• Proceedings of the Korean Ceranic Society Conference
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• 2002.10a
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• pp.160.1-160
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• 2002

• 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.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.185-185
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• 2011

ZnTe semiconductor is very attractive materials for optoelectronic devices in the visible green spectral region because of it has direct bandgap of 2.26 eV. The prototypes of ZnTe light emitting diodes (LEDs) have been reported [1], showing that their green emission peak closely matches the most sensitive region of the human eye. Another application to photovoltaics proved that ZnTe is useful for the production of high-efficiency multi-junction solar cells [2,3]. By using the pulse laser deposition system, ZnTe thin films were deposited on ZnO thin layer, which is grown on (0001) Al2O3substrates. To produce the plasma plume from an ablated ZnO and ZnTe target, a pulsed (10 Hz) YGA:Nd laser with energy density of 95 mJ/$cm^2$ and wavelength of 266 nm by a nonlinear fourth harmonic generator was used. The laser spot focused on the surface of the ZnO and ZnTe target by using an optical lens was approximately 1 mm2. The base pressure of the chamber was kept at a pressure around $10^{-6}$ Torr by using a turbo molecular pump. The oxygen gas flow was controlled around 3 sccm by using a mass flow controller system. During the ZnTe deposition, the substrate temperature was $400^{\circ}C$ and the ambient gas pressure was $10^{-2}$ Torr. The structural properties of the samples were analyzed by XRD measurement. The optical properties were investigated by using the photoluminescence spectra obtained with a 325 nm wavelength He-Cd laser. The film surface and carrier concentration were analyzed by an atomic force microscope and Hall measurement system.

• Applied Chemistry for Engineering
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• v.9 no.1
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• pp.129-134
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• 1998

Conversion of propane to acrylonitrile via ammoxidation was studied using physically mixed catalysts composed of $Nb_2O_5(10{\sim}30wt%)$ and $V_{0.4}Mo_1Te_{0.1}$. Catalytic activities of ammoxidation were improved by adding strong acidic niobium oxide to $V_{0.4}Mo_1Te_{0.1}$, the selectivities to acrylonitrile+propylene being remained constant. The maximum activity was obtained at the mixing ratio 25wt% niobium oxide in $Nb_2O_5-V_{0.4}Mo_1Te_{0.1}$. Niobium oxide was found to be a selective catalyst for the oxidative dehydrogenation of propane.

• Journal of the Korean Ceramic Society
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• v.30 no.9
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• pp.761-767
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• 1993

Electrical and mechanical properties of Pb(Mg, Te, Mn, Nb)O3-PZT ceramics are investigated as a function of CeO2 addition (0 to 0.3wt%), and the output characteristics of piezoelectric transformer are also presented. The grain size decreased and the shapes of particles were more uniform with the addition of CeO2. The coercive electric field(9500V/cm), mechanical quality factor (2500) and bend strength (1065kg/$\textrm{cm}^2$) were improved by addition of CeO2 0.2wt%. After repetition of a number of stress cycles, the degradation of k33 was not found in this sample. The voltage step-up ratio (Vdc/Vrms) of piezoelectric ceramic transformer (half wavevoltage doubler, load resistor 100M.ohm) was about 950 in a linear region, its value was relatively higher than other materials.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.49-49
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• 2008

ZnO-based varistors have been widely used for voltage stabilization or transient surge suppression in electric power systems and electronic circuits. Recently, It has reported that the varistor behavior with nonlinear coefficient of 6~17 in Mn-doped ZnO. In this study we have chosen the composition of ZnO-$TeO_2-Mn_3O_4$ (ZTM) system to the purpose of whether varistor behavior appeared in doped ZnO by the solid state sintering or not. We investigated the sintering and electric properties of 0.5~3.0 at% Mn doped ZnO-1.0 at% $TeO_2$ system. Electrical properties, such as current-voltage (I-V), capacitance-voltage (C-V), and impedance spectroscopy were conducted. $TeO_2$ itself melts at $732^{\circ}C$ in air but forms the $ZnTeO_3$ phase with ZnO as increasing temperature and therefore retards the densification of ZnO to $1000^{\circ}C$. The average grain size of sintered samples was at about $3{\mu}m$ and decreased with increasing Mn contents. It was found that a good varistor characteristics were developed in ZTM system sintered at $1100^{\circ}C$ (nonlinear coefficient $\alpha$ ~ 60). The results of C-V characteristics such as barrier height ($\Theta$), donor density ($N_d$), depletion layer (W), and interface state density ($N_t$) in ZTM ceramics were $4\times10^{17}cm^{-3}$, 0.7 V, 40 nm, and $1.6\times10^{12}cm^{-2}$, respectively. It will be discussed about the stability and homogeneity of grain boundaries using distribution parameter ($\alpha$) simulated with the Z(T)"-logf plots in ZTM system.

