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What Is the Czochralski Process?

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  • Written By: Mary McMahon
  • Edited By: Nancy Fann-Im
  • Last Modified Date: 03 April 2014
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The Czochralski process is a method for the production of single crystals, solid chunks of material with a uniform crystal matrix. Such crystals are famously used in the construction of electronic components as well as in scientific research and a number of other applications where a high quality crystal with a uniform matrix is needed. Jewelers, for instance, can utilize the Czochralski process in the formation of high performance gemstones for their projects, just as research facilities with a need for materials like diamond can grow them in the lab using this technique.

This process is named for a Polish researcher who discovered it at the start of the 20th century. It starts with melting the components of the crystals in a crucible capable of tolerating extremely high temperatures. The crucible is typically positioned in a closed kiln with very precise temperature control. High control is critical, as the process will fail if the mixture is too hot or too cold, and very exact sensors may be positioned in several locations to monitor temperature changes.

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When the mixture is heated with any dopant and other additions that may be necessary, a technician can carefully lower a rod with a seed crystal. This is usually done with the use of mechanical equipment, rather than by hand. Next, the rod is carefully and very slowly withdrawn as the mixture forms a solid matrix around the seed crystal. The end result of the Czochralski process should be a solid log of material, with some remainders at the bottom of the crucible.

In settings where the temperature rises too high, the seed crystal can melt. Introducing the crystal at low temperatures can cause the premature crystallization of the entire contents of the crucible, complete with cracks, fracture lines, and other impurities. This process is slow; withdrawal of the seed crystal is measured in millimeters per hour. The careful control needed throughout the Czochralski process can yield very high quality crystals with a minimum of impurities.

Production costs can depend on the raw materials needed and the size of the crystal. Larger crystals are more challenging to grow, and require greater degrees of control. Some raw components are very expensive. Czochralski process crystals are chemically identical to natural formations, but have a much higher quality and reliability. This is usually desirable in settings like labs and electronics manufacturers, but jewelers sometimes have difficulty selling lab-grown stones due to consumer preference for natural stones.

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Discuss this Article

orangey03
Post 4

I went to the mountains on vacation this summer, and I got to visit some mines. While in a gift shop near one, I saw big chunks of crystal for sale.

I wondered why one was way more expensive than the other while they looked almost identical. Then, I noticed that one of them was man made.

There were two chunks of ruby placed next to each other. I honestly could not tell which one was real and which was fake without looking at the price tag.

I bought the man made one because it was so beautiful and I could afford it. I put it in a display case at my house, and everyone who sees it believes it's real until I tell them otherwise.

cloudel
Post 3

I imagine that having the job of producing crystals would place lots of stress on a person. The conditions have to be so precise, and that's never easy.

Making some types of candy involves reaching a certain temperature, no more and no less, and I know that is stressful. Ruining a batch and having to start over is never fun, and I often do this.

I would imagine that is somewhat like what crystal producers go through, only their end product is worth more, so they have more responsibility placed on their shoulders. I would not want to be in that position. Being a candy maker and dealing with the crystallization of sugar is tough enough!

Oceana
Post 2

@wavy58 – I agree with you. Most of my jewelry is cubic zirconia, and I can get it really cheap. To me, it's just as lovely as a real crystal.

As long as it sparkles and has facets, I consider it to be worthy of wearing. I have many pairs of cubic zirconia earrings, and some of them even capture rainbows and reflect the colors around a room. Most of them are studs, but some have larger settings to accommodate bigger crystals.

I will probably never buy a genuine crystal, because I don't see the point in spending that much money on something when I can get a good version of it for so much less. My money will always go to more important things.

wavy58
Post 1

While some people may have issues with man made crystals, I have no problem with them. I helped my fiancee pick out my engagement ring, and I ended up getting a diamond made with the Czochralski process.

The ring looked like the real thing. It had a big crystal in the middle and two smaller ones on the sides. The reason I chose this one was the price. It was significantly less expensive than the actual diamond rings.

I could not have asked for a better ring. The way it sparkles in the light is magical. It is blindingly beautiful, and I would gladly buy it even if I had tons of money.

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