Abstract:We have used the pulsed muon source at ISIS to study high-temperature Na-ion dynamics in the quasi-one-dimensional (Q1D) metallic antiferromagnet NaV2O4. By performing systematic zero-field and longitudinal-field measurements as a function of temperature we clearly distinguish that the hopping rate increases exponentially above T diff ≈ 250 K. The data is well fitted to an Arrhenius type equation typical for a diffusion process, showing that the Na-ions starts to be mobile above T diff . Such results makes thi… Show more
“…The intrinsic diffusion dynamics of battery materials have been extensively studied using muon spin rotation (mSR) spectroscopy for lithium ion batteries [11][12][13] and cathodes in sodium ion batteries, 14,15 and have revealed activation energies for diffusion in the range of 225-571 meV for sodium ions in transition metal oxides and sodium jump frequencies of $0.15-0.2 ms À1 at room temperature. Combining this with jump distances determined by PXRD, diffusion constants can be derived, which for Na x CoO 2 are in the range 4 Â 10 À11 to 5 Â 10 À12 cm 2 s À1 depending on x.…”
Sodium ion batteries are a promising alternative to current lithium ion battery technology, providing relatively high capacity and good cycling stability at low cost.
“…The intrinsic diffusion dynamics of battery materials have been extensively studied using muon spin rotation (mSR) spectroscopy for lithium ion batteries [11][12][13] and cathodes in sodium ion batteries, 14,15 and have revealed activation energies for diffusion in the range of 225-571 meV for sodium ions in transition metal oxides and sodium jump frequencies of $0.15-0.2 ms À1 at room temperature. Combining this with jump distances determined by PXRD, diffusion constants can be derived, which for Na x CoO 2 are in the range 4 Â 10 À11 to 5 Â 10 À12 cm 2 s À1 depending on x.…”
Sodium ion batteries are a promising alternative to current lithium ion battery technology, providing relatively high capacity and good cycling stability at low cost.
“…In such systems, the formation of the magnetic ground state originates from a dominant intra-chain interaction together with a competition between the nearest and next nearest neighbor interactions 4,6 . In addition to their fundamental scientific interests, materials with similar open Q1D tunnel structures could potentially be used in future battery applications, where diffusion of the A cations is the main interest 10–12 .Figure 1The crystallographic data and structure of K 2 Cr 8 O 16 showing the tetragonal structure belonging to the I 4/ m space group with a = b = 9.76 Å and c = 2.93 Å. The middle panel shows two unit cells stacked along the c -axis, revealing the quasi-one-dimensional (Q1D) tunnel structure constructed from the Cr 2 O 4 framework and K + cation occupying the tunnel sites.…”
The K2Cr8O16 compound belongs to a series of quasi-1D compounds with intriguing magnetic properties that are stabilized through a high-pressure synthesis technique. In this study, a muon spin rotation, relaxation and resonance (μ+SR) technique is used to investigate the pressure dependent magnetic properties up to 25 kbar. μ+SR allows for measurements in true zero applied field and hereby access the true intrinsic material properties. As a result, a refined temperature/pressure phase diagram is presented revealing a novel low temperature/high pressure (pC1 = 21 kbar) transition from a ferromagnetic insulating to a high-pressure antiferromagnetic insulator. Finally, the current study also indicates the possible presence of a quantum critical point at pC2 ~ 33 kbar where the magnetic order in K2Cr8O16 is expected to be fully suppressed even at T = 0 K.
“…On the other hand, µ + SR have provided reasonable D Li for several battery materials regardless of the presence of magnetic ions, [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. Furthermore, D Na has been studied with µ + SR for Na x CoO 2 [14] and NaV 2 O 4 [25]. For NaMn 2 O 4 , the previous µ + SR experiment clarified the static nature below room temperature [26].…”
A quasi one-dimensional (1D) compound, NaMn 2 O 4 , in which Mn 2 O 4 zigzag chains form a 1D channel along the b-axis and Na ions locate at the center of the channel, is thought to be a good Na ionic conductor. In order to study Na-ion diffusion, we have measured µ + SR spectra using a powder sample in the temperature range between 100 and 500 K. A diffusive behavior was clearly observed above 325 K. Assuming a thermal activate process for jump diffusion of Na-ion between two nearest neighboring sites, a self diffusion coefficient of Na ion (D Na) and its activation energy (E a) were estimated as D Na = (3.1 ± 0.2) × 10 −11 cm 2 /s at 350 K and E a = 180(9) meV.
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