Piston-anvil method

Beyond 10 kbar, mechanical means must be used diamond anvils. The diamond anvil method uses industrial diamonds, shaped to define a small volume, and tetrahedrally mounted pistons and anvils compress the two diamonds together to achieve very high ultimate pressures (200 kbar). Beyond such pressures, explosive charges can be used to achieve very high pressures for a very short time. The maximum pressures measured are around 1 Mbar. 

Beyond this range, the pressures are normally created by static pressure devices, such as piston-cylinder apparatus, solid state presses or anvil devices (opposed, tetrahedral and cubic anvil), when the sample is simply squeezed to create pressure up to 150 kbar (15 GPa) (Figure 4.9). These methods have allowed the synthesis of compounds which could not be created in any other way. However, only very small samples are produced (50 mg) in these expensive reactions, and so industrial applications of the materials produced are unlikely. 

The piston-cylinder and opposed-anvil devices discussed in the previous subsections are most often used for the compression of solids. Nevertheless they can also be loaded with samples which are liquids or gases at ambient conditions, by cryogenic condensation methods. This is not the case with multianvil systems which require a massive environment for the experimental space and which are used exclusively for the compression of solid samples. 

Methods based on quenching from the melt, such as piston and anvil, double piston, torsion catapult and roller casting (Luborsky, 1980) permit larger quantities of amorphous materials to be obtained. The last of these, also known as melt spinning, is probably the method most used to obtain amorphous ribbons of thickness 10-60 pm, width up to 17 cm and virtually infinite length. In this method, the molten alloy is propelled through a small hole or a slot onto a massive, cold metallic disc rotating... 

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