X-ray Pole Figure Measurements Research Articles

Magnetic field effects on the crystal orientation and surface morphology of electrodeposited iron films

The effects of a magnetic field (5 T) on crystal orientation and surface morphology were investigated for iron films electrodeposited in ferrous aqueous solution. XRD measurements for the iron films showed that the preferred orientation parallel to the substrate was determined by the current density and not influenced by the magnetic field. By X-ray pole figure measurements, however, the crystal texture of the iron films electrodeposited at 10 mA cm−2 and 30 mA cm−2 was found to be controlled by the magnetic field. That is, the (110) planes were orientated in same direction of the magnetic field vector at angles of 30° and 35° to the direction normal to the substrate plane at 10 mA cm−2 and 30 mA cm−2, respectively. When the morphology was observed by SEM, iron grains at 30 mA cm−2 changed from a triangular pyramid shape at 0 T to a complex star-like shape at 5 T.

Real time in-situ stress evolution investigation of highly textured electrodeposited bismuth thin films

AbstractBismuth, a semi-metal with very long mean free path and large magnetoresistance (MR) effect, is a novel candidate material for thin film spintronic devices. Electrochemical deposition followed by a post-deposition anneal has resulted in highly textured bismuth films as characterized by x-ray diffractometry and pole figure measurements. A highly sensitive, real time in-situ stress measurement system was designed and employed to study stress generation during bismuth film growth. Bismuth films displayed a monotonically increasing compressive stress during deposition. The magnitude of the compressive stress decreased with the deposition rate in the range 1.5 Å/sec to 50 Å/sec.

Effects of Ti on the formability of Ti−IF steels

In the present study, the influence of precipitations and texture evolution on the sheet forming properties of Ti added IF (Interstitial Free) steels has been investigated. Precipitations in Ti−IF steels were examined using TEM. Equilibrium precipitation behavior was simulated to predict the proper amount of Ti addition to IF steels to fix interstitial atoms. Texture evolution was studied by employing X-ray pole figure measurement and ODF analysis. The formability of Ti−IF steels was improved by fixing interstitial atoms C, N, S with Ti. Additional improvement of formability was also found due to the existence of solute Ti of about 0.02 wt.%. A systematic analytical methodology for the precipitation behavior and texture evolution of Ti−IF steels was established for the development of IF steels.

Fabrication of epitaxial In 2O 3(ZnO) 5 thin films by RF sputtering and their characterization by X-ray and electron diffraction techniques

Thin films of In 2O 3(ZnO) m ( m=5), having two-dimensional layered structure, were synthesized by RF magnetron sputtering technique on (0 0 0 1) sapphire substrate. Effects of sputtering atmosphere and post-annealing on crystallinity and mosaic structure of the films were investigated by transmission electron microscopic (TEM) observations and X-ray pole-figure measurements. It was indicated that high oxygen partial pressure is necessary for the formation of layered structure and that the crystallinity was improved by post-annealing in oxygen gas. It was also found that electric conductivity was steeply suppressed by annealing. The mechanisms of the suppression of electric conductivity and the formation of layered structures are attributed to ordering of the defects associate with In ions.

Synthesis and Properties of Highly Oriented (Sr, Ba)(Nb, Ta)2O6 Thin Films by Chemical Solution Deposition

Transparent and highly oriented (Sr, Ba)(Nb, Ta)2O6 (SBNT) thin films have been synthesized by a chemical solution deposition method. A homogeneous and stable SBNT precursor solution was prepared by controlling the reaction of metal alkoxides in solution and by optimizing the additive as a stabilizing agent. Tantalum-substituted (Sr0.5Ba0.5)Nb2O6 powders and thin films, such as (Sr0.5Ba0.5)(Nb0.5Ta0.5)2O6 (SBNT50/50) and (Sr0.5Ba0.5)(Nb0.8Ta0.2)2O6 (SBNT50/80), directly crystallized into the tetragonal tungsten bronze phase at 700°C. The synthesized SBNT thin films on MgO(100) and Pt(100)/MgO(100) had a prominent c-axis-preferred orientation. Two crystal lattice planes of SBNT were found to intergrow at an orientation of 18.5° on MgO(100) and Pt(100)/MgO(100) substrates by X-ray pole figure measurement. The SBNT50/80 and SBNT50/50 thin films on Pt(100)/MgO(100) were paraelectric at room temperature and showed diffuse phase transition of the ε-T curves.

