Earticle

본 연구에서는 PEPC(Program for Enlightened and Productive Creativity) 모델을 이용하여 ‘회절 무늬에서의 규칙성 찾기’ 과학영재아 프로젝트형 프로그램을 개발하였다. 이 프로그램의 특징은 전 체 5단계로 구성되어 있는데 각 단계별로 다양한 과학적 탐구요소와 창의성 요소를 포함하여 일반 영재가 아닌 과학영재에게 특화된 프로그램을 만들었다. 이 프로그램을 과학영재에게 직접 투여해 본 결과 다음과 같은 결론을 내렸다. PEPC 모델은 과학영재아들이 일상생활에서 일어나는 자연현상 에 호기심을 가지고 통합하고 분류하는 능력을 키워줄 수 있다. 그리고 PEPC 모델을 통하여 과학영 재아들이 자연현상에 대해 좀 더 체계적으로 접근하고 문제 해결할 수 있는 능력을 키워줄 수 있다. 이것은 PEPC 모델을 적용한 회절무늬에서 규칙성 찾기 프로그램이 과학영재가 갖추어야 할 과학적 탐구능력과 창의성을 동시에 향상시킬 수 있는 하나의 프로그램이라는 것이다. 이 자료를 물리뿐 만 아니라 생물, 지구과학, 화학 등 과학의 다른 분야에도 꾸준히 적용시켜 지속적인 PEPC 모델의 투여 가 학생들의 생산적 창의성에 얼마나 영향을 미칠 것인지 지속적으로 연구해볼 가치가 있다고 본다.

In this study, it was intended to develop a science gifted students' project type program, ‘finding regularity in diffraction patterns’ using PEPC(Program for Enlightened and Productive Creativity) models. The program was made to develop project type study materials applied with PEPC(Program for Enlightened and Productive Creativity) models and the conclusions as follows were reached. First, PEPC models can bring up science gifted students' ability to have curiosity about natural phenomena occurring in daily lives and integrate and classify them. Second, PEPC models can bring up science gifted students' ability to approach natural phenomena more systematically and solve related problems. It is considered worthwhile to apply these materials to not only physics but also other areas such as biology, earth science and chemistry in order to continuously study how much the continuous administration of PEPC models will affect the productive creativity of students.

The soft x-ray(10nm-100nm) interferometer is a modified Mach-Zehnder type interferometer and it consists of two beam-splitters and four totally reflecting mirrors. The beam-splitters used here are 50% transmission and 50% reflection grating type. The diffraction patterns of beam splitters(1st B.S.) were investigated with a He-Ne laser. The diffraction patterns produced by the soft x-ray interferometer (2nd B.S.) were also investigated in intensities positions. The diffraction patterns of 20 degree grazing incidence on the beam splitters(1st B.S.) show a circular array of spots. Both the reflected and the transmitted beams show the same patterns but symmetric circles on the screen. The maximum intensity appears roughly when n is in the zeroth and odd orders and the suppressed peak(missing order) appears when n is in even orders. Intensities of 3 center fringes(n = 0, $\pm$1) are stronger than others. These results confirm the reduced grating equation and make agree with the intensity distribution function. It was found that the final patterns produced by the soft x-ray interferometer (2nd B.S.) consisted of fine fringes which were caused by two of three diffraction beams that were arrived at the second beam-splitter.

A series of activated carbons (ACs) were derived from sugarcane bagasse under two activation schemes: steam-pyrolysis at $600-800^{\circ}C$ and chemical activation with $H_3PO_4$ at $500^{\circ}C$. Some carbons were treated at 400, $600^{\circ}C$, or for 1-3 h, and/or in flowing air during pyrolysis of acid-impregnated mass. XRD profiles displayed two broad diffuse bands centered around $2{\theta}=23$ and $43^{\circ}$, currently associated with diffraction from the 002 and 100/101 set of planes in graphite, respectively. These correspond to the interlayer spacing, Lc, and microcrystallite lateral dimensions, La, of the turbostratic (fully disordered) graphene layers. Steam pyrolysis-activated carbons exhibit only the two mentioned broad bands with enhancement in number of layers, with temperature, and small decrease in microcrystallite diameter, La. XRD patterns of $H_3PO_4$-ACs display more developed and separated peaks in the early region with maxima at $2{\theta}=23$, 26 and $29^{\circ}$, possibly ascribed to fragmented microcrystallites (or partially organized structures). Diffraction within the $2{\theta}=43^{\circ}$ is still broad although depressed and diffuse, suggesting that the intragraphitic layers are less developed. Varying the conditions of chemical activation inflicts insignificant structural alterations. Circulating air during pyrolysis leads to enhancement of the basic graphitic structure with destruction and degradation in the lateral dimensions.

