Glancing Angle X-ray Diffractometry Research Articles

Spatial Distribution of Trehalose Dihydrate Crystallization in Tablets by X-ray Diffractometry.

Crystallization of trehalose dihydrate (C12H22O11·2H2O) was induced by storing tablets of amorphous anhydrous trehalose (C12H22O11) at 65% RH (RT). Our goal was to evaluate the advantages and limitations of two approaches of profiling spatial distribution of drug crystallization in tablets. The extent of crystallization, as a function of depth, was determined in tablets stored for different time-periods. The first approach was glancing angle X-ray diffractometry, where the penetration depth of X-rays was modulated by the incident angle. Based on the mass attenuation coefficient of the matrix, the depth of X-ray penetration was calculated as a function of incident angle, which in turn enabled us to "calculate" the extent of crystallization to different depths. In the second approach, the tablets were split into halves and the split surfaces were analyzed directly. Starting from the tablet surface and moving toward the midplane, XRD patterns were collected in 36 "regions", in increments of 0.05 mm. The results obtained by the two approaches were, in general, in good agreement. Additionally, the results obtained were validated by determining the "average" crystallization in the entire tablet by using synchrotron radiation in the transmission mode. The glancing angle method could detect crystallization up to ∼650 μm and had a "surface bias". Being a nondestructive technique, this method will permit repeated analyses of the same tablet at different time points, for example, during a stability study. However, split tablet analyses, while a "destructive" technique, provided comprehensive and unbiased depth profiling information.

Toughening effect of Ni on nc-CrAlN/a-SiNx hard nanocomposite

To combat the brittleness of hard nc-CrAlN/a-SiNx nanocomposite (nc-: nanocrystalline, a-: X-ray amorphous), different Ni content (from 0 to 39.8at.%) is doped via magnetron sputtering. Glancing Angle X-ray Diffractometry, X-ray photoelectron spectroscopy, Field Emission Scanning Electron Microscopy and Transmission Electron Microscopy are employed to investigate the microstructural evolution. With increased Ni, the grain size decreases accompanied with morphology change, from dense glassy to coarse columns. With 4.2at.% Ni, scratch toughness of nc-CrAlN/a-SiNx hard nanocomposite (28GPa) is improved by around 200% at expense of only 18% hardness.

Influence of bias voltage on the hardness and toughness of CrAlN coatings via magnetron sputtering

Chromium aluminum nitride (CrAlN) coatings were prepared via magnetron sputtering in a mixed Ar and N2 ambient. The effect of negative bias voltage (Vb) on the microstructure was investigated using a spectrum of characterizing techniques in terms of Glancing Angle X-ray Diffractometry, Field Emission Scanning Electron Microscopy and Transmission Electron Microscopy. As Vb increased from 50 to 260V, hardness was improved from 10 to 26GPa. Toughness grew at the same time and maximized at around 2MPa·m1/2 when Vb=210V. Simultaneous improvements in hardness and toughness were attributed to the densified microstructure with refined grains and increased compressive stress.

Toward hard yet tough CrAlSiN coatings via compositional grading

A set of CrAlSiN coatings was synthesized in homogenous and graded composition via magnetron sputtering in mixed Ar and N2 ambient. The microstructures are investigated using glancing angle X-ray diffractometry, field emission scanning electron microscopy and transmission electron microscopy. With compositional grading, CrAlSiN coatings exhibit much improved scratch adhesion strength and better crack propagation resistance at a little expense of hardness.

Surface evolution of titanium oxide thin film with swift heavy ion irradiation

Modification of the surface morphologies of titanium oxide nanoparticle thin films under swift heavy ion (SHI) irradiation was investigated using glancing angle X-ray diffractometry and atomic force microscopy. Irradiation at low ion fluences leads to grain fragmentation and a narrowing of the grain size distribution, whereas grain growth with increased average grain size and grain size distribution occur at high fluences. Associated with the change in the grain size and size distribution there occurs topological modifications at different fluences of SHI irradiation. The SHI-induced grain fragmentation, grain growth and modification of surface topography are explained by the thermal spike model of ion–matter interaction.

