Wali M, Hizi W, Dhahri R, Rahmouni H, Khirouni K, Dhahri E
Laboratoire de Physique Appliquée, Faculté des Sciences de Sfax, Université de Sfax B.P. 1171 3000 Sfax Tunisia.
Laboratoire de Recherche Matériaux Avancés et Nanotechnologies, Institut Supérieur des Sciences Appliquées et de Technologie de Kasserine, Université de Kairouan BP 471 Kasserine 1200 Tunisia
RSC Adv. 2024 Aug 28;14(37):27412-27423. doi: 10.1039/d4ra03519d. eCollection 2024 Aug 22.
LaNa □ MnO (0.00 ≤ ≤ 0.15) manganites were successfully synthesized using the solid-state route. X-ray diffraction was performed to check the samples' purity and phase structure. Scanning electron microscopy analysis reveals a decrease in the average grain size with an increase in the deficiency amount. Analysis of the temperature dependence of magnetization proved the presence of ferromagnetic-paramagnetic transition in all the studied samples. The magnetization derivative (d /d ) curves demonstrated a decrease in the transition temperature with an increase in the deficiency amount. Such experimental observations can be correlated with bandwidth evolution, which affected double-exchange interactions. It can be equally accounted for by the average grain size decrease. In this regard, the experimental measurements of effective paramagnetic moments revealed the existence of ferromagnetic correlations within the paramagnetic phase. Notably, different electrical findings were addressed. Indeed, the frequency dependence of electrical conductivity displayed the coexistence of two frequency slopes reflecting the presence of Jonscher's double power law for all the studied samples. A significant decrease in conductivity values was observed when the deficiency amount increased. This experimental observation could be assigned to the decrease in the grain size (conductor region). Such assumption was confirmed by the evolution of the grain boundary resistance with deficiency level. Indeed, a significant mounting in the grain boundary resistance values was obtained presenting the increase of the resistive region for = 0.15. It is worth noting that the Curie temperature for the = 0.10 sample was found to be close to room temperature ( = 297 K). These findings make the LaNa□MnO compound a powerful candidate for many technological applications.
采用固态法成功合成了LaNa□MnO（0.00≤≤0.15）锰酸盐。进行X射线衍射以检查样品的纯度和相结构。扫描电子显微镜分析表明，随着缺陷量的增加，平均晶粒尺寸减小。对磁化强度的温度依赖性分析证明，所有研究样品中都存在铁磁-顺磁转变。磁化强度导数（d/d）曲线表明，随着缺陷量的增加，转变温度降低。这些实验观察结果可以与影响双交换相互作用的带宽演化相关联。平均晶粒尺寸减小也可以同样解释这一现象。在这方面，有效顺磁矩的实验测量结果揭示了顺磁相内铁磁相关性的存在。值得注意的是，还讨论了不同的电学发现。事实上，电导率的频率依赖性显示出两个频率斜率共存，这反映了所有研究样品中琼舍尔双幂律的存在。当缺陷量增加时，观察到电导率值显著下降。这一实验观察结果可归因于晶粒尺寸（导体区域）的减小。这种假设通过晶界电阻随缺陷水平的变化得到了证实。实际上，对于=0.15，获得了晶界电阻值的显著增加，表明电阻区域增大。值得注意的是，发现=0.10样品的居里温度接近室温（=297K）。这些发现使LaNa□MnO化合物成为许多技术应用的有力候选材料。
