Study of the Dissolution of Thin Films of Cerium Oxide by Using a GaPO₄ Crystal Microbalance

Abstract

In this study, microbalance measurements with a GaPO(4) crystal were performed to determine the dissolution rate of cerium oxide thin films at room temperature after a high temperature treatment of the hydroxide precursor Ce(OH)(4) at 700 degrees C. The properties of the GaPO(4) crystal enables gravimetric measurements to be performed after being heated at high temperatures where the classical quartz crystal microbalance irreversibly loses all its piezoelectric properties. The GaPO(4) resonators were calibrated at room temperature by galvanostatic copper deposition before and after a high-temperature treatment, and the sensitivity coefficients K(S) were found to be identical, which proved the high potential of GaPO(4) at high temperatures. However the accuracy of the gravimetric measurements is lower after a high temperature treatment. The rate determining step of the cerium oxide dissolution seems to be the reduction reaction of Ce(IV) to Ce(III), which is carried out by the hydrogen peroxide present in the dissolution medium.

Solvent‐deficient method lowers grain‐boundary resistivity of doped ceria

“…Therefore, the dissolution of Ce 3+ is more dominant than Ce 4+ on the GDC particles. The reaction of CeO 2 dissolution can be estimated as follows,…”

“…In the case of CeO 2 , the dissolution rate is very slow in acids such as nitric acid and sulfuric acid regardless of the high concentration and elevated temperature utilized . The CeO 2 particles are dissolved either by the addition of a reducing agent such as Fe(II) and hydrogen peroxide (H 2 O 2 ) or by inducing oxygen vacancies by annealing in a reducing atmosphere . Jakab et al reported that the mixture of nitric acid (HNO 3 ) and H 2 O 2 significantly increases the dissolution speed of CeO 2 .…”

“…24,25 The CeO 2 particles are dissolved either by the addition of a reducing agent such as Fe(II) and hydrogen peroxide (H 2 O 2 ) or by inducing oxygen vacancies by annealing in a reducing atmosphere. [26][27][28] Jakab et al reported that the mixture of nitric acid (HNO 3 ) and H 2 O 2 significantly increases the dissolution speed of CeO 2 . 27 Therefore, this mixture can be employed as a precursor solution for CSP of gadolinium-doped cerium oxide (GDC).…”

Nitrate conversion and supercritical fluid extraction of UO2-CeO2 solid solution prepared by an electrolytic reduction-coprecipitation method

“…The dissolution of CeO 2 with acid is shown as Eqs. 9 and 10 [45]. The dissolution of CeO 2 with acid is thermodynamically unfeasible, so CeO 2 is difficult to directly dissolve by HNO 3 .…”

“…The dissolution of CeO 2 with acid is thermodynamically unfeasible, so CeO 2 is difficult to directly dissolve by HNO 3 . Often, a reducing reagent, such as H 2 O 2 , is added to reduce Ce 4+ to Ce 3+ and to facilitate the dissolution of CeO 2 with acid [45]. UO 2 is thermodynamically easily dissolved in HNO 3 [46].…”