Factor analysis was applied to study the thermal decomposition of barium titanyl oxalate (BTO) which is used as the precursor of barium titanate. BTO was synthesized in $H_2O$ solvent and calcined at various temperatures. The X-ray diffraction patterns were obtained to make the data matrix of peak intensity vs. 2${\theta}$. Abstract factor analysis and target transformation factor analysis were applied to this data matrix. It has been found that the synthesized BTO consists of the crystals of $BaC_2O_4{\cdot}0.5H_2O\;and\;BaC_2O_4{\cdot}2H_2O$ as well as the amorphous solid of TiO-oxalate. The results also indicate that the BTO was transformed via $BaCO_3\;to\;BaTiO_3\;and\;Ba_2TiO_4$ during the thermal decomposition.

임의의 각을 가진 쇄기형 유전체의양 경계면을 E-편파된 평면화가 입사할 경우 발생하는 전자파의 회절패턴을 기하광학해와 모서리회절파의 합으로 표시하였다. 모서리 회절파의 회절계수는 물리광학근사로 구한 회절계수를 모서리 끝에 분포한 다극선전원으로 수정하여 구하였다. 쇄기각 $120^{circ}$, 입사각 $60^{circ}$ 인 유전체의 비전율을 2, 5, 10으로 변화시키고, 측정거리도 모서리 끝점으로 부터 5와 10파장인 경우에 대해 기하광학해와, 물리광학해, 다극선전원으로 교정한 수정해 순으로 각각의 회절패턴을 그림으로 나타내었다. 본 논문에서 구한 수정해는 모서리 끝점으로 부터 멀리 떨어진 곳에서만 유용한 점근해임을 알 수 있으나, 유전체 경계면에서 경계조건을 만족함을 보였다.

Diffraction patterns of electromagnetic fields for the incidence of E-polarized plane wave on both interfaces of an arbitrary-angle dielect wedge are obtained by sum of geometric optics term and the edge diffracted fields. The diffraction coefficients of the edge diffracted fields are evaluated by employing the physical optics approximation and then correcting its error with the multipole line source at the dielectric edge. For the wedge angle $120^{circ}$, the incident angle $60^{circ}$, the relative dielectric constant of the dielectric wedge, 2, 5, and 10, and the observation distance from the tip of the wedge, 5 and 10 wavelength, the diffraction coefficients and the diffraction patterns corresponding to geometric optics, physical optics, and the solution corrected by the multipole line source are plotted, respectively. While the corrected solutions presented in this paper are valid only in the far-field region, these asymptotic solutions show to satisfy the boundary condition on the dielectric interfaces.

임의의 각을 갖는 쇄기형 유전체의 양 경계면에 E-편파된 입사시 전자파의 회절문제에서 쇄기형 유전체의 모서리 근방에서 정전기적 극한의 모서히 조건을 만족하는 해를 구하였다. 물리광학근사로 구한 회절계수를 유전체 경계면을 따라 분포한 Neumann 전개된 면전류로 교정하였다. 모서리 끝점에 분포한 다극선전원으로 교정된 회절계수에 비하여, 본 논문에서 구한 회절계수는 유전체 내부의 비유전율을 점차 크게 할 경우 좀 더 정확히 쇄기형 완전도체의 회절함수에 접근함을 보았다.

The electromagnetic diffraction problem for the incidence of E-polarized planewave on both interfaces of an arbitrary-angled dielectrc wedge is solved in conjunction with the edge condition near the tip of dielectric wedge in the static limit. The diffraction coefficients obtained by the tip of the wedge, the diffraction coefficients presented in this paper approach more closely to the exact pattem of a perfectly conducting wedge as the relative dielectric constants of the dielectric wedge increase.

