Effects of focused ion beam milling on electron backscatter diffraction patterns in strontium titanate and stabilized zirconia

Abstract

SummaryThis study investigates the effect of focused ion beam (FIB) current and accelerating voltage on electron backscatter diffraction pattern quality of yttria-stabilized zirconia (YSZ) and Nb-doped strontium titanate (STN) to optimize data quality and acquisition time for 3D-EBSD experiments by FIB serial sectioning. Band contrast and band slope were used to describe the pattern quality. The FIB probe currents investigated ranged from 100 to 5000 pA and the accelerating voltage was either 30 or 5 kV. The results show that 30 kV FIB milling induced a significant reduction of the pattern quality of STN samples compared to a mechanically polished surface but yielded a high pattern quality on YSZ. The difference between STN and YSZ pattern quality is thought to be caused by difference in the degree of ion damage as their backscatter coefficients and ion penetration depths are virtually identical. Reducing the FIB probe current from 5000to 100 pA improved the pattern quality by 20% for STN but only showed a marginal improvement for YSZ. On STN, a conductive coating can help to improve the pattern quality and 5 kV polishing can lead to a 100% improvement of the pattern quality relatively to 30 kV FIB milling. For 3D-EBSD experiments of a material such as STN, it is recommended to combine a high kV FIB milling and low kV polishing for each slice in order to optimize the data quality and acquisition time.

Size‐induced grain boundary energy increase may cause softening of nanocrystalline yttria‐stabilized zirconia

“…The thinning was performed using sequential milling with Ga + focused ion beam culminating with 7.7 nA at 30 kV. Previous studies on the effect of FIB conditions in stabilized zirconia have shown that 30 kV at such relatively low currents effectively leads to negligible damage, 19 what can be attributed to the inherent high resistance of zirconia to ion irradiation damage at the used energy level. 20,21 Cracks were induced in situ by compression loading at the thinned area using a flat diamond punch with 1 µm in diameter displaced at a constant rate of 0.1 nm s −1 (Hysitron PI-95 Picoindenter).…”

A global investigation intoin situnanoindentation experiments on zirconia: from the sample geometry optimization to the stress nanolocalization using convergent beam electron diffraction

“…Concerning implantation, for instance, the depth was estimated to be equal to 50 nm in the case of copper material with a perpendicular Ga + bombardment at 30 keV (Kiener et al , 2007). A recent study on yttrium‐stabilized zirconia showed through Monte Carlo simulations that Ga ions penetration was 54 Å at 30 kV when the FIB probe was at 1° from the sample surface (Saowadee et al , 2012). In our case, the bombardment angle is equal to 55°, and the Ga penetration depth is probably equal to a few tens of nanometres, that is to say between those values taken from the literature.…”

Surface Degradation of Nanocrystalline Zirconia Dental Implants

“…A possibility to realize EBSD observations using low-vacuum scanning electron microscopes [18], and the rapid scanning offered by the fast acquisition cameras [19], allow EBSD mapping of zirconia without any deleterious charging effects. There are only a few studies in literature where the EBSD approach was used to study the microstructure of 3Y-TZP [12,[20][21][22][23]. Often the drawbacks due to charging effects are circumvented by adding a thin carbon coating or by lowering the SEM voltage during OIM scan.…”