Planchets (Beryllium, Diamond & Pyrolytic Graphite)

Overview

Planchets are flat, low-background disc substrates rather than pin or stub mounts, used primarily as sample backgrounds for energy- and wavelength-dispersive x-ray (EDS/WDS) microanalysis in the SEM. SPI Supplies offers them in beryllium, diamond, and pyrolytic graphite, each chosen for producing minimal Bremsstrahlung background radiation and few or no interfering characteristic x-ray peaks in the resulting spectrum. Beryllium has long been the standard low-background substrate, but its toxicity has led many institutions to restrict its use, making the diamond and pyrolytic graphite planchets popular non-toxic or lower-risk alternatives. All three materials are designed to be cleaned and reused rather than treated as disposable consumables.

Beryllium Planchets

Beryllium planchets are 25.4 mm in diameter and 0.25 mm thick, with a highly polished surface equivalent to a 1 µm polishing abrasive finish, and are packaged individually in a plastic box. SPI Supplies notes that cleaning must follow recommended procedures to avoid generating toxic beryllium particulates, and a Safety Data Sheet is provided for the product.

Diamond & Pyrolytic Graphite Planchets

Diamond planchets measure 10 mm in diameter by a minimum 0.025 mm (25 µm) thickness, with one side fine-polished to a mirror finish and the other left with the natural crystallite texture, and can be cleaned with aggressive acids or bases in an ultrasonic bath. Pyrolytic graphite planchets are 25.4 mm in diameter, available in 1.6 mm or 3.2 mm thickness, described as substrate-nucleated (SN Grade) material that can be diamond-polished to a mirror finish and re-polished for reuse.

Specifications