Principles of electron diffraction patterns in transmission electron microscope are described for beginners in terms of reciprocal lattices and Ewald sphere. Analysis of both ring patterns and spot patterns are illustrated with practical examples as well as basic calibrations of TEM. Especially convergent beam electron diffraction method is emphasized for the determination of lattice parameters, microstrains, and thickness of thin foil followed by a review of microcomputer programs for the electron diffraction analyses explained in this paper.

Au 내부 표준시편을 이용하여 일반 전자회절도형에서도 알바이트와 올리고클레이스의 격자 상수 값을 1% 이내의 오차범위로 얻었다. 자연산 올리고클레이스 시료의 전자회절도형 지도를 작성하였고, 11개 지점의 정대축 전자회절도형을 얻었다 이러한 작업은 삼사정계민 장석으로부터 신뢰성 있는 전자현미경 연구 결과를 얻기 위해서는 필수적인 과정이다. 장식의 {001} 벽개면과 TEM의 양측경사 시료지지대를 이용하면 장석의 구조/화학 분석에 필요한 다음과 같은 정보를 획득할 수 있다: 알칼리 장석은 [001] 방향에서 ＊ 값을, [100] 방향에서 $\alpha$＊ 값을 측정하여 $\alpha$＊ - ＊ plot을 함으로써 미세 영역에서 Si-Al ordering 상태 및 화학 조성을 예측할 수 있다. Na-rich한 사장석은 [001] 방향에서 ＊ 값을 측정하여 Si-Al ordering 상태를 예측할 수 있다. Na-poor한 사장석은 [100] 방향에서 e-reflection의 유무, 회절강도 및 위치 변화를 측정하여 구조 및 화학을 예측할 수 있다.

Measurements of the lattice parameters of albite and oligoclase from electron diffraction patterns with the Au internal standard resulted in errors of less than 1 %. An electron diffraction map for natural oligoclase samples was constructed and 11 stations of zone-axes diffraction patterns were obtained. This process is indispensible for reliable TEM studies of triclinic feldspars. Utilizing the [001] cleavage plane of feldspar and the double-tilting TEM holder the following information is obtainable: Si-Al ordering and chemistry of alkali feldspars could be estimated from the $\alpha$＊ - ＊ plot, where ＊ is measured from the [001] orientation, while $\alpha$＊ is measured from the [100] orientation. Si-Al ordering of Na-rich plagioclase could be estimated from ＊ [001] patterns. Structure and chemistry or Na-poor plagioclase could be estimated from existence of e-reflections, their intensity variations as well as their positional changes.

본 실험에서 얻어진 결론을 요약하면 아래와 같다. (1) 저진공도의 sputter coater를 이용하여 Au 내부 표준시편을 제작하는 최적 조건은 9mA의 전류로 100 초간 coating하는 것이다. (2) 고진공도의 evaporation coater를 이용하여 Al 내부 표준시편을 제작하는 최적 조건은 7kV의 전압으로 10분간 coating하는 것이다. (3) Au 내부 표준시편을 이용하여 측정한 홍주석 격자상수 값의 측정오차는 정밀도가 1.2% 이하이고, 정확도는 0.3% 이하이다. (4) Au 내부 표준시편을 이용하여 측정한 알바이트 장석 격자상수 값의 측정오차는 정밀도가 0.5% 이하이고, 정확도는 1.1% 이하이다. (5) 내부 표준시편을 사용하여 격자상수를 측정할 때 가장 심각한 오차는 전자회절도형의 거리 및 각도 측정시 발생한다. 체계적인 측정 방법과 정밀도 높은 측정 도구의 사용이 필요하다. (6) 시료나 TEM 조건 때문에 분말 XRD 방법이나 수렴성빔 전자회절법으로 격자상수를 구할 수 없는 경우에는 내부 표준시편을 이용한 TEM 격자상수 측정법이 좋은 대안이 된다.

