Determination of the cubic to hexagonal structure transition in the metastable system TiN-AlN

Structural transitions of metastable Ti_1–xAl_xN coatings on technically relevant substrates were determined as a function of the Ti/Al ratio. Ti_1–xAl_xN films with different Ti/Al ratios were deposited on high speed steel (HSS) substrates at substrate temperatures of 300?° and 500?°C by means of reactive magnetron sputtering ion plating (MSIP). A Ti/Al compound target was used as well as a cluster arrangement of one Ti and one Al target for comparison. The composition of the films was determined by electron probe microanalysis (EPMA), the crystallographic structure by thin film X-ray diffraction (XRD). The analyses revealed that films deposited with Ti/Al ratios of 44/56 and 36/64 had grown in cubic NaCl structure, a film with a Ti/Al ratio of 32/68 was two-phase, and a Ti/Al ratio of 25/75 led to a hexagonal film in wurtzite structure. Only small differences of the lattice parameters could be observed in dependence of temperature: At 300?°C the lattice parameters of the cubic structure corresponded exactly to Vegard‘s law, whereas they slightly decreased in the films deposited at 500?°C. The application of a cluster arrangement instead of a compound target resulted in nearly the same lattice parameters and peak shapes.     

Morphology, structure and constitution of metastable single-phase Ti1-xAlxN films grown by reactive MSIP

Metastable, single phase, polycrystalline Ti_1–x Al _x N hard layers were deposited on HSS-substrates with reactive magnetron sputtering ion plating (MSIP). The substrate temperature was 400 °C, the bias –60 V, the argon pressure 1.2 Pa and the sputter power 6 W cm^–2. Compound targets with a Ti:Al ratio of 75/25, 50/50 and 25/75, expressed in at-%, were sputtered. The nitrogen reactive gas pressure during sputtering was 8.4 × 10^–2 Pa for the 7525 target and 1.08 × 10^–1 Pa for the 5050 and 2575 targets. The Ti_1–x Al _x N layers grew with x=0.26, 0.54 and 0.75, as determined with EPMA. Thin film XRD and HEED structure analysis showed that the Ti_0.74Al_0.26N layer had grown as B1 structure (a₀0.4214 nm) with [211] texture, the Ti_0.46Al_0.54N layer likewise as B1 structure (a₀0.4154) with [111] texture, but the Ti_0.25Al_0.75N as B4 structure (a₀0.317 nm and c₀0.5014 nm) with [110] texture. Pronounced columnar growth was observed with HR-SEM in the fractured surface of the cubic layers. The mean grain size, and consequently the surface roughness, diminished with increasing Al-content of the layer.Dedicated to Professor Dr. rer. nat. Dr. h.c. Hubertus Nickel on the occasion of his 65th birthday     

Oxidation Behaviour of PACVD-(Ti,Al)N Wear Resistance Layers

 Sputtered (Ti,Al)N hard coatings are successfully used for dry high speed cutting. These films show a lower oxidation rate than TiN or TiC coatings. In our work (Ti,Al)N films were deposited on WC-6%Co substrates at a temperature of 490°C by plasma-assisted chemical vapour deposition (PACVD) using a gas mixture of TiCl₄/AlCl₃/N₂/Ar/H₂. Investigation of microstructure, crystalline structure and chemical composition was carried out using SEM, WDXS, TEM, AES and XRD techniques. The chemical composition of the deposited films showed a Al to Ti ratio of 1.33. The film thickness was 5.5 μm. Films showed a fine crystalline size, the metastable fcc crystal structure and a columnar growth. The film surface was under low compressive stress up to several 100 MPa. For (Ti,Al)N/WC-Co compounds the oxidation behaviour up to 1100°C (high temperature range) was studied. Therefore, samples were annealed or rapidly heated in air and under high vacuum condition using the laser shock method. The results show decomposition of the (Ti,Al)N structure to the TiN and the AlN phases at temperature values above 900°C. Heating in air causes growing of a thin aluminum oxide layer at the film surface, which is a barrier for further oxygen diffusion to the alumina-film boundary. Additionally, at temperatures above 900°C oxidation of the WC-6%Co substrate surface was obtained in regions of opened cracks and film delamination.     

