• 한국결정성장학회지
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• 제7권2호
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• pp.341-348
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• 1997

2원동시 RF magnetron 방법을 이용하여 조건별(sputtering gas압력, buffer충 유무 및 etching여부 등)로 제작된 Pt/co 인공격자 다층막 ([$Pt10.7\AA/Co2.8{\AA}{\times}{12}$])의 구조정보에 대하여 알아보았다. 다층막 구조평가는 X선 회절측정을 이용하여 행하였으며 구조에 대한 정보를 보다 면밀하게 평가하기 위해서 다층막 모델을 제작하여 얻어진 결과를 실험결과와 비교분석 하였다. 제작된 다층막 구조모델의 계산결과를 실측치와 비교하면 peak의 위치나 회절강도가 상당히 일치하였으며 이것은 구조모델이 실제의 Pt/Co 인공격자 다층막구조를 잘 반영하고 있음을 알 수 있었다.

• 한국결정성장학회지
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• 제18권2호
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• pp.87-90
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• 2008

Co-Pt 합금 박막은 amino-citrate 기반의 전해액에서 Ru(30 nm)/Ta(5 nm)/Si(100)구조의 작업 전극을 사용하여 정전류 전해도금 방법으로 증착 하였다. (0002) 우선 성장된 Ru의 buffer layers를 사용하여 Co-Pt 합금 박막의 결정구조와 우선 성장을 조절하였다. 본 실험에서는 도금액 온도를 변화시킴에 따른 Co-Pt 합금 박막의 자기적 성질과 미세구조에 미치는 영향을 고찰하였다. Co-Pt 합금 박막의 형상과 조성은 FESEM 과 EDS로 확인하였고, XRD로 결정구조를 분석하였다. 자기적 성질은 진동 시료 자력계와 토오크 자력계로 분석하였다. Co-Pt 합금 박막은 박막표면과 수직한 방향에서 열처리 없이 각각 6527 Oe의 높은 보자력과 0.93의 높은 각형비를 나타내었다.

• 한국세라믹학회지
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• 제55권3호
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• pp.290-298
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• 2018

In order to investigate the effect of thickness on the dielectric and piezoelectric properties of (001) PMN-29PT single crystals, three different types of PMN-29PT samples were prepared using the solid-state single crystal growth (SSCG) method: high density crystal [99%], low density crystal [95%], and high density crystal doped with Mn [98.5%]. When their thickness decreased from 0.5 mm to 0.05 mm, their dielectric constant ($K_3{^T}$), piezoelectric constants ($d_{33}$ and $g_{33}$), and electromechanical coupling factor ($k_t$) decreased continuously. However, their dielectric loss (tan ${\delta}$) increased. The addition of Mn to PMN-PT induced an internal bias electric field ($E_I$), increased the coercive electric field ($E_C$), and prevented local depoling. Therefore, Mn-doped PMN-PT crystals show high stability as well as high performance, even in the form of very thin plates (< 0.2 mm), and thus are suitable for application to high frequency composites, medical ultrasound probes, non-destructive testing devices (NDT), and flexible devices.

• 한국결정성장학회지
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• 제10권1호
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• pp.17-22
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• 2000

수직보자력이 크고 CoCrPt에 비하여 noise 저감 효과가 큰 것으로 알려진 CoCrPtTa계 합금박막의 수직이방성을 더욱 개선하기 위해 Ti를 우선 증착하였다. 본 연구에서는 Ti 두께 변화에 따른 비교적 높은 수직보자력치를 보였던 $CoCr_{16.2}Pt_{10.8}Ta_4$Ti/glass 시편에서 자기적 특성과 자구형상의 변화를 살펴보았다. 또한 VSM(Vibrating Sample Magnetometer)을 이용하여 M-H loop를 측정하였으며 자구형상은 MFM(Magnetic Force Microscopy)로 관찰하였다. 육방정 Ti가 하지층으로서 우선증착되면 bare glass 직접 증착되는 경우보다 CoCrPtTa 자성층의 수직이방성에 현저한 향상을 가져왔으며 Ti의 두께가 두꺼울수록 c-축 배향성도 개선되었다. MFM 결과에 의하면 Ti두레가 20 nm에서 90 nm로 증가함에 따라 자구형상이 연속적인 stripe type에서 mass type으로 분절된 형태로 변하였다. 이는 Ti의 증착이 비자성 Cr 편석 거동에 영향을 미쳐 자화반전시 인접 columnar grain의 자화벡터들간의 상호교환작용을 억제하는 자기적 분리 효과에 기여했음을 의미한다. 아울러 이와 같은 거동은 Ti가 CoCr계 자성층의 수직이방성을 개선하는데 있어서 형상자기이방성적인 측면에서의 기여가 현저함을 의미하기도 한다.

