• 한국표면공학회지
• /
• 제53권1호
• /
• pp.1-8
• /
• 2020

Sulfamate-chloride baths were fabricated to study the properties of the electrodeposited Ni and NiCo thin films. The dependences of current efficiency, deposit composition of Ni and Co, residual stress, surface morphology and microstructure of electrodeposited Ni and NiCo thin films on CoCl₂ concentration in sulfamate-chloride baths were investigated. The current efficiency was measured to be more than about 90%, independent of the changes of CoCl₂ concentration in the baths. Residual stress of Ni and NiCo thin films was increased from about 45 to about 250 MPa with varying CoCl₂ concentration from 0 to 0.210 M CoCl₂ in the baths and then reached to a plateau, about 250 MPa above 0.420 M CoCl₂ concentration. Nodular surface morphologies were observed at most CoCl₂ concentrations in the baths except 0.210 M. NiCo thin film electrodeposited from the bath with 0.210 M CoCl₂ concentration showed an acicular surface morphology. Pure Ni thin film consists of FCC(111), FCC(200), FCC(220), and FCC(311) peaks without any preferred orientation. On the other hand NiCo thin films make up of HCP(100), FCC(111), HCP(101), FCC(200), FCC(220) or HCP(110), FCC(311) or HCP(112) and FCC(222) peaks. It was revealed from the analysis of XRD result that FCC(111) peak at the NiCo thin film electrodeposited from the bath with 0.084 M CoCl₂ concentration can be regarded as the preferred orientation. However the peak of the preferred orientation was changed to FCC(220) or HCP(110) above 0.084 M CoCl₂ concentration in the baths. Then the intensity of FCC(220) or HCP(110) peak was gradually decreased with increasing CoCl₂ concentration further. The crystalline size of pure Ni thin film was observed to be about 53 ㎛ and those of NiCo thin films were in the range of 35~45 ㎛.

• 한국재료학회지
• /
• 제28권10호
• /
• pp.595-600
• /
• 2018

This study investigates the microstructural properties of CoCrFeMnNi high entropy alloy (HEA) oxynitride thin film. The HEA oxynitride thin film is grown by the magnetron sputtering method using nitrogen and oxygen gases. The grown CoCrFeMnNi HEA film shows a microstructure with nanocrystalline regions of 5~20 nm in the amorphous region, which is confirmed by high-resolution transmission electron microscopy (HR-TEM). From the TEM electron diffraction pattern analysis crystal structure is determined to be a face centered cubic (FCC) structure with a lattice constant of 0.491 nm, which is larger than that of CoCrFeMnNi HEA. The HEA oxynitride film shows a single phase in which constituting elements are distributed homogeneously as confirmed by element mapping using a Cs-corrected scanning TEM (STEM). Mechanical properties of the CoCrFeMnNi HEA oxynitride thin film are addressed by a nano indentation method, and a hardness of 8.13 GPa and a Young's modulus of 157.3 GPa are obtained. The observed high hardness value is thought to be the result of hardening due to the nanocrystalline microstructure.

• 한국세라믹학회지
• /
• 제43권11호
• /
• pp.746-750
• /
• 2006

NiO films and Ru co-sputtered NiO films were deposited by reactive magnetron sputtering for micro-solid oxide fuel cell anode applications. The deposited films were reduced to form porous films. The reduction kinetics of the Ru doped NiO film was more sluggish than that of the NiO film, and the resulting microstructure of the former exhibited finer pore networks. The possibility of using the films for the anodes of single chamber micro-SOFCs was investigated using an air/fuel mixed environment. It was found that the abrupt increase in the resistance is suppressed in the Ru co-sputtered film, as compared to undoped film.

• 한국자기학회지
• /
• 제15권5호
• /
• pp.265-269
• /
• 2005

강자성 공명 측정을 통하여 다양한 층 구성을 갖는 교환 바이어스 박막들의 교환 결합 특성에 대해 연구하였다. 공명자기장의 각도의존 실험을 통하여 일축방향이방성 자기장과 일축이방성 자기장을 구하여 분석하였다. NiFe 단일 박막과 비교하여 교환 바이어스된 NiFe/IrMn, IrMn/NiFe/IrMn, NiFe/IrMn/CoFe 박막들은 큰 일축방향이방성 자기장을 나타내었으며, 일축이방성 자기장 또한 큰 값을 나타내었다. 그러나 NiFe/Cu/IrMn의 경우, Cu의 두께가 두꺼울 때는 매우 작은 일축방향이방성 자기장을 나타내었으며, NiFe 단일 박막과 비슷한 크기의 일축이방성 자기장을 나타내었다. NiFe/IrMn/CoFe 박막의 경우 NiFe와 CoFe 강자성층들에 의해 두 개의 공명 자기장이 나타났다. 그 외에 공명 자기장의 선폭에 관한 분석이 교환 바이어스 특성과 연관하여 논의되어졌다.

• Journal of the Korean Physical Society
• /
• 제73권12호
• /
• pp.1867-1872
• /
• 2018

This study proposes a route for surface modification for p-type cobalt oxide-based gas sensors. We deposit a thin layer of Ni on the Co oxide film by sputtering process and annealed at $350^{\circ}C$ for 15 min in air, which changes a typical sputtered film surface into one interlaced with a high density of hemispherical nanoparticles. Our in-depth materials characterization using transmission electron microscopy discloses that the microstructure evolution is the result of an extensive inter-diffusion of Co and Ni, and that the nanoparticles are nickel oxide dissolving some Co. Sensor performance measurement unfolds that the surface modification results in a significant sensitivity enhancement, nearly 200% increase for toluene (at $250^{\circ}C$) and CO (at $200^{\circ}C$) gases in comparison with the undoped samples.