Preparation of polycrystalline Ti-Al-O films by magnetron sputtering ion plating: constitution, structure and morphology

Ti-Al-O layers were deposited on Si-<100> wafers at 500 °C by means of reactive magnetron sputtering ion plating (R-MSIP). An Al-target was sputtered in rf-mode and a Ti-target in dc-mode simultaneously by an oxygen/argon plasma. The influence of the Al- and Ti-sputter powers on composition, structure, and morphology of the Ti-Al-O layers and the binding states of the components were investigated. The analysis with EPMA, XPS, AES and TEM yielded the following results: Ti-Al-O coatings with different Ti, Al, and O contents in the range of TiO₂ to Al₂O₃ were grown. TEM structure analysis revealed: the pure TiO₂ film consisted of the tetragonal phases rutile and anatase; the two structures were found in the titanium-rich Ti-Al-O film, too, but with significant smaller lattice constants. The aluminium-rich Ti-Al-O film displayed the same cubic structure of γ-Al₂O₃ as determined for the pure Al₂O₃ film, but the lattice constant is significant lower. Evaluation of the TEM pattern of the film with a Ti/Al ratio of 0.8 indicates a hexagonal structure with lattice constants similar to those of κ′-Al₂O₃. All films are nanocrystalline and not textured. Received: 24 June 1996 / Revised: 27 December 1996 / Accepted: 4 January 1997     

CexTi1-xO2复合氧化物表面结构和体相结构的演变

利用X射线衍射、N₂吸附等温线、X射线光电子能谱、X射线吸收谱、H₂-程序升温还原、甲基橙选择化学吸附和等电点测定等方法研究了共沉淀方法制备的一系列Ce_xTi_1-xO₂复合氧化物的结构. 成功发展了甲基橙选择化学吸附和等电点方法研究Ce_xTi_1-xO₂复合氧化物的最外层表面结构, 并定义了“等价CeO₂表面覆盖度”来描述Ce_xTi_1-xO₂复合氧化物的最外层表面结构. Ce_xTi_1-xO₂复合氧化物 (x ≥ 0.7)形成立方萤石相固溶体, Ce_0.3Ti_0.7O₂表现出纯的单斜相, 而其它复合氧化物表现出混合相. Ce_xTi_1-xO₂复合氧化物最外层表面结构的演变行为不同于其体相结构.Ce_0.7Ti_0.3O₂立方萤石相固溶体最外层表面已经部分形成了单斜相Ce_0.3Ti_0.7O₂, 随Ce含量的降低, 单斜相Ce_0.3Ti_0.7O₂从最外层表面向体相生长. Ce_xTi_1-xO₂复合氧化物立方萤石相固溶体和单斜相Ce_0.3Ti_0.7O₂分别在相对较低和较高的温度表现出好的还原性能. 上述结果提供了全面和深层次的Ce_xTi_1-xO₂复合氧化物结构信息.     

Insight into Al existing form and its role on microstructure and properties of Cr1−xAlxN films

A series of Cr_1?xAl_xN (where x denotes the atom fraction of Al in Cr_1?xAl_xN film) films with different Al contents have been deposited by unbalanced reactive magnetron sputtering technique. The chemical composition, microstructure, surface morphology, cross‐sectional structure, mechanical properties, thermal stability and tribological properties of the deposited films were studied by means of different techniques. It is found that with the increase of Al doping, the Al atoms either substitute the Cr atoms or occupy the interstitial sites in the CrN crystal lattice firstly, and when the Al doping content exceeds the solid solubility, superfluous Al atoms then exist in the form of amorphous or nanocrystal state in the films. Meanwhile, the grain size becomes smaller, and the microstructure gets denser because the Al doping leads to multiple crystal orientations and inhibits the grain growth. The Al doping induced solid solution hardening and grain boundary effects contribute to the high hardness of CrAlN films, and the dense structure as well as interstitial solid solution of Al, which can block the diffusion channel, endows the CrAlN films good oxidation resistance. Besides, a small amount of free Al existing in the films is favorable to improve the thermal stability without obvious loss of hardness. Finally, the relatively high hardness and good thermal stability make the Cr_0.29Al_0.71N film has relatively good tribological properties than CrN film under a wide temperature range, which extends the operating temperature of the CrN films in some fields. Copyright © 2015 John Wiley & Sons, Ltd.     

Composition and Structure of Anodic Oxide Films on Titanium–Aluminum Alloys by Fast Electron Reflection Diffraction, Rutherford Backscattering, and Secondary Neutral Particle Mass Spectrometry

Anodic oxide films on some Ti–Al alloys are studied using fast-electron reflection diffraction, Rutherford backscattering, and secondary neutral-particle mass spectrometry. The films are amorphous, with a small amount of crystalline phases, and comprise a mixture of TiO₂ and Al₂O₃. The Ti/Al ratio in an anodic film corresponds to that in the alloy matrix. Constants of anodic oxidation of the alloys are determined.     

