Synthetic beta‐K_0.33V₂O₅ Nanorods: A Metal–Insulator Transition in Vanadium Oxide Bronze

Abstract

We found a linear relationship between the metal-insulator transition (MIT) temperature and the A(+) ionic radius of the beta-A(0.33)V(2)O(5) bronze family, leading our attention to beta-K(0.33)V(2)O(5) which has been neglected for a long time. We have introduced a facile hydrothermal method to obtain the single-crystalline beta-K(0.33)V(2)O(5) nanorods. As expected, both the temperature-dependence of the resistivity and magnetization demonstrated MITs at about 72 K for beta-K(0.33)V(2)O(5), thus matching well with the linear relationship described above. The beta-K(0.33)V(2)O(5) was assigned as a new member of the beta-A(0.33)V(2)O(5) bronze family for their similar crystal and electronic structures and their MIT property; this addition enriches the beta-A(0.33)V(2)O(5) bronze family.

Transformers: the changing phases of low-dimensional vanadium oxide bronzes

“…52 Indeed, the resurgence of interest in these compounds stems from the realization that the fundamental electronic phase diagrams of these materials can feature colossal metalinsulator transitions once cation ordering is appropriately established. [19][20][21]26,38,45,46,53,54 Much of this intrinsic electronic phase transition behaviour was obscured in previous work as a result of imperfections such as cation disorder.…”

“…4c, inset) plots indicate a sharp nonlinearity with an abrupt increase in current at a threshold voltage signifying an insulator-conductor transition. Although the double-layered V 2 O 5 framework is similar, the starkly different behaviour observed for K + and Ag + and for the different stoichiometries (0.5 for K + and 0.88 for Ag + ) indicates the establishment of distinct charge localization patterns in each compound depending on the stoichiometry x and the metal cation M. 20 A similar strategy of scaling to nanometersized dimensions has also led to observation of metal-insulator transitions in synthetic nolanite Fe 2.5 V 1.5 V 5.6 O 16 at a temperature of 150 K and in b-K 0.33 V 2 O 5 at 72 K. 45,46 Fig. 4d plots the electric-field-induced insulator-conductor transition observed for another tunnel-structured compound, b-Pb x V 2 O 5 (x B 0.33), which crystallizes in a tunnel-structured framework analogous to b 0 -Cu x V 2 O 5 but differs in terms of the tunnel crystallographic site occupied by the Pb 2+ cations.…”

“…Indeed, this simple picture explains to a great extent the origin of metal-insulator transitions observed in many of these compounds. [19][20][21][22][23][24][25]38,45,46 In a classical Mott insulator, given the width of the Hubbard bands, decreasing the separation (d) between adjacent V 4+ sites eventually increases orbital overlap W to the extent that an abrupt transition to a metallic state can be triggered. Equivalently, if a high density of charge carriers is introduced within a Mott insulator as a result of optical, thermal, doping, or gate-voltage-induced excitations, Thomas-Fermi screening of bound excitonic states by the free carriers causes a breakdown of attractive electrostatic interactions between electrons and holes and leads to an abrupt increase of the carrier density, resulting in transformation of the system to a metallic state.…”

Carbon decorated Li3V2(PO4)3 for high-rate lithium-ion batteries: Electrochemical performance and charge compensation mechanism

“…3(a and b); the enlarged pre-edge structures are shown in Fig. S3), which are related to the coordination environment of V atoms, implies the deviations from crystallographically equivalent V sites and the formation of the distorted VO6 octahedra as a result of the strong orbital mixing between V 3d and O 2p states [45,46]. Because of the shorter lifetime and the Coster-Kronig decay process, the line shape of L2-edge is broader than that of L3-edge, and therefore, we will mainly focus on the spectral shape change of L3-edge for both TEY and TFY spectra (Fig.…”

Li0.3V2O5 with high lithium diffusion rate: a promising anode material for aqueous lithium-ion batteries with superior rate performance

“…Moreover, the stable tunnel can also provide a fast diffusion path for ion diffusion. 21 In M 0.3 V 2 O 5 , M can be substituted by Li, K, Na, Cu, Ag or Pb, 22,23 of which the Li 0.3 V 2 O 5 may be the most suitable candidate for use due to the lowest cationic hindrance in the tunnel and therefore exhibits high D Li +, based on calculations. 24 The electronic conductivity of electrode materials has been proven as another signicant limiting factor for high rate performance due to its signicant inuence on the utilization efficiency of the theoretical capacity.…”