Harnessing Selective Exsolution of Sn Metal to Enhance Electrical Conductivity in Oxygen‐Deficient Perovskite Stannates

Abstract

The versatile application of newly discovered oxide semiconductors calls for developing a simple process to generate conducting carriers. High-temperature reduction treatment leads to electrical conduction in perovskite stannate semiconductors, but carrier concentration is poorly controlled and inconsistently reported in BaSnO 3−δ films after the reduction process so far. Here, a new strategy to enhance the electrical conductivity of BaSnO 3−δ films is demonstrated by exploiting selective exsolution of Sn metals in the perovskite framework. Due to strong dependence of conductivity on initial Sn/Ba cation ratio in the reduced BaSnO 3−δ films, interestingly, only Sn-excess BaSnO 3−δ films show a dramatic increase of carrier concentration (∆n 3D = 5-7 × 10 19 cm −3 ) after high-temperature reduction; exceptionally high electrical conductivity (σ ≈ 6000 S cm −1 ) is achieved in reduced Sn-excess (La, Ba)SnO 3−δ films, which exceed full activation of La dopants in untreated (La, Ba)SnO 3 . By multiple characterizations combined with theoretical calculation, it is disclosed that a small fraction of segregated β-Sn nanoparticles is likely to contribute the additional source of n 3D in the BaSnO 3−δ matrix as a result of spontaneous charge transfer from the segregated β-Sn metallic phase to BaSnO 3−δ . These original results propose a simple strategy to further increase electrical conductivity in perovskite oxide semiconductors by non-stoichiometry-driven metal exsolution.

Anti-phase boundary accelerated exsolution of nanoparticles in non-stoichiometric perovskite thin films

“…Moreover, the socketed NP structure leads to exceptionally high thermal stability and coking resistance owing to the strong interaction between the anchored particle and the oxide support 4 . Additionally, the exsolution process can lead to creation of magnetic nanostructure 12,19 and also significantly improve the conductivity of the host oxide 14,15 . As such, exsolution has emerged as a new platform for the design of supported…”

“…heterogeneous NPs on functional oxides. Various efforts have been made to improve the exsolution process, including the electrochemical poling 1 , metal-oxygen bond strength control 6 , facetdependent interfacial energy control 7 , co-segregation from double perovskite lattices 8 , and charge-balanced doping 15 .…”

Cooperative coupling of anisotropic phonon modes intensifies visible thermochromism in layered α-MoO3

“…The optical band gap (E g ) was calculated at different temperatures using Tauc's method 26,27 from the Kubelka-Munk function to extract the extinction coefficient from the temperature-dependent diffuse reflectance spectra at the 2nd heating-cooling sweep (Fig. 1f).…”

Enhanced Catalytic Performance in Two-Electron Oxygen Reduction Reaction via ZnSnO3 Perovskite

“…The introduction of an element to the B site can not only realize the synergistic effect with the element in the A site but affect its electronic environment, which may unexpectedly activate the potential catalytic behaviors of perovskite oxides. Perovskite stannates, a kind of perovskite oxide where Sn is exploited for the B-site, have acquired remarkable attention in functional materials due to the superior charge carrier mobility and narrow bandgap. , Typically, their comparable conductivity and electrochemical activity give a broad application prospect in the electrochemical field as well . Particularly, the multivalence property of Sn makes it easy for the generation of defect structures on the catalyst surface as well, which is beneficial for enhancing catalytic performances …”