Analysis of Ti-N films by calibration of Ti X-ray spectra

Summary An energy-dispersive X-ray analysis of Ti_1–xN_x films was performed by using an Si(Li) detector. The Ti_1–xN_x films were sputtered on polished steel substrates in a mixed Ar+N₂ atmosphere by a reactive magnetron sputtering technique. Because the nitrogen X-ray line is absorbed by the Be window, an analysis method was developed based solely on the calibration of the characteristic Ti-K-intensities using a high-purity Ti standard. The film compositions were computed by means of a ZAF procedure. The samples closest to stoichiometric composition show maximum hardness.     

Improved electric properties in BiFeO3 films by the doping of Ti

We prepared BiFe_1−x Ti _x O_3+δ (BFTO) films by sol gel process and various oriented films were deposited on LaNiO₃ coated SiO₂/Si substrates with different x. The effects of Ti substitution on dielectric, ferroelectric, magnetic and leakage conduction properties in BFTO system have been studied. Enhanced ferroelectricity was observed at room temperature due to the substitution of Ti. The largest double remnant polarization of 3.8 μC/cm² was acquired in the film with x = 0.10. Further more, it was observed that the dielectric constants were also enhanced by the substitution of Ti. The film with x = 0.10 has the largest dielectric constant below 100 kHz and Debye-like relaxation were observed in the films with x = 0.05 and 0.10. The leakage conduction was reduced with the increasing of the content of Ti. More over, the magnetism was also altered by the substitution.     

Bonding structure and mechanical properties of carbon nitride bilayer films with Ti and TiN interlayer

Carbon nitride (CN_x) bilayer films with Ti and TiN interlayer were synthesized by cathode arc technique at various nitrogen pressures (P_N2). The dependences of microstructure and bonding composition of the films on the P_N2 and interlayer were analyzed by Raman spectroscopy and X‐ray photoelectron spectroscopy. Microstructure evolution consisting of the ordering and size of Csp² clusters, the faction of N–sp³/N–sp² bonds and graphite‐like/pyridine‐like configurations was dominated by P_N2, interlayer and annealing. The results showed that Ti and TiN interlayer decrease the atomic ratio of N/C and increase clustering Csp². High P_N2 induces the formation of C ≡ N and C ? N bonds, the increase of sp²‐bonding content and the growth of Csp² clusters. A large part of nitrogen atoms are coordinated with sp²‐hybridized carbon (minimum 71% for annealed CN_x monolayer). TiN/CN_x bilayer had a higher content of pyridine‐like configuration. Morphological characteristics of CN_x monolayer and bilayer mainly depend on the surface character (roughness and surface energy) of the sublayer. The internal stress in the as‐deposited Ti/CN_x bilayer is smaller, but it after annealing is higher than that of CN_x monolayer and TiN/CN_x bilayer. These results may be of interest for studying the CN_x films with controlled bonding composition and expected engineering properties. Copyright © 2014 John Wiley & Sons, Ltd.     

Effects of Zn, Al and Ti substitution on the electrochemical properties of LiNiO2 synthesized by the combustion method

LiNi_{1 ? y} Ti _y O₂ (0.000 ≤ y ≤ 0.100) and LiNi_0.990M_0.010O2 (M = Zn, Al, and Ti) were synthesized by the combustion method. The effects of Zn, Al and Ti substitution for Ni of LiNiO₂ on the electrochemical properties of LiNiO₂ were investigated. LiNi_0.995Ti_0.005O₂ has the largest first discharge capacity (188.1 mA h/g) among the Ti-substituted samples. LiNi_0.990Ti_0.010O₂ has a relatively large first discharge capacity (185.5 mA h/g) and a relatively good cycling performance. Among LiNi_0.990M_0.010O₂ (M = Ni, Zn, Al, and Ti), LiNiO₂ has the largest discharge capacities at a rate of 0.1 C from n = 1(189.3 mA h/g) to n = 10. LiNi_0.990Al_0.010O₂ has the lowest discharge capacities from n = 1 to n = 10, but it has the best cycling performance. LiNi_0.990Zn_0.010O₂ showed poor crystallinity, LiNi_0.990Ti_0.010O₂ showed high cation mixing, and LiNi_0.990Al_0.010O₂ had good crystallinity and showed low cation mixing. Fewer occurrence of phase transitions and the least change of the ?dx/|dV| vs. voltage curve at the second cycle from the curve at the first cycle of LiNi_0.990Al_0.010O₂ suggest that Al substitution stabilizes the structure and leads to a good cycling performance.     

