Pavlovska O B, Vasylechko L O, Lutsyuk I V, Koval N M, Zhydachevskii Ya A, Pieniążek A
Semiconductor Electronics Department of Lviv Polytechnic National University, 12 Bandera Street, 79013, Lviv, Ukraine.
Department of Chemical Technology of Silicates of Lviv Polytechnic National University, 12 Bandera Street, 79013, Lviv, Ukraine.
Nanoscale Res Lett. 2017 Dec;12(1):153. doi: 10.1186/s11671-017-1946-7. Epub 2017 Feb 27.
Micro- and nanocrystalline lanthanum-samarium ferrites La Sm FeO with orthorhombic perovskite structure were obtained by using both solid state reactions (x = 0.2, 0.4, 0.6 and 0.8) and sol-gel synthesis (x = 0.5) techniques. Obtained structural parameters of both series of La Sm FeO are in excellent agreement with the "pure" LaFeO and SmFeO compounds, thus proving formation of continuous solid solution in the LaFeO-SmFeO system. Peculiarity of La Sm FeO solid solution is divergence behaviour of unit cell dimensions with increasing x: systematic decrease of the a and c lattice parameters is accompanied with increasing b parameter. Such behaviour of the unit cell dimensions in La Sm FeO series led to crossover of the a and c perovskite lattice parameters and formation of dimensionally tetragonal structure near x = 0.04. Linear decrease of the unit cell volume of La Sm FeO with decreasing x according with the Vegard's rule indicate absence of short-range ordering of R-cations in the LaFeO-SmFeO system.
通过固态反应（x = 0.2、0.4、0.6和0.8）和溶胶-凝胶合成法（x = 0.5）制备了具有正交钙钛矿结构的微纳米晶镧钐铁氧体La Sm FeO。所获得的这两个系列的La Sm FeO的结构参数与“纯”LaFeO和SmFeO化合物高度吻合，从而证明在LaFeO - SmFeO体系中形成了连续固溶体。La Sm FeO固溶体的独特之处在于，随着x的增加，晶胞尺寸呈现出发散行为：a和c晶格参数系统性减小的同时，b参数却在增大。La Sm FeO系列中晶胞尺寸的这种行为导致了a和c钙钛矿晶格参数的交叉，并在x = 0.04附近形成了尺寸四方结构。根据维加德定律，随着x的减小，La Sm FeO晶胞体积呈线性减小，这表明在LaFeO - SmFeO体系中不存在R阳离子的短程有序。
