• 한국광학회:학술대회논문집
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• 한국광학회 2009년도 창립 20주년기념 특별학술발표회
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• pp.305-307
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• 2009

• 한국산학기술학회논문지
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• 제4권4호
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• pp.341-345
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• 2003

ZnWO₄는 높은 품질계수에 의해 주파수 선택성이 뛰어나지만 다층형태의 고주파 무선부품으로의 응용을 위해서는 높은 소결온도(1100℃), 큰 음의 공진주파수 온도계수(-70ppm/℃), 낮은 유전율(15.5) 등에 대한 보정이 필요하다. 본 연구에서는 ZnWO₄에 TiO₂및 LiF를 첨가하여 ZnWO₄의 저손실특성을 유지하면서 주파수 온도안정성 및 저온소결성을 부여하고자 하였다. 큰 양의 공진주파수 온도계수(＋400ppm/℃) 및 유전율(100)을 갖는 TiO₂의 첨가는 공진주파수 온도계수를 음의 값에서 양의 값으로 변화시켰으며 유전율의 증가를 가져왔다. TiO₂를 20 mol％ 첨가한 경우 공진주파수 온도계수가 0에 가깝고 유전율 19.4에 품질계수 50000㎓의 특성을 얻을 수 있었으나 소결온도는 1100℃로 높은 소결온도를 보였다. ZnWO₄에 TiO₂가 첨가된 혼합체에 LiF의 첨가는 액상형성에 의해 소결온도를 1100℃에서 850℃로 크게 저하시킬 수 있었다. LiF는 첨가는 LiF 자체의 큰 공진주파수 온도계수에 의해 온도계수를 음의 값으로 변화시켰다. 따라서 TiO₂및 LiF의 적당량의 첨가는 온도 안정성을 갖는 저손실 ZnWO₄-TiO₂-LiF 계 LTCC(Low Temperature Confined Ceramics) 소재를 제조할 수 있었다.

• 한국세라믹학회지
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• 제21권4호
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• pp.349-354
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• 1984

The purpose of present study is to find the structure crystallization mechanism and physical properties in $TiO_2$ containing lead zinc borosilicate glass system. The experiments such as differential thermal analysis infrared spectral analysis. X-ray diffraction analysis and thermal expansion measurements have been done. Differential thermal analysis of coarse and fine glass powder showed bulk nucleating mechanism for high $TiO_2$ containing glasses and surface nucleation mechanism for low $TiO_2$ containing glasses. The prepared glasses crystallized to crystalline mixture of PbO.2ZnO. $B_2O_3$ .4PbO.2ZnO.$5B_2O_3$and 2PbO.ZnO.$B_2O_3$ when heat-treated in the range of 480 and 51$0^{\circ}C$ and crystallized to PbTiO3 when heat-treated at $600^{\circ}C$. Obtained crystalline phase of $PbTiO_3$ in glass matrix strongly affects to thermal expansion coefficient and the value of crystallized glass varied 68.0 to $107.1{\times}10-7$/$^{\circ}C$ depending on the amount of $TiO_2$added. Infrared spectral analysis showed that [$BO_3$] triangle and [$BO_3$] tetrahedral units were coexisted in the glass with high content of PbO.

• Bulletin of the Korean Chemical Society
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• 제33권10호
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• pp.3213-3217
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• 2012

Reactive adsorption desulfurization (RADS) experiments were conducted over a series of commercial metal oxide supports ($Al_2O_{3-}$, $SiO_{2-}$, $TiO_{2-}$ and $ZrO_{2-}$) supported Ni/ZnO adsorbents. The adsorbents were characterized by X-ray diffraction (XRD), temperature programmed reduction (TPR), and Fourier transform infrared spectroscopy (FTIR) in order to find out the influence of specific types of surface chemistry and structural characteristics on the sulfur adsorptive capacity. The desulfurization performance of all the studied adsorbents decreased in the following order: Ni/ZnO-$TiO_2$ > Ni/ZnO-$ZrO_2$ > Ni/ZnO-$SiO_2$ > Ni/ZnO-$Al_2O_3$. Ni/ZnO-$TiO_2$ shows the best performance and the three hour sulfur capacity can achieve 12.34 mg S/g adsorbent with a WHSV of $4h^{-1}$. Various characterization techniques suggest that weak interaction between active component and support component, high dispersion of NiO and ZnO, high reducibility and large total Lewis acidity of the adsorbents are important factors in achieving better RADS performance.

• 한국세라믹학회지
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• 제40권7호
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• pp.637-643
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• 2003

PDP(Plasma Display Panel)용 녹색 형광체의 발광특성과 결정성을 향상시키기 위해 Zn$_2$SiO$_4$:Mn에 co-dopant로 Cr과 Ti 를 각각 첨가하여 졸-겔법으로 합성하였다. 이렇게 합성된 Zn$_2$SiO$_4$:Mn, M(M=Cr, Ti) 형광체는 고상반응의 경우와 비교하여 상대적으로 낮은 온도인 110$0^{\circ}C$에서 willemite 구조의 단일상이 형성되었다. 제조된 Zn$_2$SiO$_4$:Mn, M(M=Cr, Ti) 형광체에 대하여 진공자외선(Vacuum Ultraviolet, VUV) 영역의 147 nm 여기광원을 사용하여 발광특성을 조사하였다. Co-dopant의 영향을 알아보기 위해 Mn의 농도는 2 ㏖%, $H_2O$/TEOS의 비율은 36.1로 고정하였고, 이때 Cr과 Ti 모두 0.1 ㏖%에서 가장 좋은 발광특성을 나타냈다. Cr이 co-doping된 경우는 농도가 증가할수록 잔광시간은 짧아지나 발광강도는 지속적으로 감소한 반면, Ti를 co-doping했을 때는 오히려 낮은 농도에서 발광강도의 증가를 보이며 2.0 ㏖%에서 급격히 감소하였다.

