3D Imaging of Nanoparticles in an Inorganic Matrix Using TOF-SIMS Validated with STEM and EDX

Abstract

Imaging nano-objects in complex systems such as nanocomposites using time-of-flight secondary ion mass spectrometry (TOF-SIMS) is a challenging task. Due to a very small amount of the material and a matrix effect, the number of generated secondary ions can be insufficient to represent a 3D elemental distribution despite being detected in a mass spectrum. Therefore, a model sample consisting of a ZrCuAg matrix with embedded Al nanoparticles is designed. A high mass difference between the light Al and heavy matrix components limits mass interference. The chemical structure measurements using a pulsed 60 keV Bi 3 2+ beam or a continuous 30 keV Ga + beam reveals distinct Al signal segregation. This can indicate a spatially resolved detection of single 10s of nanometer large particles and/or their agglomerates for the first time. However, TOF-SIMS images of 50 nm or smaller objects do not necessarily represent their exact size and shape but can rather be their convolutions with the primary ion beam shape. Therefore, the size of nanoparticles (25−64 nm) was measured using scanning transmission electron microscopy. Our studies prove the capability of TOF-SIMS to image chemical structure of nanohybrids which is expected to help building new functional materials and optimize their properties.

The matrix effect in TOF-SIMS analysis of two-element inorganic thin films

“…Al, Si and Cu, were used as variables. The choice of these elements was closely related to intense development of Bulk Metallic Glasses (BMG [36][37][38][39][40][41][42][43][44] ) constituting a novel type of materials which are amorphous and have excellent mechanical properties but become brittle under external stress. Among various types of BMGs, particularly interesting are Zr-based BMG alloys as they combine high strength, low Young's modulus and resistance to corrosion 45 .…”

Lithium Garnet Li7La3Zr2O12 Electrolyte for All‐Solid‐State Batteries: Closing the Gap between Bulk and Thin Film Li‐Ion Conductivities

“…Other techniques with similar resolutions like STEM/EDX cannot be used for light elements like Li. [ 29 ] However, ToF‐SIMS is in general not a quantitative method because the “matrix effects” (the interactions between the analyte and the surroundings) influence the ionization yield by several orders of magnitude. [ 30 ] Figure shows the depth profiles of the matrix elements ( 7 Li + , 139 La + and 90 Zr + ), dopant ( 27 Al + ), and substrate material ( 24 Mg + ).…”

Potential of gas-assisted time-of-flight secondary ion mass spectrometry for improving the elemental characterization of complex metal-based systems

“…Until now, the highest TOF-SIMS lateral resolution 5 below 20 nm was achieved using a BAM-L200 reference sample 6 . Additionally, inorganic nanoparticles 7,8 were successfully analyzed in 3D. However, in both these cases, obtaining such impressive results was possible mainly due to the excellent ionization probability of aluminum and, most probably, would not be attainable in the case of weakly ionizing elements.…”