X-ray absorption studies of phase formation in a Ti/TiN coating on cubic boron nitride

We report on the use of X-ray absorption spectroscopy as a tool for the identification of the phases formed in the technological process of composite preparation. A composite is a mixture of several compounds and, in many cases, the use of traditional X-ray diffraction to determine the phases can be difficult because of the small amount of phases present. X-ray absorption studies (XANES and EXAFS) of the c-BN Ti/TiN layered system are presented. These materials are models of the powdered composites used in industry for tool production. XANES and EXAFS analyses showed that, after annealing up to 1300 °C, a TiB₂ phase is formed, but the chemical bonding of the Ti atoms differs slightly from that of standard TiB₂ powder, showing the presence of defects in site occupancy. Assuming that the X-ray absorption spectral shape is a linear combination of the spectra of all the components, we estimated the kind and limits of other phase inclusions.     

第一性原理研究掺杂过渡元素对碳化钨性能的影响

碳化钨(WC)在高温动力装备上应用越来越多,WC的脆性和高密度限制了其更广泛的使用,金属原子掺杂是提高WC性能的一种方法.采用基于第一原理的广义梯度作为近似交换相关函数,研究了A0.25W0.75C(A为Ti、V、Cr、Mn、Co和Ni)的弹性、电子和X射线吸收特性.数值分析结果显示,Ti0.25W075C的B/G值(...     

Investigation of metal distribution and carbide crystallite formation in metal-doped carbon films (a-C:Me, Me = Ti, V, Zr, W) with low metal content

Metal-doped amorphous carbon films (a-C:Me) were deposited at room temperature by magnetron sputtering using a metal (Me = Ti, V, Zr, W) and a graphite target. The metal distribution and the temperature-induced carbide crystallite formation were analyzed by X-ray diffraction (XRD), electron microscopy (TEM, STEM) and X-ray absorption spectroscopy (EXAFS, XANES), focusing on low metal concentrations between 6.5 and 9.5%. In as-deposited samples, the metal atoms are atomically distributed in the carbon matrix without significant formation of carbide particles. With annealing to 900 K the local atomic environment around the metal atoms becomes similar to the carbide. The carbide crystallites grow with annealing up to 1300 K, their size is dependent on the metal type: V > Ti > Zr≈W. W₂C and WC_1 − x crystallites were identified for W-doped films, whereas the monocarbides are formed for the other metals. It is demonstrated, that EXAFS and high resolution electron microscopy are required to get a correct picture of the structure of the analyzed a-C:W films.     

Surface alloying of Cu with Ti by double glow discharge process

The surface of pure copper alloyed with Ti using double glow discharge process was investigated. The morphology, structure and forming mechanism of the Cu-Ti alloying layer were analyzed. The microhardness and wear resistance of the Cu-Ti alloying layer were measured, and compared with those of pure copper. The results in-dicate that the surface of copper activated by Ar and Ti ions bombardment is favorable to absorption and diffusion of Ti element. In current experimental temperature, as the Ti content increases, the liquid phase occurs between the deposited layer and diffused layer, which makes the Ti ions and atoms easy to dissolve and the thickness of Cu-Ti al-loying layer increase rapidly. After cooling, the structure of the alloying layer is composed of CuTi, Cu4Ti and Cu(Ti) solid solution. The solid solution strengthening and precipitation strengthening effects of Ti result in high surface hardness and wear resistance.     

La1．8Ca0．2Mg14Ni3＋x% Ti合金的微结构和储氢性能

研究了机械球磨La1.8Ca0.2Mg14Ni3＋x％Ti（质量分数，下同）（x=0，5，10）合金的微结构和储氢性能。气态吸放氢研究表明。加入钛粉球磨能有效提高合金的活化性能、储氢容量和吸放氢速率。铸态合金经过6次活化后，在613K时放氢量为4．12％（质量分数，下同）。加Ti球磨改性10h后，随着X增加，合金经过2次～3次循环基本完全活化。吸放氢性能也相应提高。Ti含量在x=0，5，10时合金在613K的放氢量分别为4．69％，4．80％，4．83％：当x=10时合金在373K的吸氢量达到3％以上，在600K经过2min就能达到4．81%（为最大吸氢量的97％）。微结构分析表明。具有表面催化活性的Ti粉与合金基体表面进行复合，并使合金发生部分非晶转变，能有效改善La1.8Ca0.2Mg14Ni3合金的储氢性能。     

