Doping nanoarchitectonics through exchange of Ag${}^{+}$ with Na${}^{+}$ in La${}_{0.7}$Ca${}_{0.1}$Sr${}_{0.1}$X${}_{0.1}$MnO${}_3$ (X = Ag${}^{+}$ or Na${}^{+}$) manganite ceramics for enhancement and levelling tendency of magneto resistivity

The effect of doping exchange of monovalent alkaline metal ions Ag${}^{+}$ with Na${}^{+}$ in La${}_{0.7}$Ca${}_{0.1}$Sr${}_{0.1}$X${}_{0.1}$MnO${}_3$ (X = Na${}^{+}$ or Ag${}^{+}$) manganite ceramics on structural, electrical and magnetotransport properties is investigated. The structural characterization of both polycrystalline samples, synthesized through low-temperature nitrate route, confirm orthorhombic structure (space group pnma) and the morphology of crystal grains shows near-spherical shape. The electronic and magneto transport behavior of samples are studied in the temperature range from 2 to 350 K and in a magnetic field of strength 5 and 10 T. Electrical resistivity reveals three transitions at 313, 278 and 30 K for Ag${}^{+}$ doped sample and two transitions at 274 and 33 K for Na${}^{+}$ doped sample. The magneto resistivity (MR) shows highly contrasting performance with Ag${}^{+}$ doped sample revealing close to a proportional behavior with temperature and Na${}^{+}$ doped one showing enhancement and levelling tendency of MR in a greater range of temperature corresponding to ferromagnetic metallic region as the applied magnetic field strength is increased. Room temperature MR is also observed to be significantly larger for Na${}^{+}$ doped samples at the above magnetic field strengths. Standard temperature-dependent resistivity models such as small polaron and variable range hopping are applied to identify the kind of behavior that the resistivity simulates in the paramagnetic insulator region. In the lower temperature range, the electronic transport seems to follow a model that combines electron-electron scattering and weak localization. In the ferromagnetic metallic region, a proven model based on polaronic conduction and electron-magnon scattering is successfully used to simulate the resistivity behavior.