• Title/Summary/Keyword: 산질화

Search Result 40, Processing Time 0.025 seconds

A review on inorganic phosphor materials for white LEDs (백색 발광다이오드(White LEDs)용 무기형광체 재료의 연구개발 현황)

  • Hwang, Seok Min;Lee, Jae Bin;Kim, Se Hyeon;Ryu, Jeong Ho
    • Journal of the Korean Crystal Growth and Crystal Technology
    • /
    • v.22 no.5
    • /
    • pp.233-240
    • /
    • 2012
  • White LEDs (light-emitting diodes) are promising new-generation light sources which can replace conventional lamps due to their high reliability, low energy consumption and eco-friendly effects. This paper briefly reviews recent progress of oxy/nitride host phosphor and quantum dot materials with broad excitation band characteristics for phosphor-converted white LEDs. Among oxy/nitride host materials, $M_2Si_5N_8$ : $Eu^{2+}$, $MAlSiN_3$ : $Eu^{2+}$ M-SiON (M = Ca, Sr, Ba), ${\alpha}/{\beta}$-SiAlON : $Eu^{2+}$ are excellent phosphors for white LED using blue-emitting chip. They have very broad excitation bands in the range of 440~460 nm and exhibit emission from green to red. In this paper, In this review we focus on recent developments in the crystal structure, luminescence and applications of the oxy/nitride phosphors for white LEDs. In addition, the application prospects and current trends of research and development of quantum dot phosphors are also discussed.

Dyeing of Microfibrillar Poly(vinyl Alcohol) Fiber - Evaluation of Surface Area of Microfibrillar Fiber- (폴리비닐알코올 마이크로피브릴 섬유의 염색 -마이크로피브릴 섬유의 표면적 평가-)

  • 김한도;김재필;김삼수;류원석
    • Proceedings of the Korean Fiber Society Conference
    • /
    • 2001.10a
    • /
    • pp.368-370
    • /
    • 2001
  • 폴리비닐알코올(poly(vinyl alcohol) (PVA))은 구조적인 단량체인 비닐알코올의 호변 이성질화 때문에 직접 중합에 의해서는 얻을 수 없으며, 아세트산 비닐 (vinyl acetate (VAc))이나 피발산 비닐 (vinyl pivalate (VPi))같은 비닐에스테르 계열 단량체를 사용하여 중합과 비누화 반응을 거쳐 제조되고 비누화 반응에서 모든 측쇄기가 효과적으로 제거되는 히드록시기 함유 선형 결정성 고분자이다[1-4]. (중략)

  • PDF

Synthesis of AlON from Partially Hydrolyzed AlN Powder and its Sintering (부분 가수분해된 AlN 분말로부터 산질화 알루미늄(AlON)의 합성 및 소결)

  • 김두영;최상욱;남건태
    • Journal of the Korean Ceramic Society
    • /
    • v.31 no.11
    • /
    • pp.1362-1368
    • /
    • 1994
  • The hydrolysis of aluminum nitride was increased gradually with increasing reaction time from 1 hrs to 24 hrs and/or with decreasing the addition of the reaction water from 100 mι 100mι. Amorphous aluminum hydrate, formed in the beginning of the reaction, was transformed to bayerite and to pseudoboehmite at below and above 8$0^{\circ}C$, respectively. Aluminum oxynitride was synthesized by heating the partially hydrolyzed aluminum nitride at 1$700^{\circ}C$ for 4 hrs or at 175$0^{\circ}C$ for 30 min. AlON specimen with 1 wt% of Y2O3 that was molded and then sintered pressurelessly at 190$0^{\circ}C$, exhibits 98% of the theoretical density and a translucency of 68% in the visible ray zone.

  • PDF

Effect of Glycine Adsorption on Polishing of Silicon Nitride in Chemical Mechanical Planarization Process (CeO2 슬러리에서 Glycine의 흡착이 질화규소 박막의 연마특성에 미치는 영향)

  • 김태은;임건자;이종호;김주선;이해원;임대순
    • Journal of the Korean Ceramic Society
    • /
    • v.40 no.1
    • /
    • pp.77-80
    • /
    • 2003
  • Adsorption of glycine on$Si_3N_4$powder surface has been investigated, which is supposed to enhance the formation of passive layer inhibiting oxidation in aqueous solution. In the basic solution, multinuclear surface complexing between Si and dissociated ligands was responsible for the saturated adsorption of glycine. In addition, $CeO_2$-based CMP slurry containing glycine was manufactured and then applied to planarize$SiO_2$and$Si_3N_4$thin film. Owing to the passivation by glycine, the removal rates, Rh, were decreased, however, the selectivities, RE(SiO$_2$)/RR($Si_3N_4$), increased and showed maximum at pH=12. The suppressed oxidation and dissolution by adsorbate were correlated with the dissociation behavior of glycine at different pH and subsequent chemical adsorption.

