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COMPACT CYLINDER CELL

 

The compact cylinder cell is a high-pressure diamond cell designed to facilitate light scattering and X-ray diffraction of materials at pressures to one million atmospheres. Machined from 440C steel, the circular halves of the instrument feature a piston and cylinder arrangement. The diamond mounts are flat tungsten carbide discs. Cone angle openings of 60 are located top and bottom. Side ports provide access to the sample through the gasket for use with high-intensity radiation such as produced by a synchrotron source. Pressures are generated by tightening four Allen screws compressing Belleville spring-loaded washers. The piston and cylinder arrangement provides superior stability. The compact dimensions of this diamond cell allow it to fit a variety of instrumentation and microscope stages. Assembled with either Type I or Type IIa anvils, this cell is ideal for most high-pressure studies including Raman, Brillouin, and infrared spectroscopy as well as single-crystal or powder X-ray diffraction.

Limited production in 2004 of Vascomax cells for liquid nitrogen cryogenic experiments.

Diamond Anvils

The selection of diamond type and culet size should be based upon the choice of experimental techniques to be employed and the maximum pressures to be achieved. The diamond anvils are skillfully cut from natural, gem quality stones with 16 pavilion facets, a 70% table, and a working surface called the culet. The table and culet of the anvils are precisely cut to be parallel to the crystallographic (100) plane. The smaller the diameter of the culet the higher the pressure that can be achieved. Typical culet sizes range from 0.2 to 0.6 mm.

DIAMOND EXPERIMENTAL TECHNIQUE
Type I Diffraction
Optical
Type I
(Low fluorescence)
Raman
Diffraction
Optical
Type IIa Infrared
Diffraction
Optical

Mounts

Mounts can be constructed of various materials, with beryllium and tungsten carbide the most popular. The beryllium mounts are used in X-ray diffraction experiments because they are invisible to X-rays but they cannot withstand pressures above 40 GPa. The tungsten carbide mounts can withstand the highest pressures and are a favorite for spectroscopic studies.

Gaskets

Gasket material also defines the attainable pressure extreme. Popular choices are Inconel steel, stainless steel and rhenium. Because of its shear strength, rhenium gaskets can be used to the highest pressures. Typical thickness and hole sizes range from 0.15 to 0.25 mm.

1,000,000 atmospheres = 100 GPa = 1,000 kbar.
1 GPa = 10 kbar = 10,000 bar = 9,870 atmospheres

Compact Cell Diagram

Compact Cell

 

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Copyright 2008 by High Pressure Diamond Optics, Inc.
Last updated: August 12, 2008