Laser based analysis of transition metal boride thin films using liquid standards

Abstract

In this work the use of two laser assisted direct solid sampling methods, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and laser induced breakdown spectroscopy (LIBS) for the determination of the stoichiometry of novel diboride based materials is reported. To overcome the need for certified reference materials or matrix matched standards, which were usually required for quantitative investigations with LA-ICP-MS or LIBS, in this work liquid standards are employed. For LA-ICP-MS the concept of self-aliquoting micro-grooves and for LIBS conventional dried droplets were used. As a model for application of the developed analytical procedures the ternary system W1-xTaxB2-z was used. Fabrication of W1-xTaxB2-z thin films with varying stoichiometry was performed via magnetron sputtering. Reference compositions were obtained by liquid digestion of the samples and subsequent ICP-OES measurement. Both laser-assisted methods enabled fast and spatially resolved measurements, although the LA-ICP-MS method generally yielded more accurate results. It was shown that the method can easily be adapted for the stoichiometry determination of systems with different elemental composition.