scholarly journals Crystallite fusion in nanocellulose aggregates

2021 ◽  
Author(s):  
Kazuho Daicho ◽  
Kayoko Kobayashi ◽  
Shuji Fujisawa ◽  
Tsuguyuki Saito
Keyword(s):  
Energy Transfer ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Mechanical Stress ◽  
Thermal Energy ◽  
Structural Defect ◽  
Single Crystalline ◽  
Naturally Occurring

Abstract Crystallite refers to a single crystalline grain in crystal aggregates, and multiple crystallites form a grain boundary or the inter-crystallite interface. A grain boundary is a structural defect that hinders the efficient directional transfer of mechanical stress or thermal phonons in crystal aggregates. We observed that grain boundaries within an aggregate of a-few-nanometers-wide fibrillar crystallites of cellulose were crystallized by enhancing their inter-crystallite interactions; multiple crystallites were coupled into single fusion crystals without passing through a melting or dissolving state. Accordingly, the crystallinity of naturally occurring cellulose, which has previously been considered irreversible once decreased, was recovered, and the thermal energy transfer in the aggregate was significantly improved. Other fibrillar crystallites of chitin also showed a similar fusion phenomenon by enhancing the inter-crystallite interactions. Crystallite fusion in aggregates may occur for other biopolymers.

scholarly journals Crystallite fusion in nanocellulose aggregates

2021 ◽  
Author(s):  
Kazuho Daicho ◽  
Kayoko Kobayashi ◽  
Shuji Fujisawa ◽  
Tsuguyuki Saito
Keyword(s):  
Energy Transfer ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Mechanical Stress ◽  
Thermal Energy ◽  
Structural Defect ◽  
Single Crystalline ◽  
Naturally Occurring

Abstract Crystallite refers to a single crystalline grain in crystal aggregates, and multiple crystallites form a grain boundary or the inter-crystallite interface1. A grain boundary is a structural defect that hinders the efficient directional transfer of mechanical stress or thermal phonons in crystal aggregates. We observed that grain boundaries within anaggregate of a-few-nanometers-wide fibrillar crystallites of cellulose were crystallized by enhancing their inter-crystallite interactions; multiple crystallites were coupled into single fusion crystals without passing through a melting or dissolving state. Accordingly, the crystallinity of naturally occurring cellulose, which has previously been considered irreversible once decreased2, was recovered, and the thermal energy transfer in the aggregate was significantly improved. Other fibrillar crystallites of chitin also showed a similar fusion phenomenon by enhancing the inter-crystallite interactions. Crystallite fusion in aggregates may occur for other biopolymers.

scholarly journals Crystallite fusion in nanocellulose aggregates

2021 ◽  
Author(s):  
Kazuho Daicho ◽  
Kayoko Kobayashi ◽  
Shuji Fujisawa ◽  
Tsuguyuki Saito
Keyword(s):  
Energy Transfer ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Mechanical Stress ◽  
Thermal Energy ◽  
Structural Defect ◽  
Crab Shell ◽  
Wood Cellulose ◽  
Single Crystalline ◽  
Biological Structures

Abstract Crystallite refers to a single crystalline grain in crystal aggregates, and multiple crystallites form a grain boundary or the inter-crystallite interface. A grain boundary is a structural defect that hinders the efficient directional transfer of mechanical stress or thermal phonons in crystal aggregates. We observed that grain boundaries within an aggregate of a-few-nanometers-wide fibrillar crystallites of wood cellulose were crystallized by enhancing their inter-crystallite interactions; multiple crystallites were coupled into single fusion crystals without passing through a melting or dissolving state. Accordingly, the crystallinity of wood cellulose, which has been considered irreversible once decreased, was significantly enhanced, and the thermal energy transfer in the aggregate was improved. Other fibrillar crystallites of crab shell chitin also showed a similar fusion phenomenon by enhancing the inter-crystallite interactions. These findings imply that such crystallite fusion naturally occurs in biological structures with network skeletons of aggregated fibrillar crystallites.

scholarly journals Recovery of the Irreversible Crystallinity of Nanocellulose by　Crystallite Fusion: A Strategy for Achieving Efficient Energy Transfers in Sustainable Biopolymer Skeletons

2021 ◽  
Author(s):  
Kazuho Daicho ◽  
Kayoko Kobayashi ◽  
Shuji Fujisawa ◽  
Tsuguyuki Saito
Keyword(s):  
Energy Transfer ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Mechanical Stress ◽  
Thermal Energy ◽  
Structural Defect ◽  
Crab Shell ◽  
Wood Cellulose ◽  
Efficient Energy ◽  
Energy Transfers

Abstract Crystallite refers to a single crystalline grain in crystal aggregates, and multiple crystallites form a grain boundary or the inter-crystallite interface. A grain boundary is a structural defect that hinders the efficient directional transfer of mechanical stress or thermal phonons in crystal aggregates. We observed that grain boundaries within an aggregate of a-few-nanometers-wide fibrillar crystallites of wood cellulose were crystallized by enhancing their inter-crystallite interactions; multiple crystallites were coupled into single fusion crystals without passing through a melting or dissolving state. Accordingly, the crystallinity of wood cellulose, which has been considered irreversible once decreased, was significantly enhanced, and the thermal energy transfer in the aggregate was improved. Other fibrillar crystallites of crab shell chitin also showed a similar fusion phenomenon by enhancing the inter-crystallite interactions. These findings imply that such crystallite fusion naturally occurs in biological structures with network skeletons of aggregated fibrillar crystallites.

