Oxygen vacancy ordering and its mobility in YMnO3

Oxygen vacancies in the bulk and at neutral domain walls in hexagonal YMnO3

“…Out-of-plane migration is less favorable, with barriers of ∼1.7 eV and ∼1.9 eV for the O1 to O4 and O2 to O3 paths, respectively. Experimental reports have shown that oxygen vacancies move in plane under an applied electron beam [48]. Our calculated oxygen vacancy migration barriers are high compared to state-of-the-art oxygen conducting perovskites [49]; in Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3−δ for example the migration barrier is ∼0.4-0.5 eV [50,51].…”

“…It has been shown that large concentrations of oxygen vacancies reduce both the trimerization amplitude and the ferroelectric polarization [28], and that introduction of vacancies can enhance the mobility of the ferroelectric domain walls [12]. Previous studies further show that the domain structure evolves from the characteristic clover-leaf patterns into stripe-like patterns in highly reduced samples [10], and that the domain walls become more mobile under electric field poling [48]. This observed higher domain wall mobility can be explained by the reduced trimerization distortions when high concentrations of vacancies are introduced.…”

“…A preference for planar oxygen vacancy formation has been indicated experimentally by X-ray diffraction [28] and transmission electron microscopy [48,52]. However, distinguishing between the two planar oxygen vacancies in experiments is challenging.…”

Gas sensing properties of YMnO3 based materials for the detection of NOx and CO

“…Since the physical and chemical properties of such compounds heavily depend on the defect chemistry, these materials might be adjusted or tailored to the specific application [3]. For instance, a small change in oxygen stoichiometry can induce large differences in electronic conduction, surface redox behavior, heterogeneous catalysis [4] and gas selectivity.…”

“…In this paper we study the chemoresistive behavior of hexagonal YMnO3 produced by gel combustion both toward reducing (CO) and oxidizing gases (NO2). This material has already received much attention due to its magnetic and ferroelectric properties [4] [12][13], but its gas sensing properties are still scarcely studied, even if the large number of possible oxidation states of Mn induces to expect a highly reactive surface.…”