Shape-Control of a 0D/1D NaFe0.9Mn0.1PO4 Nano-Complex by Electrospinning

신미라,손종태 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.72 No.6

NaFePO4 with a maricite structure was one of the most promising candidates for sodium ion batteries (SIBs) due to its advantages of environmental friendly and having low cost. However, it has low electrochemical conductivity and energy density, which impose limitations on its application as commercial cathode materials. In this study, other transition-metal ions such as Mn2+ were substituted into the iron (Fe2+) site in NaFePO4 to increase the surface area and the number of nanofibers in the prepared one-dimensional (1D) nano-sized material with 0D/1D dimensions to enhance the energy density. Also, the 0D/1D NaFe0.9Mn0.1PO4 cathode material has increased electrochemical conductivity because the fiber size was reduced to the nano-scale level by using the electrospinning method in order to decrease the diffusion path of Na-ions. The morphology of the 0D/1D nanofiber was evaluated by Field-emission scanning electron microscope and atomic force microscope analyses. The NaFe0.9Mn0.1PO4 nanofibers had a diameter of approximately 180 nm, while the spherical particle had a diameter 1 μm. The 0D/1D nano-sized cathode material show a discharge capacity of 27 mAhg −1 at a 0.05 C rate within the 2.0 ~ 4.5 V voltage range and a low Rct of 110 Ω.

Effects of Cl doping on the structural and electrochemical properties of high voltage LiMn_1.5Ni_0.5O₄ cathode materials for Li-ion batteries

Kim, W.K.,Han, D.W.,Ryu, W.H.,Lim, S.J.,Eom, J.Y.,Kwon, H.S. Elsevier Sequoia 2014 JOURNAL OF ALLOYS AND COMPOUNDS Vol.592 No.-

LiMn<SUB>1.5</SUB>Ni<SUB>0.5</SUB>O<SUB>4</SUB> and LiMn<SUB>1.5</SUB>Ni<SUB>0.5</SUB>O<SUB>3.9</SUB>Cl<SUB>0.1</SUB> are prepared by a solution-based process to investigate the influences of Cl doping on the structural and electrochemical properties of high voltage LiMn<SUB>1.5</SUB>Ni<SUB>0.5</SUB>O<SUB>4</SUB> cathode materials for Li-ion batteries. LiMn<SUB>1.5</SUB>Ni<SUB>0.5</SUB>O<SUB>3.9</SUB>Cl<SUB>0.1</SUB> features an improved cyclic performance at 30<SUP>o</SUP>C and 55<SUP>o</SUP>C compared with LiMn<SUB>1.5</SUB>Ni<SUB>0.5</SUB>O<SUB>4</SUB>, which originates from the enhanced structural stability by formation of strong Mn-Cl and Ni-Cl bonds revealed by XPS analysis. The improvement in the rate capability of LiMn<SUB>1.5</SUB>Ni<SUB>0.5</SUB>O<SUB>3.9</SUB>Cl<SUB>0.1</SUB> is attributed to the facilitated Li-ion diffusion in the lattice, due primarily to the larger ionic radius of Cl than that of O. From the GITT analysis, it is revealed that the Li-ion diffusivity of LiMn<SUB>1.5</SUB>Ni<SUB>0.5</SUB>O<SUB>3.9</SUB>Cl<SUB>0.1</SUB> is improved about 2 times compared with that of LiMn<SUB>1.5</SUB>Ni<SUB>0.5</SUB>O<SUB>4</SUB>. The improved Li-ion diffusivity in the lattice is assigned to the increase in the lattice constant of LiMn<SUB>1.5</SUB>Ni<SUB>0.5</SUB>O<SUB>3.9</SUB>Cl<SUB>0.1</SUB> compared with that of LiMn<SUB>1.5</SUB>Ni<SUB>0.5</SUB>O<SUB>4</SUB> by the doping of Cl.

