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The '''Wulff construction''' is a method for determining the [[Thermodynamic equilibrium|equilibrium]] shape of a [[droplet]] or [[crystal]] of fixed volume inside a separate phase (usually its saturated solution or vapor). [[Energy minimization]] arguments are used to show that certain crystal planes are preferred over others, giving the crystal its shape.


==Theory==
In 1878 [[Josiah Willard Gibbs]] proposed<ref>Gibbs ''Collected Works'', 1928</ref> that a droplet or crystal will arrange itself such that its surface [[Gibbs free energy]] is minimized by assuming a shape of low [[surface energy]]. He defined the quantity


:<math>\Delta G_i= \sum_{j}\gamma_j O_j~</math>
There are a great deal of distinctive corporations that make watches and timepieces these days but there are handful of that have been all-around as prolonged as the Citizen Enjoy Enterprise.  Furthermore, there are only a handful of organizations that have stuck to their guns when it comes to the high-quality of the goods that they were being launched on.  Citizen Check out Corporation is the exception to the rule when it comes to this spot of business and they have however to drop to the almighty greenback and cut the good quality.  This is why they are now the most significant maker of watches and timepieces in the environment with a presence in each and every major state.  The uncompromising good quality and design of the Citizen Enjoy has manufactured this so.<br><br>THE EARLY Days<br><br>The 1st Citizen Enjoy was created in 1924 applying a new sort of technological know-how to make it the smallest and thinnest of the time. It is incredibly challenging to acknowledge this timepiece from the watches that are produced these days but anybody with a small understanding can very easily detect the craftsmanship of the piece and know that it is a Citizen Enjoy. This was the springboard for the piece and it went all uphill from there.  <br><br>The true Citizen Look at Company was formed 6 a long time afterwards in 1930 and was an fast success.  This was owing in part to the founders will need to provide greater and brighter factors to the current market as shortly as attainable. In contrast to a great deal of organizations that will maintain off on new technology so they do not damage their present market, the Citizen View Organization rolled out the several merchandise that it created from the commencing and created a significant splash in the world.  This has also created them a person of the most hated among the the other look at makers in the environment but that is nothing at all to this company as they rolled along.  <br><br>The Citizen Enjoy Firm now employs more than a few thousand men and women the entire world over.  Based in Japan, they are the initial company to make some of the best innovations in the entire world and nevertheless preserve a industry presence in the standard watches that they manufactured as nicely. This is a little something that the other businesses had been getting a good deal of problems with and generating a ton of enemies along the way was a day by day event for this firm.<br><br>THE NEW Day<br><br>The Citizen Watch Organization was the sole responsible get together for the very first shock resistant watch to ever be designed. This was a massive offer for the numerous difficult functioning persons in the globe who have been drained of getting to choose their look at in for repair service because of shock problems.<br><br>Citizen also designed its mark on the diving world with the initial qualified dive enjoy that features an digital depth sensor. This [http://Mondediplo.com/spip.php?page=recherche&recherche=enhancement enhancement] on the aged design of diving check out has at any time endeared the business to the quite a few diving lovers around the earth. <br><br>They have been also dependable for the to start with Analog Quartz view to be made which single handedly changed the way the earth instructed time. Nowadays the Citizen Observe Business has taken the watch making environment to a whole new stage with Eco Push Technique. Tapping into the useful resource of becoming environmentally welcoming, the Eco Drive Technique takes advantage of a hidden solar mobile that is embedded into the works.  This mobile gathers ability from the sunlight and artificial light-weight sources and turns it into power to push the check out.  By significantly this is the most common enjoy to be uncovered currently and it has additional positive aspects to the ecosystem.  No extended do you need to go to the retailer to acquire a new battery and fret about the old a person polluting the ground in a land fill somewhere.<br><br>All in all the Citizen Look at Company has been responsible for some of the best factors to occur in watches and timepieces for the previous several years.  Nowadays they are nevertheless a single of the most preferred watch brand names in the earth and make up a big share of the market place with the most recent products and solutions that can be identified almost anyplace.<br><br>If you have any questions relating to where and ways to make use of [http://teil.cc/LUBqt tudor], you could call us at our own web page.
 
where <math>\gamma _j</math> represents the surface energy per unit area of the <math>j</math>th crystal face and <math>O_j</math> is the area of said face. <math>\Delta G_i</math> represents the difference in energy between a real crystal composed of i molecules with a surface, and a similar configuration of i molecules located inside an infinitely large crystal. This quantity is therefore the energy associated with the surface. The equilibrium shape of the crystal will then be that which minimizes the value of <math>\Delta G_i</math>
 
In 1901 Georg Wulff stated<ref>G Wulff ''Zeitschrift fur Krystallographie und Mineralogie'', 34, 5/6, pp 449-530, '''1901'''.</ref> (without proof) that the length of a vector drawn normal to a crystal face <math>h_j</math> will be proportional to its surface energy <math>\gamma_j</math>: <math>h_j=\lambda \gamma_j</math>. The vector <math>h_j</math> is the "height" of the <math>j</math>th face, drawn from the center of the crystal to the face; for a spherical crystal this is simply the radius. This is known as the Gibbs-Wulff theorem.
 
In 1953 [[Conyers Herring]] gave a proof of the theorem and a method for determining the equilibrium shape of a crystal, consisting of two main exercises. To begin, a polar plot of surface energy as a function of orientation is made. This is known as the gamma plot and is usually denoted as <math>\gamma(\hat{n})</math> where <math>\hat{n}</math> denotes the surface normal, e.g., a particular crystal face. The second part is the Wulff construction itself in which the gamma plot is used to determine graphically which crystal faces will be present. It can be determined graphically by drawing lines from the origin to every point on the gamma plot. A plane perpendicular to the normal <math>\hat{n}</math> is drawn at each point where it intersects the gamma plot. The inner envelope of these planes forms the equilibrium shape of the crystal.
 
