Low-temperature synthesis of nanocrystalline Ca1−xHoxMnO3−δ (0⩽x⩽0.3) powders

Effect of the sintering temperature on the properties of nanocrystalline Ca1−xSmxMnO3 (0≤x≤0.4) powders

“…Our data is in agreement with the reported behaviour for the lattice parameters variation with the x value in the Ca 1−x Sm x MnO 3 series (0 ≤ x ≤ 0.4) [14][15][16][24][25][26][27]30]. The calculated lattice parameters values for the CaMnO 3 phase also agree well with the data reported in the literature [24][25][26][27]30]. In what concerns substituted samples, our data are in agreement with the ones reported earlier for the same phases prepared by high temperature ceramic route (near 1573-1873 K) [14][15][16].…”

“…This analysis was also carried out for x = 0 sample. Some results for the phase prepared at 1073 K have been already reported [26,27]. Fig.…”

“…The average crystallite size, D h k l , of the samples prepared at 1073 and 1473 • C was calculated from the main reflection of the orthorhombic unit cell using the Debye-Scherrer equation [29], synthesis temperatures, i.e., 85 nm for x = 0 [26,27] and 42 nm for x ≥ 0.1 for the samples prepared at 1073 K. For the phases synthesized at 1473 K the crystallite sizes increase to the value of 103 nm for x = 0 and 85 nm for x ≥ 0.1. As expected, the mean crystallite size increases with the increase in annealing temperature.…”

“…More recently, nanocrystalline Ca 1−x R x MnO 3−ı manganites (R = Ho, Eu) were synthesized as single-phase by a simple and instantaneous solution auto gel combustion method at low temperature, namely 1073 K for 18 h. These studies showed that all samples exhibit semiconductor behaviour. Also the resistivity at room temperature and the activation energy for electrical conduction (E a ) display an important correlation with the crystal structure and the particle grain size [26,27].…”

Enhanced thermoelectric properties of Ca1-x Sm x Mn1-y W y O3-δ for power generation

“…The linear dependence of log(σT) versus 1/T is characteristic of the polaron hopping transport mechanism. [33,34] For electrical conduction, Mn 3+ and Mn 4+ are required to be the nearest neighbors and the electron jumps from Mn 3+ to Mn 4+ via O 2− . The slope of the linear portion of log(σT) versus 1000/T corresponds to −E a /κ B .…”