Effects of the Tb-Ion Concentration in Multiferroic TbxY1-xMn1.99 57Fe0.01O5 (x = 0.0, 1.0) Materials

김철성,김동현 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.5

Multiferroic TbxY1-xMn1.9957Fe0.01O5 (x = 0.0, 1.0) was synthesized by using a sol-gel method. The lattice constants of TbxY1-xMn1.9957Fe0.01O5 with Tb substitution of x = 0.0 and x = 1.0 were determined to be a0 = 7.275 Å, b0 = 8.487 Å, c0 = 5.674 Å and a0 = 7.334 Å, b0 = 8.523 Å, c0 = 5.679 Å, respectively. The magnetic moment of YMn1.99Fe0.01O5 decreased sharply with temperature down to a temperature of 25 K due to the canted magnetic moment. However, a large increase in the magnetic moment was observed in TbMn1.99Fe0.01O5. The Mossbauer spectra of TbxY1-xMn1.9957Fe0.01O5 (x = 0.0, 1.0) exhibited two-sextet patterns at 4.2 K. There was a noticeable difference in magnetic hyperfine fields at the tetrahedral site (Y HA hf , TbHA hf ). We also observed similar behaviours in the electric quadrupole splitting values at pyramidal site (ΔY EA Q, ΔTbEA Q). Furthermore, the electric quadrupole splitting of TbxY1-xMn1.9957Fe0.01O5 (x = 0.0, 1.0) showed discontinuous jump below 30 K. These suggest that the multiferroic properties of TbxY1-xMn1.9957Fe0.01O5 are greatly affected by the magnetic ordering.

예비교사들은 0.99…<1라는 주장을 어떻게 반박하는가?

이지현 대한수학교육학회 2014 학교수학 Vol.16 No.3

This paper analyzed pre-service teachers’ justification of 0.99…=1 from their disproof of 0.99…<1. Some pre-service teachers thought of the difference between 0.99… and 1 as an infinitesimal. On the contrary, the others claimed that the difference between 0.99… and 1 was zero as the standard real, but were content with their intuitive justifications. The pre-service teachers’ limitation revealed in the process of disproving 0.99…<1 can be closely related to the orthodox view: the standard real number system is the only absolutely true number system. The existence of nonstandard real number system in which 0.99… is less than 1, shows that the plain question of whether or not 0.99… equals 1, cannot be properly answered by common explanations of textbooks or teachers’ intuitive justification. 이 연구는 예비교사들이 0.99…가 1보다 작다는 주장을 어떻게 반박하는지를 관찰함으로서 왜 0.99…=1가 참이라고 정당화하는지를 분석하였다. 일부 예비교사는 1-0.99…의 값을 무한소라고 생각하고 있었다. 표준 실수의 입장에서 1-0.99…의 값은 무한소가 아닌 0이라고 생각했던 예비교사들도 이것을 실수에 대한 가정으로부터의 논리적 결론으로 정당화하기보다는 유한과 무한은 다르다는 직관적 정당화에 안주하였다. 예비교사들이 0.99…<1의 반박에서 드러낸 인식의 한계는, 표준 실수 체계만이 수학적으로 옳은 유일한 수체계라는 믿음과 무관하지 않다. 0.99…<1이지만 표준 실수체계와 마찬가지로 무모순인 비표준 실수체계가 존재한다는 사실은, 평범한 중학생이 제기하는 0.99…가 1이냐 아니냐의 질문도 학교수학 수준의 상식적 설명 혹은 예비교사들의 직관적인 정당화만으로는 대답할 수 없는 것임을 보여주고 있다.

