Phase transitions and electrical transport in the mixed-valence V2+/V3+ oxide BaV10O15

Formation of a Three-Dimensional Network of V Trimers inA2V13O22(A=Ba, Sr)

“…2(b), and it was concluded that the space group changes from Cmce to Pbca with the phase transition [14]. This change in space group is the same as that observed in BaV 10 O 15 [15], which takes a bilayer structure composed of only the first and third layers (without the second layer) of A 2 V 13 O 22 .…”

Unusual valence state and metal-insulator transition in BaV10O15 probed by hard x-ray photoemission spectroscopy

“…The line shape of the V 3d t 2g peak is somewhat similar to that of the Co 3d t 2g peak of triangular lattice in Co oxides with positive and large Seebeck coefficient. [24] However, the Seebeck coefficient is almost zero around room temperature in BaV 10 O 15 [13,23] indicating that substantial V 3d spectral weight should exist just above the pseudogap and that the electron contribution may be canceled with the hole contribution. The O 1s HAXPES of the metallic phase exhibits substantial asymmetry at 300 K due to screening effect of the V 3d conduction electrons.…”

“…Among the various charge ordering phenomena in non-integer valence TMCs, the charge order of V 2+ and V 3+ is very rare, and a new physics is expected in a V 2+/3+ TMC. A V 2+/3+ mixed valence oxide with the composition of BaV 10 O 15 was discovered by Liu et al [9][10][11] and was found to exhibit interesting physical properties including a structural transition around 120 K. [12][13][14] Kajita et al have identified the structural transition at 123 K in single crystal BaV 10 O 15 that is driven by V trimerization [15] and V 3d orbital order. [16] The structural transition is accompanied by a resistivity drop of two orders of magnitude in going from the low to high temperature phases, and the transition may correspond to a MIT although the resistivity gradually decreases with increasing temperature even in the high temperature phase.…”

Orbital states of V trimers in BaV10O15detected by resonant x-ray scattering

“…The electronic band structure of BaV 10 O 15 for the low temperature phase (pbca structure in Ref. 8) is calculated within the local-density approximation (LDA) to the density-functional theory with the full-potential linearized augmented plane-wave method, which has been used for several transition-metal oxide systems. [18][19][20] III.…”

“…[14][15][16][17] BaV 10 O 15 contains V ions on the modified triangular lattices. This compound shows a structural phase transition at T s = 123 K, [6][7][8][9] where the electrical resistivity sharply increases by 10 3 times. It was found that the structural change at T s is characterized by the trimerization of the V ions over two layers, 9 as shown in Fig.…”