C-axis orientation

The substrate was also found to influence the properties of the electrolessly deposited vertical media CoNiMnP, CoNiReMnP, and CoNiReP. The c-axis orientation had a larger degree of perpendicular orientation for films deposited on electroless NiP than for those deposited on Cu foil, presumably because of the smaller roughness of the former substrate [43]. The double-layer (magnetically soft interface, magnetically hard bulk) properties of CoNiReP deposited on a NiMoP underlayer [57] have already been discussed. 

Electroless CoNiMnP and CoNiP were examined as underlayers for electroless CoP by Matsubara et al. [82], The CoNiMnP has a c-axis orientation normal to the film plane, whereas the CoMnP has a low degree of orientation. The CoP was found to deposit with a microstructure resembling that of the underlayer. Very thick deposits (> 0.5 fim) resume the intrinsic structure of CoP (with a low degree of PO). These composite structures have been tested as vertical recording media. 

The model proposed above accounts for orientation produced at low extension. To account for the c-axis orientation observed at high extension, either c-axis slip, or breakup of the large lamellar crystallites accompanied by rigid rotation and formation of microfibrils must occur. Both mechanisms can occur as elongation progresses, and an example of the latter is shown in Figure... 

The presence of phase transitions at 19 and 30°C provides an opportunity to test the proposed deformation model. Below 19°C the lattice contracts into a triclinic structure witli strong intermolecular interaction. 5,26 sjamplcs deformed below 19°C should develop off-c-axis orientation while samples deformed above 30°C should not. Figures 1.12 and 1.13 show inverse pole figures for samples deformed at 2 and 70°C. The observed orientation agrees with our proposed model. - With tlris set of experiments, it is possible to activate the oblique slip process or, alternatively, to deactivate it in the high-temperature phase above 30°C. 

Fig. 17.2. Results of polarized Raman spectroscopic analyses on the surface of yttria-stabilized zirconia in the presence of an indentation print (a) optical micrograph of the indentation print, (b) map of transformed monoclinic fraction, (c) map of 6-axis orientation of the monoclinic phase, and (d) map of the angle of c-axis orientation of the residual tetragonal phase. In both (c) and (d), the represented angle gives the inclination of the respective axes with respect to the sampling plane...

Fig. 17.6. Maps of in-plane crystallographic orientation of the orthorhombic cell in the crystalline part of the polyethylene structure (a) short-term and (b) longterm implanted acetabular cups (cf. the central photographs). Compare the average direction of c-axis orientation and the motion direction shown on the respective maps and on the photographs of the acetabular cups, respectively...

In this work the results for two kinds of samples are surveyed. The first type of sample is thin c-axis oriented films with a thickness of about several hundred nanometers [18]. The residual resistance is about several tens of /xQ cm with the residual resistance ratio (RRR) of 2.2 pointing out that films have a disorder between crystallites. This does not preclude the fact that, on some spots, the films contain clean, small, single crystals on which we occasionally may fabricate a point contact (PC). Normally, the contacts were prepared by touching the film surface with a noble metal counter electrode (Cu, Au, Ag) in the direction perpendicular to the substrate. Thus, nominally, the preferential current direction in the PC is along the c axis. Nevertheless, since the surface of the films contains terraces with small crystallites, a PC to the ab plane of these crystallites is also possible. 

Comprehensive PCS investigations of c-axis oriented thin films and single crystals of MgB2 lead to the following conclusions ... 

First sputtering processes for ZnO deposition were developed in the late 1960s for manufacturing surface acoustic wave devices [2]. The piezoelectric properties of ZnO films are crucial for that application and major efforts were made to develop ZnO sputtering processes which enabled c-axis oriented growth, high resistivity and unique termination of the ZnO crystallites [3,4]. 

For ZnO films with good piezoelectric properties, it is crucial to achieve c-axis oriented growth as well as a unique termination of the wurtzite phase ZnO crystallites [3]. 

This means that these films are c-axis oriented. 

In the same manner, PE-CVD of ZnO has been first studied with the goal of improving the crystallinity of c-axis oriented ZnO him growth at low substrate temperature (i.e. between 150 and 300°C) [49,50]. More recently, expanding thermal plasma has been coupled with an LP-CVD chamber in order to deposit natively rough ZnO films [51-53]. Fig. 6.46 shows the expanding thermal plasma aixtron reactor system used at Eindhoven University of Technology to deposit PE-CVD ZnO films. 

Figure 7.9 shows RHEED patterns obtained with 30keV electrons impinging on clean surfaces of optimized ZnO thin films grown on r-, a-, and c-plane sapphire. The azimuthal directions of the two types of RHEED images of the c-axis oriented ZnO films (on a- and c-sapphire) are [flOO] (top) and [2110] (bottom) [52]. 

NMR measurements were carried out on the c-axis oriented polycrystalline powder of high quality Tl2Ba2Cu06+s (Tc = 85 K) in the external field along the c-axis. The 205TI spin echo signals were obtained by a pulse NMR spectrometer under the field cooling condition (FCC) in a constant field. The spectra was obtained by convolution of the respective fourier transform spectra of the spin echo signals measured with an increment of 50 kHz. 

Self-energy effect in c-axis oriented MgB2 films... 

Morscher and Sayir (1995) studied the effect of temperature on the bend radius that a c-axis-oriented sapphire fiber can withstand for fibers of various diameters. They did this by performing bend stress rupture tests on these fibers... 

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