0과 1의 해석학 ―수학, 디지털 및 양자정보, 그리고 주역과 노장

오태석 ( Oh Tae-suk ) 한국중국어문학회 2018 中國文學 Vol.97 No.-

본고 〈0과 1의 해석학〉은 ‘0과 1’의 다양한 인문수학적 함의, 이 숫자들에 기초한 디지털 컴퓨터와 양자컴퓨터의 구동방식의 비교, 그리고 주역 음양론과 노장 세계인식의 중요한 특징으로서의 양가성(兩價性)과 양행의 독법을 정보이론의 관점에서 풀어 해석하고자 했다. 제2장에서는 ‘0과 1’의 의미를 0의 양가성, 원과 파동, 확률, 집합론, 그리고 지수⋅로그(log)의 정보 단위로서의 bit와의 관련성 등을 인문수학적으로 고찰하였다. 제3장에서는 0과 1의 선택(0/1)에 기초한 디지털컴퓨터와, 양자역학의 기본 속성인 양자중첩에 기초해 0과 1을 동시에 취하는(0&1) 양자컴퓨터의 알고리즘 구동 방식을 비교 분석함으로써 이어 행할 주역 및 노장 사유와의 상호 관련성을 가늠할 기초 자료로 삼았다. 제4장에서는 음과 양 혹은 0과 1의 이진법으로 운용되는 동아시아 주역 음양기호학의 괘의 확장과 전개가 방식으로 구동되며, 동시에 0과 1이 복희육십사괘도에서 보듯이 ‘음중양, 양중음’의 내적 상관성 속에 움직이는 점, 그리고 노장이 공히 인식한 상도(常道)적 잠재계와 가도(可道)적 현상계, 그리고 이 둘의 양면 구동인 양행(兩行) 병작(並作)의 사유가 양자택일적 디지털 컴퓨터보다는 양자컴퓨터와 더 근접함을 보았다. 이상의 고찰을 통해 서구 르네상스 이후 전개된 근대이성 중심의 세속주의(secularism) 및 데카르트와 뉴턴 이래 가속화한 분과주의 및 기계론적 이분법의 독점적 지배가 20세기초 상대성이론과 양자역학으로 흔들리기 시작하면서, 장기간 홀시되었던 동아시아 사유의 이중성과 모호성의 양가(兩價)⋅양행(兩行)의 사유가 새로운 조명을 받을 충분한 시점에 이르렀다고 논증하였다. This paper mainly put emphasis on the concept of ‘ambiguity’ and ‘ambivalence’, not on ‘clarity’ in regard to information theory. The specific contents are about the humanistic implies of the numbers ‘0 and 1’. I describe it into three parts as follows: ① Many interpretations of humanistic math about ‘0 and 1’ which could be extended to the circle and wave in TaiJI(太極) and its center line and its augural meaning of differential equation; probability; set in regard to George Cantor’s diagonal argument; and exponential function and log function which are related with the concept of information bit. ② A comparison of information theory about ‘0 and 1’ in digital computer’s bit with quantum computer’s qbit. ③ Mathematical semiotics of Yin and Yang in Book of Change(Yi-Jing), and Laozhuang’s view of ‘liangxing(兩行)’, i.e. going two-ways simultaneously from the aspect of information theory. In this paper I maintain 3 points as follows: ⓐ Similarity of ambivalence(兩價性) between 0 that includes nothing and infinity and concept of ‘Wu’(無) in Laozi(老子). ⓑ digital computer’s operating system is alternative algorithm i.e. {0/1}. Meanwhile quantum computer is simultaneously ambivalent taking algorithm i.e. {0&1}, which is based on quantum superposition and quantum entanglement. In other words, digital computer is based on the way of optional choice, and quantum computer runs in two different ways simultaneously. I think quantum computer’s operating system is much similar to the process of “Yang from Yin(陰中陽)” and “Yin from Yang(陽中陰)” in YiJing(易經), which is operated in intrinsically mutual complementary way. ⓒ For hundreds of years Western thoughts made much of rational clarity, and in result the thoughts of ambivalence’ (兩價性) in East Asian traditional thoughts are neglected relatively. I think from the impact of Einstein’s Relative Theories and Quantum Mechanics in early decades of 20th century, people start ringing that rational clarity is not always superior to ambivalence and ambiguity, especially in modern science. In this paper I considered the matter of humanistic implies about ‘0 and 1’ especially from information theory. And I would like to evoke the changing situation in recent recognition on ‘ambiguity’ or ‘ambivalence’, unlike past centuries.

