• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.8
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• pp.1153-1158
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• 2012

Niobium oxide ($Nb_2O_5$) has a strong chemical coherence and good electrical conductivity. Therefore, this material is helpful to enhance the performance of the dye sensitized solar cells (DSC) by improving the electron mobility. In this study, $Nb_2O_5$ was mixed with $TiO_2$ and this compound was applied to the DSC to improve its performance. As a result, the current density of the DSC using the $Nb_2O_5-TiO_2$ compound on the photoelectrode was increased, because the internal resistance concerned to the electron transfer in the photoelectrode of DSC was decreased. However, large amount of the $Nb_2O_5$ induces the decrease of the efficiency of the DSC because the surface area to attach dye molecules is decreased due to the large particle of $Nb_2O_5$. Therefore, it is important to optimize the mixture ratio of the $Nb_2O_5-TiO_2$ compound for maximizing the performance of the DSC. Finally, the most optimum performance of the DSC was shown in case of the $Nb_2O_5$ concentration of 10 wt% of the $Nb_2O_5-TiO_2$ compound.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.91-92
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• 2007

An anomalous positive temperature coefficient of electrical resistivity (PTCR) was investigated in a ferroelectric lead-free perovskite-type compound $(Bi_{0.5}Na_{0.5})TiO_3$ within $BaTiO_3$-based solid solution ceramics. The effect of $Nb_2O_5$ content on the electrical properties and the microstructure of (1 - x) $BaTiO_3-x\;(Bi_{0.5}Na_{0.5})TiO_3$ (BNT) ceramics made using a conventional mixed oxide process also has been studied. The Curie temperature was obviously increased with the increasing of $(Bi_{0.5}Na_{0.5})TIO_3$ content. The Nb - doped BNT ceramics (x=0.01) display low resistivity values of $10^{1{\circ}}C-10^{2{\circ}}C$ ohm.cm at room temperature and the Curie Temperature of $T_c=160^{\circ}C$.

• Electrical & Electronic Materials
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• v.9 no.7
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• pp.652-659
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• 1996

Sintering characteristics and electrical properties of xPb(Mg$_{1}$8/Te$_{1}$8/Mn$_{1}$4/Nb$_{1}$2/) $O_{3}$-(1-x) Pb (Zr$_{1}$2/ $Ti_{1}$2/) $O_{3}$ (x=0.075, 0.1, 0.125) ceramics are investigated. A sintering temperature of ceramics could be reduced to 950.deg. C by a reaction between PbO and B site compound material. The physical properties of 0.1Pb(Mg, Te, Mn, Nb) $O_{3}$ - 0.9Pb(Zr, Ti) $O_{3}$ bulk ceramic with 3wt% glass frit(0.857PbO-0.143W $O_{3}$) were following : den = 7.95 g/cm$^{3}$, T$_{c}$=340.deg. C, .epsilon.$_{33}$= 754, k$_{31}$=0.3 and Q.=1780. The 3-layer piezoelectric transformer by using a tape casting method showed a good monolithic structure, and its voltage setup ratio was 2.5 times higher than that of a single device by using bulk ceramics.s.s.

• Advances in materials Research
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• v.1 no.2
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• pp.115-128
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• 2012

The structural and electrical properties of $(1-x)Ba(Sm_{1/2}Nb_{1/2})O_3-xBaTiO_3$; ($0{\leq}x{\leq}1$) ceramics were prepared by conventional ceramic technique at $1375^{\circ}C$/7 h in air atmosphere. The crystal symmetry, space group and unit cell dimensions were derived from the X-ray diffraction (XRD) data using FullProf software whereas crystallite size and lattice strain were estimated from Williamson-Hall approach. XRD analysis of the compound indicated the formation of a single-phase cubic structure with the space group Pm m. Dielectric study revealed that the compound $0.75Ba(Sm_{1/2}Nb_{1/2})O_3-0.25BaTiO_3$ is having low and ${\varepsilon}^{\prime}$ and ${\varepsilon}^{{\prime}{\prime}}$ a low $T_{CC}$ (< 5%) in the working temperature range (up to+$100^{\circ}C$) which makes this composition suitable for capacitor application and may be designated as 'Stable Low-K' Class I material as per the specifications of the Electronic Industries Association. The correlated barrier hopping model was employed to successfully explain the mechanism of charge transport in the system. The ac conductivity data were used to evaluate the density of states at Fermi level, minimum hopping length and apparent activation energy of the compounds.

