Electric modulus approach to the analysis of electric relaxation in highly conducting (Na0.75Bi0.25)(Mn0.25Nb0.75)O3 ceramics
Electric modulus approach to the analysis of electric relaxation in highly conducting (Na0.75Bi0.25)(Mn0.25Nb0.75)O3 ceramics
复制标题
DOI：
10.1088/0022-3727/38/9/019
复制
发表时间：
2005-04
期刊：
影响因子：
--
通讯作者：
A. Molak;Marian Paluch;S. Pawlus;J. Klimontko;Z. Ujma;I. Gruszka
中科院分区：
文献类型：
--
作者：
A. Molak;Marian Paluch;S. Pawlus;J. Klimontko;Z. Ujma;I. Gruszka
利用宽带介电谱研究了无序类钙钛矿陶瓷在宽温区的电学性质。从X射线衍射分析发现，新获得的（Na 0.75Bi 0.25）（Mn 0.25Nb 0.75）O3陶瓷由两个化学上不同的相组成。主要的钙钛矿具有由Pbcm空间群描述的正交结构（No 57，在yxz设置中）。次相具有正交对称性，全面心晶格F，晶格参数a = 10.797（4）B = 7.601（3），c = 7.691（3）。在分析中使用的电模量M* 形式主义使我们能够区分和分离的弛豫过程，在ε*（ω）表示的显着的电导率为主。在所研究的陶瓷中，弛豫时间是热激活的，偶极过程具有明显的非德拜行为。使用大约0.4 eV的激活能和特征弛豫时间τ0 = 1 × 10−11 s描述的弛豫过程被发现与氧空位有关。低频弛豫表现出德拜行为，其激活能略低，特征时间较长。
Broadband dielectric spectroscopy is applied to investigate the electrical properties of disordered perovskite-like ceramics in a wide temperature range. From the x-ray diffraction analysis it was found that the newly obtained (Na0.75Bi0.25) (Mn0.25Nb0.75)O3 ceramics consist of two chemically different phases. The major perovskite one has an orthorhombic structure described by the Pbcm space group (No 57, in yxz setting). The minor phase shows an orthorhombic symmetry, all-face-centred lattice F, with the lattice parameters a = 10.797(4) Å, b = 7.601(3) Å and c = 7.691(3) Å. The electric modulus M* formalism used in the analysis enabled us to distinguish and separate the relaxation processes, dominated by marked conductivity in the ε*(ω) representation. In the ceramics studied, the relaxation times are thermally activated and the dipole process has a clearly non-Debye behaviour. The relaxation process described with the use of the activation energy of approximately 0.4 eV and the characteristic relaxation time, τ0 = 1 × 10−11 s, was found to be related to oxygen vacancies. The low frequency relaxation shows Debye behaviour with a slightly lower activation energy and a longer characteristic time.