• 한국재료학회지
• /
• 제3권2호
• /
• pp.158-165
• /
• 1993

실리콘박막의 상부에 고상반응에 의해 형성된 TiS$i_2$ 박막의 응집 거동에 미치는 기판 실리콘의 영향을 조사했다. 폴리실리콘과 어몰퍼스실리콘을 증착상태 또는 어닐링한 상태엣 TiS$i_2$를 형성시키고 90$0^{\circ}C$열처리에 따른 TiS$i_2$의 면저항값의 변화를 조사하고 XRD, SEM 및 TEM에 의한 실리콘의 조직관찰을 행했다. TiS$i_2$응집은 어몰퍼스실리콘 위의 경우가 더욱 심했다. 폴리실리콘을 어닐링하면 TiS$i_2$의 응집은 억제되며 고온에서 어닐링할수록 그 효과가 현저했다. 이는 폴리실리콘의 입도 변화보다는 증착시 존재하는 결함들이 열처리에 의해 감소된 때문이다. 폴리실리콘의 경우는 어닐링 전후에 상관없이 (110)집합조직인 주상정 조직을 갖고 있다. 어몰퍼스실리콘을 결정화시킨 경우는 (111)집합조직를 갖는 등축정 조직을 나타내었다. 실리콘의 표면에너지가 낮은 (111)면이TiS$i_2$ 막의 하부 폴리실리콘에 많이 존재할수록 응집은 촉진된다.

• 한국재료학회지
• /
• 제11권3호
• /
• pp.227-235
• /
• 2001

본 연구의 목적은 기존의 고상 반응법을 이용하여 일본의 상용 Zn$_2$SiO$_4$:Mn형광체보다 우수한 성능의 형광체를 제조하는데 있다. 이틀 위해 본 연구에서는 고상 반응법을 이용하여 Zn$_2$SiO$_4$:Mn 형광체를 합성하고, 이를 PDP(Plasma Display Panel)에 적용하기 위하여 소성온도 및 환원 온도와 주입되는 기체의 양, dopant Mn의 농도를 다양하게 하여 합성하였고, ball milling 등을 통하여 입자의 특성을 개선하는 실험을 하였다. 제조된 형광체의 발광특성 및 모양 등의 특성은 상용 Zn$_2$SiO$_4$:Mn 형광체와 비교하였다. Mn의 농도를 0.08mo1e로 하여 130$0^{\circ}C$에서 소성하였을 때 결정성 및 휘도가 가장 우수하였고, 환원시 5% H$_2$-96% N, 혼합가스의 양을 100ml/rnin으로 일정하게 주입시켰을 때 20%이상 휘도가 증가하였다. Ball rnilling은 30분 동안 100rpm으로 하였을 때 입자의 크기가 수십 $\mu\textrm{m}$에서 3$\mu\textrm{m}$이하로 줄어들었다. 특히. 발광 특성이 상용 형광체보다 월등히 우수하여 PDP에 적용할 수 있다

• 마이크로전자및패키징학회지
• /
• 제24권2호
• /
• pp.49-53
• /
• 2017

Cl 불순물 도핑에 따른 $SnSe_2$ 이차원 전자소재의 고온(300~450 K) 전도 물성 변화를 고찰하였다. 고상합성법을 통하여, 도핑이 없는 $SnSe_2$ 소재와 Cl이 도핑된 $SnSe_{1.994}Cl_{0.006}$ 소재를 합성하였으며, X선 회절 실험을 통하여, 두 재료 모두 불순물 없는 단일상이 형성되었음을 확인하였다. 비저항의 온도의존성 측정을 통하여, 전기 전도 mechanism이 Cl 도핑에 의해 hopping 전도에서 축퇴 전도로의 전이가 일어남을 관찰할 수 있었으며, 홀효과 측정을 통해 그러한 전도 mechanism의 전이가, Cl의 효과적인 donor 역할에 따른 자유전자의 농도 증가에서 기인한 것임을 확인하였다. 온도에 따른 전자이동도의 변화 분석을 통하여, 도핑이 없는 $SnSe_2$의 고온 전기 전도는 grain boundary 산란이 지배적인 영향을 미치는 반도체 전도 특성을 보이는 반면, Cl 도핑에 따라 grain boundary 산란 효과가 저하되는 금속 전도 특성을 보인다는 것을 알 수 있었다.

