Charge disproportionation in AlV2O4: A first-principles study

The charge disproportionation of V ions in the low-temperature rhombohedral phase of AlV2O4 has been studied by first-principles density functional theory (DFT) computations. The calculation results show that there exists an alone V ion (V1) and a “heptamer” constructed by two types of V ions (one V2 and six V3) in the rhombohedral AlV2O4. The theoretical results are consistent with previous experimental reports (Horibe et al., Phys. Rev. Lett. 96 (2006) 086406; Phys. Rev. Lett. 96 (2006) 169901). The valence states of the three types of V ions are found to be +(2.5 − δ1), +(2.5 + δ2) and +(2.5 + (δ1 − δ2)/6) (δ1 > δ2 > 0), respectively. The three types of V ions with different charges arrange periodically layer by layer along the c-axis direction with a sequence as V1–V3–V2–V3–V1.