Comparison of properties of titanium aluminium nitride film produced by using two different types of Ti–Al target

This work aims to study the influence of two different types of Ti–Al target (sintered and melted) which have same nominal composition (50 at% Ti, 50 at% Al) on the properties of thin films coated by using arc ion plating (AIP) method. The hardness of the melted target was of higher value than that of the sintered target. The property of the film is related to the microstructure and phase analysis of both types of target that have quite different phases. Ti and Al metals were found as major phases and TiAl₂ as minor phase in the sintered target but only TiAl compound was found in the melted target. After film coating at the same operation parameters, it was found that although the phase structures of the sintered and melted targets were quite different, the coated thin films using these targets showed the same phase structure of Ti_0.5 Al_0.5 N. However, the microstructure of films coated by using the sintered target showed higher density of droplets and pores than those of film produced by using the melted target. As a result, the hardness and adhesion strength of thin film produced by using the melted target were slightly higher than those values of film produced by using the sintered target. Copyright © 2009 John Wiley & Sons, Ltd.     

Chemical solution processing and characterization of Ba(Zr,Ti)O<Subscript>3</Subscript>/LaNiO<Subscript>3</Subscript> layered thin films

Ba(Zr,Ti)O₃/LaNiO₃ layered thin films have been synthesized by chemical solution deposition (CSD) using metal-organic precursor solutions. Ba(Zr,Ti)O₃ thin films with smooth surface morphology and excellent dielectric properties were prepared on Pt/TiO _x /SiO₂/Si substrates by controlling the Zr/Ti ratios in Ba(Zr,Ti)O₃. Chemically derived LaNiO₃ thin films crystallized into the perovskite single phase and their conductivity was sufficiently high as a thin-film electrode. Ba(Zr,Ti)O₃/LaNiO₃ layered thin films of single phase perovskite were fabricated on SiO₂/Si and fused silica substrates. The dielectric constant of a Ba(Zr_0.2Ti_0.8)O₃ thin film prepared at 700°C on a LaNiO₃/fused silica substrate was found to be approximately 830 with a dielectric loss of 5% at 1 kHz and room temperature. Although the Ba(Zr_0.2Ti_0.8)O₃ thin film on the LaNiO₃/fused silica substrate showed a smaller dielectric constant than the Ba(Zr_0.2Ti_0.8)O₃ thin film on Pt/TiO _x /SiO₂/Si, small temperature dependence of dielectric constant was achieved over a wide temperature range. Furthermore, the fabrication of the Ba(Zr,Ti)O₃/LaNiO₃ films in alternate thin layers similar to a multilayer capacitor structure was performed by the same solution deposition process.     

A Non-Hydrolytic Sol-Gel Approach for the Preparation of Mg x Al2(1−x)Ti(1+x)O5 Powders

The study of non-hydrolytic reactions for the synthesis of Mg _x Al_2(1?x)Ti_(1+x)O₅ solid solution with x = 0.6 is reported. The reagents chosen were Al(OsBu)₃, Ti(OiPr)₄, TiCl₄ and Mg(NO₃)₂·6H₂O in toluene. The reactions were followed using ¹³C Nuclear Magnetic Resonance (NMR) spectroscopy. Sol-gel synthesized powders were calcined in air at 300, 500, 1000, and 1200°C for 1 h. The powders were analysed by X-Ray Diffraction (XRD) demonstrating the formation of a Mg_0.6Al_0.8Ti_1.6O₅ phase in samples treated at the higher calcination temperature.     

Oxidation and carbidation of laser-ablated amorphized Ti particles in carbon monoxide

IR laser ablation of hexagonal titanium in vacuum leads to amorphization of ablated Ti particles and when carried out in gaseous carbon monoxide it proceeds as reactive ablation involving particles amorphization, oxidation and carbidation. The films deposited in vacuum and in the presence of CO were examined by Fourier transform infrared, Raman and X-ray photoelectron spectroscopy, X-ray and electron diffraction and electron microscopy. The Ti films become oxidized upon contact with air and the Ti/C/O films are composed of Ti–O, Ti–C and C–O bonds-containing structures with Ti in Ti²⁺–Ti⁴⁺ state and incorporating crystalline rutile and elemental carbon. The ablation in vacuum represents a new approach to amorphous titanium and it is judged that hot ablated Ti particles are modified by reactions with CO decomposition products into amorphous Ti oxycarbides which undergo rapid post-pulse amorphization.     

