• Title, Summary, Keyword: Bismuth ferrite

Search Result 16, Processing Time 0.046 seconds

Visible Light Photocatalytic Properties of Bismuth Ferrite Prepared By Sol-Gel Method (졸-겔법으로 제조된 Bismuth ferrite의 가시광 광촉매 특성)

  • Park, Byung-Geon;Chung, Kyong-Hwan
    • Korean Chemical Engineering Research
    • /
    • v.58 no.3
    • /
    • pp.486-492
    • /
    • 2020
  • The method for preparing a perovskite-type bismuth ferrite (BFO) photocatalyst which reacts to visible LED light and the characteristics of visible light photocatalysis were investigated. BFO was prepared according to the sol-gel method. The prepared BFO consisted mainly of BiFeO3 structure and formed a nano-sized crystal including Bi24Fe2O39 structure. The BFO nano crystallines were identified from the UV-visible diffuse reflectance spectra to absorb UV and visible light up to about 600 nm. The bandgap of the BFO determined from the diffuse reflectance spectrum was about 2.2 eV. Formaldehyde was decomposed by the photoreaction of BFO photocatalysts with the visible light LED lamps with wavelengths of 585 nm and 613 nm. The narrow bandgap of BFO led to elicit BFO photocatalytic activity in visible LED light.

Fabrication and Electrical Properties of PZT/BFO Multilayer Thin Films

  • Jo, Seo-Hyeon;Nam, Sung-Pil;Lee, Sung-Gap;Lee, Seung-Hwan;Lee, Young-Hie;Kim, Young-Gon
    • Transactions on Electrical and Electronic Materials
    • /
    • v.12 no.5
    • /
    • pp.193-196
    • /
    • 2011
  • Lead zirconate titanate (PZT)/ bismuth ferrite (BFO) multilayer thin films have been fabricated by the spin-coating method on Pt(200 nm)/Ti(10 nm)/$SiO_2$(100 nm)/p-Si(100) substrates using $BiFeO_3$ and $Pb(Zr_{0.52}Ti_{0.48})O_3$ metal alkoxide solutions. The PZT/BFO multilayer thin films show a uniform and void-free grain structure, and the grain size is smaller than that of PZT single films. The reason for this is assumed to be that the lower BFO layers play an important role as a nucleation site or seed layer for the formation of homogeneous and uniform upper PZT layers. The dielectric constant and dielectric losses decreased with increasing number of coatings, and the six-layer PZT/BFO thin film has good properties of 162 (dielectric constant) and 0.017 (dielectric losses) at 1 kHz. The remnant polarization and coercive field of three-layer PZT/BFO thin films were 13.86 ${\mu}C/cm^2$ and 37 kV/cm respectively.

Fabrication of barium titanate-bismuth ferrite fibers using electrospinning

  • Baji, Avinash;Abtahi, Mojtaba
    • Advances in nano research
    • /
    • v.1 no.4
    • /
    • pp.183-192
    • /
    • 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.

Nonstoichiometric Effects in the Leakage Current and Electrical Properties of Bismuth Ferrite Ceramics

  • Woo, Jeong Wook;Baek, SeungBong;Song, Tae Kwon;Lee, Myang Hwan;Rahman, Jamil Ur;Kim, Won-Jeong;Sung, Yeon Soo;Kim, Myong-Ho;Lee, Soonil
    • Journal of the Korean Ceramic Society
    • /
    • v.54 no.4
    • /
    • pp.323-330
    • /
    • 2017
  • To understand the defect chemistry of multiferroic $BiFeO_3-based$ systems, we synthesized nonstoichiometric $Bi_{1+x}FeO_{3{\pm}{\delta}}$ ceramics by conventional solid-state reaction method and studied their structural, dielectric and high-temperature charge transport properties. Incorporation of an excess amount of $Bi_2O_3$ lowered the Bi deficiency in $BiFeO_3$. Polarization versus electric field (P-E) hysteresis loop and dielectric properties were found to be improved by the $Bi_2O_3$ addition. To better understand the defect effects on the multiferroic properties, the high temperature equilibrium electrical conductivity was measured under various oxygen partial pressures ($pO_2{^{\prime}}s$). The charge transport behavior was also examined through thermopower measurement. It was found that the oxygen vacancies contribute to high ionic conduction, showing $pO_2$ independency, and the electronic carrier is electron (n-type) in air and Ar gas atmospheres.

