We investigate lattice dynamics and spin-phonon coupling as well as the magnetic and electronic properties of $\beta \text{−}{\mathrm{Na}}_{0.33}{\mathrm{V}}_2{\mathrm{O}}_5$ using temperature-dependent Raman scattering, dc magnetization and dc resistivity, x-ray photoemission, and absorption spectroscopy. The Rietveld refinement of the x-ray diffraction pattern with space group $C2/m$ confirms the monoclinic structure. The analysis of temperature-dependent Raman spectra in a temperature range of 13–673 K reveals an anharmonic dependence of the phonon frequency and full width at half maximum, which is accredited to the symmetric phonon decay. However, $<\sim 40\mathrm{K}$, the hardening of the phonon frequency beyond anharmonicity is attributed to the spin-phonon coupling. Interestingly, the estimated effective magnetic moment ${\mu }_{\mathrm{eff}}= 0.63{\mathrm{\mu }}_{\mathrm{B}}$ from the magnetization data manifests a mixed-valence state of V ions in $4+(18\pm 1\%)$ and $5+(82\pm 1\%$). A similar ratio of ${\mathrm{V}}^{4+}$ to ${\mathrm{V}}^{5+}$ is also observed in the x-ray photoemission and x-ray absorption near-edge spectra and found to be consistent with the sample stoichiometry. The analysis of extended x-ray absorption fine structure at the V $K$-edge gives the corresponding V–O bond lengths, which are utilized in the detailed analysis of Raman modes. Moreover, the temperature-dependent resistivity resembles a semiconducting behavior where the charge carrier transport is facilitated by the band conduction at higher temperatures and via hopping $\le 260\mathrm{K}$.

中文翻译：

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β−Na0.33V2O5 中的晶格动力学、磁性和电子输运研究

我们研究晶格动力学和自旋声子耦合以及磁性和电子特性$\beta \text{-}{钠}_{0.33}{\mathrm{五}}_2{\mathrm{○}}_5$使用与温度相关的拉曼散射、直流磁化强度和直流电阻率、X 射线光电子发射和吸收光谱。具有空间群的 X 射线衍射图的 Rietveld 细化$C2/米$证实了单斜结构。对 13-673 K 温度范围内的温度相关拉曼光谱的分析揭示了声子频率和半峰全宽的非谐波依赖性，这与对称声子衰变有关。然而，$<～40\mathrm{ķ}$，声子频率的硬化超出非谐性归因于自旋 - 声子耦合。有趣的是，估计的有效磁矩${\mu }_{\mathrm{效果}}= 0.63{\mathrm{\mu }}_{\mathrm{乙}}$从磁化数据中可以看出 V 离子的混合价态$4+(18\pm 1\%)$和$5+(82\pm 1\%$）。相似的比例${\mathrm{五}}^{4+}$至${\mathrm{五}}^{5+}$在 X 射线光发射和 X 射线吸收近边光谱中也观察到，发现与样品化学计量一致。V处扩展X射线吸收精细结构的分析$ķ$-edge 给出了相应的 V-O 键长，用于拉曼模式的详细分析。此外，与温度相关的电阻率类似于半导体行为，其中电荷载流子传输由较高温度下的带导和通过跳跃促进$\le 260\mathrm{ķ}$.