.9 no.4
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    • pp.373-378
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    • 2000
  • There was a great difference in the formation kinetics of $TiO_2$ and $Bi_2O_3$ on silicon, but the growth of bismuth titanate (BIT) thin film was mainly limited by the formation of $TiO_2$. As a result, the BIT film was easy to be lack of bismuth. The pulse injection metalorganic chemical vapor deposition (MOCVD) process was introduced in order to overcome this problem by recovering the insufficient bismuth content in the film. By this pulse injection method, bismuth content was increased and also the uniform in-depth composition of the film was attained with a abrupt $Bi_4Ti_3O_{12}/Si$ interface. In addition, the crystallinity of $Bi_4Ti_3O_{12}$ thin film prepared by pulse injection process was greatly improved and the leakage current density was lowered by 1/2~1/3 of magnitude. Clockwise hysteresis of C-V was observed and the ferroelectric switching was confirmed for $Bi_4Ti_3O_{12}$ film deposited by pulse injection method.

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The effect of nano-sized starting materials and excess amount of Bi on the dielectric/piezoelectric properties of 0.94[(BixNa0.5)TiO3]-0.06[BaTiO3] lead free piezoelectric ceramics

  • Khansur, Neamul Hayet;Ur, Soon-Chul;Yoon, Man-Soon
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2009.11a
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    • pp.31.1-31.1
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    • 2009
  • In an approach to acclimate ourselves torecent ecological consciousness trend, a lead-free piezoelectric material, bismuth sodium titanate (abbreviated as BNT) based bismuth sodium barium titanate (abbreviated as BNT-BT), was considered as an environment-friendly alternative for a lead based piezoelectric system. Ceramic specimens of0.94[(BixNa0.5)TiO3]-0.06[BaTiO3] (x = 0.500~0.515) compositions were prepared by a modified mixed oxide method. To increase the chemical homogeneity andre action activity, high energy mechanical milling machine and pre-milled nanosized powder has been used. In this method (BixNa0.5)TiO3 (x=0.500~0.515) andBaTiO3 were prepared separately from pre-milled constituent materials at low calcination temperature and then separately prepared BNTX (X=1, 2, 3 and 4) and BT were mixed by high energy mechanical milling machine. Without further calcination step the mixed powders were pressed into disk shape and sintered at $1110^{\circ}C$. Microstructures, phase structures and electrical properties of the ceramic specimens were systematically investigated. Highly dense ceramic specimens with homogenous grains were prepared in spite of relatively low sintering temperature. Phase structures were not significantly influenced by the excess amount Bi. Large variation on the piezoelectric and dielectric properties was detected at relative high excess Bi amounts. When $x{\leq}0.505$, the specimens exhibit insignificant variation in piezoelectric and dielectric constant though depolarization temperature is found to be decreased. Considerable amount of decrease in piezoelectric and dielectric properties are observed with higher excess of Bi amounts ($x{\geq}0.505$). This research indicates the advantages of high energy mechanical milling and importance of proper maintenance of Bi stoichiometry.

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