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It’s optical band gap was controlled through changing the grain size and crystalline volume fraction for the quanta dimension effect.
For highly crystalline nc-Si:H films the nanocrystal grains are closely packed together to form micron sized conglomerates.
QE of the solar cell is defined as the ratio of the collected photogenerated carriers to the number of incident photons of a certain λ on to the solar cell.
It has been confirmed that the crystalline volume fraction and grain size grow with the nc-Si:H layer thickness when a constant hydrogen dilution ratio is used.
Conclusions We studied the relationships between optical band gap with the crystallization ratio(Xc) and it with the nanocrystalline grain size(D).

The concept of internal variables is used to describe state quantities such as dislocation density, average grain size and average grain orientation.
The existing grain structure remains essentially unchanged but the interior of the grains is now nearly dislocation free except at the newly formed cell walls.
The behavior depending on the grain misorientation shows a maximum which results from the critical misorientation angle .
To avoid a large number of elements, the mesh should be refined locally only where it is required.
Like the standard case, the ALE-based method (Fig. 8-b) uses a constant number of elements (i.e., 900).

In particular, grain-scale shear bands were introduced during ECAP in otherwise hard-to-recrystallize <001>//ND grains by ECAP, and they facilitated the recrystallization.
After one-pass ECAP, dense deformation bands were observed parallel to the shear plane of ECAP inside a number of grains as shown in Fig.2(b,c).
It means that most fractions of {100}//ND grains were replaced by {111}//ND grains during the recrystallisation process.
grain-scale MSB has two possibilities [2].
Grain-scale microshear bands that developed during ECAP remained after post-ECAP cold- rolling inside the hard-to-recrystallise {100} grains.

In the cases of lower additive content, grain shape accommodation takes place, in which the grain shape changes to develop flat contact regions between neighbouring grains.
According to that, formation of faceted grains imply interface-reaction controlled (as found in boundary of secondary phases and SiC grains) coarsening and rounded grains imply diffusion controlled (in case of SiC-SiC grain interface) coarsening.
Interfacial debonding at the interface between the grain and grain boundary is a second mechanism for promoting intergranular fracture by weakening the grain boundary [2,123].
Typically, the microstructure is composed of SiC grains, amorphous grain-boundary films between adjacent SiC grains, and phases at triple junctions (secondary phases) of SiC grains (fig. 4(a)).
The room temperature strength of SiC sintered bodies does not depend on the thickness or chemistry of the IGF rather it depends on a number of factors including the mechanical testing method, strain rate, temperature, impurity level, size distribution of microstructural defects, and in some cases, on the orientation of the test specimen relative to the original material.

If the crystal grain size of a metal is made smaller, its strength is higher.
So, many methods of grain refinement have been proposed.
Introduction For strengthening a material by grain refinement, many techniques have been proposed [1,2].
Also, the grain refinement effect by torsional pre-strain was mentioned.
It is reported that the softening was observed in pure-copper on manufacturing process of ultra-fine grain [5]

The XRD pattern of the sample was matched with the ICDD database PDF card number 00-005-0626 (space group P4mm) which belongs to tetragonal BaTiO3.
The grain and grain boundary effect of a sample are distinguishable by its capacitance values.
The grains were well developed with narrow grain boundaries.
The average grain size is about 2.9087 μm.
The small grain size might be attributed by the lower grain growth rate which associated with the slow diffusion of the Zr4+ [10].

The grain structure evolution was analysed by electron backscatter diffraction (EBSD).
The nucleation of the cube recrystallization texture component is associated with "old" cube grains that were present in the starting material and survived the deformation, by which a configuration capable of regenerating new cube grains has been established.
RC denotes the cube fraction, D the initial average grain size and ε the effective strain.
Due to accumulation of dislocations during the deformation process, energy is stored at the high angle grain boundaries and this energy decreases by the nucleation of new grains during holding.
The density of grain boundary nuclei becomes hence ( ) ( ) [ ]1expexp )1( +−+ − = ε ε δ D SRC � GBc GB GB (11), where CGB is a constant and SGB is the density of overcritical nuclei at grain boundaries.

The fine grained structure being achieved by HPT had an average grain size of 100-200 nm.
Here, n is the number of rotations, r the distance from rotation axis, and h the sample thickness achieved after HPT processing.
The evaluation of TEM micrographs were carried out by statistical methods providing grain size distributions and average grain sizes.
The overwhelming part of grains here has sizes between 100-200 nm, while individual grains up to 1 µm in size were observed.
The average grain size here amounts to 170 nm.

Atomic force microscopy (AFM) micrographs showed the improvement of RMS roughness and grain size as annealing temperature increased.
This is probably due to the higher calcinations temperature (>450 °C) affect the unidirectional grains growth and cause the demolishment of ZnO films crystallization [9].
From the AFM images, we observed that ZnO films annealed above 450 °C consists of many columnar and uniform grains.
From Table 1, we can summarize that the average grain size that is determined by AFM is consistent with the estimated crystallites size by XRD.
With the decreasing number of zinc atoms and large numbers of oxygen molecules being absorbed at the grains boundaries, it will create potential barriers which resist the transportation of electron [3].

Introduction Shear deformation is known to effective to produce ultra fine grain.
The research of grain refinement by phase transformation after severe shear deformation for low carbon steel was limited in a torsion test.
Fig.3 shows the relationship between hardness and number of pass.
Fig.3 Relationship between hardness and number of ECAE pass for Nb alloyed steel.
The fine grain is obtained by hot shear deformation in the austenite region and subsequent transformation.