• 제목/요약/키워드: alkaline earth metal

검색결과 123건 처리시간 0.021초

A DFT Study on Alkali and Alkaline Earth Metal Encapsulated Fullerene-Like BeO Cluster

  • Ravaei, Isa;Beheshtian, Javad
    • 대한화학회지
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    • 제61권6호
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    • pp.311-319
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    • 2017
  • By using Density Functional Theory (DFT), we have performed alkali metal and alkaline earth metal inside fullerene-like BeO cluster (FLBeOC) in terms of energetic, geometric, charge transfer, work function and electronic properties. It has been found that encapsulated processes of the alkali metal are exothermic and thermodynamically more favorable than alkaline earth metal encapsulation, so that interaction energy ($E_{int}$) of the alkali metal encapsulation FLBeOC is in the range of -0.02 to -1.15 eV at level of theory. It is found that, the electronic properties of the pristine fullerene-like BeO cluster are much more sensitive to the alkali metal encapsulation in comparison to alkaline earth metal encapsulation. The alkali and alkaline earth metal encapsulated fullerene-like BeO cluster systems exhibit good sensitivity, promising electronic properties which may be useful for a wide variety of next-generation nano-sensor device components. The encapsulation of alkali and alkali earth metal may increase the electron emission current from the FLBeOC surface by reducing of the work function.

이온성 크라운에테르 포스포닉산에 의한 알칼리 금속 양이온과 알칼리 토금속 양이온의 용매추출 (Solvent Extractions of Alkali Metal Cations and Alkaline Earth Cations by Ionizable Crown Ether Phosphonic Acids)

  • 정연진
    • 한국응용과학기술학회지
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    • 제22권1호
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    • pp.50-55
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    • 2005
  • A comparison of alkali metal cation and alkaline earth cation solvent extraction was made for three additional monoionizable crown ethers and one diionizable crown ether. sym-(n-Octyldibenzo)-16-crown-5-oxyacetic acid $\underline{1}$ exhibited high efficiency and selecvity in solvent extraction of alkali metal cations with respect to that observed with alkaline earth cations. Sizes of $Na^+$ and $Ca^{2+}$ appropriately match with the cavity size of monoethyl sym-bis[4(5)-tert-butylbenzo]-16-crown-5-oxymethylphosphonic acid $\underline{3}$. As the result, $Na^+$ and $Ca^{2+}$ are the best extracted. sym-(n-Octyldibenzo)-16-crown-5-oxymethyldiphosphonic acid $\underline{4}$was found to be somewhat selective for $Na^+$ over $Li^+$ and other alkaline earth metal cations. In the complexation of alklaine earth cations by crown ether diphosphonic acid $\underline{4}$, $Ca^{2+}$ and $Sr^{2+}$ are the appropriate sizes, but lager $Ba^{2+}$ may be due to favorable formation of a sandwich type complex between the crown ether cavity and the dianion of the deprotonated crown ether phoaphonic acid moiety.

크라운에테르 포스포닉산 모노에틸 에스테르에 의한 알칼리 토금속 양이온의 경쟁 용매추출 (Competitive Solvent Extractions of Alkaline Earth Metal Cations by Crown Ether Phosphonic Acid Monoethyl Esters)

  • 정영진
    • 한국응용과학기술학회지
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    • 제22권1호
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    • pp.9-14
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    • 2005
  • Competitive solvent extraction of alkaline earth metal cations from water into organic solvent containing the carboxylic acid crown ether and analogous crown ether phosphonic acid monoethyl esters were investigated. sym-(n-Decyldibenzo)-16-crown-5xyacetic acid $\underline{1}$ and monoethyl sym-(n-decyldibenzo)-16-crown-5-oxymethylphosphonic acid $\underline{3}$ are structurally identical except for the ionizable groups. Both of them provide similar extraction behavior in terms of efficiency and selectivity, but monoethyl sym-(n-decyldibenzo)-16-crown-5-oxymethylphosphonic acid $\underline{3}$ showed higher alkaline earth metals loadings at acidic or neutral media. Monoethylsym-(n-octyldibenzo)-16-rown-5-oxymethylphosphonic acid $\underline{2}$ showed better selectivity and alkaline earth metals loading than did the analogous sym-(n-octyldibenzo)-16-crown-5-oxymethyldiphosphonic acid $\underline{6}$.

