In this work, a series of Sr-substituted lanthanum orthoferrite perovskites, La_1−xSr_xFeO₃ (x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0), were prepared using the sucrose-assisted auto-combustion route to study the effect of Sr-substitution on the structural, magnetic, and electrical properties and to investigate the impact of the entire method on different properties. The auto-combustion process and the perovskites formation were followed using differential thermal analysis–thermogravimetry techniques. The obtained different phases were characterized using X-ray diffractometer (XRD), Fourier transform infrared spectroscopy, and high-resolution transmission electron microscopy HRTEM measurements. XRD revealed peaks attributed to SrCO₃ secondary phase increases in their intensity by increasing Sr-content till predominate at x = 1.0. It also showed a transfer from orthorhombic symmetry to rhombohedral one by increasing Sr-content. The obvious contraction in the unit cell parameters by Sr-substitution could be attributed to the Fe³⁺ → Fe⁴⁺ oxidation occurred to balance the total charge on molecule. The obvious increase in the magnetization by increasing Sr could be attributed to the formation of Fe⁴⁺ ions, strengthening the ferromagnetic component through sharing in the double-exchange interaction, Fe⁴⁺–O–Fe³⁺, as well as the formation of oxygen vacancies that disturb the uncompensated surface spin. Ac-conductivity measurements indicated a change in the entire conduction mechanism from electronic to ionic with improving conductivity by increasing Sr-content. Generally, the utilized sucrose method indicated an improvement in the obtained magnetization accompanied by lowering conductivity than previously reported systems in literature.

中文翻译：

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通过蔗糖自燃路线合成的Sr取代LaFeO 3钙钛矿的结构，磁性和电学表征

在这项工作中，一系列的Sr取代的镧正铁氧体钙钛矿La _{1- x} Sr _x FeO ₃（x = 0.0、0.2、0.4、0.6、0.8和1.0），使用蔗糖辅助自动燃烧路线制备，以研究Sr取代对结构，磁性和电学性质的影响，并研究Sr替代对结构的影响。整个方法在不同的属性上。使用差示热分析-热重分析技术跟踪自燃过程和钙钛矿的形成。使用X射线衍射仪（XRD），傅立叶变换红外光谱和高分辨率透射电子显微镜HRTEM测量对获得的不同相进行表征。XRD显示归因于SrCO ₃第二相的峰强度通过增加Sr含量直至在x处占优势而增加 = 1.0。它也显示出通过增加Sr含量从斜方对称向菱面体的转移。Sr取代引起的晶胞参数的明显收缩，可能是由于Fe ³⁺ →Fe ⁴⁺发生氧化而使分子上的总电荷平衡所致。通过增加Sr引起的磁化强度的明显增加可能归因于Fe ⁴⁺离子的形成，通过共享双交换相互作用Fe ⁴⁺ –O–Fe ³⁺增强了铁磁成分。以及氧空位的形成会干扰未补偿的表面自旋。交流电导率测量表明，通过增加Sr含量可以改善电导率，从而使整个导电机理从电子方式转变为离子方式。通常，与文献中先前报道的系统相比，所利用的蔗糖方法表明所获得的磁化强度得到改善，同时电导率降低。