Surface Modification of ZnAg Sample - Sample Preparation for SEM

Application Note for Leica EM RES102 - Material Research

October 17, 2016

By means of cleaning, polishing and contrast enhancement a soft ZnAg sample should be prepared to obtain information concerning the grain structure and interfaces of the sample.

The sample is contaminated after mechanical polishing. There are still some scratches on the surface. Grain structure is almost invisible. Cleaning, polishing and contrast enhancement are successively carried out.

The deep scratch in the sample is just to recognize the same sample area after each preparation step.

Preparation Conditions and Results

Mechanical polishing

Fig.1: ZnAg after mechanical polishing
Fig.2: ZnAg sample after cleaning


Acceleration voltage:3 kV
Gun current:1.8 mA
Milling angle:10°
Milling time:30 min


The surface looks much better after cleaning (see Fig.2). It was possible to remove all contamination from the sample. A weak grain structure is visible.

Fig.3: ZnAg sample after polishing


Acceleration voltage:7 kV
Gun current:2.6 mA
Milling angle:
Milling time:1 h

We could achieve further improvement of the surface quality after polishing. The grain structure looks clearer (see Fig.3).

Fig.4: ZnAg sample after cleaning, polishing and contrast enhancement

Contrast Enhancement

Acceleration voltage:4 kV
Gun current:1.8 mA
Milling angle:90°
Milling time:1.5 min


The last short contrast enhancement step provides a very clear grain and interface structure.

Fig.5: ZnAg Sample after mechanical polishing
Fig.6: ZnAg sample after all additional ion milling steps
Fig.7: ZnAg sample after mechanical polishing and the complete ion milling treatment