Electrical characteristics of grain boundaries

Electrical characteristics of grain boundaries

The structure of grain boundaries (GBs) is dependent on the crystallographic structure of the material, orientation of the neighbouring grains, composition of material and temperature. The abovementioned conditions set a specific structure of the GB which dictates several properties of the materials, e.g. mechanical behaviour, diffusion, and electrical properties. The latest properties are usually captured through macroscopic characterisation which limits investigation of individual GB types. This project aims to probe the electrical resistivity of individual GB segments having well-known structural and thermodynamic characters, and consequently interconnect their structural and electrical properties.

In this project, we developed a novel SEM in-situ and ex-situ methodology for local electrical characterisation of GBs [1]. The method includes (i) A proper thin film and bulk materials processing, in purpose to obtain single GB zones. (ii) High spatial resolution probing system achieved by micromanipulators, and (iii) Highly sensitive electrical measurements system. The method was applied on copper to systematically study the effect of GB type, normal planes, inclination and curvature on its resistivity [2]. New materials systems are being currently studied. The freshly gained knowledge is already applied for functional materials to understand the microstructure-electrical properties relationships [3-4].

Publication References

Bishara, H.; Ghidelli, M.; Dehm, G.: Approaches to Measure the Resistivity of Grain Boundaries in Metals with High Sensitivity and Spatial Resolution: A Case Study Employing Cu. ACS Applied Electronic Materials 2 (7), pp. 2049 - 2056 (2020)
Bishara, H.; Lee, S.; Brink, T.; Ghidelli, M.; Dehm, G.: Understanding Grain Boundary Electrical Resistivity in Cu: The Effect of Boundary Structure. ACS Nano 15 (10), pp. 16607 - 16615 (2021)
Gomell, L.; Roscher, M.; Bishara, H.; Jägle, E. A.; Scheu, C.; Gault, B.: Properties and influence of microstructure and crystal defects in Fe2VAl modified by laser surface remelting. Scripta Materialia 193, pp. 153 - 157 (2021)
Luo, T.; Serrano Sanchez, F. M.; Bishara, H.; Zhang, S.; Bueno Villoro, R.; Kuo, J. J.; Felser, C.; Scheu, C.; Snyder, G. J.; Best, J. P. et al.; Dehm, G.; Yu, Y.; Raabe, D.; Fu, C.; Gault, B.: Dopant-segregation to grain boundaries controls electrical conductivity of η-type NbCo(Pt)Sn half-Heusler alloy mediating thermoelectric performance. Acta Materialia 217, 117147 (2021)


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