FTIR spectroscopy of metal oxide insertion electrodes: thermally induced phase transitions in LixMn2O4 spinels

Synthesis, characterization, DC-electrical conductivity and γ-ray effect on Ag1+, Y3+ double doped nano lithium manganates (LiMn2−2x AgxYxO4) for rechargeable batteries

“…In the spectra of pure nano LiMn 2 O 4 , the observed high-frequency bands, located around 618 and 517 cm −1 , are associated with the asymmetric stretching modes of MnO 6 octahedron whereas the band at 260 cm −1 is attributable to mixed characters: octahedral MnO 6 and tetrahedral LiO 4 building the cubic lattice of nano LiMn 2 O 4 . These results are quite similar to those given in earlier reports [21,22]. It can also be seen from Fig.…”

Significance of Mg doped LiMn2O4 spinels as attractive 4 V cathode materials for use in lithium batteries

“…The 617 cm-1 band may be ascribed to the LiO4 tetrahedral unit and the one at 525 cm 1 to MnO6 octahedra or tetragonally distorted octahedral MnO 6 unit [ 11]. Figures 2 a-e depict no change in the FTIR spectra as the Mg content is increased in the LiMgyMn2_yO4.…”

Lattice vibrations of materials for lithium rechargeable batteries. VI: Ordered spinels

“…2) The two most intense bands at 597 and 611 cm −1 are assigned to the modes of A 1 and F 2 symmetry derived from the Raman- active modes A 1g and F (3) 2g modes under O 7 h spectroscopic group [17]. The band at 483 cm −1 is attributed to the F 2 mode which is related to the F (2) 2g mode under O 7 h spectroscopic group.…”

“…In spite of the fact that LiMn 2 O 4 has apparently a simple cubic structure (Fd3m symmetry) with a normal cationic distribution (A[B 2 ]O 4 in spinel notation), it presents several peculiarities in its crystal chemistry as follows: (i) it is a mixed-valence compound (Mn 3+ , Mn 4+ ) with an average oxidation state of +3.5, (ii) the occurrence of a phase transition below room temperature (at ca. 280 K) from cubic to orthorhombic, attributed to a partial charge ordering [2], (iii) a complex superstructure is observed for the delithiated phase Li 0.5 Mn 2 O 4 [3], and (iv) cation ordering has been predicted from ab initio calculations for most dopants [4].…”