X-ray Pole Figure Research Articles

Intrinsic effective elastic tensor of ferroelectric polycrystalline lead titanate based thin films with fiber-type texture

The intrinsic effective elastic tensor of polycrystalline lead titanate based thin films with mixed <001>,<100> fiber-type texture has been calculated by a volume average of the elastic coefficients of the individual crystallites, taking into account their actual crystallographic orientation relative to the film reference system. This is introduced in the calculations through an orientation distribution function, which is obtained by the quantitative analysis of experimental X-ray pole figures using a recently developed method: the combined approach. PbTiO 3 single crystal data have been used in the calculations. The elastic anisotropy of the single crystal tensor is strongly reduced for the textured thin films and depends on the relative contributions of the <001> and <100> texture components, being only negligible when both contributions are similar. The results presented in this work, and that can be applied to any other textured films with different compositions, contribute to the knowledge of the effective elastic tensor of these ferroelectric films, an important class of materials used in micro-electro-mechanical-systems, which is essential for the design of the devices.

Deformation Textures in FCC Metals Subjected to Frictional and to Abrasive Wear

The surface texture in fcc metals has been investigated after wear tests in a dry-running pin-on-disk test machine and after metallographic surface grinding. X-ray pole figures have been measured at a low angle of incidence of the primary beam, using an area detector for recording the diffraction patterns. SAD pole figures have been acquired on cross sections on-line in the TEM for examining the gradient of texture and microstructure beneath the surface. The XRD and SAD pole figures have been evaluated by ODF calculation. Wear and abrasion textures are distinctly different both for copper and bronze as well as for brass.

Microstructure and ferroelectric properties of low-fatigue epitaxial, all (001)-oriented (Bi,La)4Ti3O12∕Pb(Zr0.4Ti0.6)O3∕(Bi,La)4Ti3O12 trilayered thin films on (001) SrTiO3 substrates

( Bi , La ) 4 Ti 3 O 12 ( BLT ) ∕ Pb ( Zr , Ti ) O 3 ( PZT ) ∕ ( Bi , La ) 4 Ti 3 O 12 trilayered ferroelectric thin films were epitaxially grown by pulsed laser deposition onto (001) SrTiO3 (STO) substrates with and without SrRuO3 (SRO) bottom electrodes. From x-ray pole figures and electron-diffraction patterns, the epitaxial relationships between BLT, PZT, SRO, and STO were identified to be BLT(001)‖PZT(001)‖SRO(001)‖SrTiO3(001); BLT[110]‖PZT[100]‖SRO[100]‖SrTiO3[100]. Cross-sectional transmission electron microscopy investigations revealed that 90° ferroelectric domain boundaries lying on {110} planes are present in the PZT layer, with an average domain width of 20nm and an average spacing of 120nm. These long 90° ferroelectric domains, as a rule having nucleated at the bottom of the PZT layer, extend to the top of the latter. The thin films have sharp BLT/PZT interfaces and a very flat surface. The remanent polarization and coercive field were determined as 13.9μC∕cm2 and 72.9kV∕cm, respectively, indicating that the epitaxial, all (001)-oriented trilayered thin films have rather good ferroelectric properties, although single epitaxial (001)-oriented BLT films are usually not favored for application due to their very poor ferroelectric properties. The thin films showed a high fatigue resistance at least up to 1010 switching pulse cycles, confirming that such a trilayered structure effectively shows the fatigue-free behavior of BLT.

Microstructure and Texture in Copper Sheets after Reverse and Cross Rolling

The objectives of this investigation are structural effects in electrolytic copper sheets which are caused by the change of the direction of rolling. Unidirectional, reverse as well as cross-rolling at 90° respectively at 45° to the precedent rolling direction have been applied down to final deformations as low as 80% reduction in thickness. Texture has been determined by ACOM (Automated Crystal Orientation Measurement, “Automated EBSD”) in the SEM and by X-ray pole figure measurement. The main benefits of ACOM are a high spatial resolution which enables the investigation of texture gradients from the mid plane to the surface of the sheet, and the visualization of the microstructure by crystal orientation mapping. In addition to local texture, statistical distributions of misorientations across grain boundaries and of S grain boundaries have been derived from the individual grain orientation data. The change of the path of plastic deformation induces a destabilization of the substructure which is formed during the primary step of unidirectional rolling. A distinct change of texture is found depending on the deformation process. In cross rolling, the b fiber changes into the unstable b90 fiber which almost disappears with progressive deformation along the new rolling direction.

