scholarly journals E-field controlled phase transformation in bismuth ferrite thin films, and effect of laser energy density

2017 ◽  
Vol 111 (15) ◽  
pp. 152905 ◽  
Author(s):  
Min Gao ◽  
Ravindranath Viswan ◽  
Xiao Tang ◽  
Chung Ming Leung ◽  
Jiefang Li ◽  
...  
Keyword(s):  
Thin Films ◽  
Phase Transformation ◽  
Energy Density ◽  
Laser Energy ◽  
Bismuth Ferrite ◽  
Laser Energy Density ◽  
Ferrite Thin Films

Inhibition of phase transformation from β- to α-tricalcium phosphate with addition of poly (L-lactic acid) in selective laser sintering

2014 ◽  
Vol 20 (5) ◽  
pp. 369-376 ◽  
Author(s):  
Cijun Shuai ◽  
Jingyu Zhuang ◽  
Shuping Peng ◽  
Xuejun Wen
Keyword(s):  
Phase Transformation ◽  
Lactic Acid ◽  
Liquid Phase ◽  
Energy Density ◽  
Porous Structure ◽  
Laser Energy ◽  
Selective Laser Sintering ◽  
Transient Liquid Phase ◽  
Laser Energy Density ◽  
Content Type

Purpose – The paper aims to fabricate an α-tricalcium phosphate (TCP) scaffold with an interconnected porous structure via selective laser sintering (SLS). To inhibit the phase transformation from β- to α-TCP in fabrication process of porous scaffolds, a small amount (1 weight per cent) of poly (L-lactic acid) (PLLA) is added into β-TCP powder to introduce the transient liquid phase. Design/methodology/approach – The paper opted for the transient liquid phase of melting PLLA to decrease the sintering temperature in SLS. Meanwhile, the densification of β-TCP is enhanced with a combined effect of the capillary force caused by melting PLLA and the surface energy of β-TCP particles. Moreover, the PLLA will gradually decompose and completely disappear with laser irradiation. Findings – The testing results show the addition of PLLA enables the scaffolds to achieve a higher β-TCP content of 77 ± 1.49 weight per cent compared with the scaffold sintered from β-TCP powder (60 ± 1.65 weight per cent), when the laser energy density is 0.4 J/mm2. The paper provides the mechanism of PLLA inhibition on the phase transformation from β- to α-TCP. And the optimum sintering parameters are obtained based on experimental results, which are used to prepare a TCP scaffold with an interconnected porous structure via SLS. Research limitations/implications – This paper shows that the laser energy density is an important sintering parameter that can provide the means to control the micro-porous structure of the scaffold. If the laser energy density is too low, the densification is not enough. On the other hand, if the laser energy density is too high, the microcracks are observed which are attributed to the volume expansion during the phase transformation from β- to α-TCP. Therefore, the laser energy density must be optimized. Originality/value – The paper provides a feasible method for fabricating TCP artificial bone scaffold with good biological and mechanical properties.

Effect of Excimer Laser Annealing on Optical Properties of GaN Films Deposited by R.F. Magnetron Sputtering

2001 ◽  
Vol 693 ◽  
Author(s):  
Man Young Sung ◽  
Woong-Je Sung ◽  
Yong-Il Lee ◽  
Chun-Il Park ◽  
Woo-Boem Choi ◽  
...  
Keyword(s):  
Thin Films ◽  
Energy Density ◽  
Magnetron Sputtering ◽  
Buffer Layer ◽  
Excimer Laser ◽  
Laser Annealing ◽  
Laser Energy ◽  
Laser Energy Density ◽  
Excimer Laser Annealing ◽  
Zno Buffer Layer

Abstract:GaN thin films on sapphire were grown by RF magnetron sputtering with ZnO buffer layer. The tremendous mismatch between the lattices of GaN and sapphire can be partly overcome by the use of thin buffer layer of ZnO. The dependence of GaN film quality on ZnO buffer layer was investigated by X-ray diffraction(XRD). The properties of the sputtered GaN are strongly dependent on ZnO buffer layer thickness. The optimum thickness of ZnO buffer layer is around 30nm. Using XRD analysis, we have found the optimal substrate temperature which can grow high quality GaN thin film. In addition, the effect of excimer laser annealing(ELA) on structural and electrical properties of GaN thin films was investigated. The surface roughness and images according to the laser energy density were investigated by atomic force microscopy(AFM) and it was confirmed that the crystallization was improved by increasing laser energy density.