• 한국전기전자재료학회논문지
• /
• 제29권6호
• /
• pp.342-347
• /
• 2016

We investigated the effect of $Bi_{1/2}(Na_{0.82}K_{0.18})_{1/2}TiO_3$ (BNKT) modification on the ferroelectric and electric-field-induced strain (EFIS) properties of lead-free $0.97Bi_{1/2}(Na_{0.82}K_{0.18})_{1/2}TiO_3-0.03LaFeO_3$ (BNKTLF) ceramics as a function of BNKT content (x= 0, 0.1, 0.2, 0.3, 0.5, and 1). BNKT-modified BNKTLF powders were synthesized using a conventional solid-state reaction method. As the BNKT content x increased from 0 to 1 the normalized electric-field-induced strain ($S_{max}/E_{max}$) was observed to increase at relatively low fields, i.e., below the poling field. Moreover, BNKTLF-30BNKT showed about 460 pm/V as low as at 3 kV/mm, which is a considerably high value among the lead-free systems reported so far. Consequently, it was confirmed that ceramic-ceramic composite, a mixture of an ergodic relaxor matrix and embedded ferroelectric seeds, is a salient way to make lead-free piezoelectrics practical with enhanced EFIS at low field as well as less hysterical.

• 한국전기전자재료학회논문지
• /
• 제27권12호
• /
• pp.803-808
• /
• 2014

$Bi_{0.5+x}(Na_{0.78}K_{0.22})_{0.5-3x}TiO_3$ ceramics with an excess $Bi^{3+}$ and a deficiency of $Na^+$ and $K^+$ were synthesized by a conventional solid state reaction method. The structure and morphology of $Bi_{0.5+x}(Na_{0.78}K_{0.22})_{0.5-3x}TiO_3$ ceramics were characterized by X-ray diffraction and field emission scanning electron microscopy. The electric polarization and mechanical strain induced by external electric field, and the temperature dependence of dielectric constant were investigated. These results demonstrated that an ergodic relaxor phase can be induced by controls of the mole ratio of $Bi^{3+}$, $Na^+$ and $K^+$. A phase boundary between non-ergodic and ergodic relaxor phases can be observed at ambient temperature. The ergodic relaxor phase can be transferred to the ferroelectric phase by application of the electric field. The stability of the induced ferroelectric phases strongly depends on the mole ratio of $Bi^{3+}$, $Na^+$ and $K^+$. The maximum strain of 0.31% was observed in $Bi_{0.51}(Na_{0.78}K_{0.22})_{0.47}TiO_3$ ceramics sintered at $1,150^{\circ}C$ for 2 h.

• 한국재료학회지
• /
• 제27권6호
• /
• pp.339-344
• /
• 2017

A series of $CaNb_2O_6:Dy^{3+}$, $CaNb_2O_6$:$Eu^{3+}$ and $CaNb_2O_6:Dy^{3+}$, $Eu^{3+}$ phosphors were prepared by solid-state reaction process. The effects of activator ions on the structural, morphological and optical properties of the phosphor particles were investigated. XRD patterns showed that all the phosphors had an orthorhombic system with a main (131) diffraction peak. For the $Dy^{3+}$-doped $CaNb_2O_6$ phosphor powders, the excitation spectra consisted of one broad band centered at 267 nm in the range of 210-310 nm and three weak peaks; the main emission band showed an intense yellow band at 575 nm that corresponded to the $^4F_{9/2}{\rightarrow}^6H_{13/2}$ transition of $Dy^{3+}$ ions. For the $Eu^{3+}$-doped $CaNb_2O_6$ phosphor, the emission spectra under ultraviolet excitation at 263 nm exhibited one strong reddish-orange band centered at 612 nm and four weak bands at 536, 593, 650, and 705 nm. For the $Dy^{3+}$ and $Eu^{3+}$-codoped $CaNb_2O_6$ phosphor powders, blue and yellow emission bands due to the $^4F_{9/2}{\rightarrow}^6H_{15/2}$ and $^4F_{9/2}{\rightarrow}^6H_{13/2}$ transitions of $Dy^{3+}$ ions and a main reddish-orange emission line at 612 nm resulting from the $^5D_0{\rightarrow}^7F_2$ transition of $Eu^{3+}$ ions were observed. As the concentration of $Eu^{3+}$ ions increased from 1 mol% to 10 mol%, the intensities of the emissions due to $Dy^{3+}$ ions rapidly decreased, while those of the emission bands originating from the $Eu^{3+}$ ions gradually increased, reached maxima at 10 mol%, and then slightly decreased at 15 mol% of $Eu^{3+}$. These results indicate that white light emission can be achieved by modulating the concentrations of the $Eu^{3+}$ ions incorporated into the $Dy^{3+}$-doped $CaNb_2O_6$ host lattice.

