Redox controllable switch of crystalline phase and physical property in SrVOx epitaxial films

Abstract

Transition-metal oxides have attracted much attention due to its abundant crystalline phases and intriguing physical properties. However, some of these compounds are difficult to be fabricated directly in film form due to the ease of valence variation of transition-metal elements. In this work, we reveal the reversible structural transition between SrVO3 and Sr2V2O7 films via thermal treatment in oxygen atmosphere or in vacuum. Based on this, Sr2V2O7 epitaxial films are successfully synthesized and studied. Property characterizations show that the semitransparent and metallic SrVO3 could reversibly switch into transparent and insulating Sr2V2O7, implying potential applications in controllable electronic and optical devices.

Artificial Aging of Thin Films of the Indium-Free Transparent Conducting Oxide SrVO3

“…The XAS V L 2,3 edges of the aged surface of a 200 °C treated polycrystalline sample, i.e., the aged state, are shown in Figure , black curve, labeled “before water”. The shape of the two edges, and especially the narrow V L 3 edge and its prepeak shoulder, is typical of a strong contribution of V 5+ , which is characteristic of the formation of V 2 O 5 , but also of Sr 3 V 2 O 8 or Sr 2 V 2 O 7 , phases that were observed at the surface of SVO films heated under oxygen at higher temperatures ,, or deposited by hybrid MBE . For qualitative analysis, a linear combination fit using reference spectra extracted from ref has been performed taking into account the weight of each oxidization state at these absorption energies (dashed lines in Figure ).…”

“…However, due to the presence of the 4+ oxidation state of the vanadium ion, which corresponds to one remaining electron in the ion’s 3d orbital and is a rather unstable oxidation state, the material faces a specific risk of chemical degradation under ambient conditions, compromising its long-term stability. Losing the remaining 3d electron is energetically favorable for the V ion, so that SVO is prone to oxidation and to transformation to Sr 2 V 2 O 7 − or Sr 3 V 2 O 8 . ,, Despite being transparent phases, the related V 5+ oxidation state may increase substantially the electrical resistivity of SVO and therefore deteriorates its functional properties as a TCO. The formation of these phases has been shown in the case of high-temperature annealing under oxygen, , but they may be also responsible for certain electrical contact issues observed with samples not having undergone special treatment but which have only been stored at ambient conditions for some months.…”

“…Losing the remaining 3d electron is energetically favorable for the V ion, so that SVO is prone to oxidation and to transformation to Sr 2 V 2 O 7 − or Sr 3 V 2 O 8 . ,, Despite being transparent phases, the related V 5+ oxidation state may increase substantially the electrical resistivity of SVO and therefore deteriorates its functional properties as a TCO. The formation of these phases has been shown in the case of high-temperature annealing under oxygen, , but they may be also responsible for certain electrical contact issues observed with samples not having undergone special treatment but which have only been stored at ambient conditions for some months. Due to the impact on the electrical conduction of SVO, knowledge of the oxidation mechanisms at low to intermediate temperatures is important to avoid chemical instabilities of the indium-free TCO in future applications.…”

Strontium vanadate-supported graphitic carbon nitride nanocomposite for simultaneous voltammetric determination of acetaminophen and levofloxacin in complex biological samples

“…22,23 So far, several types of mixed oxide phase structures of SrV NPs have been reported, such as SrV 2 O 6 , SrVO 3 , Sr 3 V 2 O 8 , Sr 2 V 2 O 7 , and Sr 3 (VO 4 ) 2 . [23][24][25] Despite this, very few studies on the synthesis of SrV-based nanostructures with various morphologies and phases for the sensitive detection of various biomolecules have been presented, 26,27 and Sr 2 V 2 O 7 has not yet been explored enough.…”

Solid-phase epitaxial growth of the correlated-electron transparent conducting oxide SrVO3

“…[14,15] A further complication arises because V ions in Sr-V-O with a 1:1 Sr:V ratio, including Sr2V2O7, can adopt a 5+ oxidation state and can be thermodynamically favored in oxidizing environments. [16] The competing phases interrupt the epitaxy of SrVO3 and are electrically insulating. [15,17] Minimizing the formation of competing phases is a thus a key challenge for the epitaxial growth of SrVO3.…”