Structure of titanium-doped goethite rust

To investigate the influence of titanium addition on the formation and structure of goethite (α-FeOOH) rust which is one of main corrosion products of weathering steel, the artificially synthesized α-FeOOH rusts were prepared by hydrolysis of aqueous solutions of Fe(III) containing Ti(IV) at different atomic ratios (Ti/Fe) in the range 0-0.1. The obtained rusts particles were observed by TEM. Characterization by XRD, N₂ absorption, Mössbauer spectroscopy was also done. TEM observation revealed that the α-FeOOH rust particle size increased with the increase of Ti/Fe, and that Ti-enriched poorly crystalline particles were formed around the rust particles. XRD confirmed that the crystallite size increased with the increase of Ti/Fe, while the XRD peaks decreased in intensity. Specific surface area obtained by N₂ absorption increased with the increase of Ti/Fe. It is deduced from the obtained results that the addition of Ti(IV) increases the crystallite size of α-FeOOH, and produces double domain particles consisting of the particle core and a porous poorly crystalline shell. It is thought that such unique rust structure produced by titanium addition contributes to the protective properties of rust layer of the weathering steel.     

TiN单层和TiN/Ti(C,N)多层涂层的结构和性能研究

借助XRD、SEM、纳米压痕和划痕仪研究了采用磁控溅射在硬质合金基体上沉积的TiN单层和TiN/Ti(C,N)多层涂层的组织结构和力学性能。研究表明:TiN与TiN/Ti(C,N)多层涂层的晶粒形貌均呈柱状晶结构,而TiN/Ti(C,N)多层涂层形成了TiN、Ti(C,N)交替的调制结构。由于界面强化作用,TiN/Ti(C,N)多层涂层表现出比TiN更高的硬度及与基体更好的结合力。     

TOTAL ENERGIES AND ELECTRONIC STRUCTURES OF CO_3Ti AND HYDROGENIZED Co_3Ti

1.IntroductionAgreatdealofinteresthasbeenshowninL12typeintermetalliccompoundSandalloyssincetheyshowasubstantialincreaseinflowstresswithincreasingtemperature[1--3].However,thebrittlenessofthistypeofalloyhaspreventeditfrombeingusedasanalloybaseforastructuralmaterial.TakasugiandI...i[4]hadfoundCo3Ticompoundtohaveintrinsicallygoodductilityatawidetemperaturerange.TheyhadinvestigatedtheinfluenceofahydrogenenvironmentORthemechanicalpropertiesofL12typeCo3Ticompoundandemphasizedthathydrogenembrittl…     

Local metal and deuterium ordering in the deuterated ZrTiNi C14 Laves phase

Local structure of the hexagonal C14 Laves phase in an annealed approximately equiatomic ZrTiNi alloy was studied before and after deuteration using neutron total scattering. Rietveld refinements of the P6₃/mmc AB₂ model demonstrate that the A-sites are shared by Zr and Ti, whereas the two non-equivalent B-sites are occupied by a mixture of Ti and Ni. Reverse Monte Carlo refinements using a joint fit of the neutron total scattering data in real and reciprocal spaces revealed significant short-range ordering of Ti and Ni on the B-sites. The refined Ti-Ni nearest-neighbor distances are appreciably shorter than the corresponding Ti-Ti and Ni-Ni distances. Nevertheless, the differences in the effective sizes of chemically distinct tetrahedral interstices (i.e. [Zr₂Ti₂], [Zr₂TiNi], [Zr₂Ni₂], etc.), which are important for hydrogen absorption, remain rather small. Rietveld refinements of the structure of the deuterated sample TiZrNiD_2.14 confirmed that deuterium occupies various [A₂B₂] tetrahedral interstices. RMC refinements suggested a strong preferential occupation of deuterium in the [Zr₂Ti₂] and [Zr₂TiNi] tetrahedra whereas the [Zr₂Ni₂] sites remained nearly empty. These results support earlier models which predicted preferential occupancy by hydrogen in sites coordinated by metals that form the most stable binary hydrides. The deuterium atoms in the [Zr₂TiNi] tetrahedra are displaced toward Ni. X-ray absorption near-edge structure measured for Ti, Zr, and Ni K-edges demonstrated that deuteration is accompanied by the reduction in the density of unoccupied electronic states (just above the Fermi level) associated with Ti and Zr.     

