Dependence of segregated microstructure in sputter-deposited CoCr film on deposition conditions

The compositional segregation of sputter-deposited CoCr films prepared under substrate temperatures Ts of 90-160°C and Ar gas pressures PAr of 4-30 mTorr are studied by transmission electron microscopy. The segregated microstructure depends on Ts and PAr. The degree of the segregation increases as Ts increases, and is maximized at a medium PAr. Saturation magnetization increases as the degree of the segregation increases. Vertical coercivity in film with the same degree of the c-axis orientation increases as the degree of segregation increases.     

Influence of temperature on magnetic properties of ion-beam sputter-deposited perpendicular magnetic media

Co-Cr perpendicular magnetic media deposited by ion-beam sputter methods show magnetic properties similar to those obtained by radio frequency (RF) sputtering. Coercivity, ratio of perpendicular to parallel squareness, and X-ray orientation are strikingly improved when the substrate is heated. Independent control of substrate temperature makes ion-beam sputter deposition an attractive candidate for deposition of perpendicular magnetic films.     

The role of atomic mobility during film growth in the structural and magnetic properties of CoCr

We have studied the morphological, crystallographic, and magnetic properties of CoCr thin films sputtered at different substrate temperatures and pressures. Conditions which produce high adatom mobility on the surface of the growing film lead to good c-axis orientation and magnetic anisotropy normal to the substrate, while low mobility leads to poor c-axis orientation and anisotropy. These results are explained in terms of van der Drift's model of the evolutionary growth of vapor-deposited films. The perpendicular coercivities of our samples depend only on the substrate temperature and we find no correlation with the film morphology or grain size.     

Effect of addition of carbon nanofibers and carbon nanotubes on properties of thermoplastic biopolymers

This paper presents the properties of nano-bio-composites of solvent cast polyhydroxybutyrate-co-valerate (PHBV) and polycaprolactone (PCL) containing carbon nanofiber or carbon nanotubes as a function of filler content. It is found that carbon nanotubes and nanofibers can be used to enhance the conductivity, thermal, mechanical and to enhance gas barrier properties of thermoplastic biopolyesters.     

Mechanical properties of sputter-deposited nanocrystalline Cr3Si film

The sputter-deposited Cr-Si film prepared by glow discharge was comprised of equiaxed nanocrystalline Cr₃Si with a grain size of less than 5 nm. The hardness of the nanocrystalline Cr₃Si film was 2.37 times higher than that of coarse-grained Cr₃Si, whereas the elastic modulus of nanocrystalline Cr₃Si was equal to that of coarse-grained Cr₃Si. Compared with the coarse grain of Cr₃Si, the sputter-deposited nanocrystalline Cr₃Si film exhibited higher ductility or toughness due to the GB-mediated deformation.     

CoCr2O4纳米晶的制备及其磁性研究

通过高分子金属络合物热解法制备了COCr2O4纳米晶，并对它的表面微结构和磁性能进行了表征。通过高分辨电镜和傅立叶红外光谱的研究发现在平均粒径为12nm的纳米晶表面不仅有晶格炔陷，而且吸附有大量聚合物分解后的有机碎片，这些有机碎片对纳米晶表面磁矩的钉扎以及纳米晶自身的表面晶格缺陷．导致自旋无序的表面和相对自旋有序的核之间产生强的交换耦合作用．从而使得纳料晶呈现出奇特的磁性能，如低温下存在较走的矫顽力和偏置场等。     

Effect of hafnium addition on the electrical properties of indium zinc oxide thin film transistors

This study reports the performance and stability of hafnium-indium zinc oxide (HfInZnO) thin film transistors (TFTs) with thermally grown SiO2. The HfInZnO channel layer was deposited at room temperature by a co-sputtering system. We examined the effects of hafnium addition on the X-ray photoelectron spectroscopy properties and on the electrical characteristics of the TFTs varying the concentration of the added hafnium. We found that the transistor on-off currents were greatly influenced by the composition of hafnium addition, which suppressed the formation of oxygen vacancies. The field-effect mobility of optimized HfInZnO TFT was 1.34 cm² V⁻¹ s⁻¹, along with an on-off current ratio of 10⁸ and a threshold voltage of 4.54 V. We also investigated the effects of bias stress on HfInZnO TFTs with passivated and non-passivated layers. The threshold voltage change in the passivated device after positive gate bias stress was lower than that in the non-passivated device. This result indicates that HfInZnO TFTs are sensitive to the ambient conditions of the back surface.     