• 한국결정성장학회지
• /
• 제13권6호
• /
• pp.297-303
• /
• 2003

rf magnetron sputtering법을 이용하여 Mn-Ni-Co계 써미스터 박막을 증착하였다. $300^{\circ}C$ 및 $Ar/O_2$ = 10/0에서, cubic spinel 상형성이 이루어졌으며 공정가스에 산소 첨가 시, cubic spinel 상은 열처리를 통해서도 형성되지 않았다. 써미스터 박막은 Mn, Ni, Co 성분 외 다른 이종 성분은 포함되어 있지 않았다. 써미스터 박막에 대한 적외선 반사 특성을 분석으로 증착된 박막은 일정 각도로 입사되는 적외선에 대해 비교적 높은 반사율을 가짐을 관찰할 수 있었다. DI water : $HNO_3$: HCI=60 : 30 : 10 vo1%에서 써미스터 박막의 식각 속도는 약 63 nm/min였다. 박막 써미스터의 B상수는 약 3500 K였으며 TCR은 약 -3.95%/K였다 전압감도는 약 108.5 V/W였으며 NEP와 specific detectivity는 각각 $5.1\times 10^{-7}$ W/$Hz^{-1/2}$ $0.2\times 10^6$cm $Hz^{1/2}$/W였다.

• 센서학회지
• /
• 제14권1호
• /
• pp.52-55
• /
• 2005

Ni oxide thin films with thermal sensitivity superior to Pt and Ni thin films were formed through annealing treatment after Ni thin films were deposited by a r.f. magnetron sputtering method. Resistivity values of Ni oxide thin films were in the range of $10.5{\mu}{\Omega}cm$ to $2.84{\times}10^{4}{\mu}{\Omega}cm$ according to the degree of Ni oxidation. Also temperature coefficient of resistance(TCR) values of Ni oxide thin films depended on the degree of Ni oxidation from 2,188 ppm/$^{\circ}C$ to 5,630 ppm/$^{\circ}C$ in the temperature range of $0{\sim}150^{\circ}C$. Because of the high linear TCR and resistivity characteristics, Ni oxide thin films exhibit much higher sensitivity to flow and temperature changes than pure Ni thin films and Pt thin films.

• 열처리공학회지
• /
• 제21권1호
• /
• pp.26-32
• /
• 2008

Effects of annealing treatment on microstructure and mechanical property of co-sputtered TiNi thin films were studied. As-deposited films showed amorphous state. However, above annealing temperature of $500^{\circ}C$ martensite phase (B19'), precipitate phase ($Ti_2Ni$) and a small amount of parent phase ($B_2$) were present, and phase transformation behaviors were three multi-step phase transformations $B19^{\prime}{\rightarrow}B_2$ and $B_2{\rightarrow}R-phase$ and $R-phase{\rightarrow}B19^{\prime}$. Increase of martensite transformation temperature, increase of microhardness and Young's modulus of TiNi films annealed above $500^{\circ}C$ were discussed in terms of precipitate phase.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 1999년도 제17회 학술발표회 논문개요집
• /
• pp.182-182
• /
• 1999

The chemisorption effect of CO on the Ni/Cu(001) surface was investigated using LEED(Low Energy Electron Diffraction) and EELS(Electron Energy Loss Spectrscopy0 under the UHV conditions. after mounting the Cu(001) single crystal in the UHV chamber (base pressure 1$\times$10-10Torr), a clean surface was obtained after a few cycles of repeated Ar+ ion sputtering and annealing at about 40$0^{\circ}C$. The epitaxial thin Ni films were formed on the Cu(001) by evaporation from 99.999% Ni block. The pseudomorphic growth and the orderness of the thin Ni films were monitored by c(2$^{\circ}C$2) LEED pattern. CO adlayers on Ni epitaxial thin films were prepared by dosing pure CO has through a leak valve. After CO adsorpton at room temperature, two pairs of peaks were observed by EELS, whose relative intensities are changed as the film thickness is varied and time is elapsed. These two pair of peaks are likely related to different bonding sites (-top and bridge sites) of C-Ni as well as C-O vibration. Experimental results and qualitative interpretation of the spectra wille be discussed. The possibility of using EELS in combination with probe species (CO) to investigate the nature of thin film growth is mentioned. We will report the experimental result of O2 dosage on Ni film and interaction of CO and O2.

• 한국자기학회지
• /
• 제3권3호
• /
• pp.215-220
• /
• 1993

RF/DC 스퍼터된 $Co_{69.0}Ni_{18.5}Cr_{12.5}/Cr$ 이중박막의 미세구조와 자기적 성질과의 관계를 조사하였다. Cr 하지층과 CoNiCr 자성층의 두께는 각각 50-200 nm와 10-50 nm였으며, 기판 의 온도는 $100-200^{\circ}C$로 하였다. 기판의 온도, Cr 하지층 두께가 증가함에 따라 결정립은 미세해졌으며 보자력은 증가하였다. 기판의 온도가 $100^{\circ}C$에서 $200^{\circ}C$로 증가함에 따라 Cr(200), CoNiCr(1120) 결정방위가 강하게 나타났다. CoNiCr/Cr 이중박막의 보자력은 CoNiCr(1120) 결정방위 증가와 결정립의 미세 화에 따라 증가한다. 높은 보자력을 나타내는 박막에서 Cr 하지층위에 자성층의 epitaxial growth를 확인하였다.