Synthesis by coprecipitation of india-stabilized zirconia and codoping with MoO3, WO3, TaO2.5, or NbO2.5 for application as thermal barrier coatings

Abstract

Coprecipitation synthesis of nanocrystalline india-stabilized zirconia with high surface area and codoping with MoO 3 , WO 3 , TaO 2.5 , or NbO 2.5 is reported. The concentration of codopants was defined by the charge-compensating mechanism. Ethanol washing followed by azeotropic distillation and freeze drying were compared as dehydration techniques for the gels. As determined by XRD and Raman scattering, 9 mol% of InO 1.5 plus charge-compensating dopants is sufficient to completely stabilize the high-temperature tetragonal phase of zirconia. The effect of alloying hexavalent and pentavalent oxides was secondary compared to the InO 1.5 concentration in the retention of the tetragonal structure. Improved specific surface area of 106.1 m 2 g -1 and crystallite size between 8 and 9 nm were achieved through ethanol washing and subsequent azeotropic distillation even after calcination at 600 ºC. This result is attributed to the effect of the incorporation of ethoxy and butoxy groups after the treatment of the gels in organic medium, as detected by FT-IR spectroscopy and DSC/TG.

Influence of oxygen partial pressure on the structural, optical and electrical properties of magnetron sputtered Zr0.7Nb0.3O2 films

“…In recent years, there was much attention on enhancing the dielectric properties and eventually the thermal stability of ZrO 2 with Si by adding pentavalent ions. In particular, Piva et al, investigated the effect of addition of Ta, Mo, W and Nb to ZrO 2 to avoid lower-temperature crystallization effects [2]. The chemical and structural similarities of niobium-and zirconium-based oxide triggers the idea of mixing them to enhance the dielectric properties of resulting oxide materials.…”