Optimum conditions for making the Au and Al internal standards for TEM have been determined experimentally. The Au internal standard was produced by sputter coating at 9mA for 100 seconds in low vacuum $(\leq1\times10^{-3})$. The Al internal standard was produced by evaporation coating at 7kV for 10 minutes in high vacuum $(\leq1\times10^{-5})$. Measurements of the lattice parameters of andalusite and albite feldspars with this Au internal standard resulted in errors of (a) $ \leq1.2%$ in precion and $\leq0.3%$ in accuracy for andalusite: (b) $\leq0.5%$ in precision and $\leq1.1%$ in accuracy for albite feldspars. The most significant error occurred from the measuring processes of distances and angles of electron diffraction patterns. By employing systematic procedures of measurement with high precision devices, this lattice parameter determination method utilizing the internal standard should be a good alternative to the conventional powder XRD method or the sophisticated CBED method for special samples.

본 연구에서는 PEPC(Program for Enlightened and Productive Creativity) 모델을 이용하여 ‘회절무늬에서의 규칙성 찾기’ 과학영재아 프로젝트형 프로그램을 개발하였다. 이 프로그램의 특징은 전체 5단계로 구성되어 있는데 각 단계별로 다양한 과학적 탐구요소와 창의성 요소를 포함하여 일반 영재가 아닌 과학영재에게 특화된 프로그램을 만들었다. 이 프로그램을 과학영재에게 직접 투여해본 결과 다음과 같은 결론을 내렸다. PEPC 모델은 과학영재아들이 일상생활에서 일어나는 자연현상에 호기심을 가지고 통합하고 분류하는 능력을 키워줄 수 있다. 그리고 PEPC 모델을 통하여 과학영재아들이 자연현상에 대해 좀 더 체계적으로 접근하고 문제 해결할 수 있는 능력을 키워줄 수 있다. 이것은 PEPC 모델을 적용한 회절무늬에서 규칙성 찾기 프로그램이 과학영재가 갖추어야 할 과학적 탐구능력과 창의성을 동시에 향상시킬 수 있는 하나의 프로그램이라는 것이다. 이 자료를 물리뿐 만아니라 생물, 지구과학, 화학 등 과학의 다른 분야에도 꾸준히 적용시켜 지속적인 PEPC 모델의 투여가 학생들의 생산적 창의성에 얼마나 영향을 미칠 것인지 지속적으로 연구해볼 가치가 있다고 본다.

In this study, it was intended to develop a science gifted students' project type program, ‘finding regularity in diffraction patterns’ using PEPC(Program for Enlightened and Productive Creativity) models. The program was made to develop project type study materials applied with PEPC(Program for Enlightened and Productive Creativity) models and the conclusions as follows were reached. First, PEPC models can bring up science gifted students' ability to have curiosity about natural phenomena occurring in daily lives and integrate and classify them. Second, PEPC models can bring up science gifted students' ability to approach natural phenomena more systematically and solve related problems. It is considered worthwhile to apply these materials to not only physics but also other areas such as biology, earth science and chemistry in order to continuously study how much the continuous administration of PEPC models will affect the productive creativity of students.

In this study, nano-scale copper powders were reduction treated in a hydrogen atmosphere at the relatively high temperature of $350^{\circ}C$ in order to eliminate surface oxide layers, which are the main obstacles for fabricating a nano/ultrafine grained bulk parts from the nano-scale powders. The changes in composition and microstructure before and after the hydrogen reduction treatment were evaluated by analyzing X-ray diffraction (XRD) line profile patterns using the convolutional multiple whole profile (CMWP) procedure. In order to confirm the result from the XRD line profile analysis, transmitted electron microscope observations were performed on the specimen of the hydrogen reduction treated powders fabricated using a focused ion beam process. A quasi-statically compacted specimen from the nano-scale powders was produced and Vickers micro-hardness was measured to verify the potential of the powders as the basis for a bulk nano/ultrafine grained material. Although the bonding between particles and the growth in size of the particles occurred, crystallites retained their nano-scale size evaluated using the XRD results. The hardness results demonstrate the usefulness of the powders for a nano/ultrafine grained material, once a good consolidation of powders is achieved.