Grain Boundary Mechanics – Influence of Mechanical Stress Fields on Grain Boundaries

2004 ◽  
Vol 819 ◽  
Author(s):  
Myrjam Winning
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Mechanical Stress ◽  
Rotation Axis ◽  
Temperature Deformation ◽  
High Angle ◽  
Symmetric Tilt ◽  
In Situ Experiments ◽  
Grain Boundary Motion

AbstractThe reaction of grain boundaries to mechanical stresses is reviewed. Results of in-situ experiments on planar, symmetric tilt grain boundaries with different tilt axes (<112>, <111> and <100>) as well as twist grain boundaries with <100> rotation axis will be presented. It was found that the motion of planar grain boundaries can be induced by an imposed external stress irrespective of the angle of misorientation i.e. irrespective whether the grain boundary was a low or high angle grain boundary. The observed activation enthalpies of the stress induced grain boundary motion allow conclusions on the migration mechanism. The motion of planar low and high angle grain boundaries under the influence of a mechanical stress field can be attributed to the movement of the grain boundary dislocations which comprise the structure of the boundary. A sharp transition between low and high angle grain boundaries was observed for different tilt axes. The fact that boundaries can also be moved by mechanical forces sheds new light on microstructure evolution during elevated temperature deformation.

Single Crystalline SOI Square Islands Fabricated by Laser Recrystallization Using a Surrounding Antireflection Cap and Successive Self-Aligned Isolation Utilizing the Same Cap

1984 ◽  
Vol 35 ◽  
Author(s):  
R. Mukai ◽  
N. Sasaki ◽  
T. Iwai ◽  
S. Kawamura ◽  
M. Nakano
Keyword(s):  
Grain Boundary ◽  
Laser Beam ◽  
Grain Boundaries ◽  
Crystalline Silicon ◽  
Silicon Film ◽  
High Density ◽  
Single Crystalline Silicon ◽  
Single Crystalline ◽  
Laser Recrystallization ◽  
Silicon Islands

ABSTRACTA new laser recrystallizing technique has been developedfor high density SOI-LSI's. This technique produces single crystalline silicon islands on an amorphous insulating layerwithout seed. Square windows are opened at arbitrary places in an antireflection cap over a polycrystalline film on an amorphous insulatinq layer. Grain boundaries of the polycrystalline Si in the window are removed completely at the subsequent laser-recrystallization step. Single crystalline silicon islands are formed by self-aligned etching of silicon film which was covered by the antireflection cap. This technique is an effective method for fabricating high density SOI-LSI's, since the singlecrystalline islands can be fabricated at arbitrarily selected places. Yield of the grain-boundary-free islands was 95% the size of the island is 1O x 20μm, and the irradiation oyerlap of laser-beam traces is 70%.

Grain Boundary Engineering by Application of Mechanical Stresses

2007 ◽  
Vol 558-559 ◽  
pp. 987-992
Author(s):  
Myrjam Winning
Keyword(s):  
Stress Field ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Mechanical Stress ◽  
Grain Growth ◽  
Microstructure Evolution ◽  
Mechanical Stresses ◽  
Grain Boundary Engineering ◽  
New Approach ◽  
Kinetics Of

It is shown that an externally applied mechanical stress field can change the kinetics of individual grain boundaries. Moreover, such mechanical stresses also have influence on grain growth and recrystallization kinetics and can strongly affect the microstructure evolution, so that the application of mechanical stresses during annealing can be used as a new approach in the field of grain boundary engineering.

scholarly journals Influencing Martensitic Transition in Epitaxial Ni-Mn-Ga-Co Films with Large Angle Grain Boundaries

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3674
Author(s):  
Klara Lünser ◽  
Anett Diestel ◽  
Kornelius Nielsch ◽  
Sebastian Fähler
Keyword(s):  
Martensitic Transformation ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Thermal Hysteresis ◽  
Electron Backscatter Diffraction ◽  
Large Angle ◽  
Martensitic Transition ◽  
Single Crystalline ◽  
Boundary Density ◽  
Different Strains