• Analytical Science and Technology
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• v.10 no.6
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• pp.439-444
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• 1997

Twelve kinds (1set) standard materials of chemical ingredients of lead zirconate titanate[$Pb(ZrTi)O_3$] have been developed in order to determine fast and accurate measurement of X-ray fluorescence spectrometry. Especially, we used diluted(ahout sixteen times) filling compound($Li_2B_4O_7/LiBO_2=4/1$) to consider removal effect of matrix, storage convenience, and homogenous characteristics. As a result from the four different laboratories, we obtained extremly good agreement about the standard curve on twelve standard materials which containing eleven elements, PbO, $ZrO_2$, $TiO_2$, SrO, $WO_3$, $La_2O_3$, $Cr_2O_3$, MgO, $Nb_2O_5$, and $MnO_2$. The correlation factor of standard curve was over 0.998. However, ZnO has relatively low correlation factor, 0.977, because the concentration was 10ppm lower than other original materials. This analysis reveals that ZnO has shown the poor linearity as well as low fluorescence intensity. In present work, XRF standard materials are useful for determining a rapid and accurate results for major and minor elements concentration among PZT.

• Corrosion Science and Technology
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• v.16 no.5
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• pp.257-264
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• 2017

Film of new Ti-15Zr-5Nb alloy formed during galvanic anodizing in orthophosphoric acid solution was characterized by optical microscope, scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and Raman micro-spectroscopy. Its anticorrosive properties were determined by electrochemical techniques. The film had a layer with nanotube-like porosity with diameters in 500-1000 nm range. The nano layer contained significant amounts of P and O as well as alloying element. Additionally, Raman micro-spectroscopy identified oxygen as oxygen ion in $TiO_2$ anatase and phosphorous as $P_2O_7{^{4-}}$ ion in phosphotitanate compound. All potentiodynamic polarization curves in artificial Carter-Brugirard saliva with pH values (pH= 3.96, 7.84, and 9.11) depending on the addition of 0.05M NaF revealed nobler behavior of anodized alloy and higher polarization resistance indicating the film is thicker and more compact nanolayer. Lower corrosion rates of the anodized alloy reduced toxicity due to less released ions into saliva. Bigger curvature radii in Nyquist plot and higher phase angle in Bode plot for the anodized alloy ascertain a thicker, more protective, insulating nanolayer existing on the anodized alloy. Additionally, ESI results indicate anodized film consists of an inner, compact, barrier, layer and an outer, less protective, porous layer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.10
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• pp.796-801
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• 2001

Ferroelectric 0.05PZN-xPZT(90/10)-(0.95-x)PZT(10/90) (x=0.65, 0.85) specimens were fabricated by the solid-state reaction method, and especially PZT(90/10) and PZT(10/90) powders were derived by the sol-gel method. All specimens showed a uniform ferroelectric grain without the presence of the pyrocholre phase. Average grain size increased with an increased in sintering temperature, the values for the x=0.65 and x=0.85 specimens sintered at 125$0^{\circ}C$ were 14.4$\mu$m and 9.8$\mu$m, respectively. The dielectric constant and dielectric loss of the x=0.65 specimen sintered at 125$0^{\circ}C$ were 1247. 2.06%, respectively. The coercive field and the remanent polarization of x=0.65 and x=0.85 specimens sintered at 125$0^{\circ}C$ were 8.5kV/cm, 13$\mu$C/$\textrm{cm}^2$ and 17.2kV/cm, 28 $\mu$C/$\textrm{cm}^2$, respectively. The pyroelectric coefficient of the x=0.65 and x=0.85 specimens sintered at 125$0^{\circ}C$ were 5.64$\times$10$^{-8}$ C/$\textrm{cm}^2$K and 2.76$\times$10$^{-8}$ C/$\textrm{cm}^2$K, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.543-546
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• 2000

Ferroeleclric 0.05PZN-xPZT(90/10)-(0.95-x)PZT(10/90) (x=0.65, 0.85) specimens were fabricated by the mixed-oxide method and cold-pressing method using sol-gel derived PZT(90/10) and PZT(10/90) powders. All specimens show a uniform ferroelectric grain without the presence of the pyrocholre phase. Average grain size increased with an increase in sintering temperature, the value for the x=0.65 specimen sintered at 125$0^{\circ}C$ was 14.4$\mu$m. The dielectric constant and dielectric loss of the x=0.65 specimen sintered at 125$0^{\circ}C$ were 1247, 2.06%, respectively. All specimens showed fairly good temperature and frequency stability of dielectric constant with the range from -2$0^{\circ}C$ to 6$0^{\circ}C$ and 100Hz to 10MHz. The coercive field and the remanent polarization of x = 0.65 specimen sintered at 125$0^{\circ}C$ were 8.5 kV/cm and 13 $\mu$C/cm$^2$, respectively. The pyroelectric coefficient of the x=0.65 specimen sintered at 125$0^{\circ}C$ was 5.64$\times$10$^{-8}$ C/cm$^2$K, respectively.