Dielectric Properties in the Pb1-3x/2Lax[(Mg1/3Ta2/3)0.66Zr0.34]O3 Systems

김연중 한국진공학회 2017 Applied Science and Convergence Technology Vol.26 No.4

The dielectric constant and loss of poling/non-poling was measured in the Pb1-3x/2Lax[(Mg1/3Ta2/ 3)0.66Zr0.34]O3 samples. The addition of La3+ to the Pb1-3x/2Lax[(Mg1/3Ta2/3)0.66Zr0.34]O3 did not cause a large change in grain size. But the addition of La3+ did show transition temperature, which shifted toward low temperature in the Pb[(Mg1/3Ta2/3)Zr]O3 systems. In addition, the dielectric and pyroelectric properties (Ɛ~20000, p~0.03 C/m2K) of this system using La3+ have been greatly improved. Pyroelectrics Pb0.97La0.02(Mg1/3Ta2/3)0.66Zr0.34]O3 system was found to have a relatively high ferroelectric FOMs (FV~0.035 m2/C, FD~0.52 × 10−4 Pa−1/2) at room temperature. Spontaneous polarization showed a value of 0.27~0.35 C/m2 in the composition added to La3+. The piezoelectric constant (d33=350~490 pC/N) and electromechanical coupling factor (kP=0.25~0.35) are obtained in Pb1-3x/2Lax[(Mg1/3Ta2/3)0.66 Zr0.34]O3 compositions with La3+ dopant.

Dielectric Properties in the Pb<SUB>1-3x/2</SUB>La<SUB>x</SUB>[(Mg<SUB>1/3</SUB>Ta<SUB>2/3</SUB>)<SUB>0.66</SUB>Zr<SUB>0.34</SUB>]O<SUB>3</SUB> Systems

Yeon Jung Kim 한국진공학회(ASCT) 2017 Applied Science and Convergence Technology Vol.26 No.4

The dielectric constant and loss of poling/non-poling was measured in the Pb1-3x/2Lax[(Mg1/3Ta2/3)0.66Zr0.34]O3 samples. The addition of La<SUP>3+</SUP> to the Pb1-3x/2Lax[(Mg1/3Ta2/3)0.66Zr0.34]O3 did not cause a large change in grain size. But the addition of La<SUP>3+</SUP> did show transition temperature, which shifted toward low temperature in the Pb[(Mg1/3Ta2/3)Zr]O3 systems. In addition, the dielectric and pyroelectric properties (Ɛ~20000, p~0.03 C/m2K) of this system using La<SUP>3+</SUP> have been greatly improved. Pyroelectrics Pb0.97La0.02(Mg1/3Ta2/3) 0.66Zr0.34]O3 system was found to have a relatively high ferroelectric FOMs (FV~0.035 m<SUP>2</SUP>/C, FD~0.52 × 10<SUP>−4</SUP> Pa<SUP>−1/2</SUP>) at room temperature. Spontaneous polarization showed a value of 0.27~0.35 C/m<SUP>2</SUP> in the composition added to La<SUP>3+</SUP>. The piezoelectric constant (d33=350~490 pC/N) and electromechanical coupling factor (kP=0.25~0.35) are obtained in Pb1-3x/2Lax[(Mg1/3Ta2/3) 0.66Zr0.34]O3 compositions with La3<SUP>+</SUP> dopant.