Local and Global Effects in Texture and Microstructure Observed after Channel-Die Compression of Copper Single Crystals and after Cross-Rolling of Copper Sheets

The change of the deformation path leads to destabilization of the substructure and affects the texture of the deformed metal. The observed changes of texture and microstructure are, as a rule, significant and their characteristics depend on the geometry of the deformation process. Previous investigations on copper (and copper alloy) samples after deformation by rolling and channel-die compression were based on X-ray pole figure measurements and on observations in the light microscope. Hereby only global texture and structural characteristics have been obtained. The present study is mainly based on measurements of individual crystal orientations performed by ACOM (Automated Crystal Orientation Measurement, “Automated EBSD”) in the SEM which enables a precise local analysis of the investigated phenomena. For the channel-die experiments, (1 1 2)[1 1 -1] and (1 1 2)[1 -1 0] oriented copper single crystals have been used. After pre-deformation, a second deformation step has been carried out in transverse direction. The {1 1 2}&lt;1 1 0&gt; orientations are destabilized by channel-die compression, and clusters of layers develop which are composed of complementary {1 1 0}&lt;1 1 2&gt; components. The deformation process in polycrystalline sheets after rotating the rolling direction leads again to a distinct disintegration of the microstructure and destabilization of the b fiber. This process of microstructure reorganization after pre-deformation is fast and of high dynamics.

Development of Textured Au Layer on Ni Substrate for YBCO Coated Conductors

Much effort has been made to develop new metallic buffers to explore the possibility of designing YBCO coated conductors (CC's) with a simple architecture. We selected Au because of its small lattice mismatch to Ni and chemical novelty, and plated it on a biaxially textured Ni substrate by the electroless-plating method. The texture of Au/Ni template was evaluated by X-ray pole-figure and orientation distribution function (ODF) analysis. The surface roughness and grain boundary morphology were characterized by atomic force microscopy (AFM). We fabricated the cube textured Au/Ni template for the CC and evaluated its texture formation and microstructural evolution. Texture analysis indicated that the Au layer was epitaxially deposited on the Ni substrate and formed a strong cube texture when the processing variables were optimized. The full-width at half-maximum (FWHM) was 8.4/spl deg/ for out-of-plane and 9.98/spl deg/ for in-plane texture when the plating time was 30 min. In addition, the root-mean-square (RMS) and the depth of the grain boundary for the Au layer were 14.6 nm and 160 /spl Aring/, respectively, which are significantly smaller than the corresponding values for the Ni substrate (27.0 nm and 800 /spl Aring/), indicating that the electroless-plated Au layer had a relatively smooth surface and effectively mollified grain grooves.

Growth and Properties of YBCO-Coated Conductors Fabricated by Inclined-Substrate Deposition

YBCO-coated conductors with high current-carrying capability are desirable for electric power transmission applications. Inclined-substrate deposition (ISD) is capable of producing high-quality biaxially textured template films, which are important for fabrication of YBCO-coated conductors. We have grown biaxially textured ISD-MgO template films on flexible metallic substrates at deposition rates of 2-10 nm/sec. Columnar grains with a roof-tile-shaped surface structure were observed on the ISD-MgO films. X-ray pole figure analysis revealed that the ISD-MgO film is biaxially textured and its c-axis is titled at an angle from the substrate normal. Strontium ruthenium oxide (SRO) buffer films were epitaxially grown on ISD-MgO by pulsed laser deposition prior to the deposition of YBCO. Low /spl phi/-scan full-width at half maximum (FWHM) values of 6/spl deg/ and 7/spl deg/ were observed for YBCO and SRO, respectively. T/sub c/ of 91 K with a sharp transition and transport J/sub c/ over 1.4 MA/cm/sup 2/ at 77 K in self-field were measured on YBCO coated conductors grown with ISD MgO architectures using a SRO buffer.