Superconducting property of Re123 films formed on textured silver tapes by chemical vapor deposition

Cube-textured Ag tapes of Ag{1 0 0} 〈0 0 1〉 were investigated to obtain in-plane aligned Re123 films, where Re represents Y, Gd, Sm and Nd by a continuous chemical vapor deposition technique. Y123 and Gd123 films formed on Ag{1 0 0} 〈0 0 1〉 tapes showed two types of the location, cube-on-cube and diagonal-on-cube, because of the lattice mis-fit between Ag and Y(Gd)123. On the other hand, Nd123 and Sm123 films formed at lower deposition temperature of 760°C indicated the good in-plane texturing. The in-plane aligning defined from the ratio of the (1 0 3) peak intensities by X-ray pole figure measurement was improved to 89% for Nd(Sm)123 films compared with 50% for Y(Gd)123 films.

Structure and formation mechanism of subgrains in large single-grain RE–Ba–Cu–O (RE=Y, Sm, Nd) bulk superconductors

We have studied the subgrain structures in large single-grain RE–Ba–Cu–O (RE=Y, Nd, Sm) bulk superconductors with polarized optical microscopic observations and micro-area X-ray pole figure measurements. Subgrains were formed in the early stage of grain growth, and were elongated along the growth direction with increasing their misalignment. Based on the comparative study of misorientation angles with the geometry of the second-phase particles, as well as microstructural defect studies using transmission electron microscope, the subgrains are created by the particle incorporation and their related lattice defects through the instability at the solidification front.

Recrystallisation textures of particle-containing Al–Cu and Al–Mn single crystals

The influence of second-phase particles on the recrystallisation textures of rolled Al–Cu and Al–Mn single crystals is studied. Single crystals with the initial orientations (011)[100], (011)[21 1 ̄ ] , (112)[11 1 ̄ ] and (001)[100] are investigated by means of X-ray pole figure measurements and TEM microstructure analysis. The recrystallisation textures are interpreted in terms of a growth selection out of a limited spectrum of nucleus orientations. In the case of stable initial orientations the nucleus spectrum is produced by the lattice rotations within the deformation zones around the second-phase particles. For unstable orientations the nucleus spectrum can be attributed to the rotation paths during the orientation changes upon rolling deformation (orientation splitting or rotations). During the subsequent growth selection, orientations with a 40°〈111〉 orientation relation to the rolling texture prevail and, thus, form the recrystallisation textures observed. Interestingly, this preference of grains with a 40°〈111〉 orientation relation occurs at the very early phases of recrystallisation, right at the transition from a potential nucleus to a recrystallised grain. This process is labelled micro-growth selection.

Preparation of heteroepitaxial Pb(Mg 1/3Nb 2/3)O 3 (PMN) thin film by pulsed laser deposition on Si(001) substrate using La 0.5Sr 0.5CoO 3 (LSCO)/CeO 2/YSZ triple buffer

Preparation of heteroepitaxial Pb(Mg 1/3Nb 2/3)O 3 (PMN) thin films by pulsed laser deposition (PLD) was successful on Si(001) substrate using La 0.5Sr 0.5CoO 3 (LSCO)/CeO 2/YSZ triple buffer structure for the first time. Using this triple buffer, the formation of pyrochlore type compounds was completely suppressed. The heteroepitaxial growth of PMN, LSCO, CeO 2 and YSZ on Si(001) substrate was confirmed by both X-ray pole figure measurement and RHEED observation. In this work, the thickness dependency of both crystal structure and electrical properties of PMN thin film was examined as a function of the thickness of PMN between 1.6 and 130 nm. The lattice parameter and FWHM (ω scan) of PMN thin films increased with the decrease of the thickness of PMN. The current density of PMN thin film was low irrespective of the thickness of PMN (9.2×10 −7 and 2.9×10 −6 A/cm 2 for 130- and 6.3-nm-thick, respectively. Dielectric constant of heteroepitaxial PMN thin film was decreased with the thickness, which was attributed to the depletion width.