실시간 에어로졸 질량분석기를 이용한 PM1.0의 화학적성분의특성에 관한 연구

박진수,최진수,김현재,오준,성민영,안준영,이상보,김정호 한국도시환경학회 2018 한국도시환경학회지 Vol.18 No.4

This study aims to identify the characteristics of oxidation and chemical composition of PM in winter season, 2017 at Incheon area. The mean concentration of air pollutants were 46 ± 22 µg/m3-PM10, 29 ± 18 µg/m3/-PM2.5, 5 ± 3 ppb-SO2, 0.56 ± 0.24 ppm-CO, 21 ± 13 ppb-O3 and 28 ± 17 ppb-NO2, respectively. The dominant ion of the PM1.0 chemical component were organic with 3.2 µg/m3 and nitrate with 1.9 µg/m3. The day and night variation of the PM1.0 chemical components was higher in nighttime than those of daytime. The averaged nitrate oxidation rate (SOR) was 0.06 and sulfate oxidation rate was 0.11 during the field campaign. In the high mass loading period, nitrate oxidation rate (NOR) was up to 0.6 and also the nitrate in PM1.0 was increased. The averaged ratio of NOx/SO2 was 8.7 and nitrate/sulfate was 3.1, respectively. In this results, the nitrate component in PM1.0 was influenced by NOx from the stationary source as power plant and the mobile source around the measurement site. 2017년 겨울철 인천에서 미세먼지(PM1.0)의 화학적 성분과 산화특성을 파악하였다. 측정기간 대기오염물질 농도는PM10 46 ± 22 µg/m3, PM2.5 29 ± 18 µg/m3, SO2 5(± 3) ppb, CO 0.56(± 0.24) ppm, O3 21(± 13) ppb, NO2 28(± 17) ppb이었다. PM1.0 화학적 성분은 organic 성분이 3.2 µg/m3, nitrate 1.9 µg/m3로 주요성분으로 나타났다. 주간과 야간에서 대부분 야간에 높은 농도를 나타냈다. 측정기간 NOR(nitrate oxidation rate)은 0.06 이었고, SOR(sulfate oxidation rate)은0.11이었다. 고농도기간, NOR은 0.6까지 증가하였으며, nitrate 성분도 증가하였다. NOx/SO2 비는 평균 8.7이었으며, nitrate/sulfate 비율은 평균 2.1로서 측정지점에 위치한 발전소, 산업 보일러를 포함한 고정오염원과 이동오염원인 자동차로부터 배출된 NOx가 기여요인으로 작용한 것으로 판단된다.

다양한 합성 방법으로 제조된 BiFe0.65MoP0.1 산화물 촉매 상에서 n-부텐의 산화탈수소화 반응

박정현 ( Jung Hyun Park ),신채호 ( Chae Ho Shin ) 한국화학공학회 2015 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.53 No.3

n-부텐의 산화탈수소화에서 제조방법이 촉매의 반응활성에 미치는 영향을 조사하기 위하여 BiFe0.65MoP0.1 산화물 촉매를 모델 촉매로 선정하여 공침법, 시트르산법, 수열합성법, 주형법 등의 방법으로 촉매를 제조하였다. 제조한 촉매의 물리·화학적 특성을 알아보고 반응 활성과 연관시키기 위하여 X-선 회절분석(XRD), 질소 흡착·탈착분석(N2 sorption), 암모니아/1-부텐-승온탈착분석(NH3/1-butene-TPD) 등의 특성분석을 수행하였다. 공침법으로 제조한 촉매의 활성이 가 장 높게 관찰되었으며, 14시간 동안의 산화탈수소화 반응 기준으로 n-부텐의 전환율은 79.5%, 1,3-부타디엔의 선택도는 85.1%, 1,3-부타디엔 수율은 67.7%의 수치를 보였다. 암모니아 승온탈착 실험으로부터 촉매의 반응 활성은 촉매의 산 특성과 밀접하게 관련이 있으며, 공침법으로 제조한 산화물 촉매가 다른 합성방법으로 제조한 촉매와 비교하여 가장 큰 산량을 갖는 것으로 관찰되었다. 또한, 1-부텐의 승온탈착 분석결과, 촉매의 활성은 흡착된 1-부텐과 촉매의 표면반응에 기인한 중간체의 흡,탈착 특성, 즉 약하게 흡착된 중간체(<200 oC)의 상대적인 양과 강하게 흡착된 중간체의 탈착 온도 (>200 oC)와 밀접하게 관련이 있었다. To investigate the effect of the catalyst synthesis method on the oxidative dehydrogenation (ODH) of nbutenes, BiFe0.65MoP0.1 oxide catalysts were prepared with various synthesis methods such as co-precipitation, citric acid method, hydrothermal method, and surfactant templated method. The catalysts were characterized by X ray Diffraction (XRD), N2 sorption, and NH3/1-butene-temperature programmed desorption (NH3/1-butene-TPD) to correlate with catalytic activity in ODH reaction. Among the catalysts studied here, BiFe0.65MoP0.1 oxide catalyst prepared with co-precipitation method marked the highest activity showing 1-butene conversion, 79.5%, butadiene selectivity, 85.1% and yield, 67.7% after reaction for 14 h. From the result of NH3-TPD, the catalytic activity is closely related to the acidity of the BiFe0.65MoP0.1-x oxide catalyst and acidity of the BiFe0.65MoP0.1 oxde catalyst prepared with co precipitation method was higher than that of other catalysts. In addition, combined with the 1-butene TPD, the higher catalytic activity is closely related to the amount of weakly adsorbed intermediate (<200 oC) and the desorbing temperature of strongly adsorbed intermediates (>200 oC).

