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Tuesday, 15 February, 2000, 16:02 GMT
Lab grows monster crystal

Crystal It measures 66 (cm) by 53 by 58


If you ever struggled to grow copper sulphate crystals in a jam jar at school, look enviously at this monster.

The pyramid-shaped KDP (potassium dihydrogen phosphate) crystal is a record breaker. It weighs in at an astonishing 318 kilograms (701 lbs) - more than 20 kilos heavier than the previous record holder.

It was grown in just 52 days by researchers at the US Department of Energy's Lawrence Livermore National Laboratory, California.

The enormous crystal is to be sliced into plates for use in a giant laser now under construction at Lawrence Livermore. The crystal plates will convert the laser's infrared light beams to ultraviolet light just before the beams strike the laser target.

The new equipment will test the safety and reliability of America's nuclear weapons stockpile.

Crystal The growth technique builds on Russian methods



Russian technique

To grow crystals this big, Lawrence Livermore built on a rapid-growth technique first developed in Russia.

A thumbnail-sized seed crystal is placed inside a two-metre-high tank filled with nearly a tonne of supersaturated KDP solution at 65 degrees Celsius (150 degrees Fahrenheit).

The temperature is gradually decreased to maintain supersaturation as the growing crystal extracts salt from the solution.

The record size of the latest crystal was achieved by giving the solution a transfusion of additional salt through a device called a continuous filtration system, which helps maintain crystal quality.

"This technique offers the possibility of producing even larger and higher quality crystals in the future," said Ruth Hawley-Fedder, group leader for the Livermore crystal growing team.

"Our newest record holder could have grown even larger, but we simply ran out of room in our growth tank."

Images by Jackie McBride and Bryan Quintard, Lawrence Livermore National Laboratory

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