==Proof==
Various proofs of the theorem have been given by Hilton, Liebman, von Laue,<ref>M von Laue ''Zeitschrift fur Kristallographie'' 105,2 pp:124-133, AUG 1943</ref> Herring,<ref>Herring ''Angewandte Chemie'' 63, 1 p: 34, '''1953''' http://onlinelibrary.wiley.com/doi/10.1002/ange.19530650106/pdf</ref> and a rather extensive treatment by Cerf.<ref>R Cerf: ''The Wulff Crystal in Ising and Percolation Models'', Springer, 2006</ref> The following is after the method of R. F. Strickland-Constable.<ref>R. F. Strickland-Constable: ''Kinetics and Mechanism of Crystallization,'' page 77, Academic Press, 1968.</ref>
We begin with the surface energy for a crystal
:<math>\Delta G_{i}= \sum_{j}\gamma_j O_j \,\!</math>
which is the product of the surface energy per unit area times the area of each face, summed over all faces, which is minimized for a given volume when
:<math>\delta \sum_{j}\gamma_j O_j = \sum_{j}\gamma_j \delta O_j = 0\,\!</math>
We then consider a small change in shape for a constant volume
:<math>\delta V_c =\frac{1}{3} \delta \sum_{j} h_j O_j = 0 </math>
which can be written as
:<math> \sum_{j}h_j \delta O_j + \sum_{j}O_j\delta h_j= 0 \,\!</math>
the second term of which must be zero, as it represents the change in volume, and we wish only to find the lowest surface energy at a constant volume (i.e. without adding or removing material.) We are then given from above
:<math>\sum_{j}h_j \delta O_j = 0 \,\!</math>
and
:<math>\sum_{j}\gamma_j \delta O_j = 0\,\!</math>
which can be combined by a constant of proportionality as
:<math>\sum_{j}(h_i - \lambda \gamma_j) \delta O_j = 0\,\!</math>
The change in shape <math>(\delta O_j)</math> must be allowed to be arbitrary, which then requires that <math>h_j=\lambda \gamma_j</math> which then proves Gibbs-Wulff Theorem.
 
==References==
<references />
 
[[Category:Thermodynamics]]
[[Category:Crystallography]]

Latest revision as of 10:23, 26 April 2014


There are a great deal of distinctive corporations that make watches and timepieces these days but there are handful of that have been all-around as prolonged as the Citizen Enjoy Enterprise. Furthermore, there are only a handful of organizations that have stuck to their guns when it comes to the high-quality of the goods that they were being launched on. Citizen Check out Corporation is the exception to the rule when it comes to this spot of business and they have however to drop to the almighty greenback and cut the good quality. This is why they are now the most significant maker of watches and timepieces in the environment with a presence in each and every major state. The uncompromising good quality and design of the Citizen Enjoy has manufactured this so.

THE EARLY Days

The 1st Citizen Enjoy was created in 1924 applying a new sort of technological know-how to make it the smallest and thinnest of the time. It is incredibly challenging to acknowledge this timepiece from the watches that are produced these days but anybody with a small understanding can very easily detect the craftsmanship of the piece and know that it is a Citizen Enjoy. This was the springboard for the piece and it went all uphill from there.

The true Citizen Look at Company was formed 6 a long time afterwards in 1930 and was an fast success. This was owing in part to the founders will need to provide greater and brighter factors to the current market as shortly as attainable. In contrast to a great deal of organizations that will maintain off on new technology so they do not damage their present market, the Citizen View Organization rolled out the several merchandise that it created from the commencing and created a significant splash in the world. This has also created them a person of the most hated among the the other look at makers in the environment but that is nothing at all to this company as they rolled along.

The Citizen Enjoy Firm now employs more than a few thousand men and women the entire world over. Based in Japan, they are the initial company to make some of the best innovations in the entire world and nevertheless preserve a industry presence in the standard watches that they manufactured as nicely. This is a little something that the other businesses had been getting a good deal of problems with and generating a ton of enemies along the way was a day by day event for this firm.

THE NEW Day

The Citizen Watch Organization was the sole responsible get together for the very first shock resistant watch to ever be designed. This was a massive offer for the numerous difficult functioning persons in the globe who have been drained of getting to choose their look at in for repair service because of shock problems.

Citizen also designed its mark on the diving world with the initial qualified dive enjoy that features an digital depth sensor. This enhancement on the aged design of diving check out has at any time endeared the business to the quite a few diving lovers around the earth.

They have been also dependable for the to start with Analog Quartz view to be made which single handedly changed the way the earth instructed time. Nowadays the Citizen Observe Business has taken the watch making environment to a whole new stage with Eco Push Technique. Tapping into the useful resource of becoming environmentally welcoming, the Eco Drive Technique takes advantage of a hidden solar mobile that is embedded into the works. This mobile gathers ability from the sunlight and artificial light-weight sources and turns it into power to push the check out. By significantly this is the most common enjoy to be uncovered currently and it has additional positive aspects to the ecosystem. No extended do you need to go to the retailer to acquire a new battery and fret about the old a person polluting the ground in a land fill somewhere.

All in all the Citizen Look at Company has been responsible for some of the best factors to occur in watches and timepieces for the previous several years. Nowadays they are nevertheless a single of the most preferred watch brand names in the earth and make up a big share of the market place with the most recent products and solutions that can be identified almost anyplace.

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