Investigation of ionic conductivity in sodium ytterbium phosphate NaYbP2O7 compound

Investigation of optical, dielectric properties and conduction mechanism of LiCo0.7Mn0.3O2

“…The energy band gaps Eg can be determined from the intercepts of these plots on the energy axis, since Eg=hν when (αhν) 0.5 =0 (Figure (4) indirect allowed transition).. For our compound the band gap energy is 1.88 eV, which is lower than the value obtained for LiCoO2 (2.17eV) [6]. We notice that the insertion of Mn in LiCoO2 compound leads to the retreatment of the forbidden band, which can be explained by the s-p-d exchange interaction between the dopant Mn 2+ and the host CoO.…”

“…The obtained phase was fully indexed in the R -3m space group of the hexagonal system .The X-Ray study proves the existence of a trace of Co3O4 indexed by a small peak shown in the XRD diffractogram. The crystalline structure of our compound is similar to that of the LiCoO2 sample [6]. The unit cell parameters and the fit criteria are reported in Table 1.…”

“…The batteries whose electrode is made of the LiCoO2 compound have a theoretical specific capacity equal to 274 mAh/g and an energy density of around 1070 Wh/kg, yet they deliver less than half of their capacity (140 mAh/g) due to structural disorders [3][4][5].This compound presents good electrical and optical properties making it a good candidate for many applications. In fact, its electrical conductivity is in the order of 10 -4 cm -1 and its optical gap is 2.17eV [6] indicating that the LiCoO2 compound is a semiconductor. The other compound is the LiMnO2 which has been widely studied as an active cathode material with a charge capacity ∼270mAhg -1 and preliminary results indicate good stability over repeated chargedischarge cycles.…”