Growth process and corrosion resistance of micro-arc oxidation coating on Mg-Zn-Gd magnesium alloys

A Mg-6Zn-3Gd (mass fraction, %) alloy, noted as ZG63, was coated by different micro-arc oxidation (MAO) processes, and the coating structure and corrosion resistance of the alloy were studied using scanning electron microscopy (SEM), glancing angle X-ray diffractometry (GAXRD) and various electrochemical methods. The micro-arc oxidation process consists of three stages and corresponds with different coating structures. In the initial stage, the coating thickness is linearly increased and is controlled by electrochemical polarization. In the second stage, the coating grows mainly inward and accords with parabolic regularity. In the third stage, the loose coating forms and is controlled by local arc light. The looser coating is mainly composed of MgSiO 3 and the compact coating is mainly composed of MgO. From micro-arc oxidation stage to local arc light stage, the corrosion resistance of the coated alloy firstly increases and then decreases. The satisfied corrosion resistance corresponds to the coating time ranging from 6 to10 min.

Deposition and characterization of TiBCN films by cathodic arc plasma evaporation

TiBCN thin films were deposited on Si(100) substrate by reactive cathodic arc evaporation from a graphite/boron-containing composite target and Ti target in an N 2 atmosphere. Characteristics and microstructures of the films were investigated, deposited under different target currents. Raman spectroscopy and high resolution X-ray photoelectron spectroscopy (HRXPS) were employed to investigate the spectrum and bonding states of films. The film microstructures were evaluated by using an atomic force microscope (AFM), a field emission scanning electron microscopy (FEGSEM), a glancing angle X-ray diffractometry (GAXRD) and a high-resolution transmission electron microscopy (HRTEM). Results demonstrated that the TiBCN films were synthesized successfully and adhered well to the silicon substrate. The Raman spectra showed that wavenumbers ranging from 900 to 1800 cm − 1 consisted of D and G bands, similar to that of cathodic arc plasma deposited DLC. Raman spectra proved that the intensity of D and G bands decreased by increasing Ti target currents. HRTEM results established that TiBCN films revealed an amorphous structure while the Ti target current was low. As the Ti target current increased, the TiBCN films revealed a nanocomposite structure, an amorphous matrix consisting of nano scale Ti(C,N) and TiB crystalline, which were comparable to GAXRD, Raman and HRXPS results. The HRXPS spectra of B1s, C1s, N1s and Ti2p in the TiBCN films reveal much broader peaks; this indicated that there is more than one category of bonding state surrounding each of Ti, B, C and N atoms. Morphology, characteristics and film concentration as a function of deposition parameters were also investigated in this study.

The effects of deposition parameters on the structure and properties of titanium-containing DLC films synthesized by cathodic arc plasma evaporation

Titanium-containing diamond-like carbon films were deposited by mixing C+ and Ti+ plasma streams originating from cathodic arc plasma sources in argon (Ar). The deposition was processed at substrate bias voltages ranging from −50 to −300 V and a Ti target current ranging between 20 and 70 Amps. Film characteristics were investigated using Raman spectroscopy and high resolution X-ray photoelectron spectroscopy (HRXPS). The film microstructures were evaluated by using an atomic force microscope (AFM), a field emission scanning electron microscopy (FEGSEM), a glancing angle X-ray diffractometry (GAXRD) and a high-resolution transmission electron microscopy (HRTEM). Mechanical properties were investigated by using a nanoindentation tester, a ball on disc wear test and a scratch test. Raman spectra proved that the intensity of D and G bands decreased by increasing the bias voltage and Ti target currents. HRTEM results established that titanium-containing DLC films revealed a snake-skin like structure, consisting of nano scale TiC particles, comparable to GAXRD and HRXPS results. HRXPS analysis showed that the concentrations of titanium increased from 4.9 to 23.9 at.% and the C concentration proportionally decreased from 91.6 to 69.3 at.% as the Ti target current was gradually increased from 30 Amp to 70 Amp. Wear tests proved that the friction coefficient of titanium-containing DLC films were lower than that of DLC films. The scratch test also proved that the adhesive strength of Ti-DLC was significantly higher than that of conventional DLC.