Stoichiography in the study of spatial heterogeneity of the chemical composition and structure of thin films and nanostructured systems

We present the principles of stoichiography and a reference-free stoichiographic differential (separating) dissolution method used to study the composition and structure of thin films and nanostructured systems: HTS films with 123 different compositions, Al–Au–Sn–Co–Mn, Si/SiO₂/Ni(Cr)–Cu–Cu2S, Cr–Cu–S, and Cu–S multilayer films, Bi–Ti–O films on Ru/SiO₂/Si, Mn_1–xZn _x S, and ZnS–EuS supports, and also nanostructured manganese ferrite in borate glass matrices, nanodisperse composite sorbents and the Co–Si–Pt–O/Al₂O₃ catalyst modified by Pt nanoparticles, and oxide catalyst precursor Fe₂Co/Al₂O₃ for the synthesis of carbon nanotubes.     

Weitere magnetische Untersuchungen an Ti3−xMxO5-Phasen (M = Al3+, Fe2+, Mn2+, Mg2+) mit einem Beitrag über CrTi2O5

Additional Magnetic Examinations of Ti_3?xM_xO₅-Phases (M = Al³⁺, Fe²⁺, Mn²⁺, Mg²⁺) with a Contribution about CrTi₂O₅ Ti_3?xM_xO₅ was prepared with M = Al³⁺, Fe²⁺, Mn²⁺, and Mg²⁺. Die magnetic properties of this phases were examinated by the Faraday method in respect to the temperature. The well known magnetic effect of Ti₃O₅ near 450 K is shifted to lower degrees if Ti is replaced by Al, Fe, Mn, or Mg. Compared to Ti_3?xV_xO₅ and Ti_3?xCr_xO₅ the stability of the low temperature-form of Ti₃O₅ is much more reduced in Ti_3?xM_xO₅ (M = Al, Fe, Mn, Mg). The crystal structure investigation of CrTi₂O₅ explained the anomalous behaviour of the Cr³⁺ and V³⁺ doped Ti₃O₅.     

Low energy ion bombardment of Ti and TiNx films

The influence of low energy ion bombardment on TiN_x film growth and film properties was investigated. The discharge was characterized using Langmuir probe technique as well as energy resolved mass spectrometry with a plasma monitor (Hiden HAL 301 S/EQP). The deposited films were investigated by means of X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Increasing the N₂ gas flow as well as increasing the negative substrate voltage at constant gas flow effect an increase of the N/Ti ratio in the films determined by XPS. The influence of the energy flux to the surface due to ion bombardment was mainly recognized in the substructure of the films. In addition, pure Ti films were modified by nitrogen ion bombardment after deposition using an ion gun. An increase of the N/Ti ratio was observed with increasing ion energy. Finally saturation is reached.     

Structure,Electrical and Oxygen Transport Properties of Fe-Doped SrCoO3?δ Perovskites

The structure-property relationship of Fe-doped SrCoO_3-δ was studied. With increase of Fe content in SrCo_1-xFe_xO_3-δ from x=0 to x=0.2, the phase composition changed progressively in the order of hexagonal→brownmillerite (main)+hexagonal→cubic (main)+brownmillerite→single cubic phase. Transition between the hexagonal/brownmillerite phase and the cubic phase took place with variation of the operating conditions, and was associated with remarkable changes in the electrical conductivity and oxygen permeation flux.     

Room Temperature Ferromagnetism in Ga1-xHoxN (x=0.0 and 0.05) Diluted Magnetic Semiconductor Thin Films

Holmium doped GaN diluted magnetic semiconductor thin films have been prepared by thermal evaporation technique and subsequent ammonia annealing. X-ray diffraction mea-surements reveal all peaks belong to the purely hexagonal wurtzite structure. Surface mor-phology and composition analysis were carried out by scanning electron microscopy and energy dispersive spectroscopy respectively. The room temperature ferromagnetic proper-ties of Ga_1-xHo_xN(x=0.0, 0.05) films were analyzed using vibrating sample magnetometer at room temperature. Magnetic measurements showed that the undoped films (i.e. GaN) exhibited diamagnetic behavior, while the Ho-doped (Ga_0.95Ho_0.05N) film exhibited a ferro-magnetic behavior.