• 한국수소및신에너지학회논문집
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• 제16권2호
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• pp.142-149
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• 2005

[ $LiNiO_2$ ] was mixed with $TiO_2$ or ZnO for the preparation of a cathode. The electrochemical properties of the cathode were investigated and the effects of the addition of $TiO_2$ or ZnO were discussed. The first discharge capacity decreased as the quantity of the added $TiO_2$ or ZnO increased. It is probably due to the decrease in the area of reaction interface according to the increase in the amount of the added oxide. When 2wt.% and 5wt.% of oxides are added, the discharge capacity increased as the number of cycles increased. It is considered that this results from the increase in the area of reaction interface because the oxide is detached from the $LiNiO_2$ with the increase in the number of cycles. The 1wt.% $TiO_2$ or ZnO-added $LiNiO_2$ had a larger first charge capacity than $LiNiO_2$. This is considered to result from the deintercalation of Li ions in the Ni sites along with the Li ions in the Li sites.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1993년도 추계 학술발표 강연 및 논문 개요집
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• pp.114-114
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• 1993

• 한국재료학회지
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• 제22권2호
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• pp.91-96
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• 2012

AC and ZnS modified $TiO_2$ composites (AC/ZnS/$TiO_2$) were prepared using a sol-gel method. The composite obtained was characterized by Brunauer-Emmett-Teller (BET) surface area measurements, X-ray diffraction (XRD), energy dispersive X-ray (EDX) analysis, scanning electron microscope (SEM) analysis, and according to the UV-vis absorption spectra (UV-vis). XRD patterns of the composites showed that the AC/ZnS/$TiO_2$ composites contain a typical single and clear anatase phase. The surface properties as observed by SEM present the characterization of the texture of the AC/ZnS/$TiO_2$ composites, showing a homogenous composition in the particles showing the micro-surface structures and morphology of the composites. The EDX spectra of the elemental identification showed the presence of C and Ti with Zn and S peaks for the AC/ZnS/$TiO_2$ composite. UV-vis patterns of the composites showed that these composites had greater photocatalytic activity under visible light irradiation. A rhodamine B (Rh.B) solution under visible light irradiation was used to determine the photocatalytic activity. The degradation of Rh.B was determined using UV/Vis spectrophotometry. An increase in the photocatalytic activity was observed. From the photocatalytic results, the excellent activity of the Y-fullerene/$TiO_2$ composites for the degradation of methylene blue under visible irradiation could be attributed to an increase in the photo-absorption effect caused by the ZnS and to the cooperative effect of the AC.

• 한국전기전자재료학회논문지
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• 제13권12호
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• pp.1017-1024
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• 2000

Effect of the microwave dielectric properties and the microstructure on a mole fraction(x=0.1~0.9) of (1-x)Mg$_2$SiO$_4$-xZnAl$_2$O$_4$ ceramics was investigated. When (1-x)Mg$_2$SiO$_4$-xZnAl$_2$O$_4$(x=0.1~0.9) ceramics were sintered at 130$0^{\circ}C$, 135$0^{\circ}C$ and 140$0^{\circ}C$ for 2hr, the microwave dielectric properties were obtained $\varepsilon$r=6.8~8.3, Q.f$_{0}$=36000~77600. On the other hand, the temperature coefficients of resonant frequency($\tau$$_{f}$) were obtained in the properties of -62ppm/$^{\circ}C$ to -49ppm/$^{\circ}C$. In order to adjust the temperature coefficient of resonant frequency($\tau$$_{f}$), CaTiO$_3$was added in (1-x)Mg$_2$SiO$_4$-xZnAl$_2$O$_4$ceramics. 0.7Mg$_2$SiO$_4$-0.2ZnAl$_2$O$_4$-0.1CaTiO$_3$ceramics sintered at 135$0^{\circ}C$ for 2hr showed the excellent microwave dielectric properties of $\varepsilon$r=7.7, Q.f$_{0}$=32000, and $\tau$$_{f}$=-7.9 ppm/$^{\circ}C$.EX>.>.EX>.

• 한국전기전자재료학회논문지
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• 제11권3호
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• pp.214-220
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• 1998

ZnO varistors are characterized by the features of excellent nonlinearity and surge withstand capability. In this paper, in order to investigate the use of ZnO varistor as surge absorption device in low voltage, metal oxide material($TiO_2$) was selected as control material of grain growth. Samples of ZnO varistors were fabricated with varying the contents, and then the microstructures and V-I characteristics were measured. It was observed by SEM that the mean grain size increased with the increase of the additive. From the measurement of V-I characteristics, it was observed that according to the increase of the quantity of $TiO_2$ as additive, the operating voltage was lowered.