Determination of the hydrogen content of thick tristearin layers prepared by physical vapour deposition

In the frame of reference fluence measurements with a proton recoil telescope, solid layers with thicknesses up to 25 mg•cm-2 and with well-known and stable hydrogen content above 12% were requested on circular tantalum discs. Tristearin was chosen as the most suitable compound meeting these requirements. The best available deposition method to prepare homogeneous layers with this material at the European Commission Joint Research Centre IRMM (EC JRC-IRMM) is physical vapor deposition. Although never confirmed, it is very unlikely that stoichiometric changes occur during evaporation. Therefore the hydrogen content of the layer can be known from the bulk tristearin powder and its respective purity prior to the evaporation. However, no hydrogen analysis has been performed yet with a suitable accuracy confirming the stoichiometry of the starting material as well as the stability of the hydrogen content prior and after evaporation. In this work, thick tristearin deposits were prepared with a modified evaporation setup. The deposited thickness was determined by means of accurate weighing and the hydrogen content before and after evaporation was characterized by combustion analysis with a relative combined uncertainty of 0.82 %, which is accurate enough to observe possible stoichiometric differences.

VANLEEUW David;  SIBBENS Goedele;  PLOMPEN Arjan; 

2015-05-13

SPRINGER

JRC91666

0236-5731,   

http://rd.springer.com/article/10.1007/s10967-015-4156-8#,    https://publications.jrc.ec.europa.eu/repository/handle/JRC91666,   

10.1007/s10967-015-4156-8,