Effects of Temperature and Reagent Concentration on the Morphology of Chemically Vapor Deposited β‐Ta 2 O 5

Crystalline β‐Ta 2 O 5 coatings were deposited on hot‐isostatically‐pressed Si 3 N 4 by reacting TaCl 5 with H 2 and CO 2 in the temperature range of 1000°–1300°C and at a pressure of 660 Pa. The Ta 2 O 5 coatings generally consisted of wellcoalesced 2–3 μm grains, resulting in the formation of a nonporous coating morphology. However, the presence of microcracks on the as‐deposited surface was consistently observed. The surface morphology, texture, and growth rate of the coatings were examined as a function of deposition parameters.