|The triangular shaped instrument, with the
corners rounded, is 3 cm from the base of the triangle to the center of the curvature. The
thickness, with the diamonds in place, is 1.5 cm. The weight of the cell with mounting
bracket is 85 grams. The beryllium discs are 12.5 mm in diameter and 3 mm thick; the
diameter of the opening is 1 mm. Each Type I diamond, with 16 pavilion facets, weighs
approximately 1/6 carat (1 carat = .20 g) and has a pressure bearing surface of 0.6 mm.
Type IIa anvils are used with IR.
This diamond cell has been assembled with two diamonds each weighing approximately .20 carats with 0.6 mm culets or pressure bearing surfaces. The anvils are attached to beryllium discs with epoxy cement unless annealed stainless steel discs are requested.
The alignment and the parallelism have been completed by H.P.D.O., Inc. prior to shipping, therefore simply position the red markings when loading your sample. Also, check the opposition and the parallelism under a low power microscope consistently.
Diamond is the hardest and least compressible material formed in nature, however diamond will easily scratch diamond. To avoid damaging the diamond anvils certain precautions must be observed. Keep a piece of paper between the anvils when the instrument is not in use. Care must be taken when assembling the cell to prevent the damage of the diamonds.
CAUTION: DO NOT DEVELOP PRESSURE ON THE BARE DIAMOND ANVIL SURFACES.
The working surface can be cleaned by wiping with a Chem-Wipe or other lint free tissue. Solvents such as acetone or alcohol are used to wipe the anvil faces.
WARNING: Excessive contact of solvents to the epoxy and glue will loosen the bonding of the anvil to its mount.
The undersides of the diamond anvils are cleaned by placing a drop of acetone in the aperture and scrubbing with a round toothpick.
The diamond cell can also be attached to a guide plate in the sample compartment of FTIR spectrometer or on the stage of IR microscope.
Although a pre-drilled gasket without indentation works fine as well, a pre-indented gasket is recommended before a hole is drilled. Inconel, a metal foil 0.01" thick, is supplied as gasket material. Any burrs around the hole should be removed with a tip needle or a micro drill bit. The sample, usually a 100 micron die or less, with a pressure calibrant and pressure transmitting medium is sealed by tightening three Allen cap screws. In order to maintain the alignment and the parallelism of the anvils during the change of each pressures, it is very important to monitor the thickness for the cell. A micrometer can then be used. It is also a common phenomenon that the hole will wander around under pressures; which might result in the failure of the chamber seal if the pressure is not evenly applied to the diamond anvils. Hence, it is always a good idea to re-exam your sample under a microscope each time you have the pressure changed. The pressure range of this instrument is about 100 kbars. The pressure increase is very sensitive with the squeeze of the cell. Therefore, a good sense of very fine adjustment is necessary when tightening three screws sequentially.
Also be aware that the indented gasket won't return to the previous thickness after routinely altering the pressures.
The Merrill-Basset type diamond anvil cell can be used to study physical properties of liquid or solid samples under measurable pressure conditions.
Store the instrument with a piece of cardboard between the two diamond anvils to prevent abrasions. Anvils should be inspected before and after each use.
CLEANING THE ANVILS
The anvils can be cleaned by wiping acetone or alcohol across the working surfaces using tissue paper twisted into a pointed tip. Do not let the solvent come into contact with the epoxy as it will eventually loosen the bond holding the diamond to its mount. The undersides of the diamond anvils are cleaned by scrubbing with a round toothpick or placing a drop of acetone into the aperture if necessary.
HIGH PRESSURE STUDIES:
1 Pressure calibrants such as ruby chips should be distributed evenly around the sample for monitoring hydrostatic pressure conditions.