Swelling and Gas Release in ZnO

Abstract

Swelling and gas release in a model ceramic system, ZnO, were studied under known internal and external pressures, oxygen partial pressures, and temperatures. When gas was not released, the instantaneous swelling strain rate was: &(DF exp -Q/RT) where DF is the instantaneous pressure driving force for swelling, Q = 141k 13 kcaymol, and RT has its usual meaning. For a fixed initial driving force for swelling, the strain rate decreased as t-lI3 where t is time. Volumetric swelling strains of 3 11% were measured prior to gas release, indicating that swelling is not simply reversed sintering. Gas release was usually observed and occurred by the interconnection of intergranular porosity. A resintering process immediately followed gas release, but at a slower rate than the initial sintering rate at the same density. Analysis of the swelling experiments yielded a surface energy of -0.3 J/m2 at 920°C for ZnO.

Analysis of Optical Absorbance Spectra for the Determination of ZnO Nanoparticle Size Distribution, Solubility, and Surface Energy

“…The solubility increases between 10 and 50 °C by 2 orders of magnitude from 1.7 × 10 −13 to 2.5 × 10 −11 mol/L (Figure a), whereas the surface energy decreases from 0.64 to 0.62 J/m 2 (Figure b). Compared to the literature, where theoretically estimated surface energies of macroscopic ZnO between 0.1 and 0.7 J/m 2 have been reported, − the values are quite reasonable. Our approach does not consider adsorption of ions at the particle surface.…”

Gadolinium doped ceria interlayers for Solid Oxide Fuel Cells cathodes: Enhanced reactivity with sintering aids (Li, Cu, Zn), and improved densification by infiltration

“…In the case of sintering aids, a preliminary study on GDC pellets was carried out using dilatometry measurements. De-densification phenomena have been observed in many ceramics materials such as ZnO [31,32],…”

De‐densification mechanisms of yttria‐doped cerium oxide during sintering in a reducing atmosphere

“…In some cases, however, swelling can occur to result in the destruction of the ceramic. Such de‐densification phenomena (or de‐sintering) have been observed in many materials such as ZnO, Fe 2 O 3 , superconductors, some carbides and nitrides, nuclear fuels, ITO, (LaSr)FeO 3 , and BaTiO 3 ceramics.…”