Massarotti V, Capsoni D, Bini M, Mustarelli P, Chiodelli G, Azzoni C B, Galinetto P, Mozzati M C
Dipartimento di Chimica Fisica M. Rolla dell'Università, viale Taramelli 16, 27100 Pavia, Italy.
J Phys Chem B. 2005 Aug 11;109(31):14845-51. doi: 10.1021/jp051166v.
This study deals with the effects of 5 and 10% chromium additions on the transport and structural properties of Li3VO4. The Cr substitution is easily obtained without impurity phases and does not affect the room- and high-temperature host crystal structure, as evidenced by X-ray powder diffraction and micro-Raman analysis. The EPR signals are interpreted in terms of quantified amounts of Cr ions in 5+ and 3+ valence states. Suitable 7Li and 51V MAS NMR spectra simulations agree with the EPR results about the relative amount of Cr5+ and Cr3+ ions substituted in V5+ and Li+ sites, respectively. The Cr3+ presence on Li site, also suggested by Raman results and Rietveld refinements, requires Li vacancies to maintain the charge neutrality. The p-type conductivity, suggested by the positive thermoelectric power coefficients, significantly increases by the cation doping up to an order of magnitude.
本研究探讨了添加5%和10%的铬对Li3VO4传输和结构性质的影响。通过X射线粉末衍射和显微拉曼分析表明，铬替代容易实现且无杂质相，并且不影响室温及高温下的主体晶体结构。电子顺磁共振（EPR）信号根据5价和3价铬离子的定量含量进行解释。合适的7Li和51V 魔角旋转（MAS）核磁共振光谱模拟结果与EPR结果一致，即Cr5+和Cr3+离子分别替代了V5+和Li+位点上的相对含量。拉曼结果和Rietveld精修也表明Li位点上存在Cr3+，这需要锂空位来维持电荷中性。由正热电功率系数表明的p型导电性通过阳离子掺杂显著增加，最高可达一个数量级。
