• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
• /
• pp.987-990
• /
• 1999

본 연구에서는 $BaTiO_3$를 기본 조성으로 하여 PTC 써미스터를 제조하였으며 여기에 첨가제로서 Ca, Mn, Nb의 양을 순차적으로 변화시켜 미세구조 및 전기적 특성을 연구하였다. 또한 복소 임피던스 측정을 통해서 PTC 효과에 미치는 주 저항 성분에 대해서 고찰하였다. Ca 첨가 실험에서는 5[mol%] 첨가된 시편에서 $2.3{\times}10^7[\Omega{\cdot}cm]$의 높은 peak 비저항이 나왔으며 Mn과 Nb에서는 각각 0.1[mol%], 0.2[mol%]에서 $1.5{\times}10^8[\Omega{\cdot}cm]$와 $3.71{\times}10^9[\Omega{\cdot}cm]$의 수치가 측정되었다. 또한 Nb 첨가 실험에서는 첨가량이 증가할수록 결정립의 크기가 조밀해지는 현상을 보였다. PTC 효과에 미치는 주 저항 요소에 대해서 관찰한 복소 임피던스 측정에서는 결정립계 저항 성분이 주가 됨을 확인 하였다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
• /
• pp.460-463
• /
• 2002

$MoO_3$ thin films were deposited on electrode and heater screen-printed alumina substrates in $O_2$ atmosphere by RF reactive sputtering using Molybdenum metal target. The deposition was performed at $300^{\circ}C$ with 350W of a forward power in an $Ar-O_2$ atmosphere. The working pressure was maintained at $3{\times}10^{-2}mtorr$ and all deposited films were annealed at $500^{\circ}C$ for 5hours. To investigate gas sensing characteristics of the addition doped $MoO_3$ thin film, Co, Ni and Pt were used as adding dopants. The sensing properties were investigated in tenn of gas concentration under exposure of reducing gases such as $H_2$, $NH_3$ and CO at optimum working temperature. Co-doped $MoO_3$ thin film shows the maximum 46.8% of sensitivity in $NH_3$ and Ni-doped $MoO_3$ thin film exhibits 49.7% of sensitivity in $H_2$.

• Macromolecular Research
• /
• 제12권1호
• /
• pp.22-25
• /
• 2004

We have synthesized aniline oligomer composites by using heteropoly acid (H$_4$SiW$_{12}$O$_{40}$ ) as a dopant. The doping and dedoping processes of the aniline oligomer composites were investigated with the aid of UV- Vis spectra. The bands of the aniline oligomer at 572 nm weakened or disappeared, and the bands at 268, 412, and 771 nm appeared, after the aniline oligomer was doped. When the solution of the aniline oligomer doped with H$_4$SiW$_{12}$O$_{40}$ was kept at lower values of pH, the aniline oligomer could not be dedoped by dilution. The turning point of doping and dedoping occurred at pH 5.5. The band at 771 nm shifted towards longer wavelengths when the aniline oligomer composites were synthesized using acetone as the solvent. This observation indicates that the molecular chain became stretched. In addition, we also investigated the change of the electronic absorption spectra of the composites with respect to the time laid up.id up.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2000년도 하계학술대회 논문집
• /
• pp.387-390
• /
• 2000

The $Al_2$O$_3$specimens were prepared by the conventional mixed oxide method with addition La$_2$O$_3$, Bi$_2$O$_3$. The specimens were sintered at 15$25^{\circ}C$, 5hr., in air. The structural properties of the specimens were investigated by XRD and SEM. The $Al_2$O$_3$ceramics with dopants had hexagonal structure and didn't show secondary phases. In the case of specimens with 0.25wt% La$_2$O$_3$and 0.25wt% Bi$_2$O$_3$bulk densities and lattice parameter of c/a were 3.818g/cm$^3$, 3.783g/cm$^3$and ca=2.725, c/a=2.723, respectively. The bulk densities of $Al_2$O$_3$ceramics were decreased with dopants.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
• /
• pp.481-482
• /
• 2006

플라즈마 화상표시기 (PDP)의 보호막 물질로 사용 중인 다결정 MgO의 특성을 개선하기 위하여 본 연구에서는 MgO에 희토류계 원소를 치환하여 제조하였으며, 치환량에 따른 MgO 보호막의 광학적 특성과 전기적 특성을 고찰하였다. MgO + 100 ppm $Gd_2O_3$조성으로 제작한 MgO 박막의 이차전자 방출계수 값이 순수 MgO 보다 35% 높게 나타났다. $Gd_2O_3$ dopant가 100 ppm 첨가시까지 밀도가 증가하였으나, 그 이상 첨가시 감소하는 경향을 나타냈다. 가속전압 200 V에서 이차전자 방출계수는 0.138 이었고 표면거칠기는 5.77 nm 이었으며 투과율은 550 nm 에서 95.76% 이었다.

• 반도체디스플레이기술학회지
• /
• 제18권1호
• /
• pp.105-111
• /
• 2019

The TADF (Thermally Activated Delayed Fluorescence)-based OLED patents were analyzed and 4410 of patents were selected at the first step. And 975 patents were screened at second step. Finally, 39 key patents were selected. Patent qualitative analysis was performed in these patents to find which of the four property (lifetime, efficiency, color purity, driving voltage) of TADF was improved. Also, the variation of the hosts and dopants in patented TADF material were surveyed and their combination was analyzed. According to the analysis of the variation and the combination, some of TADF compounds were used as an assistant dopant to transfer energy. In addition, it tended to transfer energy by forming exciplex that shows TADF characteristics. These were similar to the mechanism of the introduced hyper fluorescence and could solve the inherent TADF problems. Finally, patent citation network was illustrated to visualize the patent citations and citations relationship of the major applicants in the current TADF-based OLED technology. The leading patent applicant organization was revealed as Idemitsu Kosan, Semiconductor Energy Laboratory, UDC, Princeton University, Merck and Nippon Steel & Sumikin Chemical, which had lots of reference patents 559, 524, 477, 310, 258, and 167, respectively.