• 멤브레인
• /
• 제25권5호
• /
• pp.415-421
• /
• 2015

고상반응법을 이용하여 $SrCo_{0.8}Fe_{0.1}Nb_{0.1}O_{3-{\delta}}$ 조성의 산화물을 합성하였으며, 합성된 분말은 압축 성형 후 $1250^{\circ}C$에서 소결하여 치밀한 세라믹 분리막을 제조하였다. XRD 분석을 통해 단일상의 페롭스카이트 구조를 확인하였다. 산소 분압이 0.21 atm, 측정 온도가 $800{\sim}950^{\circ}C$인 조건하에서 산소투과를 분석한 결과 온도가 증가할수록 산소투과량은 증가하였고, $950^{\circ}C$에서 $1.839mL/min{\cdot}cm^2$로 최대값을 나타내었다. 니오븀(Nb)을 포함한 세라믹 분리막의 상안정성 및 이산화탄소 내성을 확인하기 위하여 $900^{\circ}C$에서 이산화탄소가 500 ppm이 포함된 혼합공기를 이용하여 장기투과 실험을 수행하였다. 이산화탄소에 노출된 $SrCo_{0.8}Fe_{0.1}Nb_{0.1}O_{3-{\delta}}$의 상안정성은 XRD와 TG로 분석하였다. 분석 결과, 이산화탄소에 노출된 $SrCo_{0.8}Fe_{0.1}Nb_{0.1}O_{3-{\delta}}$ 조성의 경우 약 8%의 $SrCO_3$가 생성되었으나, 이 수준의 $SrCO_3$ 생성량은 분리막의 산소투과도에 큰 영향을 주지 않는 것을 확인하였다.

• 한국재료학회지
• /
• 제26권2호
• /
• pp.67-72
• /
• 2016

$BaMoO_4:Tb^{3+}$ phosphor powders were synthesized with different concentrations of $Tb^{3+}$ ions using the solid-state reaction method. XRD patterns showed that all the phosphors, irrespective of the concentration of $Tb^{3+}$ ions, had tetragonal systems with two main (112) and (004) diffraction peaks. The excitation spectra of the $Tb^{3+}$-doped $BaMoO_4$ phosphors consisted of an intense broad band centered at 290 nm in the range of 230-330 nm and two weak bands. The former broad band corresponded to the $4f^8{\rightarrow}4f^75d^1$ transition of $Tb^{3+}$ ions; the latter two weak bands were ascribed to the $^7F_2{\rightarrow}^5D_3$ (471 nm) and $^7F_6{\rightarrow}^5D_4$ (492 nm) transitions of $Tb^{3+}$. The main emission band, when excited at 290 nm, showed a strong green band at 550 nm arising from the $^5D_4{\rightarrow}^7F_5$ transition of $Tb^{3+}$ ions. As the concentration of $Tb^{3+}$ increased from 1 to 10 mol%, the intensities of all the emission lines gradually increased, approached maxima at 10 mol% of $Tb^{3+}$ ions, and then showed a decreasing tendency with further increase in the $Tb^{3+}$ ions due to the concentration quenching effect. The critical distance between neighboring $Tb^{3+}$ ions for concentration quenching was calculated and found to be $12.3{\AA}$, which indicates that dipole-dipole interaction was the main mechanism for the concentration quenching of the $^5D_4{\rightarrow}^7F_5$ transition of $Tb^{3+}$ in the $BaMoO_4:Tb^{3+}$ phosphors.