비납계 $(1-x)(Bi_{0.5}K_{0.5})TiO_3-xBiFeO_3$ 세라믹의 유전 및 압전 특성

  • Kim, Jeong-Min;Seong, Yeon-Su;Song, Tae-Gwon;Kim, Myeong-Ho
    • Proceedings of the Materials Research Society of Korea Conference
    • /
    • /
    • pp.33.2-33.2
    • /
    • 2009
  • Dielectric and piezoelectric properties of Lead-free $(1-x)(Bi_{0.5}K_{0.5})TiO_3-xBiFeO_3$ceramics prepared by a conventional solid state reaction method were investigated in the range of x = 0~10 mol%. Piezoelectric coefficient was increased from 31 pC/N at x = 0 mol% to 64 pC/N at x = 6 mol% then decreased with increasing x. Electromechanical coupling factor ($K_p$) was increased up to 0.18 at x = 10 mol%. On the other hand, mechanical quality factor ($Q_m$) was decreased. Grain size was not much changed with various x and a single perovskite with tetragonal symmetry was maintained at all compositions forming a solid solution between $(Bi_{0.5}K_{0.5})TiO_3$ and $BiFeO_3$. Depolarization temperature ($T_d$) was gradually decreased with increasing x from $302^{\circ}C$ at x = 0 to $245^{\circ}C$ at x = 10 mol%.

  • PDF

Magnetic and Electric Properties of Multiferroic Ni-doped BiFeO3

  • Yu, Yeong-Jun;Hwang, Ji-Seop;Park, Jeong-Su;Lee, Ju-Yeol;Gang, Ji-Hun;Kim, Gi-Won;Lee, Gwang-Hun;Lee, Bo-Hwa;Lee, Yeong-Baek
    • Proceedings of the Korean Vacuum Society Conference
    • /
    • /
    • pp.182-182
    • /
    • 2014
  • Multiferroic materials have attracted much attention due to their own fascinating fundamental physical properties and potential technological applications to magnetic/ferroelectric data storage systems, quantum electromagnets, spintronics, and sensor devices. Among single-phase multiferroic materials, $BiFeO_3$, in particular, has received considerable attention because the enhanced ferromagnetism was found by the Fe-site ion substitution with magnetic ions. The structural, the magnetic and the ferroelectric properties of polycrystalline $BiFe_{1-x}Ni_xO_3$ (x=0, 0.01, 0.02, 0.03 and 0.05), which were prepared by the solid-state reaction and the rapid-sintering method, have been investigated. The x-ray diffraction patterns reveal that all the samples are in single phase and show rhombohedral structure with R3c space group. The magnetic properties are enhanced according to the doping content. The Ni-doped $BiFeO_3$ samples exhibit lossy P-E loop due to the oxygen vacancy. The leakage current density of Ni-doped samples (x=0.01 and 0.02) is increased by four orders of magnitude. On the other hand, the x=0.03 and 0.05 samples show the relative reduction of the leakage current.

  • PDF

Domain engineering in BiFeO3 thin films

  • Baek, Seung-Hyub;Choi, Seokhoon;Kim, Taemin Ludvic;Jang, Ho Won
    • Current Applied Physics
    • /
    • v.17 no.5
    • /
    • pp.688-703
    • /
    • 2017
  • Recent advances in synthesizing complex oxide epitaxial heterostructures with precise control in atomic scale have opened a new era of materials science and engineering research, enabling discoveries of novel physical phenomena even from materials that have been studied for a long time. The exquisite control of high-quality thin films through composition, defects, strain, and microstructure allows us to clearly distinguish intrinsic and extrinsic properties that were obscured by the limitation of sample quality. This is vividly exemplified by the recent research on bismuth ferrite ($BiFeO_3$). Due to the moderately low symmetry of $BiFeO_3$ with a rhombohedral structure, domain engineering, controlling the configuration of domains and domain walls, plays a critical role not only in understanding fundamental physics of electrical and magnetic properties, but also in inducing novel functionalities such as photovoltaic and photocatalysis. In this review, various ways to control domain structures of $BiFeO_3$ will be described with the consequent modification in the physical properties of $BiFeO_3$. This methodology can be expanded to other low-symmetric thin film materials for designing new functionalities.

Phase Evolution Behavior of (Bi,Nd)(Fe,Ti)O3 Ceramics and Thin Films ((Bi,Nd)(Fe,Ti)O3 세라믹스와 박막의 상형성 거동)

  • Kim, Kyung-Man;Lee, Hee-Young
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.23 no.12
    • /
    • pp.949-955
    • /
    • 2010
  • Nd and Ti co-doped bismuth ferrite $(Bi_{1-x}Nd_x)(Fe_{1-y}Ti_y)O_3$ (x, y = 0, 0.05, 0.1, 0.2) ceramics and thin films were synthesized through the conventional mixed-oxide process and pulsed laser deposition (PLD), respectively. Nd and Ti co-doping effect was examined with emphasis on how these impurities affect phase formation behavior as there could be the improvement in leakage current problems often associated with multiferroic $BiFeO_3$ (BFO) thin films. The lattice constants of BFO ceramics decreased with Nd doping concentration up to 10mol%, while they further decreased with Nd and Ti co-doping to about 20%. BFO thin films obtained by the PLD process revealed random polycrystalline structure. Similar to bulk BFO ceramic, Nd and Ti co-doping effectively suppressed the formation of unwanted secondary phase and thus stabilized the perovskite phase in BFO thin films.