• Nuclear Engineering and Technology
• /
• 제54권1호
• /
• pp.283-292
• /
• 2022

Advanced radiation applications have been widely used and extended to many fields. As a result of this fact, choosing an appropriate shielding material based on the radiation application has become vital. In this regard, the integration of elements into polymer composites has been investigated and contributed to the quantity and quality of radiation shielding materials. This study reports photon attenuation parameters and electromagnetic shielding effectiveness of a novel polymer composite prepared with a matrix reinforced with three different proportions (5, 10, and 15 wt%) of niobium content. Addition of Nb dopant improves both photon attenuation and electromagnetic shielding effectiveness for the investigated composites. Therefore, Nb(15%) polymer composite with highest concentration has been found to be the best absorber for ionizing and non-ionizing radiations. Consequently, the performed analyzes provide evidences that the prepared Nb-reinforced polymer composite could be effectively used as photon radiation attenuator and electromagnetic shielding material.

• Nuclear Engineering and Technology
• /
• 제56권2호
• /
• pp.477-484
• /
• 2024

Experimental investigations on gamma - rays attenuation parameters and dielectric spectroscopic properties were done on a polymeric mixture with chemical composition (100-x) polyethylene + x basalt, where x = 0, 1, 3, 5, 10, and 20 wt%. Using the melting blending technique,six nanocomposite polymeric samples were prepared. The linear attenuation coefficient µ of each prepared set of samples was measured using a gamma-ray spectrometer including High Purity Germanium detector (HPGe) at energies 662.5, 1173.24, and 1332.51 keV. Based on the measured values of (µ) and sample density, the other effective shielding parameters were calculated. The values of µ showed an increase with increasing the dopant ratios from 0.0 up to 20.0 wt%. In addition, the µ values decreased with the photon's energy. The µ values were found 0.0847 up to 0.1175 cm^-1, 0.0571 up to 0.0855 cm^-1, and 0.0543 up to 0.075 cm^-1 at 662.5, 1173.24, and 1332.51 keV. for B0 up to B20, respectively. The ATR spectroscopy was done on the prepared samples, and a good evidence of adding the filler to the pure polyethylene (HDPE) was obtained. Besides, an enhancement in dielectric constant by insertion of basalt NPs also recorded and can be attributed to the large dielectric constant of basalt compared to pure HDPE.

• 한국재료학회지
• /
• 제8권5호
• /
• pp.408-412
• /
• 1998

Bi$_{2}$(Te$_{1-x}$Se$_{ x}$)$_{3}$(0.05$\leq$x$\leq$0.25)합금분말을 기계적 합금화 공정으로 제조하여 가압소결 후, $Bi_{2}$Se$_{3}$함량에 따른 열전특성의 변화거동을 분석하였다. 기계적 합금화로 제조한 $ Bi_{2}$(Te$_{1-x}$ $Se_{x}$$_{3}$ 가압소결체는 단결정과는 달리 donor dopant의 첨가없이도 n형 전도를 나타내었다. $Bi_2(Te_{0.85}Se_{0.15})_3$ 합금분말을 (50%H$_{2}$+50% Ar)분위기 중에서 환원처리하여 가압소결시, 분말 효면의 산화층 제거와 과잉 Te 공격자의 소멸에 기인한 전자 농도의 감소로 p형으로 천이되었다. 기계적 합금화로 제조한 $ Bi_{2}$($Te_{1-x}$ $Se_{x}$$_{3}$가압소결체는 x=0.15조성에서 $1.92{\times}10^{-3}$ K의 최대 성능지수를 나타내었다.

• 한국전기전자재료학회논문지
• /
• 제19권2호
• /
• pp.145-152
• /
• 2006

The densification behavior and electrical conductivity of $Ce_{0.8}Gd_{0.2}O_{1.9}$ ceramics were investigated with the strontium gallate concentration ranging from 0 to $5\;mol\%$. Both the sintered density and grain size were found to increase rapidly up to $0.5\;mol\%$ $Sr_2Ga_2O_5$, and then to decrease with further addition. Dense $Ce_{0.8}Gd_{0.2}O_{1.9}$ ceramics with $97\%$ of the theoretical density could be obtained for $0.5\;mol\%$ $Sr_2Ga_2O_5$-added specimen sintered at $1250^{\circ}C$ for 5 h, whereas pure $Ce_{0.8}Gd_{0.2}O_{1.9}$ ceramics needed to be sintered at $1550^{\circ}C$ in order to obtain an equivalent theoretical density, Electrical conductivity was measured as a function of dopant content, over the temperature range of $350\;-\;600^{\circ}C$ in air. Total conductivity of $0.5\;mol\%$ $Sr_2Ga_2O_5$-added specimen showed the maximum conductivity of $2.37{\times}10^{-2}{{\Omega}-1}{\cdot}cm^{-1}$ at $500^{\circ}C$, The addition of strontium gallate was found to promote the sintering properties and electrical conductivities of $Gd_2O_3$-doped $CeO_2$.