Re: [Vo]:A theory of zone melting
Mike Carrell wrote: Zone melting purification is standard in the semiconductor industry since > the 1940’s when it was developed at Bell Laboratories, enabling the > development of the transistor. . . . > It was secretly developed after hours, against the explicit orders of management, with the equipment stashed in a closet during working hours so that no one would find out and put the kibosh on the project. Does that sound familiar? See: http://www.lenr-canr.org/acrobat/RothwellJtransistor.pdf William Shockley was in charge and he did not want people wasting their time on ultra-pure materials. If he had had his way, transistors would have remained a useless laboratory curiosity for many years. Shockley was brilliant but he had poor judgement when it came to engineering, technology, and business. He was kind of a paranoid nut too. He started a company, "Shockley Transistor Company" and ran it into the ground. But it was a great accomplishment despite everything, because it was training ground for the people who started Fairchild and the subsequent "Fairchildren." - Jed
Re: [Vo]:A theory of zone melting
In reply to David Jonsson's message of Mon, 4 Oct 2010 18:49:04 +0200: Hi, [snip] >Zone melting is a technique to separate impurities in a material. >http://en.wikipedia.org/wiki/Zone_melting > >There is no public theory on the purification effect of zone melting. It is >an empirical subject. Wikipedia says just blankly that the impurities >diffuse more towards the center of the melt. Why would they diffuse more >than the fluid? Elsewhere it is described as if the impurities "prefer" to >stay in the melt: >http://www.tf.uni-kiel.de/matwis/amat/elmat_en/kap_6/backbone/r6_1_2.html#_1, >That article is linked two clicks away from the Wikipedia article on >zone >melting. >Typical for the lack of theory is to have animistic ideas and attribute the >phenomena with properties of live beings having preferences. > >I have an idea where the heat gradients in zone melting causes different >thermal expansion and thus different pressure so that matters move >differently towards or away in the gradient. The force on foreign matter in >the fluid in the melted zone are determined by the derivative of pressure in >regard to temperature dP/dT = ßK (ß = coefficient of thermal expansion and K >= bulk modulus) as I have shown on two Iwone conferences. The gradient has >opposite directions around the heated zone so both type of impurities are >forced away. If ßK is higher for the impurity compared to ßK for the fluid >it will be move against the gradient and thus flow ahead of the moving >melted zone. Likewise if ßK is lower for the impurity than for the >surrounding melted fluid it will move towards the gradient and thus gather >just behind the moving melted zone. An impurity with similar ßK as the fluid >would not be possible to purify with zone melting. I suspect that it's not so much about the melting as the recrystalization at the boundary of the zone. Impurities tend to disrupt the crystal lattice making it less ordered. Consequently the energy release when the crystal forms is greater if the crystal is pure. The same force tends to cause sea salt to separate from sea ice as it forms. By moving the melt zone through the mass what is really happening is that the recrystalization boundary moves through the mass, pushing the impurities ahead of it. Regards, Robin van Spaandonk http://rvanspaa.freehostia.com/Project.html
RE: [Vo]:A theory of zone melting
Zone melting purification is standard in the semiconductor industry since the 1940s when it was developed at Bell Laboratories, enabling the development of the transistor. After standard purification of the silicon or germanium bole, zone melting provides the final step of purification before a wafer is sliced off and implanted by the doping impurities which produce the transistor effect. Mike Carrell From: David Jonsson [mailto:davidjonssonswe...@gmail.com] Sent: Monday, October 04, 2010 12:49 PM To: vortex-l Subject: [Vo]:A theory of zone melting Zone melting is a technique to separate impurities in a material. http://en.wikipedia.org/wiki/Zone_melting There is no public theory on the purification effect of zone melting. It is an empirical subject. Wikipedia says just blankly that the impurities diffuse more towards the center of the melt. Why would they diffuse more than the fluid? Elsewhere it is described as if the impurities "prefer" to stay in the melt: http://www.tf.uni-kiel.de/matwis/amat/elmat_en/kap_6/backbone/r6_1_2.html#_1 , That article is linked two clicks away from the Wikipedia article on zone melting. Typical for the lack of theory is to have animistic ideas and attribute the phenomena with properties of live beings having preferences. I have an idea where the heat gradients in zone melting causes different thermal expansion and thus different pressure so that matters move differently towards or away in the gradient. The force on foreign matter in the fluid in the melted zone are determined by the derivative of pressure in regard to temperature dP/dT = ßK (ß = coefficient of thermal expansion and K = bulk modulus) as I have shown on two Iwone conferences. The gradient has opposite directions around the heated zone so both type of impurities are forced away. If ßK is higher for the impurity compared to ßK for the fluid it will be move against the gradient and thus flow ahead of the moving melted zone. Likewise if ßK is lower for the impurity than for the surrounding melted fluid it will move towards the gradient and thus gather just behind the moving melted zone. An impurity with similar ßK as the fluid would not be possible to purify with zone melting. Together with other knowledge this theory can be helpful in designing an efficient zone melting process. David David Jonsson, Sweden, phone callto:+46703000370 This Email has been scanned for all viruses by Medford Leas I.T. Department.