Recovery of Gallium and Indium from Waste Light Emitting Diodes

  • Chen, Wei-Sheng;Chung, Yi-Fan;Tien, Ko-Wei
    • Resources Recycling
    • /
    • v.29 no.1
    • /
    • pp.81-88
    • /
    • 2020
  • Recovery of gallium and indium from waste light emitting diodes has been emphasized gradually owing to high content of gallium and indium. This study was established the recovery of gallium (Ga3+) and indium (In3+) from waste gallium nitride was contained in waste light-emitting diodes. The procedure was divided into the following steps; characteristic analysis, alkaline roasting, and leaching. In characteristic analysis part, the results were used as a theoretical basis for the acid leaching part, and the chemical composition of waste light emitting diodes is 70.32% Ga, 5.31% Si, 2.27% Al and 2.07% In. Secondly, with reduction of non-metallic components by alkaline roasting, gallium nitride was reacted into sodium gallium oxide, in this section, the optimal condition of alkaline roasting is that the furnace was soaked at 900℃ for 3 hours with mixing Na2CO3. Next, leaching of waste light emitting diodes was extremely important in the process of recovery of gallium and indium. The result of leaching efficiency was investigated on the optimal condition accounting for the acid agent, concentration of acid, the ratio of liquid and solid, and reaction time. The optimal condition of leaching procedures was carried out for 2.0M of HCl liquid-solid mass ratio of 30 ml/g in 32minutes at 25℃ and about 96.88% Ga and 96.61% In were leached.

A Study on the Various Noerok from Janggi-myeon, Pohang (포항 장기면 일대에 산출되는 뇌록의 다양성 연구)

  • Mun, Seong Woo;Kim, Jae Hwan;Kong, Dal-Yong;Moon, Dong Hyeok;Jeong, Hye Young
    • The Journal of the Petrological Society of Korea
    • /
    • v.27 no.4
    • /
    • pp.195-205
    • /
    • 2018
  • Noerok is a green pigment made of mineral used the Gachil(priming coat) of wooden architecture in Chosun Dynasty era. It has been reported that various Noerok are discovered in Janggimyeon, Pohang. In this study, The Noerok from two places is compared and discussed. Noerok in the two places has blulsh-green to green color, and it is similar to their occurrences on fracture filling, vein and dike on outcrop. However, there are differences between two sites according to its petrological feature, mineral composition and geochemistry. While the Noeseongsan sample is mostly celadonite, Gwangjeongsan samples are characterized by celadonite with varying contents of cristobalite, tridymite, feldspar, along with some vitrified contents. In terms of major elements, the amount of $Al_2O_3$, $Fe_2O_3$, MgO and $K_2O$ decreases linearly with increasing $SiO_2$, whereas $Fe_2O_3$ is linearly proportional to MgO. In summary, Noerok in the study areas can be classified into 4 types (type 1, type 2, type 3-1, type 3-2) base on color, mineral composition, elemental composition, and vitrification grade.

A Study on the Photoisomerization of Fatty Acid and Polyamic Acid Mixture (지방산과 폴리아미드산 혼합물의 광이성질화 현상에 관한 연구)

  • 박근호;박태곤
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.15 no.8
    • /
    • pp.695-701
    • /
    • 2002
  • Maxwell displacement current (MDC) measuring technique has been applied on the study of monolayers of fatty acid and polyamic acid mixture. The displacement current was generated from monolayers on the water surface by monolayer compression and expansion. Displacement current was generated when the area per molecule was about 132 $^2$and 115 $^2$just before the initial rise of the surface pressure during the 1st and 2nd mixed monolayer compressions cycle, respectively. Maxwell displacement currents were investigated in connection with mixed monolayer compression cycles. It was found that the maximum of MDC appeared at the molecular area just before the initial rise of surface pressure in compression cycles. Ultra thin film of fatty acid and polyamic acid mixture was prepared on the hydrophilic quartz plate by Langmuir-Blodgett (LB) method. The precursor LB film was heated in a vacuum dry oven at 12$0^{\circ}C$ in order to convert it into the LB film of polyimide. The absorption spectra of LB films were also induced photoisomerization by UV and visible light irradiation.

Photoisomerization LB Monolayer Films Mixed with Fatty Acid and Phospholipid at Difference Mixture Ratio (지방산과 인지질의 혼합 단분자 LB막의 혼합비에 따른 광이성질화에 관한 연구)

  • Kang, Dong-Wan;Park, Keun-Ho
    • Journal of the Korean Applied Science and Technology
    • /
    • v.17 no.3
    • /
    • pp.178-182
    • /
    • 2000
  • We have investgated UV-Vis absorbance to observe the photoisomerization using the mixture solutions in chloroform and LB monolayers mixed with DLPE and 8A5H containing azobenzene which showed reversible cis-trans photoisomerization irradiated by alternate lights. We have found that the absorbance spectrums of the mixture solutions and LB monolayers were reversibly induced to cis-trans photoisomerization irradiated by alternate lights. In addition, the absorbance of both solution and LB monolayer mixed with 8A5H and DLPE were reversibly by alternate temperatures. As a results, the 1:1(by volume) mixture ratio of 8A5H and DLPE was more flexible and reversible cis-trans photoisomerization than the others.

Photoisomerization of Monolayer LB Films mixed with Fatty Acid and Phospholipid at mixture ratios (지방산과 인지질의 혼합비에 따른 단분자 LB막의 광이성질화 현상에 관한 연구)

  • 박근호;강동완;김성일;박태곤
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2000.07a
    • /
    • pp.479-482
    • /
    • 2000
  • We investigated UV-vis absorbances to observe photoisimerization and effect of temperature using the mixture solution in chloroform and the LB monolayer mixed with DLPE and 8A5H containing azobenzene which shows reversible cis-trans isomerization irradiated by alternate lights. We could find that the absorption spectrum of the mixtures solution and LB monolayer was reversibly induced to photoisomerization irradiated by Uv of both and visible lights, in addition the absorbance by alternate temperatures.

  • PDF