Microwave Dielectric Properties of (${Pb_{0.2}}{Ca_{0.8}}$)[$({Ca_{1/3}}{Nb_{2/3}})_{1-x}{Ti_x}$$O_3$ 세라믹스의 마이크로파 유전특성

김응수,김용현,김준철,방규석,Kim, Eung-Soo,Kim, Yong-Hyun,Kim, Jun-Chul,Bang, Kyu-Seok 한국재료학회 2001 한국재료학회지 Vol.11 No.8

($Pb_{0.2}$$Ca_{0.8}$ )[($Ca_{1}$3$Nb_{2}$3/)$_{1-x}$ $Ti_{x}$ ]O$_{3}$ 세라믹스의 $^{4+}$ 치환량 변화에 따른 마이크로파 유전특성을 고찰하였다. $Ti^{4+}$ 치환량이 증가함에 따라 x=0.05부터 x=0.15까지의 조성범위에서는 단일상의 페롭스카이트상을 얻을 수 있었으며, x=0.2이상에서는 $Ti_2$와 $CaNb_2$$O_{6}$ 가 제 2상으로 존재하였고, 결정구조는 x=0.05에서 사방정(orthorhombic) 구조가 x=0.35에서 이방정(cubic) 구조로 전이하였다. 유전상수(K)는 $Ti^{4+}$ 치환량의 증가에 따라 rattling 효과의 증가로 인하여 증가되었으며, B-자리 양이온의 평균이온반겨의 세제곱의 반비례하였다. 그러나 결정립 크기의 감소와 제 2상의 존재로 인하여 Qf값은 감소하였다. $Ti^{4+}$ 치환량이 증가됨에 따리 tolerance factor(t)와 B-자리 결합원자가의 영향으로 공진주파수의 온도계수(TCF)는 -27.36ppm/$^{\circ}C$값으로부터 +18ppm/$^{\circ}C$r값으로 조절되었다. $1350^{\circ}C$d서 3시간 소결한 ($Pb_{0.2}$ $Ca_{0.8}$ )[(Ca$_{1}$3$Nb_{2}$3)$_{1-x}$ /$Ti_{x}$]$O_{3}$ 시편에서 K=51.67, Qf=7268(GHz), TCF=0 ppm/$^{\circ}C$의 우수한 특성을 얻을 수 있었다. Microwave dielectric properties of $(Pb_{0.2}Ca_{0.8})[(Ca_{1/3}Nb{2/3})_{1-x}Ti_x]O_3$ ceramics were investigated as a function of $Ti^{4+}$ content (0.05$\leq$x$\leq$0.35). A single perovskite phase was obtained from x=0.05 to x=0.15, and $TiO_2$ and $CaNb_2O^6$ were detected as a secondary phase beyond x=0.2. The structure was changed from orthorhombic at x=0.05 to cubic at x=0.35. Dielectric constant(K) was increased with increase of $Ti^{4+}$ content due to increase of rattling effect, and was inversely proportional to the cube of the average radius of B-site cation, however, Qf value was decreased, which was due to the decrease of grain size and the secondary phase. With the increase of $Ti^{4+}$ content, the temperature coefficient of resonant frequency(TCF) was controlled from -27.36 ppm/$^{\circ}C$ value to +18.4 ppm/$^{\circ}C$ value, which was caused by the influence of tolerance factor(t) and the bond valence of B-site. Typically, K of 51.67, Qf of 7268(GHz), TCF of 0 ppm/$^{\circ}C$ were obtained in the $(Pb_{0.2}Ca_{0.8})[(Ca_{1/3}Nb_{2/3})_{0.8}Ti_0.2]O_3$ sintered at 13$50^{\circ}C$ for 3h.