防氧化剂对烧结NdFeB永磁性能的影响

研究了防氧化剂的添加对Nd13.6Dy0.39Tb0.14FecalAl0.8B625的烧结永磁体的微观结构与磁性能的影响规律.结果表明,添加一定量防氧化剂后的主相晶粒尺寸较小且较为均匀,晶界清晰,空隙及缺陷较少.由于磁体微结构的改善,磁体的性能得到了较大的提高.同时发现防氧化剂复合添加的方式对磁性能的效果优于球磨或气流磨时单独添加防氧化剂时的效果.     

Magnetic properties of evaporated CoCr films

Perpendicular magnetic CoCr films were prepared on glass substrates using electron beam evaporation. The magnetic properties depend strongly on the substrate temperature, Ts. The anisotropy field,H_{k}^{eff}, and the perpendicular coercivity, Hc(perp) show maximum values at Tsaround 250°C. In this case, the alignment of c-axis is optimal and the grain size is smallest. The lattice spacing of the c-planes increases wlth Tsuntil 300°C. When the films prepared below 200°C were annealed around 300°C in high vacuum, the saturation magnetization, Ms, increased. The value of Ms, however, decrease by annealing above 400°C. In spite of the decrease of Msdue to the annealing above 400°C,H_{k}^{eff}and Hc(perp) increase by annealing above 400°C. If the films were bombarded by argon ions during film growth, Msdecreased and the internal stress changed from tensile to compressive. For low substrate temperature (below 150°C),H_{k}^{eff}decreased due to ion bombardment.     

Effect of crystallographic orientations on electrical properties of sputter-deposited nickel oxide thin films

Nickel oxide thin films of various preferred orientations were deposited by radio-frequency (RF) magnetron sputtering process in different gas ratios of oxygen atmosphere at RF power 200 W on unheated and heated for (673 K) substrates. The relationships among substrate temperature, preferred orientation and electrical properties of the NiO films were investigated. The resulting films were analyzed by grazing-incidence X-ray diffraction, high-resolution transmission electron microscopy (HR-TEM), and ultrahigh resolution scanning electron microscopy (HR-SEM). The electrical properties were measured using four probe and Hall effects measurements. The results show that films deposited at room temperature with the ratio of oxygen varying from 0 to 100% develop a (111) preferred orientation. At temperature of 673 K, while the (111)-orientated film was obtained under a low ratio of oxygen (<50% O₂), a (200) preferred orientation was developed under 100% oxygen. The lowest sheet resistance 0.01 MΩ/□, resistivity 0.83 Ω-cm and higher carrier density 7.35 × 10¹⁸ cm⁻³ could be obtained on (111) preferred orientation samples prepared on unheated substrates in pure oxygen atmosphere. The relationship between preferred orientation and electrical properties was proposed in this paper.     

弱磁场对SnO2薄膜性能的影响

利用等离子体增强化学气相沉积（PECVD）技术制备了SnO2薄膜。实验中通过改变磁镜场的磁镜比和磁场大小,研究了弱磁场对SnO2薄膜方块电阻及电阻分布的影响。实验结果表明,随着磁比和磁场强度的增加,SnO2薄膜的方块电阻在降低,且电阻分布变得比较均匀;但是,当磁镜比超过5．5时,SnO2薄膜的电阻分布变得越来越不均匀。     

Effect of nitrogen addition on the properties and thermal stability of fluorinated amorphous carbon films

Continuous fluorinated amorphous carbon (a-C : F) films doped with nitrogen (a-C : F : N) were deposited by plasma enhanced chemical vapor deposition using CF₄ and C₂H₂ gases as precursors with the addition of N₂ gas. The surface morphologies, chemical compositions, deposition rates, thermal stability and mechanical properties of these films varied with the deposition parameters, including CF₄ and N₂ feed gas concentrations, processing pressure, plasma power and substrate temperature. With increasing N₂ feed gas concentration, the nitrogen content of the a-C : F : N films increased to about 6 at.% and contributed to higher mechanical properties. After thermal annealing, the a-C : F films with higher fluorine contents exhibited more obvious fluorine release and extensive film thickness shrinkage, whereas the a-C : F : N films with higher contents of nitrogen doping yielded less composition variations, smaller thickness shrinkages, higher mechanical properties, and conclusively better thermal stability.     