In this study, nano-scale copper powders were reduction treated in a hydrogen atmosphere at the relativelyhigh temperature of 350oC in order to eliminate surface oxide layers, which are the main obstacles for fabricating anano/ultrafine grained bulk parts from the nano-scale powders. The changes in composition and microstructure beforeand after the hydrogen reduction treatment were evaluated by analyzing X-ray diffraction (XRD) line profile patternsusing the convolutional multiple whole profile (CMWP) procedure. In order to confirm the result from the XRD lineprofile analysis, transmitted electron microscope observations were performed on the specimen of the hydrogen reductiontreated powders fabricated using a focused ion beam process. A quasi-statically compacted specimen from the nanoscalepowders was produced and Vickers micro-hardness was measured to verify the potential of the powders as thebasis for a bulk nano/ultrafine grained material. Although the bonding between particles and the growth in size of theparticles occurred, crystallites retained their nano-scale size evaluated using the XRD results. The hardness results demonstratethe usefulness of the powders for a nano/ultrafine grained material, once a good consolidation of powders isachieved.

물리 탐구실험에 활용할 수 있도록 상용 DSLR 카메라를 이용하여 단일슬릿 회절 및 이중슬릿 간섭무늬를 촬영하였다. 카메라의 CMOS 이미지 센서의 픽셀들에 저장된 회절 및 간섭무늬들의 세기에 해당하는 JPEG 파일의 2진수 비트값은 Matlab 프로그램을 이용하여 10 진수값으로 변환하였다. 추출된 비트값은 통계 분석용 Origin 프로그램을 이용하여 회절 및 간섭에 대한 이론적인 함수로 각각 적합하였다. 효과적인 탐구 실험을 위하여 카메라 촬영의 과정과 기술에 대한 응용을 상세히 기술하였다. 결과적으로, 촬영된 무늬들의 JPEG 사진의 비트값을 이론적인 회절과 간섭의 함수로 적합하여 3 개의 매개변수를 - 슬릿 폭, 슬릿 사이의 간격 및 스크린과 슬릿 사이의 거리 - 만족스럽게 구할 수 있었다.

Both single slit diffraction patterns and the Young's double slit interference patterns were photographed with a commercial digital single lens refractor(DSLR) camera for school physics experiments. The photographed JPEG file's binary bitmap data which were correspond to diffraction and interference intensities were transformed to decimal bitmap data by the Matlab software. This transformed bitmap data were fitted by well known theoretical single slit diffraction and double slit interference functions using the statistical Origin pro(ver.8.0) package. The application of our experimental procedures and techniques were described in details for school physics inquiry activities. From both the bit map data and theoretical functions, three important experimental parameters (i.e., slit width, slit interval, and distance between slit and screen) were obtained by computer analysis with satisfaction.

투과식 전자현미경에서 상과 그 회절패턴은 현미경의 자기렌즈 작용에 의하여 상오 회전되어 나타난다. 이 회전각의 측정 결정은 결정 시료의 결함 관찰 분석에서 중요하다. 이 회전각 측정에 대해 잘 알려진 방법은 $MoO_3$의 분말 결정을 이용하는 것이다. 그러나 이 방법에는 측정된 각에 항상 $180^{\circ}$의 불확실성이 따른다. 따라서 이 불확실성을 제거하기 위한 또 다른 방안이 강구되어야 한다. 본 논문에서는 결정시료의 LACBED 패턴을 얻는 과정을 통해 간단하게 이 회전각을 측정하는 새로운 방법을 제시한다. 이 방법은 특정 결정을 필요로 하지 않는다. 이 방법을 통해 JEM 2010 TEM에서 상(image)과 그 회절패턴의 회전각은 $180^{\circ}$로 측정되었고, 이 각은 확대 배율이나 카메라 길이의 변화에도 변하지 않음이 관찰되었다.

When electron microscope images and selected area diffraction patterns of crystalline materials are being compared, it is important to know for the rotation of the diffraction pattern with respect to the image caused by the magnetic lens in the Electron Microscope. A well-known method to determine this rotation is to use a test crystal of $MoO_3$. But this method of determination of the rotation angle contains an uncertainty of $180^{\circ}$. Thus one has to devise another way to eliminate this uncertainty. In this paper we present a new and simple method of determining this rotation without any complexity. The method involves a process of obtaining LACBED patterns of crystalline materials. For the J2010 electron microscope, the rotation is determined to be $180^{\circ}$ and this angle remains unchanged for changing of the magnification and the camera length.