Preparation of 27Ni6Zr4O143M(M=Mg, Ca, Sr, or Ba)O/70 Zeolite Y Catalysts and Hydrogen-rich Gas Production by Ethanol Steam Reforming

  • Kim, Dongjin;Lee, Jun Su;Lee, Gayoung;Choi, Byung-Hyun;Ji, Mi-Jung;Park, Sun-Min;Kang, Misook
    • Bulletin of the Korean Chemical Society
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    • 제34권7호
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    • pp.2073-2080
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    • 2013
  • In this study the effects of adding alkaline-earth (IIA) metal oxides to NiZr-loaded Zeolite Y catalysts were investigated on hydrogen rich production by ethanol steam reforming (ESR). Four kinds of alkaline-earth metal (Mg, Ca, Sr, or Ba) oxides of 3.0% by weight were loaded between the $Ni_6Zr_4O_{14}$ main catalytic species and the microporous Zeolite Y support. The characterizations of these catalysts were examined by XRD, TEM, $H_2$-TPR, $NH_3$-TPD, and XPS. Catalytic performances during ESR were found to depend on the basicity of the added alkaline-earth metal oxides and $H_2$ production and ethanol conversion were maximized to 82% and 98% respectively in 27($Ni_6Zr_4O_{14}$)3MgO/70Zeolite Y catalyst at $600^{\circ}C$. Many carbon deposits and carbon nano fibers were seen on the surface of $30Ni_6Zr_4O_{14}$/70Zeolite Y catalyst but lesser amounts were observed on alkaline-earth metal oxide-loaded 27($Ni_6Zr_4O_{14}$)3MO/70Zeolite Y catalysts in TEM photos after ESR. This study demonstrates that hydrogen yields from ESR are closely related to the acidities of catalysts and that alkaline-earth metal oxides reduce the acidities of 27($Ni_6Zr_4O_{14}$)3MO/70Zeolite Y catalysts and promote hydrogen evolution by preventing progression to hydrocarbons.

Simultaneous Determination of Alkaline Earth Metal Ions by a Conventional High Performance Liquid Chromatographic System

  • Rho, Young-Soo;Choi, Seung-Gi
    • Archives of Pharmacal Research
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    • 제9권4호
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    • pp.211-214
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    • 1986
  • A simultaneous determination method of alkaline earth metals was attempted with the conventional high performance liquid chromatographic system. Four cations, namely, magnesium, calcium, strontium and barium ion, were injected directly as aqueous solution into an eluent containing copper chloride solution and and were successfully separated and determined on a separating column (Zipax SCX, 4.6 mm i.d. ${\times}25$ cm length, Du Pont, USA) by using a variable wavelength UV detector. The linear calibration curves were obtianed in the range from $1.0{\times}10^{-4}M$ to $5.0{\times}10^{-4}M$ and the correlation coefficient of the calibration curve for each metal of magnesium and calcium in tap water. Alkaline earth metals were determined with the conventional high performance liquid chromatographic system.

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Sequential Formation of Multiple Gap States by Interfacial Reaction between Alq3 and Alkaline-earth Metal

  • Kim, Tae Gun;Kim, Jeong Won
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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    • pp.129.2-129.2
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    • 2013
  • Electron injection enhancement at OLED (organic light-emitting diodes) cathode side has mostly been achieved by insertion of a low work function layer between metal electrode and emissive layer. We investigated the interfacial chemical reactions and electronic structures of alkaline-earth metal (Ca, Ba)/Alq3 [tris(8-hydroxyquinolinato)aluminium] and Ca/BaF2/Alq3 using in-situ X-ray & ultraviolet photoelectron spectroscopy. The alkaline-earth metal deposited on Alq3 generates two energetically separated gap states in sequential manner. This phenomenon is explained by step-by-step charge transfer from alkali-earth metal to the lowest unoccupied molecular orbital (LUMO) states of Alq3, forming new occupied states below Fermi level. The BaF2 interlayer initially prevents from direct contact between Alq3 and reactive Ca metal, but it is dissociated into Ba and CaF2. However, as the Ca thickness increases, the Ca penetrates the interlayer to directly participate in the reaction with underlying Alq3. The influence of the multiple gap state formation by the interfacial chemical reaction on the OLED performance will be discussed.

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새로운 HDBPDA 이온교환체를 사용한 알칼리 및 알칼리토금속 이온들의 분리와 그의 이온교환특성 (Separation of Alkali and Alkaline Earth Metal Ions using Novel HDBPDA Ion Exchanger and Its Ion Exchange Characteristics)

