Investigations on structural disorder-induced modifications in the transport behaviour of rare-earth manganites

Bulletin of Materials Science

关键词: Manganites;    structural disorder;    transport behaviour;    phase segregation.;   

学科分类：材料工程

来源: Indian Academy of Sciences

【 摘 要 】

The results of the studies on structural disorder-induced modifications in the transport behaviour of La$_{0.5}$Pr$_{0.2}$Ca$_{0.3−x}$Ba$_x$MnO$_3$(LPCBMO) ($0.05 ≤ x ≤ 0.30$) manganites were reported. Structural studies using X-ray diffraction (XRD) measurements confirmed the single phasic nature of all the samples without any detectable impurities. The A-site size disorder ($σ_2$ A) increased from $3.81 \times 10^{−5} (x = 0.05)$ to $14.9 \times 10−5 (x = 0.30)$. With the increase in structural disorder in LPCBMO system, the transport improved for the range: $0.15 ≤ x ≤ 0.30$, which can be ascribed to the enhancement in one electron bandwidth which dominates over the structural disorder effect, while for lower values of $x$, strong competition existed between size disorder and one electron bandwidth. Below 50 K, all $\rho–T$ plots showed resistivity minimum behaviour, which modified with disorder. This behaviour wasdiscussed in detail on the basis of electron–electron interaction having the form: $\rho = [1/(\rho_0 + BT^{1/2})] + \rho_nT_n$. Variation in temperature sensitivity with disorder was also discussed in context of granular morphology and phasesegregation scenario.

【 授权许可】

CC BY