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The dependence of the magnetic iron oxide characteristics on the particle grain size and shape is well known [1].
Experimental To establish the optimal procedure, a large number of experiments under various conditions were carried out [7].
For the same synthesis temperature (T = 333 K), more fine-grained powders, with better expressed super-paramagnetic behaviour form at higher current densities.
The samples (3) and (4) synthesised at higher temperatures, with larger crystal grains, reach (and slightly surpass) TC ≈ 853 K of magnetite.
At higher current densities (I = 300, 500, and 1000 mA/dm2), the concentration of magnetite nucleation sites increases, leading to the synthesis of more fine-grained powders.

Fig.1 XRD patterns of CdS films According to the diffraction spectrum, the grain size of the samples can be calculated by scherrer's formula: (1) Where D is grain size, K = 0.89, λ is the X-ray wavelength of incident light, b is the half high width of the diffraction peak and θ is Bragg Angle.
According to the calculations, it was indicated that the grain size of Dy-doped sample is larger than no-doped sample, and Dy doping makes the lattice constant and crystal cell volume of CdS bigger.
The grain size,lattice constant and crystal cell volume of the samples samples lattice constant (nm) grain size (nm) crystal cell volume (10-3nm3) CdS(pure) 0.57254 26.2 187.68 CdS(7nm-Dy) 0.57382 31.9 188.95 Fig.2 shows the SEM images of pure CdS and 4nm-Dy doped CdS films.
This showed that Dy doped in CdS will help to promote the growth of crystal grain and improve the crystallization condition of the films.
The large grain size and smooth surface should Contribute to the formation of CdS/CdTe and CdS/CuInSe heterojunction and to grow a uniform absorption films[9].

Melting parameters Sample: Zr-1.0Nb Pressure before melting 6.35×10-2 Torr Pressure during melting 5.58×10-2 Torr Pressure between purges 2.54×10-2 Torr Current 275 A Cooling time 35 min Number of purges 3 X-ray diffraction The Fig. 3 shows the standards applied in the X-ray diffraction of the Zr-1.0Nb alloy after melting.
Before heat treatment, the grains were accumulated non-homogenously some regions, whereas after heat treatment, the grains were distributed more evenly, with relief of residual stresses in the samples, thereby minimising deformations in the grain boundaries [9,10].
Microstructural analyses by SEM revealed no discernible grain boundaries in the alloy, see Fig. 6b.
The result indicates that that the processes under a melting and annealing temperature of 1273 K caused grain growth in the Zr and Nb samples.
Consequently, in the Zr-1.0Nb alloy, the grains were of the same magnitude as the field of view of the microscope, thereby preventing the grain boundaries from being verified.

Additionally, there is an increase in the activation energy with the increase in atomic number indicating the increase in activation barrier with the atomic number.
Based on the image shown in Figure 33, it is clear that VSi2 phase has columnar grains covering the whole interdiffusion zone.
Relatively columnar and fine grains seen in the sublayer that are grown from the Nb5Si3 phase side.
Relatively equiaxed and bigger grains are found to grow from the Si end member.
Fine grains have grown from the Ta5Si3 phase and a relatively coarse grain morphology has grown from the Si side.

The structural disordering made thicker films (4 mm) show degenerated cell performance ascribed to the presence of increased number of recombination centers.
It suggests that the nanoparticles are probably single crystals each, and packed rather orderly with clear contact area between the grains.
The neck connections between grains that provide pathways for electron transport shall have a noticeable effect on the photocurrent events [11-13].
This behavior is ascribed to the enhanced electron transport in the regularly packed titania network due to the enhanced crystalline grain connectivity.
Peter, “Influence of Grain Morphology on Electron Transport in Dye Sensitized Nanocrystalline Solar Cells,” J.

Addition of TiB2 particles exhibited grain refinement, thereby improving the mechanical properties.
Nano composite exhibits fine grain structure but high porosity.
There was a reduction in grain size with increase in TiB2 particles.
The presence of TiB2 particles acted as nucleation sites during the solidification phase, increasing the number of smaller grains, and contributing to grain refinement.
TiB2 particles act as grain refiners to the matrix material.

The dominant microstructure in weld metal at as-welded condition is coarse Widmanstatten type structure with high hardness; post-weld heat treatment resulted in significant grain refinement and hardness reduction in weld metal.
The HAZ retained the large sections of alpha phase, however closer to the fusion line appeared partially decomposed, also the martensite was replaced with a fine grain alpha phase and kappa precipitates (Figure 4a).
The weld bead had a fairly fine grain leading to only small disparities between readings.
Olszewski, “Dealloying of a Nickel-Aluminium Bronze Impeller”, Journal of Failure Analysis and Prevention, (2008), Volume 8, Number 6, p.505.

The results show that the failure mechanism of the coating eroded by corundum sand is cracking between WC grains, while for the coating eroded by quartz sand, the failure mechanism is microcutting and microploughing.
Although a number of studies were carried out, there still exist many uncertain or confused problems up to date.
Table 1 Powder characteristics Feedstock powder Feedstock size/μm WC grain size Nanostructured WC-17Co 5~45 50-500nm Coated samples were obtained from a commercial coater.
If the cracking between WC grains dominates the main failure mechanism, increasing the toughness of the coating to improve the erosion wear resistance is significant. 4.
If cracking between WC grains dominates the main failure mechanism, increasing the toughness of the coating to improve the erosion wear resistance is significant.

The effect of the helium plasma resulted in the increment of the grain size after prolonged exposure.
The last samples which were treated for 300s showed the largest grain size and the boundaries between the grains were lesser in comparison to the other samples.
In the images of the treated surfaces, there were an increased number of high points with low points could no longer be visible.
The surface morphology of the treated samples indicates modifications which were represented by the surface roughness and the formation of a grain-like structure.
The 300 seconds samples showed the biggest grain structures of all and the boundaries are lesser to the others.

The oxide scales formed in wet air are not as dense as that formed in dry air, and the grain size of the oxide is coarser.
In our previous work on the oxidation behavior of the Cr-Al-N coatings at 1000oC, pure Cr2O3 grains were observed to be embedded in the composite oxide scale of Cr2O3+Al2O3 [6].
Similar phenomenon was also observed in the present work, however, the amount of the pure Cr2O3 grains is larger than that formed in dry air and the grain size is coarser.
It was demonstrated that the formation of the pure Cr2O3 grains results from the out diffusion of element Cr in the coatings [6].
Fig. 3 Surface morphologies of the oxide scales formed on (a) Cr0.82Al0.18N, (b) Cr0.63Al0.37N coated samples after oxidation at 1000oC for 20 h in air + 10 vol.% H2O A number of mechanisms have been proposed to explain the effect of water vapor on the oxidation behavior of the alloys and coatings.