Photochemical Vapor Deposition of Aluminum Thin Films

1988 ◽  
Vol 129 ◽  
Author(s):  
Mitsugu Hanabusa ◽  
Akira Oikawa ◽  
Peng Ying Cai ◽  
Shigeo Furuno ◽  
Satoshi Iguchi
Keyword(s):  
Thin Films ◽  
Energy Density ◽  
Substrate Temperature ◽  
Laser Energy ◽  
Photochemical Reactions ◽  
Nonlinear Dependence ◽  
Laser Energy Density ◽  
Aluminum Films ◽  
Incremental Change ◽  
Strongly Nonlinear

ABSTRACTUsing dimethylaluminum hydride as the source gas and an ArF laser as the light source, aluminum thin films with low electrical conductivity were deposited via photochemical reactions. To emphasize surface reactions, vapor pressure was kept low with a t pical value of 6.7×10−3 Pa. The laser energy density was typically 23 mJ/cm2 per pulse. The deposition rate of aluminum films became reasonably high above a substrate temperature of 90 °C and increased thereafter with substrate temperature. The electrical resistivity was about four times greater than the bulk aluminum value. A strongly nonlinear dependence of the deposition rates on laser energy density was observed. The incremental change in thickness per pulse increased with the inverse of the pulse repetition rate, which indicated, together with area selectivity, the importance of surface photolysis of absorbed molecules.

scholarly journals A Controllability Investigation of Magnetic Properties for FePt Alloy Nanocomposite Thin Films

Nanomaterials ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 53
Author(s):  
Jian Yu ◽  
Tingting Xiao ◽  
Xuemin Wang ◽  
Xiuwen Zhou ◽  
Xinming Wang ◽  
...  
Keyword(s):  
Thin Films ◽  
Magnetic Properties ◽  
Energy Density ◽  
Magnetic Phase ◽  
Laser Energy ◽  
Pulsed Laser ◽  
Laser Energy Density ◽  
Soft Magnetic ◽  
Fept Alloy ◽  
Nanocomposite Thin Films

An appropriate writing field is very important for magnetic storage application of L10 FePt nanocomposite thin films. However, the applications of pure L10 FePt are limited due to its large coercivity. In this paper, the ratios of L10 and non-L10 phase FePt alloy nanoparticles in FePt/MgO (100) nanocomposite thin films were successfully tuned by pulsed laser deposition method. By adjusting the pulsed laser energy density from 3 to 7 J/cm2, the ordering parameter initially increased, and then decreased. The highest ordering parameter of 0.9 was obtained at the pulsed laser energy density of 5 J/cm2. At this maximum value, the sample had the least amount of the soft magnetic phase of almost 0%, as analyzed by a magnetic susceptibility study. The saturation magnetization decreased with the increase in the content of soft magnetic phase. Therefore, the magnetic properties of FePt nanocomposite thin films can be controlled, which would be beneficial for the magnetic applications of these thin films.

Pulse-to-Pulse Laser Stability Effects on Multiple Shot Excimer Laser Crystallized a-Si Thin Films

1994 ◽  
Vol 343 ◽  
Author(s):  
R. I. Johnson ◽  
G. B. Anderson ◽  
J. B. Boyce ◽  
D. K. Fork ◽  
P. Mei ◽  
...  
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Energy Density ◽  
Pulse Laser ◽  
Laser Fluence ◽  
Laser Energy ◽  
Laser Energy Density ◽  
Distribution Profile ◽  
X Ray ◽  
Silicon Thin Films

ABSTRACTLaser crystallized amorphous silicon thin films on quartz exhibit a peak in the grain size, electron mobility and the Si (111) x-ray intensity as a function of the laser fluence, substrate temperature, film thickness, and the number of laser shots per unit area. The peak in grain size has also been shown to be dependent: on the stability of the pulse-to-pulse laser energy density, particularly at high shot densities. The shape of the distribution profile of the pulse-to-pulse laser fluence can significantly alter the grain growth at higher shot densities. The modified growth can be expressed by a simple model based on the mean and standard deviation of the laser energy density relative to the characteristic fluence at which the grain size, mobility, and Si (111) x-ray intensities are maximized.

Preparation of ATO Thin Films from SPS-Derived Large Size ATO Ceramic Targets by PVD Methods

2014 ◽  
Vol 783-786 ◽  
pp. 1973-1978
Author(s):  
Fei Chen ◽  
Jun Yan Wu ◽  
Qiang Shen ◽  
Julie M. Schoenung ◽  
Lian Meng Zhang
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Optical Properties ◽  
High Temperature ◽  
Energy Density ◽  
Laser Energy ◽  
Laser Energy Density ◽  
Electrical And Optical Properties ◽  
Large Size ◽  
Ceramic Targets

Good crystalline of ATO thin films is necessary to improve the electrical and optical properties. In this paper, ATO thin films were fabricated using PLD method at high temperature of 550 °C, and the effect of laser energy density on the microstructure, electrical property and optical property of the ATO films is discussed. The results suggest that ATO films show good crystalline when deposited at high temperature of 550 °C. Both the electrical and optical properties have been enhanced with the increasing of laser energy density. When the laser energy density is 5.4 J/cm2, the lowest resistivity of ATO thin film is obtained with the value of 6.52×10-4 Ω·cm and the average optical transmittances is 82.0 %.

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