添加Ni对FeZrNbB合金的非晶形成能力与软磁性能的影响

利用单铜辊甩带法制备Fe(86-x)Zr2Nb2B10Nix(x=0、1、3和5)非晶合金带材。采用X射线衍射仪、差示扫描量热仪、振动样品磁强计以及精密磁性器件分析仪研究Ni元素对FeZrNbB合金带材的非晶形成能力和软磁性能影响。结果表明Ni元素能明显提高该体系合金的非晶形成能力,并使淬火态非晶合金带材的一级起始晶化温度提高;通过合金的退火处理,在Fe(86-x)Zr2Nb2B10Nix合金体系中含Ni元素的合金带材可以析出最小粒径为12(12.15)nm的α-Fe(a)纳米晶,获得较低的矫顽力为8.1A/m;其中Fe85Zr2Nb2B10Ni1非晶合金带材经过510℃保温20min热处理后可以获得较高的饱和磁感应强度为1.61T,有效磁导率提升到48.4k,矫顽力下降到8.3A/m。     

纳米磁性液体薄膜磁光特性研究

制备出了纳米磁性液体薄膜，研究了纳米磁性液体薄膜在不同外加磁场（垂直和平行）下，其透射光学特性随着磁场变化的规律，对纳米磁性液体薄膜磁光现象产生的原因进行了解释。研究发现：（1）薄膜外加垂直磁场时，光透射强度随着磁场强度的增加而减小；（2）薄膜外加平行磁场时，垂直偏振光和平行偏振光的透射强度随着磁场强度的增加而变化规律不同；（3）存在一个临界磁场，其值约为4776A/m，当外加磁场（垂直和平行）强度＞4776A/m后，薄膜透射光强的变化规律有明显不同，这种现象是由于外加磁场使纳米磁性液体微粒产生聚集，磁场〉4776A/m后，形成有规则的排列结构所造成；（4）纳米磁性液体外加垂直磁场下透射强度的响应时间随磁场强度的变化情况。     

Effect of carbon nanotube and aluminum oxide addition on plasma-sprayed hydroxyapatite coating's mechanical properties and biocompatibility

This study reports on the synthesis of novel bioceramic composite coating of hydroxyapatite (HA) reinforced with carbon nanotubes (CNTs) and aluminum oxide (Al₂O₃) using plasma spray technique. Fracture toughness of HA–20 wt.% Al₂O₃ improved by 158% as compared to HA coating whereas HA–18.4 wt.% Al₂O₃–1.6 wt.% CNT showed an improvement of 300%. Carbon nanotubes provided reinforcement via rebar mechanism. Human fiber osteoblast cell-growth studies showed that biocompatibility of the coating remained unaltered, as Al₂O₃ retained its bio-inertness and CNT, its bioactivity, within the composite coatings. Composite coating showed lower attachment, but higher proliferation rate, for the osteoblast cells, which has been attributed to the surface roughness. An optimized relation between coating composition, its biocompatibility and mechanical properties was established to predict the most suited coating material for orthopedic implants. HA–Al₂O₃–CNT composite coating displayed most improved mechanical properties while retaining its biocompatibility.     

Enhanced perpendicular coercive force of CoCr film formed on a verythin initial sublayer

Perpendicular coercivity of CoCr sputtered films on Ti adhesive layers decreases drastically as RF sputtering power increases. A very thin CoCr sublayer deposited at low power enhances the coercivity of the succeeding CoCr layer. Magnetic properties and segregated microstructures show that the initial segregated microstructure is inherited by the main CoCr layer even though the RF sputtering power changes during the sputtering process. Its segregated microstructure is enhanced by the initial 100-Å segregated structure     

Effect of carbon and phosphorus addition on sintered density and effect of carbon removal on mechanical properties of high density sintered steel

Abstract

This paper provides data on the effect of carbon and phosphorus levels on the density of liquid phase sintered steel and the impact of subsequent carbon removal on the mechanical properties. After sintering die pressed samples composed of liquid forming additives and coarse water atomised powder at 1250°C or below, followed by postsintering decarburisation, densities of >95% relative density and non-brittle microstructures are achieved. Tensile testing shows the important effect of the microstructure on the mechanical properties. Ductility is improved by the post-sintering decarburisation, corresponding to elongation to fracture of 12% for certain compositions. Apparent diffusion coefficients for carbon were also estimated.