Investigation of Processing Variables of Ni Substrate for YBCO Coated Conductors

We fabricated cube textured Ni substrates for YBCO coated conductors from the initial specimens prepared by powder metallurgy (P/M) and casting and evaluated the effects of annealing temperature on microstructural evolution and texture formation. To characterize the roles of the two preparation methods, the initial specimens were prepared to be of the same size and experienced the same rolling conditions, and were then annealed in the temperature range of 600/spl deg/C to 1200/spl deg/C. The texture was evaluated by X-ray pole-figure analysis and transmission electron microscopy (TEM). The texture analysis indicated that a strong cube texture formed for the substrate made by P/M and this texture did not vary significantly with annealing temperature in the range of 600-1200/spl deg/C. On the other hand, the texture of the substrate made by casting was more dependent on the annealing temperature, and a twin texture ({221} ) and several minor texture components began to form at 1000/spl deg/C. Microstructural observation showed that the morphology of deformation band together with micro-band in the as-rolled tape prepared by P/M was more homogeneous and of higher density than that produced by casting, resulting in a strong cube texture in wider range of annealing temperatures and a finer microstructure after recrystallization.

Biaxial orientation in HDPE films: comparison of infrared spectroscopy, X-ray pole figures and birefringence techniques

In this study, high-density polyethylene films (HDPE) were produced using different processes (film blowing and biaxial orientation) and processing conditions. The orientation of the films was characterized in terms of their biaxial crystalline, amorphous and global orientation factors using birefringence, Fourier transform infrared spectroscopy (FTIR) using a tilted incidence technique and X-ray pole figures. Evaluation of a simplified FTIR procedure without using the tilted method for the determination of crystalline orientation factors proposed in the literature is also evaluated and assessed. The results indicate that FTIR overestimate the crystalline orientation factors, particularly for the crystalline a-axis. Significant discrepancies are also observed for the b-axis orientation, which may be due to an overlap of the amorphous contribution and/or saturation of FTIR bands. Those differences are larger for films with low orientation, such as blown films. Amorphous phase orientation from FTIR depends on the band used and is not necessarily in agreement with that determined from combination of X-ray and birefringence.

Biaxial Orientation Characterization in PE and PP Using WAXD X-Ray Pole Figures, FTIR Spectroscopy, and Birefringence

In this study, different polyethylene and polypropylene films (LDPE, LLDPE, HDPE, and PP) are produced using different processes (film blowing and biaxial orientation) and processing conditions. The orientation of the films is characterized in terms of their biaxial crystalline, amorphous, and global orientation factors using birefringence, Fourier transform infrared spectroscopy (FTIR) using a tilted incidence technique, and X-ray pole figures. The results indicate that FTIR overestimates the crystalline orientation factors, particularly for the crystalline a-axis. Significant discrepancies are also observed for the b-axis orientation, which may be due to an overlap of the amorphous contribution and/or saturation of FTIR bands. These differences are larger for films with low orientation, such as blown films. Amorphous phase orientation from FTIR depends on the band used and is not necessarily in agreement with that determined from the combination of X-ray and birefringence.

Oriented structure of PP/LLDPE multilayer and blends films

Polypropylene/linear low-density polyethylene (PP/LLDPE) multilayer and blends blown films are investigated in terms of crystalline morphology and orientation. The crystalline structures were probed using microscopy, infrared trichroism and X-ray pole figures. Two different PPs were used, one was a homopolymer and the other was a copolymer. Similar orientation characteristics were observed for both PP components in the blends and multilayer films, the PE component, however, showed very different structure, especially for the crystalline a- and b-axes orientation. The row-nucleated structure, epitaxial crystallization and transcrystallization observed in the films are discussed.

High growth rate deposition of oriented InN pillar crystals

High growth rate deposition of highly oriented indium nitride (InN) pillar crystals were successfully grown on Si(100) substrate prepared under atmospheric pressure using a halide CVD method (AP-HCVD). The growth rate of InN pillar crystal can be enhanced threefold by AP-HCVD system with metal halide dual sources zone, and the maximum growth rate of 8.33 nm/s was achieved. X-ray diffraction and X-ray pole-figure analyses showed that the each InN pillar crystal grows with a different rotation angle around the 〈001〉 axis. Selected area transmission electron diffraction showed that that they are of high crystal quality.