Micro-Arc oxidation of Ti in a solution of sulfuric acid and Ti +3 salt

A comparative study was performed on the behavior of titanium electrode in a sulfuric acid solution with and without Ti +3 during micro-arc oxidation under the constant current density control regime. The composition and microstructure of the obtained micro-arc films were analyzed using scanning electron microscopy, glancing-angle X-ray diffractometry, Raman and energy-dispersive X-ray spectroscopies. We have shown that addition of a Ti +3 salt extends the region of current densities ( j a) can be used for micro-arc oxidation of Ti and results in an obvious change of sparking behavior from extensive, large and long-played sparks to numerous, small and short sparks. As a consequence, the titania films formed in the Ti +3-containing solutions are relatively thick, more uniform, composed of almost pure crystalline anatase and rutile phases of TiO 2, and contain a network of evenly distributed small pores. It has also been shown that these films are promising for applications in catalysis, sensors and optoelectronics. The Raman spectra indicate that an increase in the electrolysis time of titanium in the Ti +3-containing solution leads to the increase in rutile content, as expected.

Process monitoring during AlN deposition by reactive magnetron sputtering

The effect of pressure on the reactivity of sputtered Al during reactive magnetron deposition was monitored by optical emission spectroscopy (OES) and a Langmuir probe. The deposition experiments were carried out varying the total pressure from 0.1 Pa to 1.2 Pa in an Ar/N 2 7:1 flow ratio gas mixture. The deposited layers were analyzed by scanning electron microscopy (SEM) + energy dispersive analysis (EDS), glancing angle X-ray diffractometry (GAXRD) and X-ray photoelectron spectroscopy (XPS). Analysis of the films formed was based on the process parameters via plasma characterization. A correlation was found between the OES results and the amount of Al deposited. Under the present conditions, the base pressure was found to have a significant effect on the nature of the products deposited.

Swift heavy ion irradiation of a-Si∕Fe∕c-Si trilayers

Si ∕ Fe ∕ Si trilayers, with 12nm amorphous Si and 45nm polycrystalline Fe films deposited on Si(100) wafers, were irradiated with 350MeV Au26+ ions at fluences of (0.6–11.3)×1014ions∕cm2. The ion-induced modifications of their structural and magnetic properties were characterized by means of Rutherford backscattering, glancing angle x-ray diffractometry, and the magneto-optical Kerr effect. The mixing rate at the upper a-Si∕Fe interface was three times as high as that at the lower Fe∕c-Si interface. A simple formula is proposed, which on the basis of (nuclear) thermal-spike mixing reproduces the observed (electronic) mixing rates. Ion irradiation at a moderate fluence (6.7×1014∕cm2) induced a magnetic anisotropy in the sample, which was magnetically isotropic after deposition. At the highest fluence, full interface mixing occurred and the magnetic anisotropy almost disappeared. The results are compared with those obtained in Fe∕Si and Ni∕Si bilayers ion irradiated in the regimes of nuclear and electronic stopping.

Oxidation Resistance of TiAl Improved by Ion Implantation of Beta-Former Elements