• Journal of the Korean Ceramic Society
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• v.51 no.3
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• pp.170-176
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• 2014

Effective glass frit compositions enabled to absorb laser energy, and to seal a commercial dye-sensitized solar-cell-panel substrate were developed by using $V_2O_5$-based glasses with various amounts of $TeO_2$ substitution. The latter was intended to increase the lifetime of the solar cells. Substitution of $V_2O_5$ by $TeO_2$ provided a strong network structure for the glasses via the formation of tetrahedral pyramids in the glass, and changed the various glass properties, such as glass transition temperature ($T_g$), dilatometric softening point ($T_d$), crystallization temperature, coefficient of thermal expansion (CTE), and glass flowage without any detrimental effect on the laser absorption property of the glasses. The thermal expansion mismatch (${\Delta}{\alpha}$) between the glass frit and the substrate could be controlled within less than ${\pm}5%$ by addition of 10 wt% of ${\beta}$-eucryptite. An 810 nm diode laser was used for the sealing test. The laser sealing test revealed that the VZBT20 glass frit with 10 wt% ${\beta}$-eucryptite was successfully sealed the substrates without interfacial cracks and pores. The optimum sealing conditions were provided by a beam size of 3 mm, laser power of 40 watt, scan speed of 300 mm/s, and 200 irradiation cycles.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.741-742
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• 2011

XRD 결과와 TEM 분석으로부터 열처리효과에 따른 Bi-Te 박막의 미세구조 변화를 확인하였다. $Bi_2Te_3$ 상이 $SiO_2$ 와 Bi-Te 박막의 경계면을 따라서 성장하였고 이는 열전성능에 중요한 영향을 미치는 것을 확인하였다.

• ETRI Journal
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• v.23 no.4
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• pp.151-157
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• 2001

Spectroscopic and thermal analysis indicates that tellurite glasses doped with $B_2O_3$ and $GeO_2$ are promising candidate host materials for wide-band erbium doped fiber amplifier (EDFA) with a high 980 nm pump efficiency. In this study, we measured the thermal stabilities and the emission cross-sections for $Er^{3+}:^{4}I_{13/2}\;{\to}\;^{4}I_{15/2}$ transition in this tellurite glass system. We also determined the Judd-Ofelt parameters and calculated the radiative transition rates and the multiphonon relaxation rates in this glass system. The 15 mol% substitution of $B_2O_3$ for $TeO_2$ in the $Er^{3+}-doped\;75TeO_2-20ZnO-5K_2O$ glass raised the multiphonon relaxation rate for $^4I_{11/2}\;{\to}\;^4I_{13/2}$ transition from 4960 $s^{-1}$ to 24700 $s^{-1}$, but shortened the lifetime of the $^4I_{13/2}$ level by 14 % and reduced the emission cross-section for the $^4I_{13/2}\;{\to}\;^4I_{15/2}$ transition by 11%. The 15 mol% $GeO_2$ substitution in the same glass system also reduced the emission cross-section but increased the lifetime by 7%. However, the multiphonon relaxation rate for $^4I_{11/2}{\to}^4I_{13/2}$ transition was raised merely by 1000 $s^{-1}$. Therefore, a mixed substitution of $B_2O_3$ and $GeO_2$ for $TeO_2$ was concluded to be suitable for the 980 nm pump efficiency and the fluorescence efficiency of $^4I_{13/2}{\to}^4I_{15/2}$ transition in $Er^{3+}-doped$ tellurite glasses.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.1
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• pp.86-91
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• 2007

Contact material is widely used as electrical parts. Ag-CdO has a good wear resistance and stable contact resistance. But the disadvantages of Ag-Cd alloy are coarse Cd oxides and harmful metal, Cd. Then Ag-Sn alloy that has stable and fine Sn oxide at high temperature has been developed. In order to investigate the effect of Te additional that affects the formation of the oxide layer on the surface and the formation of oxide in matrix Ag, we studied the microstructures and properties of Ag-Sn-In(-Te) material fabricated by rapid solidification process. The experimental procedure were melting using high frequency induction, melt spinning, and internal oxidation. Specimens were examined and analyzed by Transmission electron microscopy(TEM), energy dispersive X-ray spectroscopy(EDS) and Vickers hardness. As a result, internal oxidation was completed even at $600^{\circ}C$. Te forms coarse $In_{2}TeO_{6}$ phase and makes fine and well dispersed $SnO_{2}$ Phase. 0.3 wt% Te shows favorable properties.