  • 김동원;김창석;최기영;전영신;윤여학
    • 대한화학회지
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    • 제37권9호
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    • pp.820-825
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    • 1993
  • 새로운 HDBPDA 이온교환체, {(4,5) : (13,14)-dibenzo-6,9,12-trioxa-3,15,21-triazabicyclo[15.3.l]heneicosa-(1,17,19)(18,20,21) triene ion exchanger: HDBPDA ion exchanger}의 이온교환용량은 3.8 meq/g이었다. 그리고 이 이온교환체에 대한 알칼리 및 알칼리토금속 이온들의 분포계수를 물과, 여러 농도의 염산용액중에서 측정하였다. 금속이온들의 분포계수는 염산농도의 영향을 거의 받지 않았으나, 대체적으로 염산의 농도가 감소할수록 점진적으로 약간 증가하는 경향을 보였다. 그리고 물속에서의 분포계수가 가장 컸다. HDBPDA 이온교환체를 사용하여 알칼리 및 알칼리토금속 이온들을 컬럼이온교환크로마토그래피로 분리하였으며, 이때 용리액으로 물을 사용하였다. 또한 알칼리 및 알칼리토금속 이온들의 분포계수는 그들 이온들의 이온반경이 증가함에 따라 증가하였다.

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새로운 DBPDA 이온교환체를 사용한 알칼리 및 알칼리 토금속 이온들의 분리와 그의 이온교환 성질 (Separation of Alkali and Alkaline Earth Metal Ions Using Novel DBPDA Ion Exchanger and Its Ion Exchange Properties)

  • 김동원;김창석;최기영;전영신
    • 분석과학
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    • 제6권3호
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    • pp.261-265
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    • 1993
  • 새로운 DBPDA이온교체, {(4,5):(13,14)-dibenzo-6, 9, 12-trioxa-3, 15, 21-triazabicyclo [15.3.1] heneicosa-1(21), 17, 19-triene-2, 16-dione : DBPDA 이온교환체}의 이온교환용량은 4.2meq/g이었다. 그리고 이 이온교환체에 대한 알칼리 및 알칼리 토금속 이온들의 분배계수를 여러 농도의 염산용액 중에서 측정하였다. 또한 DBPDA 이온교환체를 사용하여 알칼리 및 알칼리 토금속 이온들을 이온교환 컬럼 크로마토그라피로 분리하였다. 이러한 결과로부터 알칼리 및 알칼리 토금속 이온들의 분배계수에 미치는 용액의 pH와 금속 이온들의 이온반경 효과를 고찰하였다.

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PDP 보호막용 MgO 박막의 저전압 특성에 미치는 알카리토금속산화물 첨가 효과 (Effect of Alkaline Earth Metal Oxides addition on the Low-voltage Characteristics of MgO Films as a Protective layer for AC PDPs)

  • 조진희;김락환;김정열;이유기;김희재;박종완
    • 한국재료학회지
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    • 제9권5호
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    • pp.441-445
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    • 1999
  • Alkaline earth metal oxides were added to the conventional MgO films as a protective layer for dielectric materials to have lower firing voltage(Vf) of the plasma display panel(PDP). Panels with various protective layers of MgO-alkaline earth metal oxides were prepared on glass by using e-beam evaporation and its effect on firing voltage characteristics were investigated. (Ba-Mg)O films had poor voltage characteristics because of higher activation energy of BaO. But, (Sr-Mg)O, (Ca-Mg)O and (Ca-Sr-Mg) O had better voltage characteristics than the conventional MgO. A mixture film of (Mg-Ca-Sr)O show the lowest firing voltage which is less than that of MgO by 20V. The chemical composition to have lowest firing voltage is MgO:SrO:CaO ratio of 6:2:2. The mixture of MgO-Alkaline earth metal oxides films showed good transmittance properties within the visual range.

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Grain Growth Behavior of (K0.5Na0.5)NbO3 Ceramics Doped with Alkaline Earth Metal Ions

  • Il-Ryeol Yoo;Seong-Hui Choi;Kyung-Hoon Cho
    • 한국재료학회지
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    • 제33권4호
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    • pp.135-141
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    • 2023
  • The volatilization of alkali ions in (K,Na)NbO3 (KNN) ceramics was inhibited by doping them with alkaline earth metal ions. In addition, the grain growth behavior changed significantly as the sintering duration (ts) increased. At 1,100 ℃, the volatilization of alkali ions in KNN ceramics was more suppressed when doped with alkaline earth metal ions with smaller ionic size. A Ca2+-doped KNN specimen with the least alkali ion volatilization exhibited a microstructure in which grain growth was completely suppressed, even under long-term sintering for ts = 30 h. The grain growth in Sr2+-doped and Ba2+-doped KNN specimens was suppressed until ts = 10 h. However, at ts = 30 h, a heterogeneous microstructure with abnormal grains and small-sized matrix grains was observed. The size and number of abnormal grains and size distribution of matrix grains were considerably different between the Sr2+-doped and Ba2+-doped specimens. This microstructural diversity in KNN ceramics could be explained in terms of the crystal growth driving force required for two-dimensional nucleation, which was directly related to the number of vacancies in the material.