TiAl coupon specimens were implanted with Fe. Mo, Ta or W ions and then cyclically oxidised with temperature varying between room temperature and 1200 K in a flow of purified oxygen under atmospheric pressure. The surfacemodification by the ion implantation was characterised by glancing angle X-ray diffractometry (GAXRD), Auger electron spectroscopy (AES) and transmission electron microscopy (TEM). The oxidised specimens were examined by AES, GAXRD, X-ray diffractometry, scanning electron microscopy and electron probe microanalysis. The oxidation resistance of TiAl is significantly improved by the implantation of Mo, Ta or W ions with a dose of 10 2 1 ios.m - 2 at acceleration voltages ranging from 50 to 340 kV. The acceleration voltage has a small influence. The oxide scales consist predominantly of α-Al 2 O 3 and are very adherent to the substrates even after 20 cycles (400 h). On the other hand. the implantation of Fe has a little effect. The significant effect brought about by the implantation is attributable to the formation of a thin β-Ti phase layer in the modified area. Therefore, a possible explanation for the improved oxidation resistance is the formation of β-Ti phase which is a solid solution where diffusion of Al seems much faster than in γ-ΤiAl which has an ordered structure. The enhanced Al diffusion results in the formation of a thin but continuous Al 2 O 3 -rich layer in the scale during the initial oxidation stages The enrichment of Al relative to Ti by the implantation was thought playing some role. The so-called doping effect of Mo, Ta and W is also contributing to the early formation of Al 2 O 3 -rich layers by retarding TiO 2 growth.

Failure paths at copper-base leadframe/epoxy molding compound interfaces

Black-oxide and/or brown-oxide layers were formed on the surface of copper-base leadframe sheets in hot alkaline solutions, and then the oxide-coated leadframe sheets were molded with epoxy molding compound (EMC). The molded bodies were machined to form sandwiched-double-cantilever-beam (SDCB) specimens, and the adhesion strength between oxide-coated leadframes to EMC was measured in terms of critical energy-release rate (GIC) using SDCB specimens. Results revealed that untreated leadframe and Cu2O-coated leadframe showed almost no adhesion to EMC, however once a continuous CuO layer formed on the leadframe surface (brown oxide) or on the Cu2O layer (black oxide), GIC increased to around 80 J/m2. A study of failure surfaces base on the scanning electron microscopy (SEM), glancing-angle X-ray diffractometry (XRD), Auger electron microscopy (AES), electron dispersive spectroscopy (EDS), and atomic force microscopy (AFM) analyses indicated that the failure path was closely related to the surface condition of leadframe prior to molding with EMC.

Influence of silicon ion implantation and post-implantation annealing on the oxidation behaviour of TiAl under thermal cycle conditions

Abstract TiAl coupon specimens measuring 15×10×1 in mm were implanted with Si ions at varying acceleration voltages ranging from 80 to 260 keV with a constant dose of 2.5×10 21 ions·m −2 . In addition, three-step implantation was performed to obtain a wider and flat distribution of Si along a depth direction. Their oxidation resistance was assessed by a cyclic oxidation test with temperature varying between room temperature and 1200 K in a flow of purified oxygen under atmospheric pressure. The holding time at temperature was 72 ks (20 h). Conventional metallographic examinations were performed for implanted specimens and oxidised specimens using X-ray diffractometry, glancing angle X-ray diffractometry, AES, SEM and EDS. The implantation under all the conditions examined does not improve the oxidation resistance. The scales on all the specimens partially spall after a few oxidation cycles. The post-implantation annealing at 800 K for 600 s in an Ar atmosphere enhances the oxidation with the formation of scales spalling earlier. However, the vacuum annealing at 1100 K for 3.6 ks decreases the oxidation rates and improves the scale adherence. The best oxidation resistance is obtained by vacuum annealing at 1100 K for 36 ks. The scales are very adherent and oxidation becomes very slow. This excellent oxidation resistance is attributable to the formation of a layer consisting mainly of SiO 2 and Al 2 O 3 in the scale during the initial periods of oxidation. This initially formed SiO 2 layer seems to have resulted in the enrichment of Al 2 O 3 beneath it. The influence of acceleration voltage is small and the three-step implantation is not so effective.

