期刊
JOURNAL OF MATERIALS CHEMISTRY A
卷 9, 期 31, 页码 16917-16927出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/d1ta02352g
关键词
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资金
- EPSRC [EP/P019951]
- Johnson Matthey
- EPSRC [EP/P019951/1] Funding Source: UKRI
CW EPR spectroscopy was used to study defect structure and electron transfer mechanism in LiBO2-V2O5 mixed conductive glasses. Different signal features and activation energy consistent with other conducting glasses were observed, indicating distinct electron transfer mechanisms with increasing V2O5 content.
Continuous Wave (CW) Electron Paramagnetic Resonance (EPR) spectroscopy was used to study the defect structure and electron transfer mechanism in a series of LiBO2-V2O5 mixed conductive glasses of varying V2O5 content. These glassy materials are attracting growing interest for energy storage devices. At low V2O5 content (VLB1), an isolated S = 1/2 vanadium defect centre is found at a network modifying position within the LiBO2 matrix. The observed spin Hamiltonian parameters are consistent with a V4+ centre possessing a distorted octahedral configuration and d(xy) orbital ground state. At high V2O5 content (VLB3), the vanadium hyperfine structure is absent indicative of a distinct exchange-narrowed signal. A model was developed to analyse the linewidth and g-tensor component of the EPR signals, revealing a marked temperature dependent behaviour, consistent with a polaron hopping mechanism of electron transfer and inter-electronic exchange along the g(3) direction, coincident with the electron transfer axis. The activation energy (E-a) was estimated to be 0.081 eV, consistent with other conducting glasses. A relaxation-dominated line broadening mechanism was further supported by multi-frequency EPR measurements, which also identified unresolved features at high frequencies due to unaccounted for anisotropic exchange/speciation within the disordered network. This analysis provides a straight-forward method for the use of EPR to investigate solid-state glassy materials.
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