Hydrogen reduction of vanadium in vanadium-doped LiMnPO4

Effect of vanadium doping on the magnetic properties of LiMnPO4

“…Thus, we suppose that the enhancement of the ferromagnetic effects in hydrogen treated V‐doped LiMnPO 4 can be associated with a change in the oxidation state of vanadium. As is shown in our previous work , vanadium located in the tetrahedral sites in the structure of V‐doped LiMnPO 4 has the average degree of oxidation +(4.3 ÷ 4.7) as opposed to +5 in the as‐prepared samples. This leads to the appearance of electrons in the orbitals of the ion occupying the central position in the tetrahedron and, consequently, to a variation in the ferromagnetic super‐superexchanges along the b‐ and c‐ axes realized through the oxygen ions belonging to the tetrahedra (Fig.…”

“…Previously , we found that the O3 site in LiMnPO 4 and LiMn(P,V)O 4 is more favorable for oxygen vacancy than the O1 and O2 positions. Here, we considered the case when the O3 vacancy is close to the V and Mn atoms (the V–O3 and Mn–O3 distances are 1.75 and 2.25 Å, respectively).…”

“…This is caused by the fact that the radius of P 5+ is much smaller than those of V 5+ and V 4+ (IR P = 0.17 Å, IR V5+ = 0.355 Å, IR V4+ = 0.53 Å ). We compare the vanadium ions with phosphorus, but not with manganese ions as vanadium was shown to substitute for tetrahedral P rather than for octahedral Mn . The results of Rietveld refinement of the neutron data are listed in Table .…”

“…The allocation of vanadium in LiMnPO 4 was investigated using a number of diffraction and spectral methods , which like the results of the ab initio calculations , clearly indicated that the vanadium atoms in the vanadium‐substituted LiMnPO 4 indeed occupy the phosphorus sites. Vanadium is an element with variable valence.…”

Magnetic and soft X-ray absorption spectroscopy characterization of Mn and Co doped lithium nickel phosphate LiNiPO4

“…For substituting Mn ions, the situation is not so easy since Mn ions in LiNiMnPO can be both in the 2 + and 3 + valence states. To prevent the appearance of Mn states, LiMnPO usually produced in non‐oxidizing conditions (in inert or reducing atmosphere) .…”