Fuertes V C, Blanco M C, Franco D G, Ceppi S, Sánchez R D, Fernández-Díaz M T, Tirao G, Carbonio R E
INFIQC-CONICET, Dpto. de Fisicoquímica, Fac. de Ciencias Químicas, U.N.C., Córdoba 5000, Argentina.
Dalton Trans. 2015 Jun 21;44(23):10721-7. doi: 10.1039/c4dt03858d. Epub 2015 Feb 13.
In the course of an investigation to prepare the hypothetic new double perovskite La(3)Co(2)VO(9) with Co(2+) and V(5+) in octahedral sites, we obtained the new simple perovskite LaCo(0.71(1))V(0.29(1))O(2.97(3)) as the main phase. The pure compound was then synthesized by the citrate decomposition method. The crystal structure was studied by X-ray (PXRD) and powder neutron diffraction (PND). Physical properties were characterized by X-ray absorption spectroscopy (XAS), X-ray emission spectroscopy (XES) and thermogravimetric analysis (TGA). Rietveld refinements were performed in the orthorhombic space group Pnma (#62). Refined cell parameters were a = 5.4762(2) Å, b = 7.7609(2) Å and c = 5.5122(1) Å. Magnetization measurements showed that this perovskite is an antiferromagnet with a Neel temperature of 15 K. At high T the magnetization follows the Curie-Weiss law corrected by temperature independent paramagnetism (TIP) showing an effective magnetic moment of 3.03μ(B) well described by the contribution of Co(2+) (HS), Co(3+) (IS), V(3+) and V(4+) ions. The crystallographic formula was refined by PND and oxidation state distribution was determined by the combination of PND, XAS, TGA and magnetic measurements.
在一项旨在制备假设的新型双钙钛矿La(3)Co(2)VO(9)（其中Co(2+)和V(5+)位于八面体位置）的研究过程中，我们得到了新型简单钙钛矿LaCo(0.71(1))V(0.29(1))O(2.97(3))作为主要相。然后通过柠檬酸盐分解法合成了纯化合物。通过X射线（PXRD）和粉末中子衍射（PND）研究了晶体结构。通过X射线吸收光谱（XAS）、X射线发射光谱（XES）和热重分析（TGA）对物理性质进行了表征。在正交空间群Pnma（#62）中进行了Rietveld精修。精修后的晶胞参数为a = 5.4762(2) Å，b = 7.7609(2) Å，c = 5.5122(1) Å。磁化测量表明，这种钙钛矿是一种反铁磁体，奈尔温度为15 K。在高温下，磁化遵循由与温度无关的顺磁性（TIP）校正的居里-外斯定律，显示出3.03μ(B)的有效磁矩，这可以很好地由Co(2+)（高自旋）、Co(3+)（低自旋）、V(3+)和V(4+)离子的贡献来描述。通过PND精修了晶体学公式，并通过PND、XAS、TGA和磁性测量的组合确定了氧化态分布。
