Radovan Vanta¹, Sousan Abolhassani¹, Shiv Ashish Kumar², Massoud Dadras², Adrienn Baris¹, Guillaume Boetsch³, Harry Brandenberger⁴, Andreas Rummel⁵

¹ Laboratory for Materials Behaviour, Paul Scherrer Institut, 5232 Villigen-PSI, Switzerland, ² Service of Microscopy and Nanoscopy, IMT, University of Neuchâtel, Neuchâtel, Switzerland, ³ Imina Technologies SA, EPFL Innovation Park, Bâtiment E, 1015 Lausanne, Switzerland, ⁴ Gloor Instruments AG,  Schaffhauserstrasse 121, 8301 Kloten, Switzerland, ⁵ Kleindiek Nanotechnik GmbH, Aspenhaustr. 25, 72770 Reutlingen, Germany,

This paper provides a brief overview of the studies performed on semi-conducting properties of oxides and the change of these properties, for specific materials. A direct method is developed to measure the properties of the oxide by means of micromanipulators, in the SEM.

The interest of this method is to evaluate the role of such change of properties in the vicinity of interface of metal-oxides and to correlate the properties to the oxidation behavior and also to the hydrogen uptake of the alloy.

In a previous study the properties of a material has been measured by means of micromanipulators, outside of the microscope. This study has been performed in the SEM. The present study reports the properties of two families of alloys. It shows that an alloy with a sub-stoichiometric oxide in the vicinity of the interface has a lower resistivity.  The method consists of using a fine micromanipulator installed in the SEM; a surface is created by FIB micromachining and the measurements are made by means of the micromanipulators inside the SEM, in this manner an accurate positioning is possible.

As it can be observed in Figure 1, the oxide in alloy Zr2.5%Nb is sub-stoichiometric near the metal oxide interface [1]. Figure 2 presents the results of measurements of the Zr2.5%Nb and low-tin Zircaloy-4. The results of measurements and the comparison of the two alloys show that the second alloy having a stoichiometric oxide does not show such variation in resistivity in the vicinity of the metal-oxide interface. The results will be discussed to confirm the role of the different properties of the oxide, on the oxidation behavior.

Acknowledgements: Mr. Andrej Bullemer (AHL) and Dr. Elisabeth Müller (EMF) are acknowledged for the assistance for sample preparation.

Reference: [1] Abolhassani, S., Bart, G., and Jakob, A., “Examination of the Chemical Composition of Irradiated Zirconium Based Fuel Claddings at the Metal/Oxide Interface by TEM,” J. Nucl. Mater., Vol. 399, 2010, pp. 1–12.

Figures:

Figure 1: Analysis of the oxygen concentration of the oxide in the vicinity of the interface for an oxide, showing sub-stoichiometry near the interface [1].

Figure 2: Resistivity values calculated from measured resistance values by method described in the text. a) Zr-2.5% Nb sample compared to Zircalloy-4 low tin, all data are from measurements with Imina micromanipulators. b) Zr-2.5% Nb sample compared to Zircalloy-4 low tin, for the second one data from Kleidniediek measurements are plotted.

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