Anvils cubic-octahedral

High-pressure treatments were carried out in two units a hot isostatic press (HIP) and a multiple anvil-type high-pressure generator. The powder sample for HIP treatment were pelletized and sealed in Ag tubes in vacuo, and was then sintered at 0.15 GPa and 823 K for 2 h in N2. High pressures up to 5 GPa were applied to the powder sample in the cubic/ octahedral anvil apparatus according to a technique described elsewhere.34 Briefly, the raw powder sample was packed into a BN capsule and placed at a center of the inner octahedral anvils with pyrophyllite pieces as... 

Two multiple-anvil devices are currently in practical use. They are cubic-anvil devices and the two-stage cubic-octahedral systems. 

Fig. 1.21 The second stage of a cubic-octahedral system. Eight tungsten carbide cubic anvils with a truncation edge length of a compress an octahedral sample (reference 17).

The principle of most multiple-anvil systems is to compress a sample volume, in the shape of a regular polyhedron, by a variable number of identically shaped pistons which advance towards each other. Thus, tetrahedral, cubic, and octahedral compression have successfully been achieved. In this type of compression, the thrust is strictly along the axis of the pistons. Other geometries which introduce nonaxial (shear) components, such as hexahedral geometries, have proven to be remarkably unsuccessful and have been abandoned. Sliding-... 

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