Magnetocaloric materials based on field-induced first order transformations such as Ni-Mn-Ga-Co are promising for more environmentally friendly cooling. Due to the underlying martensitic transformation, a large hysteresis can occur, which in turn reduces the efficiency of a cooling cycle. Here, we analyse the influence of the film microstructure on the thermal hysteresis and focus especially on large angle grain boundaries. We control the microstructure and grain boundary density by depositing films with local epitaxy on different substrates: Single crystalline MgO(0 0 1), MgO(1 1 0) and Al2O3(0 0 0 1). By combining local electron backscatter diffraction (EBSD) and global texture measurements with thermomagnetic measurements, we correlate a smaller hysteresis with the presence of grain boundaries. In films with grain boundaries, the hysteresis is decreased by about 30% compared to single crystalline films. Nevertheless, a large grain boundary density leads to a broadened transition. To explain this behaviour, we discuss the influence of grain boundaries on the martensitic transformation. While grain boundaries act as nucleation sites, they also lead to different strains in the material, which gives rise to various transition temperatures inside one film. We can show that a thoughtful design of the grain boundary microstructure is an important step to optimize the hysteresis.

Measurement of the Displacement Across a Coincidence Grain Boundary

1977 ◽  
Vol 35 ◽  
pp. 124-125
Author(s):  
J. W. Matthews ◽  
W. M. Stobbs
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Stacking Fault ◽  
The Other ◽  
Measuring Technique ◽  
High Angle ◽  
Twin Boundaries ◽  
Rigid Displacement ◽  
Cubic Crystals ◽  
Lattice Displacement

Many high-angle grain boundaries in cubic crystals are thought to be either coincidence boundaries (1) or coincidence boundaries to which grain boundary dislocations have been added (1,2). Calculations of the arrangement of atoms inside coincidence boundaries suggest that the coincidence lattice will usually not be continuous across a coincidence boundary (3). There will usually be a rigid displacement of the lattice on one side of the boundary relative to that on the other. This displacement gives rise to a stacking fault in the coincidence lattice.Recently, Pond (4) and Smith (5) have measured the lattice displacement at coincidence boundaries in aluminum. We have developed (6) an alternative to the measuring technique used by them, and have used it to find two of the three components of the displacement at {112} lateral twin boundaries in gold. This paper describes our method and presents a brief account of the results we have obtained.

Observations of dislocation interactions with recrystallized grain boundaries

1988 ◽  
Vol 46 ◽  
pp. 628-629
Author(s):  
C. W. Price
Keyword(s):  
Dislocation Density ◽  
Grain Boundary ◽  
Strain Rate ◽  
Grain Boundaries ◽  
Dislocation Structure ◽  
Hot Deformation ◽  
Static Recrystallization ◽  
High Dislocation Density ◽  
High Angle ◽  
Dislocation Interactions

Little evidence exists on the interaction of individual dislocations with recrystallized grain boundaries, primarily because of the severely overlapping contrast of the high dislocation density usually present during recrystallization. Interesting evidence of such interaction, Fig. 1, was discovered during examination of some old work on the hot deformation of Al-4.64 Cu. The specimen was deformed in a programmable thermomechanical instrument at 527 C and a strain rate of 25 cm/cm/s to a strain of 0.7. Static recrystallization occurred during a post anneal of 23 s also at 527 C. The figure shows evidence of dissociation of a subboundary at an intersection with a recrystallized high-angle grain boundary. At least one set of dislocations appears to be out of contrast in Fig. 1, and a grainboundary precipitate also is visible. Unfortunately, only subgrain sizes were of interest at the time the micrograph was recorded, and no attempt was made to analyze the dislocation structure.

Measurement of solute segregation to grain boundaries in the AEM: A review

1988 ◽  
Vol 46 ◽  
pp. 606-607
Author(s):  
D. B. Williams ◽  
A. D. Romig
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Boundary Misorientation ◽  
Collector Plate ◽  
Segregation Process ◽  
Grain Boundary Misorientation ◽  
Structure Boundary ◽  
Equilibrium Segregation

The segregation of solute or imparity elements to grain boundaries can occur by three well-defined processes. The first is Gibbsian segregation in which an element of minimal matrix solubility confines itself to a monolayer at the grain boundary. Classical examples include Bi in Cu and S or P in Fe. The second process involves the depletion of excess matrix solute by volume diffusion to the boundary. In the boundary, the solute atoms diffuse rapidly to precipitates, causing them to grow by the ‘collector-plate mechanism.’ Such grain boundary diffusion is thought to initiate “Diffusion-Induced Grain Boundary Migration,” (DIGM). This process has been proposed as the origin of eutectoid transformations or discontinuous grain boundary reactions. The third segregation process is non-equilibrium segregation which result in a solute build-up around the boundary because of solute-vacancy interactions.All of these segregation phenomena usually occur on a sub-micron scale and are often affected by the nature of the grain boundary (misorientation, defect structure, boundary plane).

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