Synthesis of epitaxial GaN single-crystalline film by ultra high vacuum r.f. magnetron sputtering method

GaN films were prepared by an ultra high vacuum r.f. magnetron sputtering method, and their crystalline structures depending on total gas pressure, growth temperature, substrate material and film thickness were examined. In X-ray diffraction measurements, GaN film grown at room temperature and gas pressures less than 0.53 Pa, indicated a higher c-axis preferred orientation. When the growth temperature was increased up to 800 °C, crystalline quality of the GaN film was dramatically improved as compared with those prepared at temperatures less than 800 °C. For GaN films on α-Al 2O 3 (0001) substrates, full width at half maximum values of both X-ray rocking curve for α-GaN (0002) plane and E 2 (high) phonon peak at Raman spectra, became narrower than those for GaN films on Si (100) substrates. Moreover, the crystalline quality of GaN film was improved with an increasing film thickness, in the case of α-Al 2O 3 substrate. A scanning electron microscope image of 1.5 μm thick GaN film surface on α-Al 2O 3 substrate indicated a number of hexagonal pyramids with six {10–11} facets. The X-ray pole-figure indicated that the GaN film on α-Al 2O 3 substrate was epitaxially grown single crystal.

Formation of uniaxially (1 1 2¯ 0) textured ZnO films on glass substrates

Making use of the RF magnetron sputtering technique, we have succeeded in fabricating ZnO films where c-axis of crystallites are unidirectionally aligned in the plane, without the mechanism of epitaxy. The alignment of c-axis in the plane was then carefully investigated by the X-ray pole figure analysis and atomic force microscope measurements. From these results, we have revealed the effect of substrate position during sputtering on the c-axis alignment in the plane. We have also pointed out the important effect of the oxygen ions in the RF plasma on the (1 1 2¯ 0) texture formation.

Growth and properties of YBCO-coated conductors on biaxially textured MgO filmsprepared by inclined substrate deposition

YBa2Cu3O7−δ (YBCO) filmswere fabricated on SrRuO3 (SRO)-buffered MgO templates grown on Hastelloy C276 metallic substrates, on which theMgO layers had been deposited by inclined substrate deposition (ISD) using electron beamevaporation. YBCO and SRO films were deposited by pulsed laser deposition (PLD).ISD-MgO substrates fabricated with two different substrate inclination angles(α = 35° and 55°) were used to grow YBCO films. High transport critical current density,Jc = 1.4 × 106 A cm−2, has been measured at 77 K in self-field for YBCO film grown on ISD-MgO withα = 35°, whereas YBCO film grown on ISD-MgO withα = 55° had alower Jc = 0.5 × 106 A cm−2. X-ray pole figure patterns revealed a cube-on-cube orientationrelationship among YBCO, SRO, and ISD-MgO films, with thec-axis of the YBCO filmbeing tilted. X-ray ω and ϕ-scans revealed good in-plane and out-of-plane textures of YBCO film grown on ISD-MgOsubstrate. The YBCO film grown on ISD-MgO with substrate inclination angleα = 35° had a YBCO(005)ϕ-scan full widthat half maximum (FWHM) = 5.8° and a YBCO(007) ω-scan FWHM = 2.8°, whileYBCO film with α = 55° had YBCO(005) ϕ-scan FWHM = 5.4° andYBCO(007) ω-scan FWHM = 2.6°.

Epitaxial Growth of (001)ZrN Thin Films on (001)Si by Low Temperature Process

We have prepared (001)ZrN films epitaxially grown on (001)Si substrates by a low temperature process using an ultrahigh vacuum magnetron sputtering system, and evaluated their epitaxial relationships and film qualities, using X-ray diffraction (XRD) analysis, X-ray pole figure, grazing incidence angle X-ray reflectivity (GIXR), transmission electron microscopy (TEM) and atomic force microscopy (AFM). It is clarified that (001)ZrN films grow epitaxially on (001)Si even at room temperature with the directional relationship of ZrN(001)[110]∥Si(001)[110], and the lattice mismatch at the interface between (001)ZrN and (001)Si is relaxed due to the existence of a very thin transition layer. It is also revealed from GIXR and AFM that the epitaxial ZrN films have a high film density and a flat surface morphology, irrespective of substrate temperature.

