Influence of sintering temperature and oxygen stoichiometry on electrical transport properties of La0.67Na0.33MnO3 manganite

Study of complex impedance spectroscopic properties of La 0.7− x Dy x Sr 0.3 MnO 3 perovskite oxides

“…However, it was suggested that the DE model is not enough to explain the CMR phenomenon. Some authors suggested that other factors such as the Jahn Teller effect [4] and phase separation [5,6] are responsible for the behaviour observed in manganite.…”

Effects of Ball Milling Time on the Microwave Properties of Mg₄Nb₂O₉ Ceramics by the Solid-State Process

“…In addition, the effect on dielectric constants caused by the second phase of Mg 5 Nb 4 O 15 could be negligible due to its minor quantity and approximate dielectric constant of ε r ~11 reported by I.N. Jawahar et al [13] and S. Kamba et al [14]. Similarly, the minor Mg 5 Nb 4 O 15 phase had not significant effect on the τ ƒ values of MN ceramics due to the approximate τ ƒ value of -54 ppm/℃.…”

Understanding the transport properties of perovskite compounds as a function of temperature, frequency and DC-bias voltage using experimental measurements and appropriate theoretical models

“…In this context, numerous factors can be modified to reach the desired properties such as doping, heat treatment, synthesis conditions, and applied polarization. 16–24 These factors can affect the material structure (A and B sites’ average radius, bond angle θ Mn–O–Mn , bond length d Mn–O–Mn , oxygen deficiency, etc .) and morphology (grain size, grain boundary effects, etc .…”

“…), leading to modifications in their physical properties (Mn 3+ /Mn 4+ ratio, electrical and magnetic transition temperatures, system behavior, etc .). 16–24 In addition, Zhan et al 25 have used the defect chemistry of perovskite systems to understand the nature of ionic conductivity and predict the properties of grain boundaries and heterogeneous solid interfaces. The partial substitution of the trivalent lanthanum ions (La 3+ ) by the monovalent sodium element (Na + ) leads to the conversion of Mn 3+ to Mn 4+ ions to maintain the charge balance.…”

“…Many assumptions can explain these observed results. 22,26 Indeed, the small difference between the cationic radii of sodium and lanthanum (size mismatch) can cause the increase in the A-site average radius 〈 r A 〉 as well as the cationic disorder. This affects the bond angle θ Mn–O–Mn and bond length d Mn–O–Mn , which in turn controls Mn 3+ /Mn 4+ amounts and thus the electrical response of La 1− x Na x MnO 3 systems.…”