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Key engineering materials
Trans Tech Publications Ltd.
Key engineering materials

Trans Tech Publications Ltd.

半月刊

1013-9826

Key engineering materials/Journal Key engineering materials
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    The Influence of Annealing Temperature on the Characteristics of 0.95 (Na_(0.5)Bi_(0.5))TiO_3-0.05 BaTiO_3 Thin Films

    Chien-Chen DiaoChia-Ching WuCheng-Fu YangChao-Chin Chan...
    263-266页
    查看更多>>摘要：In this study, 0.95 (Na_(0.5)Bi_(0.5))TiO_3-0.05 BaTiO_3 + 1 wt% Bi_2O_3 (NBT-BT3) composition sintered at 1200℃ for 2h is used as target to deposit the NBT-BT3 thin films. The excess lwt% Bi_2O_3 is used to compensate the vaporization of Bi_2O_3 during the deposition process. Ferroelectric NBT-BT3 thin films are deposited on SiO_2/Si and Pt/Ti/SiO_/Si substrates using RF magnetron sputter method using the ceramic target fabricated by ourselves. After depositing under the optimal parameters, the thin films are then heated by a conventional thermal annealing (CFA) process conducted in air at temperatures ranging from 600- 800℃ for 60min. The morphologies of NBT- BT3 thin films are observed using SEM the crystalline structures of NBT-BT3 thin films are investigated using XRD patterns. The large memory window and stable leakage current density examination reveals that NBT-BT3 thin films annealed on 600℃ are better than other thin films under different CTA temperatures. Finally, the top view and cross-sectional images of SEM, memory windows, leakage currents and polarization characteristics of NBT-BT3 thin films are also well developed.
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    The Influence of Oxygen Plasma Treatment on the Electrical Properties of (Ba_(0.7)Sr_(0.3))(Ti_(0.9)Zr_(0.1))O_3 Thin Films

    Kai-Huang ChenCheng-Fu Yang
    267-270页
    查看更多>>摘要：The (Ba_(0.7)Sr_(0.3))(Ti_(0.9)Zr_(0.1))O_3 (BSTZ) thin films are deposited using radio frequency (RF) magnetron sputtering, then oxygen gas plasma is treated on the surface of BSTZ thin films. The influence of oxygen plasma on the structure of BSTZ thin films is studied using X-ray diffraction patterns and the influence on the electrical characteristics is developed using an Al/BSTZ/Pt/Ti/SiO_2/Si capacitor structure. As compared to that of the BSTZ thin films are not subjected to oxygen plasma treatment, experimental results reveal that the leakage current density of the BSTZ thin films in oxygen plasma treatment decreases as much as two orders in magnitude. In addition, the dielectric constants apparently increase and the leakage current density critically decrease as the oxygen-plasma-treated time increases. These results clearly indicate that the electrical characteristics of the BSTZ films are effectively improved using the process of oxygen plasma surface treatment.
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    The Electrical and Physical Properties of (Ba_(0.7)Sr_(0.3))(Ti_(0.9)Zr_(0.1))O_3 Thin Films under Conventional Annealing Process

    Kai-Huang ChenCheng-Fu YangChien-Chen Diao
    271-274页
    查看更多>>摘要：In this study, conventional furnace annealing (CFA) is used as the post-treated process, the effects of annealing temperatures on the crystallization and microstructure of (Ba_(0.7)Sr_(0.3))(Ti_(0.9)Zr_(0.1))O_3 (BSTZ) thin films will be developed, and the further influences on the electrical properties of BSTZ thin films are also investigated. A previous study made in our laboratory had shown that the dielectric constant and leakage current density of BSTZ thin film with 640 nm thickness are 192 and 10~(-6) A/cm~2 under the frequency of 100 KHz, respectively. However, the maximum dielectric constant and minimum leakage current density of BSTZ thin films under CFA process are 420 (annealed at 800℃) and 10~(-8) A/cm~2 (700℃), respectively. Besides, the X-ray diffraction (XRD) patterns and the SEM morphology show that crystalline features and grain size of BSTZ thin films increase with the increase of CFA-treated temperatures. These experiment results suggest that a strong correlation exhibits that the physical properties will influence the dielectric properties and nucleation features of BSTZ thin films.
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    Fabrication and Characterization of Sr_(0.7)Ca_(0.3)TiO_3 Substrates Using Aqueous Tape Casting Process

