Report on Y₂O₃ Coating

Y₂O₃ coating on inner surface of quartz tube OD=25.4mm, ID=22mm.
The coating was examined by the following methods:

• Surface morphology by HRSEM (High Resolution)

• EDS analysis on the inner surface (Carbon coating for the analysis)

• Metallographic cross-section (SEM Philips XL-30)

The results were as follows:
The surface morphology is shown in Figs 1, 2 and reveals dense coating of nano-sized crystals (~30nm). No pin-holes were revealed.

Fig 1: The surface morphology of the Y2O3 layer	Fig 2 : The same as in Fig 1 at the higher magnification. The particle size is ~30nm.

EDS (LINK ISIS) spectrum obtained in the middle of the tube is shown in Fig 3 and reveals 88wt% Y₂O₃+ 12wt% SiO₂ (substrate). Since the depth of EDS analysis is ~ 1µm, there is the indication that Y₂O₃ layer thickness is close to 1µm.

Fig 3: EDS spectrum of Y2O3 coating on SiO2 substrate.

Metallographic cross-section prepared at the end of the tube reveals dense, uniform coating of ~0.5µm - see arrows in Figs 4 and 5. No discontinuities or other defects were revealed at the quartz/ Y₂O₃ layer interface. In the central part of the tube a coating thickness of ~0.75µm was observed, see Fig 6.

Fig 4: The cross-section through the coating at the end of the tube- 0.5µm.	Fig 5: Additional area in sample at the end of the tube- dense uniform coating.
Fig 6: The cross-section of the central tube part. The Yttria layer thickness is ~0.75µm.