X-ray texture investigations of bacterial cellulose

Never dried highly swollen bacterial cellulose fleeces produced by the bacteria Acetobacter xylinum were deformed uniaxially and kept under strain during the drying process. The orientation of the crystalline nano-fibrils was determined by X-ray pole figure measurements of the (1–10) lattice plane in reflection mode and the (004) interference in transmission mode. Appropriate cuts through the pole figures were used for the determination of planar and axial degrees of orientation. Generally, a uniplanar texture with the (1–10) planes parallel to the fleece surface and an axial component in the draw direction were found. With increasing draw ratio both the axial orientation and the uniplanar orientation in draw direction were improved, whereas transversely the uniplanar texture component broadened slightly. Mechanical strength and modulus were almost doubled and tripled, respectively, for favoured cases. As compared to the wet aqueous samples, a higher coherent deformation of the bacterial cellulose membrane could be achieved by drawing the samples soaked in NaOH solutions with concentrations in the range of 8 to 10 wt.-%. By the presence of the lye significant improvements of the axial chain orientation of up to 100% could be obtained resulting in a maximum strength of 580 MPa. The improved orientability is likely to be explained by a NaOH-induced reduction in the number of inter-fibrillar bridging points formed by H-bonds

Characteristics of GaN films grown on the stress-imposed Si(111)

Characteristics of the GaN film affected by the strain field existing in the implanted Si(111) substrate have been investigated. The Si(111) substrates were implanted with N + prior to the film growth. GaN epitaxial films with AlN-buffered and GaN/AlN-buffered layers, respectively, were grown on implanted-substrates by metalorganic chemical vapor deposition. From the Raman scattering and X-ray pole figure measurements, characteristics of GaN films, especially, with AlN-buffered layer were highly affected by the stress-imposed substrates and the better crystalline quality was obtained by employing a highly dosed substrate.

Heteroepitaxial growth of CeO 2 thin film on Si(001) with an ultra thin YSZ buffer layer

The effect of YSZ thickness on the epitaxial growth of CeO 2 on Si(001) was investigated. The CeO 2/YSZ/Si thin films were prepared by pulsed laser deposition. The X-ray pole figure measurement revealed that heteroepitaxial growth of CeO 2 is realized with a 0.5-nm-thick YSZ thin film which corresponds to one unit cell of YSZ. However, when the thickness of the YSZ thin film was 0.5 nm, traces of the CeO 2(111) diffraction were also detected. The CeO 2(111) diffraction was not detected for samples having more than 1.5 nm of YSZ thickness. Therefore 1.5 nm YSZ is enough to permit the complete epitaxial growth of CeO 2 on Si(001). The effect of such ultra thin YSZ on the heteroepitaxial growth of CeO 2 has not been reported thus far.

Design of new UV/blue/green light emitters made of hexagonal-phase ZnMgCdOSSe mixed-crystal system fabricated on GaAs- and InP-(1 1 1) substrates

A new candidate for long lifetime short-wavelength light emitters made of hexagonal II–VI compounds has been proposed. In this paper, the results of theoretical design of ZnMgCdOSSe-based light emitters fabricated on (1 1 1) plane of GaAs and InP substrates is presented. The band lineups of CdZnS/ZnSSe and CdZnS/ZnMgS structures were estimated with Harrison's LCAO theory. Further, as for the first step of an experimental investigation on the growth of high phase-quality hexagonal II–VI compounds, growth of CdZnS epilayers were examined on GaAs(1 1 1) substrate. The epilayers were characterized by high-resolution X-ray diffraction reciprocal space and pole figure measurements. In this study, the optimum growth temperature was 300°C for hexagonal phase CdZnS, and the inclusion of cubic phase CdZnS drastically decreased with increasing Cd content at 300°C.

Cube Texture in A3004 Alloy Sheet Processed by Partial Annealing and Light Rolling Method

Formation of cube texture by two step process of partial annealing and rolling of small reduction was investigated by optical metallography and X-ray pole figure measurements. Hot rolled sheet with 3.5 mm thickness was cold rolled to 90% reduction and annealed at 300 °C to various partially softened states. Subsequently, cold rolled and annealed sheets were lightly rolled up to 20 % reduction and annealed at 350 °C for 1 h. Cube texture was sharper than that obtained without partial annealing and light rolling. In addition to the first step of partial annealing and small reduction, the second process of partial annealing at 300 °C for 64 min and light rolling to 10 % was conducted, resulting in formation of sharper cube texture than that obtained by the first step process. There was tendency in the cube grains to grow to large size, being elongated to rolling direction with orientational spread around rolling direction.