    Weiliang LiuShuoqi LiuDusong Mao
    275-277页
    查看更多>>摘要：Sr_(0.7)Ca_(0.3)TiO_3 (SCT) substrates were prepared through aqueous tape casting. Properties of SCT slurries with and without ammonium polyacrylate (NH4PAA) dispersant were characterized by zeta potential. The zeta potential measurement result shows that the isoelectric point (IEP) of the powder changed obviously with the addition of the dispersant. The optimum pH value of the slurry is in the range of 9-10. The rheological test result indicates that the proper content of the dispersant is between 0.6 and 0.8 wt%. The effect of different plasticizer/binder ratio (R) on the properties of the green tapes was investigated. For 56 wt% solid loading, the tensile strength of the green tape reached 2.02 MPa and the breaking elongation rate was about 8%. SEM micrographs show that the microstructure of the green tapes is homogeneous and the microstructure of the sintered tapes is dense.
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    Dielectric Properties of BiFeO_3 Ceramics with Equal and Unequal Substitutions of Ti for Fe

    Yan Hong GuWan Ping ChenMing Jian DingJian Quan Qi...
    278-280页
    查看更多>>摘要：BiFeO_3, BiFe_(0.9)Ti_(0.1)O_3 and BiFe_(0.9)Ti_(0.05)O_3 ceramics were prepared by solid state reactions and were compared in electrical and dielectric properties. The resistivity of BiFe_(0.9)Ti_(0.1)O_3 was 1.3×10~(12) Ω cm, which was about two and a half orders of magnitude higher than that of BiFeO_3. and three times higher than that of BiFe_(0.9)Ti_(0.1)O_3. The dielectric loss of BiFe_(0.9)Ti_(0.05)O_3 was 0.1 and 0.02 at 100Hz and 1MHz, respectively. These phenomena can be explained base on the decrease of oxygen vacancies V_O~(**) and defect complexes between the ferrum vacancies V_(fe)" and oxygen vacancies V_O~(**) in the ceramics.
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    Ferroelectric Properties and Microstructures of Pr_6O_(11)-Doped Bi_4Ti_3O_(12) Thin Films

    M. ChenA. H. CaiX. A. MeiK. L. Su...
    281-284页
    查看更多>>摘要：Pr_6O_(11)-doped bismuth titanate (Bi_xPr_yTi_3O_(12): BPT) thin films with random oriention were fabricated on Pt/Ti/SiO_2/Si substrates by rf magnetron sputtering technique, and the structures and ferroelectric properties of the films were investigated. XRD studies indicated that all of BPT films consisted of single phase of a bismuth-layered structure with well-developed rod-like grains. For samples with y=0.06, 0.3, 1.2 and 1.5, ferroelectric hysteresis loops were characterized by large leakage current, whereas for samples with y=0.6 and 0.9, ferroelectric hysteresis loops were the saturated and undistorted hysteresis loops. The remanent polarization (P_r) and coercive field (E_c) of the BPT Film with y=0.9 were above 35μC/cm~2 and 80KV/cm , respectively. After 3 × 10~(10) switching cycles, 20% degradation of 2P_r is observed in the film with y=0.9.
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    Dielectric Characteristics of the Lead-free Piezoelectric Ceramics K_(0.50)Na_(0.50)Nb_(0.95)Ta_(0.05)O_3