Fracture Resistance of Highly Textured Alumina

Textured alumina has been fabricated previously by either hot-deformation processing, to produce moderate texture, or templating with aligned platelets, to produce stronger texture. Fracture-toughness measurements on ceramics fabricated by hot deformation have indicated only a modest improvement in toughness compared with that of untextured ceramics, while measurements on more strongly textured ceramics have been very limited. In this work, a simplified process for fabricating highly textured alumina was developed, using a solvent-based slurry, tape casting, and liquid-phase sintering. Grain size was tailored to maximize the likelihood of grain bridging and crack deflection. Image analysis was used to characterize morphologic texture, and X-ray pole-figure analysis was used to measure crystallographic texture. Fracture tests revealed significant changes to the crack path as a result of the texture. However, the apparent fracture resistances measured using single-edge notched-beam samples were similar for textured and untextured ceramics. The lack of apparent toughening resulting from texturing is discussed in light of previous results.

Tensile/compressive behaviour of non-layered tetragonal Ni52.8Mn25.7Ga21.5 alloy

The stress–strain behaviour of the alloy Ni52.8Mn25.7Ga21.5 with the non-modulated tetragonal martensite (T) crystal structure was studied below Ms temperature with stresses needed for the martensite variant structure reorientation, i.e. detwinning. At ambient temperature the stress plateau of the detwinning showed a total strain of 21–22% with 18–20 MPa stress. After the first cycle, the tensile/compression cycles were repeatable. With maximum strain the single variant structure was obtained which was verified with X-ray pole figures. The tension-compression cycling decreased the stress plateau to 10–12 MPa, while the increasing testing temperature lead to a value of 6.7 MPa close to the reverse transformation temperature.

Crystal quality, electrical and optical properties of single crystal pyrite films prepared by chemical vapor deposition under atmospheric pressure

Crystal quality, electrical and optical properties of single crystal thin films of pyrite prepared by means of chemical vapor deposition under atmospheric pressure (AP-CVD) using FeCl 3 and CH 3CSNH 2 as starting materials have been studied by various analytical method. X-ray diffraction and pole figure measurements showed that the as-grown films are single crystal. It was found that the quality of the pyrite films grown on a Si(100) substrate is significantly dependent upon the ratio of CH 3CSNH 2:FeCl 3 used as source materials. Electrical conductivity and Hall mobility increases as the CH 3CSNH 2:FeCl 3 ratio is increased, while carrier concentration decreases. This is explained in term of the formation of sulphur vacancies. A decrease of the CH 3CSNH 2:FeCl 3 ratio causes the increase of sulphur defects in the pyrite film. This also increases the number of electrons being trapped by the defects, while their mobility is reduced because of the electron being scattering at the vacancies. Strong absorption occurs in the photon energy range higher than 1 eV, and then reaches plateau with an absorption coefficient of about 5 × 10 4 cm − 1 at E > 2 eV .

Tensile/compressive behaviour of non-layered tetragonal Ni52.8Mn25.7Ga21.5 alloy

The stress–strain behaviour of the alloy Ni 52.8 Mn 25.7 Ga 21.5 with the non-modulated tetragonal martensite (T) crystal structure was studied below M s temperature with stresses needed for the martensite variant structure reorientation, i.e. detwinning. At ambient temperature the stress plateau of the detwinning showed a total strain of 21–22% with 18–20 MPa stress. After the first cycle, the tensile/compression cycles were repeatable. With maximum strain the single variant structure was obtained which was verified with X-ray pole figures. The tension-compression cycling decreased the stress plateau to 10–12 MPa, while the increasing testing temperature lead to a value of 6.7 MPa close to the reverse transformation temperature.