Comparative investigation of multilayer TiB2/C and co-sputtered TiB2-C coatings for low-friction applications

Composite low-friction coatings have been produced by combining a lubricating phase (C) and a hard wear-resistant phase (TiB2), deposited in the form of either multilayer (TiB2/C) or homogeneous (TiB2-C) films. The multilayer coatings were prepared by sequential magnetron sputtering, and the homogeneous coatings by co-sputtering from TiB2 and C targets. The coatings were characterised by glancing angle X-ray diffractometry and photoelectron spectroscopy. Friction coefficients were measured using a pin-on-disk tribometer, and hardness was determined by nanoindentation. Co-sputtered coatings were found to consist of two phases: diamond-like carbon (DLC) and a hexagonal TiB2-type structure into which carbon is incorporated. In the case of the co-sputtered coatings, overall C concentrations as high as 50 at.% were required to produce a friction-reducing effect. This can be explained by the preferential incorporation of the carbon atoms into the TiB2 lattice, the lubricating DLC phase only starting to form once saturation is reached. In the case of multilayers, it was found that there was an increase in the overall carbon content required to obtain a friction-reducing effect from about 10 to 50 at.% as the TiB2 sublayer thickness was decreased from 100 to 1 nm. This was attributed to an increase in the relative proportion of carbon bonded with TiB2 in the interface regions. It was shown that coatings with a hardness of the order of 20 GPa and displaying friction coefficients against steel as low as 0.1 for temperatures not exceeding 200°C could be obtained by selecting a suitable composition.

Influence of implantation of Al, Si, Cr or Mo ions on the oxidation behaviour of TiAl under thermal cycle conditions

Abstract TiAl specimens measuring 15×10×2 in mm were implanted with Al, Si, Cr or Mo ions of a dose of 1021 or 1.2×1021 (for Cr only) ions m−2 at an acceleration voltage of 50 keV. Their oxidation resistance was assessed by cyclic oxidation tests with temperature varying between room temperature and 1200 K in a flow of purified oxygen under atmospheric pressure. The holding time at temperature was 72 ks (20 h) or 3.6 ks (1 h). Conventional metallographic examinations were performed for implanted specimens and oxidised specimens using glancing angle X-ray diffractometry (XRD), Auger electron spectroscopy (AES), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The implantation of Al or Si is effective to decrease the oxidation rate during the first near parabolic period of 130 ks, after which the implantation of Al results in breakaway oxidation, while the implantation of Si gives low oxidation rate for at least up to 800 ks. The implantation of Cr accelerates the oxidation during the initial period and then the partial scale spallation takes place leading to occasional mass losses. The implantation of Mo results in very slow oxidation rate for up to 1500 ks when the experiment was terminated. The same effect was obtained for the implantation of Mo under conditions of 40 keV and 2×1021 ions m−2. The excellent oxidation resistance obtained by the implantation of Si or Mo is attributable to the formation of virtually Al2O3 scales during the initial oxidation periods.

Microstructure and mechanical properties of multilayer TiB 2/C and co-sputtered TiB 2-C coatings for cutting tools

The feasibility of reducing the friction coefficient of TiB 2-based coatings by the incorporation of carbon has been investigated for both multilayer and co-sputtered coatings. Characterisation was performed using pin-on-disk tribometry, nanoindentation, glancing angle X-ray diffractometry, X-ray photoelectron and Auger electron spectroscopy. The co-sputtered coatings were found to consist of two phases: a hexagonal TiB 2-type structure into which carbon is incorporated and a diamond-like carbon (DLC) phase. C is preferentially incorporated into the Ti(B,C) 2 phase and the lubricating DLC phase only starts to form once saturation is reached. Consequently, a reduction in the friction is only found at total C concentrations higher than 50 at%. For the multilayers, there was an increase in the overall carbon content required to obtain a friction-reducing effect from about 10–50 at% as the TiB 2 sublayer thickness was decreased from 100 to 1 nm. This was attributed to an increase in the relative proportion of carbon bonded with TiB 2 in the interface regions. Coatings with a hardness of about 20–30 GPa and friction coefficients of <0.2 against a steel ball could be obtained at a suitable composition.