Grain texture and bulk magnetic anisotropy correlation in polycrystalline Bi 2Sr 2CaCu 2O 8+ δ thin rods

The texture of Bi–Sr–Ca–Cu–O (BSCCO)-2212 polycrystalline thin rods, fabricated with a laser induced floating zone melting technique has been quantified and correlated with their bulk magnetic anisotropy. Scanning Electron Microscopy (SEM) determinations and X-ray Pole figure measurements on longitudinal and transverse cross-sections have been used to derive the spatial distribution of the crystallographic axes of the grains. The magnetic anisotropy has been deduced from the angular field dependence of the irreversible dc magnetisation. The correlation between these properties has been analysed in samples with a very different microstructure associated to slow and fast growth rates.

Anisotropy in magnetic and mechanical properties in textured Hiperco® FeCoV alloys

Hiperco ® FeCoV alloys are soft magnetic materials suitable for applications at high temperatures and under high stresses. We have studied the evolution of the rolling texture and its effects on the mechanical and magnetic properties after annealing the Hiperco® sheets at high temperatures. X-ray pole-figure measurements reveal that the main texture of the as-rolled HA50HS and HA50 sheets is {001}〈11̄0〉. This rolling texture causes the mechanical and magnetic properties to exhibit a uniaxial anisotropy, which is reduced by annealing.

High-purity cubic GaN grown on a AlGaAs buffer layer by molecular beam epitaxy

High-purity cubic GaN films have been successfully grown on a AlGaAs buffer layer by molecular beam epitaxy. A characteristic nitrided AlGaAs smooth faceted surface was observed. It was found that GaN epilayers grown on a nitrided Al 0.17Ga 0.83As buffer layer were epitaxial and contained only the cubic phase. No diffraction peaks associated with the hexagonal phase of GaN were observed by X-ray pole-figure measurements.

Preparations and Characterizations of Epitaxial SrBi2Ta2O9 Thin Films

AbstractEpitaxial (001)-, (116)- and pseudo (103)-oriented Sr0.35Bi2.2Ta2O9 (SBT (0.35/2.2/2.0)) films were successfully grown on (001), (110) and (111) SrTiO3 substrates, respectively. High-resolution X-ray diffraction reciprocal space mapping (HRXRD-RSM) measurements and pole figure measurements clearly indicated that the (116)-oriented SBT (0.35/2.2/2.0) film consisted of two growth domains those c-axis are separated 180° apart in in-plane and pseudo (103)-oriented SBT film consisted of three growth domains those c-axis are separated 120° apart in in-plane. Moreover, lattice parameter measurements indicated that SBT films grew in fully relaxed state.

Ｐｔ下地層上にスパッタしたＣｏ‐Ｐｔ合金膜の結晶構造と垂直磁気異方性

Co-Pt alloy films were sputtered on (111)- and (100)- oriented Pt underlayers. The crystal structure was analyzed by means of X-ray pole figure measurements. On (111)-oriented Pt underlayers, the crystal structure of Co-Pt alloy film was (0001)-oriented hcp when the Pt content was less than 40%, but changed to (111)-oriented fcc when the Pt content exceeded 50%. In the region between 40% and 50%, both hcp and fcc structures existed. On the other hand, the Co-Pt alloy films on (100)-oriented Pt underlayers had a (100)-oriented fcc structure. Torque measurements revealed that the perpendicular anisotropy constant Ku was relatively small in the films with the (111)- or (100)-oriented fcc structure. However, Ku was quite large in the films with the (0001)-oriented hcp structure, reaching 0.7 MJ/m3 at a Pt content of about 30%. The perpendicular anisotropy seems to originate in the crystalline anisotropy of the hcp Co-Pt alloy.

Structural investigations of silicon carbide films formed by fullerene carbonization of silicon

Abstract Silicon carbide films with a thickness of up to half a micron have been formed on silicon substrates by evaporating fullerene (C60) molecules onto the heated substrates (T≥800°C). Rutherford backscattering spectrometry (RBS) shows the 1:1 stoichiometry of Si:C in all cases. The phase composition and microstructure of the films have been investigated by X-ray pole figure measurements and by cross-sectional transmission electron microscopy (XTEM). The pole figure measurements show that the silicon carbide mainly consists of hexagonal phases with the hexagonal unit cell declined at about 17° with respect to the surface. XTEM analysis confirms this observation, as columnar growth of hexagonal SiC platelets with the platelets being declined with respect to the surface is seen. With this carbonization technique, silicon carbide films can be deposited at comparably low temperatures onto several materials, if prior to carbonization a silicon film has been evaporated.