热处理对TiO2溅射薄膜结构和光谱性能的影响

用直流反应磁控溅射法制备了TiO2薄膜,并对热处理前后试样的紫外可见光谱（UV-Vis spectrum）和荧光发射光谱（PL Spectrunm）做了研究。发现热处理后试样的紫外可见光谱在496nm处出现了一个较为明显的吸收峰，荧光发射光谱496．5nm处出现一个荧光发射带肩。X射线光电予能谱（XPS）的分析结果表明，热处理可使薄膜中晶格氧扩散出去，生成Ti^3＋离子和氧空位。结合XPS的分析结果和理论计算，可推断热处理后出现的位于496nm处的吸收峰和496．5nm处的荧光带肩可被指认为薄膜中Ti^3＋离子的d电子跃迁产生。     

热处理对TiO_2溅射薄膜结构和光谱性能的影响

用直流反应磁控溅射法制备了TiO2薄膜,并对热处理前后试样的紫外可见光谱(UV-Visspectrum)和荧光发射光谱(PLSpectrunm)做了研究。发现热处理后试样的紫外可见光谱在496nm处出现了一个较为明显的吸收峰,荧光发射光谱496.5nm处出现一个荧光发射带肩。X射线光电子能谱(XPS)的分析结果表明,热处理可使薄膜中晶格氧扩散出去,生成Ti3+离子和氧空位。结合XPS的分析结果和理论计算,可推断热处理后出现的位于496nm处的吸收峰和496.5nm处的荧光带肩可被指认为薄膜中Ti3+离子的d电子跃迁产生。     

Structural investigation of thin films of Ti1−xAlxN ternary nitrides using Ti K-edge X-ray absorption fine structure

Thin films of Ti_1−xAl_xN nitrides were prepared over a large range of composition (0 ≤ x < 1) on Si substrates using nitrogen reactive magnetron sputtering from composite metallic targets. Ti K-edge X-ray Absorption Spectroscopy experiments were carried for a better understanding of the local structure. The evolution of the intensity of Ti K-edge pre-edge peak gives evidence of the incorporation of Ti in hexagonal lattice of AlN for Al-rich films and in cubic lattice of TiN for Ti-rich films. An attempt to determine their atomic structure by combining X-ray diffraction and Ti K-edge Extended X-ray Absorption Fine Structure is presented. The evolution of the nearest neighbour and next-nearest neighbour distances depending on the composition is presented and discussed together the cubic and hexagonal lattice parameters. A possible contribution of amorphous nitrides is suggested.     

Electrochemical Performance of Li4Ti5O12 Synthesized by a PVP Combustion Assisted Sol-gel Method

Li4Ti5O12 samples were synthesized via a PVP (polyvinylpyrrolidone) assisted gel-combustion method by varying the calcination temperature. The effect of different roasting temperatures on the structure, the morphology, and the electrochemical performance of the Li4Ti5O12 material was analyzed. The cycle performance, the structure and the morphology of the prepared material were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and charge/discharge test system. The results show that the Li4Ti5O12 powder has a single-phase spinel structure with uniform particles size. The average particle size is 500 nm. The Li4Ti5O12 material synthesized at 800 oC for 8 h possesses excellent performance, and its first discharge capacity is 167.4 mAh/g     

（V30Ti35Cr25Fe10）97．5Si2．5合金的结构与吸放氢性能

采用XRD，SEM和PCT测试研究了（V30Ti35Cr25Fe10）97.5Si2.5（at％）合金的组织结构与吸放氢性能。结果表明：合金由BCC相和C14 Laves相组成，BCC相含量为75％，晶胞参数为α=0．3021nm，Laves相含量为25％，晶胞参数为α=0．4920nm和c=0．7996nm。由于含有大量的Laves相，合金具有良好的活化性能，室温下不需孕育期就可以快速吸氢，5min内达到吸氢饱和状态，饱和吸氢量达到2．98％（质量分数，下同）。在一定氢压下，合金的容量可由合金中BCC相和Laves相的容量按组分的含量进行线性组合而成。     