High temperature deformation properties of HIP processed titanium boride-titanium aluminide : S.Ochiai et al. (Teikyo University of Science and Technology, Yamanashi, Japan.) J. Jpn Soc. Powder Powder Metall., vol 44, no 7, 1997, 647–652. (In Japanese.)

Hard, low-friction, TiB2-based coatings incorporating C or MoS2 have been synthesised by magnetron co-sputtering from TiB2 and C or MoS2 targets. The coating microstructure was characterised by glancing angle X-ray diffractometry and photoelectron spectroscopy. The friction coefficient was measured using pin-on-disk tribometry and hardness by nanoindentation. Our TiB2–C coatings were found to consist of two phases, diamond-like carbon (DLC) and a hexagonal TiB2 type structure into which carbon is incorporated. A friction-reducing effect was observed only at C concentrations above 66%, where a significant quantity of DLC phase was able to form. For TiB2–MoS2 coatings, a reduced friction was observed, even at low concentrations of MoS2. With both types of lubricants, a trade-off between hardness and friction coefficient was found. Coatings exhibiting a relatively high hardness of 20 GPa and friction coefficients as low as 0.05 could be obtained by choosing a suitable composition. Low friction could be obtained for temperatures as high as 400 °C for the TiB2–MoS2 coatings, whilst the TiB2–C coatings exhibited a sharp increase in friction coefficient above 150 °C.

Preparation and characterisation of low-friction TiB 2-based coatings by incorporation of C or MoS 2

Hard, low-friction, TiB 2-based coatings incorporating C or MoS 2 have been synthesised by magnetron co-sputtering from TiB 2 and C or MoS 2 targets. The coating microstructure was characterised by glancing angle X-ray diffractometry and photoelectron spectroscopy. The friction coefficient was measured using pin-on-disk tribometry and hardness by nanoindentation. Our TiB 2–C coatings were found to consist of two phases, diamond-like carbon (DLC) and a hexagonal TiB 2 type structure into which carbon is incorporated. A friction-reducing effect was observed only at C concentrations above 66%, where a significant quantity of DLC phase was able to form. For TiB 2–MoS 2 coatings, a reduced friction was observed, even at low concentrations of MoS 2. With both types of lubricants, a trade-off between hardness and friction coefficient was found. Coatings exhibiting a relatively high hardness of 20 GPa and friction coefficients as low as 0.05 could be obtained by choosing a suitable composition. Low friction could be obtained for temperatures as high as 400 °C for the TiB 2–MoS 2 coatings, whilst the TiB 2–C coatings exhibited a sharp increase in friction coefficient above 150 °C.

Crystallographic and morphological characterization of reactively sputtered Ta, Ta [sbnd]N and Ta [sbnd]N [sbnd]O thin films

This paper concentrates on the deposition of Ta, Ta N and Ta N O thin films by r.f. magnetron sputtering in Ar/N 2/O 2 gas mixtures. The film properties and their suitability as diffusion barriers and protective coatings in silicon devices were characterized using four-point probe measurements, Auger electron spectroscopy, Rutherford backscattering, glancing angle X-ray diffractometry, atomic force microscopy and scanning electron microscopy. With the addition of N 2 to the gas mixture a transition from tetragonal Ta to b.c.c.-Ta(N) was detected, leading to the nanocrystalline metastable b.c.c.-Ta(N) phase with approximately 20 at.% interstitially incorporated nitrogen. Increasing the nitrogen flow above a critical value, an abrupt transition between metal-sputtering to nitride-sputtering mode was observed, resulting in a sharp increase in the N:Ta atomic ratio slightly above the stoichiometric value for the TaN phase, which was found to exhibit f.c.c. structure. With the addition of oxygen at fixed nitrogen flow the films tend to grow in an amorphous state. Due to the lack of short-circuit diffusion paths, the as-deposited amorphous Ta(N,O) films are considered as excellent candidates for ultra-thin diffusion barriers and protection layers in future Cu-metallized ULSI devices.