• 한국결정성장학회지
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• 제18권3호
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• pp.105-108
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• 2008

PZ와 PT를 각각 3층씩 그 순서를 달리하고 열처리 과정을 달리하여 4가지 시료를 만들었다. PZ와 PT를 독립적으로 열처리 한 시료들에서는 PZ와 PT가 독립적으로 존재하는 경향이 강한 반면 PZ와 PT를 동시에 열처리 한 시료들은 PZT 복합상이 존재하는 확률이 더 높아졌다. 후자의 경우 PT를 먼저 증착한 쪽이 더 안정적인 PZT 상을 만든다는 결론을 지을 수 있었다.

• Journal of Magnetics
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• 제8권3호
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• pp.113-117
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• 2003

$Co_{78-x}Pt_xB_{10}Si_{12}$ alloys were produced using the melt-spin process in order to study the crystallization behavior and ensuing magnetic properties of the $Co_{78-x}Pt_xB_{10}Si_{12}$ (Co-Pt) amorphous alloys as a function of the Pt content. We showed that when $\chi$ $>$ 15 well below its stoichiometric composition, CoPt crystallized in the amorphous alloy, thus greatly altering the crystallized microstructure and magnetic properties during annealing. Below this composition, the main crystallization product was Co with Pt dissolved in its lattice. In spite of the nucleation of CoPt with high magnetic anisotropy, the highest coercivity was obtained when x was 15. It was also concluded that the Pt addition deteriorated the glass stability, triggering the devitrification at a progressively lower temperature.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.203-203
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• 2011

The importance of stepped single-crystal surfaces as model catalysts has been well recognized [1]. We re-investigated the adsorption properties of $H_2$ and CO, most important species in platinum-based catalysts, on nearly defect-free and highly stepped surfaces of one and the same Pt(111) crystal. While both being symmetric and single-peaked from the nearly defect-free surface, temperature-programmed desorption (TPD) spectra from the highly stepped surface saturated at 90 K with H and CO were triply- and doubly-peaked, respectively. Once pre-adsorbed, CO preempted step and then terrace sites, inhibiting the dissociative $H_2$ adsorption completely. Pre-adsorbed H inhibited the CO adsorption on terrace sites only, leaving defect sites intact for CO adsorption even at the saturation H precoverage. On defect-free Pt(111), while pre-adsorbed CO inhibited the dissociative $H_2$ adsorption completely, pre-adsorbed H could not inhibit the CO adsorption completely. These intriguing, but interesting results are discussed in terms of energetics/kinetics and the role of surface step sites in the dissociative adsorption of $H_2$ on Pt(111) [2].

• 한국재료학회지
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• 제19권5호
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• pp.233-239
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• 2009

The electrocatalytic behavior of the PtCo catalyst supported on the multi-walled carbon nanotubes (MWNTs) has been evaluated and compared with commercial Pt/C catalyst in a polymer electrolyte membrane fuel cell(PEMFC). A PtCo/MWNTs electrocatalyst with a Pt:Co atomic ratio of 79:21 was synthesized and applied to a cathode of PEMFC. The structure and morphology of the synthesized PtCo/MWNTs electrocatalysts were characterized by X-ray diffraction and transmission electron microscopy. As a result of the X-ray studies, the crystal structure of a PtCo particle was determined to be a face-centered cubic(FCC) that was the same as the platinum structure. The particle size of PtCo in PtCo/MWNTs and Pt in Pt/C were 2.0 nm and 2.7 nm, respectively, which were calculated by Scherrer's formula from X-ray diffraction data. As a result we concluded that the specific surface activity of PtCo/MWNTs is superior to Pt/C's activity because of its smaller particle size. From the electrochemical impedance measurement, the membrane electrode assembly(MEA) fabricated with PtCo/MWNTs showed smaller anodic and cathodic activation losses than the MEA with Pt/C, although ohmic loss was the same as Pt/C. Finally, from the evaluation of cyclic voltammetry(CV), the unit cell using PtCo/MWNTs as the cathode electrocatalyst showed slightly higher fuel cell performance than the cell with a commercial Pt/C electrocatalyst.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2001년도 추계연구발표회 논문개요집
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• pp.102-103
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• 2001

• Bulletin of the Korean Chemical Society
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• 제33권6호
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• pp.1993-1997
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• 2012

Mg-doped ZnO one-dimensional (1D) nanostrutures were synthesized by using a thermal evaporation technique. The morphology, crystal structure, and sensing properties of the Mg-doped ZnO nanostructures functionalized with Pt to CO gas at $100^{\circ}C$ were examined. The diameters of the 1D nanostructures ranged from 80 to 120 nm and that the lengths were up to a few tens of micrometers. The gas sensors fabricated from multiple networked Mg-doped ZnO nanowires functionalized with Pt showed enhanced electrical response to CO gas. The responses of the nanowires were improved by approximately 70, 69, 111, and 81 times at CO concentrations of 10, 25, 50, and 100 ppm, respectively. Both the response and recovery times of the nanowire sensor for CO gas sensing were not nearly changed by Pt functionalization. It also appeared that the Mg doping concentration did not influence the sensing properties of ZnO nanowires as strongly as Pt-functionalization. In addition, the mechanism for the enhancement in the CO gas sensing properties of Mg-doped ZnO nanowires by Pt functionalization is discussed.