Lattice Disorder, Electric Properties, and Magnetic Behavior of La_1-xNa_xMnO_3+δ Manganites

Abstract

La 1-x Na x MnO 3+δ samples with well-defined cation molecularity and oxygen contents (x ) 0.05, x ) 0.13, and -0.04 e δ e 0.078) are analyzed with XRPD, electrical conductivity, static magnetization, and EPR measurements. The majority defects induced by oxygen over-and under-stoichiometry are cation and oxygen vacancies; the cation vacancies affect the magnetic properties by interrupting the interaction paths between Mn(III) and Mn(IV) ions, whereas the oxygen vacancies have a stronger influence on the structural and electrical properties and act on the magnetic properties by the overall decrease of the Mn(IV) amount and by the creation of sample regions with different magnetic features. We can state that the basic magnetic and electrical behaviors of the Na-doped lanthanum manganite compounds are driven from the Mn(IV)/Mn(III) ratio and all the peculiar behaviors are indeed caused by defects, concentration gradient and, more generally, by lattice disorder.

Synthesis and Characterization of Lamn1-XFexO3 (X=0, 0.1, 0.2) by Coprecipitation Route

“…The conductivity of the sample increases with the dopant concentration because of the mobility of the charge carriers which is depend on hopping mechanism. As the voltage increases, the mobility of the hopping ions increases which in turn increases the conductivity of the material [28]. If increase the iron content in the sample, the oxygen vacancies increased.…”

Structural, morphological and magnetic properties of La1−x Na y MnO3 (y ≤ x) nanoparticles produced by the solution combustion method

“…[1][2][3][4][5][6][7][8][9][10] Manganite perovskites have the general formula R 1−x A x MnO 3 (where R is a rare earth cation and A the doping cation). Undoped LaMnO 3 manganite is an insulator having A-type antiferromagnetic ordering.…”

“…By substitution of La 3+ with a divalent or monovalent cation, LaMnO 3 can be driven into a metallic and ferromagnetic (FM) state. 11 These unusual and interesting changes observed in the properties of mixed valent manganites have been traditionally explained by the Zener double exchange (ZDE) mechanism 12 and in recent times various other factors such as the strong electron-phonon interaction, 10,13 the charge and orbital ordering, 14 the average sizes of the R and A cations 15,16 and the oxygen stoichiometry 10,17,18 have also been implicated.…”

Metallic and semi-conducting resistivity behaviour of La0.7Ca0.3−x K x MnO3 (x = 0.05, 0.1) manganites

“…Of particular interest are the monovalent-doped manganites as the substitution with alkali metal ions can induce twice the increase in Mn 41 ions as compared to the alkaline-earth metal substitution. Most of the literature is devoted to the interplay between magnetic and transport properties [1,2]. While discussing the correlation between the magnetic and transport properties, ideas such as double-exchange (DE) mechanism and the Jahn-Teller (JT) formation have been proposed.…”