Structure and antibacterial activity of new layered perovskite compounds

New layered perovskite compounds, AgxNa（2-x）La2Ti3O10（x=0.2, 0.3 and 0.5） were synthesized by an ion-exchange reaction of Na2La2Ti3O10 with AgNO3 solution and characterized by energy dispersive X-ray analysis（EDX）, X-ray diffractometly（XRD）, scanning electron microscopy（SEM） and X-ray photoelectron spectroscopy（XPS）. The ion-exchange processes were optimized, and the antibacterial activity, light permanency and water-resistance were evaluated. Surprisedly, no significant changes in crystal structure of Na2La2Ti3O10 are found by the exchange of silver ions. The Ago.3Na1.7La2Ti3O10 particles conglomerate obviously with irregular shape and size. Ago.3Na1.7La2Ti3O10, possessing the minimum inhibitory concentrations（MICs） against Escherichia coli （E. coli）, Staphylococcus aureus （S. aureus） of 180 mg/L and 240 mg/L, has high antibacterial activity, good light permanency and water-resistance. The ionic state silver in AgxNa（2-x）La2Ti3O10 is the antibacterial active component.     

Ti0.9Zr0.2Mn（1.8—x）MxV0.2（M=Ni,Cr;x=0,0.2）合金的贮氢性能

研究了Ti0.9Zr0.2Mn(1.8-x)MxV0.2(M=Ni,Cr;x=0,0.2)合金的晶体结构与贮氢性能。结果表明,Ti0.9Zr0.2Mn1.6Ni0.2V0.2和Ti0.9Zr0.2Mn1.6Cr0.2V0.2的贮氢量达到240mL/g。合金的主相均为C14 Laves相,镍,铬的取代使点阵常数和晶胞体积增大,P－C－T曲线的滞后降低,压力平台的倾斜度增加。     

Ni对V55Ti20．5Cr18．1Fe6．4合金吸放氢性能的影响

研究了用Ni元素取代一定量V对V55Ti20．5Cr18．1Fe6．4合金结构与性能的影响。结果表明，随Ni含量的增加，合金有效吸氢量先增大后减小，放氢压力增大，合金吸氢动力学性能也是先有所改善，而后又变差。添加0．1at％Ni有利于改善基体合金V55Ti20．5Cr18．1Fe6．4的吸放氢性能。用Ni元素取代V引起的晶胞体积的变化、放氢平台压力的升高以及杂质相的出现，是影响合金有效吸氢量和吸氢动力学性能的主要因素。     

Ti600，TC21和Ti40合金吸放氢行为

研究Ti600,TC21和Ti40合金的吸放氢行为。结果表明,Ti600,TC21和Ti40合金的吸氢与放氢的初始温度分别为573和578.5 °C,580和628.1 °C,515和540 °C。Ti600和TC21合金的吸放氢行为相似,而Ti40合金的吸放氢能力优于其他两种合金。     

TiN/Ti(C,N)涂层的显微组织与力学性能

采用磁控溅射在TNMG120408型号的硬质合金刀片上沉积了TiN/Ti(C,N)单层与多层涂层,通过XRD、SEM、纳米压痕、划痕仪与冲击测试等方法,比较分析了TiN/Ti(C,N)涂层的显微组织与力学性能。结果表明,TiN单层涂层的晶粒形貌为典型的喇叭口结构,Ti(C,N)单层涂层为平直的柱状晶结构;而TiN/Ti(C,N)多层涂层为柱状晶结构,形成了TiN、Ti(C,N)交替排列的结构。TiN与Ti(C,N)单层涂层均呈(220)生长织构,而TiN/Ti(C,N)多层涂层呈(111)生长织构。Ti(C,N)单层涂层表现出较好的硬度,而TiN/Ti(C,N)多层涂层则表现出与基体更好的结合力。     

Synthesis and grain growth kinetics of in-situ FeAl matrix nanocomposites（ Ⅰ ）： Mechanical alloying of Fe-A1-Ti-B composite powder

Three nanocrystalline alloys, FesoAlso, Fe42.5Al42.5Ti5B10 and Fe35Al35Ti10B20 （molar fraction, %）, were synthesized from elemental powders by high-energy ball milling. The structural evolutions and morphological changes of the milled powders were characterized by X-ray diffractometry（XRD）, transmission electron microscopy（TEM） and scanning electron microscopy（SEM）. The effects of different Ti, B additions on the structure and phase transformation in these alloys were also discussed. It is observed that the diffusion of AI, Ti, B atoms into Fe lattice occurs during milling, leading to the formation of a BCC phase identified as Fe（Al） or Fe（Al, Ti, B） supersaturated solid solution. Fe-based solid solution with nanocrystalline structure is observed to be present as the only phase in all the alloy compositions after milling. Furthermore, the contents of Ti, B affect the formation of mechanical alloying products, changes in the lattice parameter as well as the grain size.