• 한국자기학회지
• /
• 제5권5호
• /
• pp.782-785
• /
• 1995

In this paper, $Mn^{2+}$ ion was doped in Y-Ba-Cu-O as an EPR probe. The following samples were prepared by conventional solid-state reaction method : $YBa_{2}Cu_{2.96}Mn_{0.04}O_{7-\delta}$ (MN-I), annealed $YBa_{2}Cu_{2.96}Mn_{0.04}O_{7-\delta}$ (AMN) and $YBa_{2}Cu_{2.94}Mn_{0.06}O_{7-\delta}$ (MN-II). AMN sample was obtained from MN-I by annealing for 1 hr under the Ar gas atmosphere at $600^{\circ}C$. X-band (~9.05 GHz) EPR spectra were measured from 103 K to room temperature by employing a JES-RE3X spectroscopy with a $TE_{0.11}$ cylindrical cavity and 100 kHz modulation frequency. In MN-I we have observed only the $Cu^{2+}$ signal. The fact that no $Mn^{2+}$ signal was observed, in spite of $Mn^{2+}$ being a very sensitive EPR probe, indicates that most likely isolated $Mn^{2+}$ ions don't exist in the MN-I sample. Most probably $Mn^{2+}$ ions in the MN-I sample interact antiferromagnetically and hence are EPR silent. The AMN spectra of at room temperature and 103 K indicate not only the $Cu^{2+}$ signal but also an extra signal, which increases with decreasing temperature. It is suggested that the extra signal originates from Mn ions that were antiferromagnetically coupled before the annealing process. In MN-II, from 103 K to room temperature, also, the extra signal was observed together with the $Cu^{2+}$ signal. The extra signal in MN-II, however, decreases with decreasing temperature and nearly disappears at 103 K. The signal originates from Mn ions in impurity phases that include $Mn^{2+}$ ions. We suppose that there exist at least two $Mn^{2+}$ doped phases in Y-Ba-Cu-O. The $Mn^{2+}$ signal of one phase is undectable at all temperature and that of another phase decreases with decreasing temperature and disappears around 103 K.

• 대한한의학방제학회지
• /
• 제26권4호
• /
• pp.295-306
• /
• 2018

Schisandra chinensis (SC) and Lycium chinense (LC) were widely distributed in Asia and the fruit has been used traditionally for medicinal herbs. The processing method was solid-state fermentation using Aspergillus oryzae for 48 h after stir-frying treatment at $220^{\circ}C$ for 12 min. In this study, in vitro the anti-inflammatory effect and in vivo hangover reduction were compared to unprocessed SC and LC water extract. Anti-inflammatory effects have been evaluated in pro-inflammatory mediators which were secreted by lipopolysaccharide (LPS)-induced RAW 264.7 macrophages. Nitric oxide (NO) was determined using Griess reaction. Proinflammatory cytokines such as tumor necrosis factor $(TNF)-{\alpha}$ and interleukin $(IL)-1{\beta}$ were measured by enzyme-linked immunosorbent assays (ELISA). Alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH) activities were compared to processed SC or LC and mixtures thereof (1:1). In vivo study was compared to hangover relief in alcohol-fed mice. After administering a mixture of SC and LC (300 mg/kg) water extract (1:1), mice were fed 3 g/kg of ethanol. Serum was collected at 1, 3, and 5 h intervals to analyze ethanol and acetaldehyde levels using a colorimetric assay kit. The processed SC and LC water extracts compared to raw materials significantly inhibited LPS-induced NO and inflammatory cytokine production in RAW 264.7 cells. The results of the hangover mouse model are also consistent with anti-inflammatory effects. These results suggest that processed SC and LC extracts may be functional materials for the treatment of inflammation and hangover.