    Chien-Min ChengKai-Huang ChenHung-Chi YangCheng-Fu Yang...
    285-288页
    查看更多>>摘要：In order to improve the sintering density and dielectric properties of the lead-free K_(0.5)Na_(0.5)NbO_3-based ceramics, bythe use of solid-state reaction, part of the Nb atoms are substituted by the Ta atoms to form K_(0.50)Na_(0.50)Nb_(0.95)Ta_(0.05)O_3 ceramics and the dielectric characteristics are detail investigated in this letter. It is found that the phases of K_(0.50)Na_(0.50)Nb_(0.95)Ta_(0.05)O_3 ceramics are pure perovskite with typical orthorhombic symmetry, in addition, no other secondary phases could be certified. For pure K_(0.50)Na_(0.50)Nb_(0.95)Ta_(0.05)O_3 ceramics, the shapes of the grains are quadrate and which would due to the increase of the porosity and can not be eliminated easily. Because of the phase stability of pure K_(0.50)Na_(0.50)Nb_(0.95)Ta_(0.05)O_3 ceramics is limited to 1140℃ in this study, higher sintering temperature (over than 1140℃) is not suitable for the fabrication of K_(0.50)Na_(0.50)Nb_(0.95)Ta_(0.05)O_3 ceramics. Moreover, the Ta atoms in the K_(0.5)Na_(0.5)NbO_3-based ceramics could be used to improve the dielectric properties effectively, and it also reveals lower Curie temperature and lower phase transition temperature than the pure K_(0.5)Na_(0.5)NbO_3 ceramics. In this letter, for 1120℃-sintered K_(0.50)Na_(0.50)Nb_(0.95)Ta_(0.05)O_3 ceramics, the optimum bulk density is 95.6 % of the theorical density, the Curie temperature is 380℃, and the optimum relative dielectric constant is 6107 at 10 kHz.
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    The Influence of Annealing Treatment on Physics and Electrical Characteristics of Ba(Zr_(0.1)Ti_(0.9))O_3 Ferroelectric Films on ITO/glass Substrate

    Wen-Cheng TzouChien-Min ChengKai-Huang ChenHung-Chi Yang...
    289-292页
    查看更多>>摘要：Perovskite Ba(Zr_(0.1)Ti_(0.9))O_3 (BZ1T9) ferroelectric thin films well deposited on ITO/glass substrates for applications in system-on-panel (SOP) devices are produced and investigated. The sputtering parameters of as-deposited BZ1T9 thin films were rf power of 160 W, chamber pressure of 10 mTorr, substrate temperature of 550℃, and an oxygen concentration of 40%. From the SEM cross-sectional observation, the deposition rate were about 2.5 nm/min. Additionally, the maximum dielectric constant and leakage current density of annealed BZT films under the rapid temperature annealing would be increased, as the temperature increased to 650℃. Further, the maximum remnant polarization and coercive field of BZT films were found and calculated from the p-E curves.
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    Extrinsic Scaling Effects on the Dielectric Response of Grained BaTiO_3 Films

    Liben LiLiqiu SuZhiqiang ZhenXinZhong Li...
    293-295页
    查看更多>>摘要：A set of gradient stresses is used in Landau thermodynamic theory to explain the dielectric diffusion of BaTiO_3 films grown on thick copper foils. Every grain in the films is treated as a single domain core that is surrounded by boundaries with low dielectric constant. The dielectric diffusion is mainly induced by the diffusive phase transition caused by the gradient stresses. The low dielectric constant boundaries suppress the peak value of the dielectric constant. The results agree with the experiments.
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    Bi_4Ti_3O_(12) and Bi_(3.25)La_(0.75)Ti_3O_(12) Thin Films Prepared by RF Magnetron Sputtering

    Jian-Ping YangXing-Ao LiAn-You ZuoZuo-Bin Yuan...
    296-299页
    查看更多>>摘要：Bi_4Ti_3O_(12) (BTO) and Bi_(3.25)La_(0.75)Ti_3O_(12) (BLT) ferroelectric thin films were deposited on Pt/Si substrates by RF magnetron sputtering with Bi_4Ti_3O_(12) (BTO) and Bi_(3.25)La_(0.75)Ti_3O_(12) (BLT) targets with 50-mm diameter and 5-mm thickness. The microstructure and ferroelectric properties of thin films were investigated. The grain growth behavior and ferroelectric properties such as remanent polarization were different in these two kinds of film, the effects of La doping in the BLT thin film were very obvious.
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