Papers by Keyword: Preferred Orientation

Abstract: Six samples of Nd-Fe-B-permanent magnets, distinguished in the texture degree, have been measured by neutron diffraction in the reflection and transmission regimes. The texture in the samples was formed by application of impulses of external magnetic field 0H = 4 T. Analysis of the obtained neutron diagrams by means of the Fullprof program allowed quantitative determination of the texture degree and conclusion to be made that the texture degree grows with an increase in numbers of magnetic field impulses.

Abstract: CrNx films were synthesized under graded/constant bias by DC magnetron sputtering. In the present work, the graded bias deposited CrNx films have both (111) and (200) orientations while only (111) orientation in low bias (-20 V) and (200) orientation in high bias (-200 V). Both the magnitude of bias and preferred orientation result in the variation in their surface morphology from pyramidal (loosen) to cellular (dense) structure. The hardness of the graded films is between the low and high constant bias ones. The relationship between the hardness and bias gradient is similar with the relationship of hardness and the content of (200) preferred crystallites, which implies the fine (200) preferred crystallites is an important factor for hardness of graded bias films.

Abstract: This present investigation describes the orientation and its influence factors of unidirectional C/C composites prepared by PAN-based carbon fiber and mesophase pitch (AR-MP) through hot pressure molding process. And the orientation of C/C composites was analyzed by POM and XRD. The experimental results indicated that the AR-MP dispersed in carbon fiber had a strong flow texture, showed a matrix preferentially oriented parallel to fiber surface. Under the pressure of 25MPa, the orientation of composites was better than under 50MPa. Moreover, the sample orientation varies in the two directions both perpendicular to the direction of carbon fiber. Better orientation was obtained in the testing direction which was perpendicular to the direction of carbon fiber and molding pressure.

Abstract: Preferred orientation of AlN film has been changed from random to c-axis textured by inserting the ultra-thin Pt/AlN underlayer. The ultra-thin Pt underlayer also exhibits the same effect on the preferred orientation control of AlN film. According to intensity distributions of diffracted X-ray collected as the function of 2θ and ψ on these films, it is clearly shown that c-axis of AlN is altered from titled to the surface normal. AlN film and AlN films with underlayers demonstrate tensile stress, and it can be reduced by inserting underlayers. The effects of underlayers on the development of the preferred orientation and the reduction of stresses are similar to that of decreasing sputtering gas pressure.

Abstract: We have developed a bottom-up growth technology for nanostructures from a Cu surface by Ar ion irradiation. Cu2O conical nano-/micro-protrusions have been nucleated and grown from the surface of a preoxidized Cu plate by Ar ion irradiation in low vacuum. In this study, the growth direction or preferred orientation of the protrusions was analysed using glancing angle X-ray diffraction (GAXRD) analysis and an X-ray diffraction pole figure (XRD-PF) measurement. The GAXRD patterns showed that the main phase of the product obtained by Ar irradiation was Cu2O, shown as the highest peak of Cu2O (111), and CuO was additionally formed. The intensity ratio of Cu2O (110) to Cu2O (111) increased as the X-ray incident angle decreased from 10.0 to 0.5 deg, which indicated that the basal plane of the protrusions including the substrate was (110). Additionally, the XRD-PF {011}<001> 3-D plots showed the <110> preferred orientation of the product. These results explain that the growth direction or preferred orientation of the Cu2O protrusions is mainly <110>. The growth direction of the protrusions was separated and confirmed as <110> by checking the electron backscatter diffraction pattern (EBSP) of each protrusion.

Abstract: The degree of preference of thin anatase TiO2 films prepared by CVD for the <112> orientation was enhanced by pretreating the soda-lime glass substrates with a plasma. The relationships between the preferred orientation and plasma pretreatments were investigated. It was founded that the TiO2 films on the plasma pretreated soda-lime glass substrates exhibited a higher degree of preference for the (112) orientation than those without the pretreatment. To confirm the effect of the plasma pretreatments on the soda-lime glass substrates, TOF-SIMS, contact angle measurement and TEM were used to determine the changes in the components, surface energy and crystallinity of the substrates, respectively. It was found the components added as network modifiers, such as Na+, Ca2+, and K+ ions, was depleted in the surface region of the substrates after the plasma pretreatment, and that the surface energy of the substrates was increased. Finally, it was observed that the substrate surface was changed from an amorphous phase to polycrystalline. To sum up, it was assumed that the surface of the soda-lime glass substrates with their partially crystalline, namely poly-crystalline, structures artificially induced the thin anatase TiO2 films to develop with a <112>-preferred orientation. In conclusion, the plasma pretreatment of the glass substrate caused the TiO2 thin films to exhibit a higher preference for the <112> orientation, thereby optimizing their photocatalytic efficiency.

Abstract: Giant magnetostrictive composites have attracted a great deal of attention by supplementing shortcomings of monolithic Terfenol-D such as brittleness, eddy current loss and formability. Recently, infiltrated Terfenol-D/Epoxy composite has been developed as an alternative composite. This composite was fabricated by an unidirectional solidification of Terfenol-D followed by an infiltration of epoxy. The iron content in composite has been changed in order to control volume fraction of RFe2 phase producing magnetostriction on Terfenol-D/Epoxy composite. The magnetostriction of both as-grown and infiltrated Terfenol-D/Epoxy composite was measured to confirm the effects of eutectic phase and heat treatment on magnetostriction. The enhancement of magnetostriction of Terfenol-D/Epoxy composite was mostly contributed by the eutectic phase through the hindering of movement and rotation of domain walls. The magnetostriction modelling of Terfenol-D/Epoxy composite was suggested, based on the change of texture and elastic modulus. The suggested model was in good agreements with the experimental results on the measurement of magnetostriction of Terfenol-D/Epoxy composite.

Abstract: Bilayer Ba0.6Sr0.4TiO3 - Ba0.4Sr0.6TiO3 and Ba0.4Sr0.6TiO3 - Ba0.6Sr0.4TiO3 thin films were deposited on the LaNiO3-buffered Pt/Ti/SiO2/Si substrates using pulse laser deposition method. A (100)preferred orientation was obtained. The structure was characterized using x-ray diffraction (XRD) and Raman spectroscopy. The leakage current, and dielectric permittivity versus temperature were characterized. Results indicated that the (100) preferred bilayer structure had less leakage current and smaller loss tangent, which was in favor of enhancing the quality of thin film used as microwave dielectrics.

Abstract: The purpose of this study is to examine the effect of crystallite preferred orientation on the mechanical strength of TiCN thin films in highly compressive residual stress. TiCN thin films were deposited by PVD on JIS-SKH55 (AISI M35) steel. The applied substrate bias voltages were set for –50, -80, -100, -120 and –150V. Subsequently, residual stress and crystalline preferred orientation of these specimens were investigated by X-ray diffraction methodology. The crystalline preferred orientation in thin films was evaluated by the ODF calculated from pole figures. On the other hand, dynamic hardness test (DH) and scratch test were executed to evaluate the mechanical strength of thin films. In our study, it was observed that negative bias voltages had an effect on the preferred orientation. The orientation density at –120V was the highest of all specimens. In addition, the value of scratch section area at –120V was the largest of all specimens. As a conclusion, the relation between the scratch area and the negative bias voltages corresponded to the relation between the preferred orientation and the bias voltages.