Abstract
The polycrystalline Na2SmV5O15 (NSV), a new member of the tungsten bronze (TB) family, was prepared by a mixed-oxide technique. The room-temperature X-ray diffraction (XRD) confirmed the formation of single phase compound with orthorhombic crystal structure. The scanning electron microscopy (SEM) analysis indicated that the compound has homogeneous micrograph with a uniform distribution of small grains over the entire surface of the sample. The analysis of impedance spectra of NSV in a low-temperature range (−100 °C to 100 °C) at different frequencies exhibited interesting electrical properties like the contribution of bulk effect in conduction process. The study of imaginary part of the impedance at different temperatures showed existence of relaxation peak with its shift towards higher frequency on increasing temperature. This suggested the presence of frequency and temperature dependent relaxation process in the material. The loss peak spectra were found to abide by Arrhenius law with small activation energy of 0.12 eV. The temperature dependence of AC and DC electrical conductivity (σAC and σDC) was also obtained.
Highlights
Due to the structural versatility of vanadiumcontaining compounds, some vanadates have attracted much attention of the researchers to work in such new compounds
The tungsten bronze (TB) structure with a general formula (A1)2(A2)4(C)4(B1)2(B2)8O30 is a network of octahedral sharing of corners of a unit cell, and it would be said that this structural family stands at an intermediate position of perovskite and pyrochlore types of structures
The octahedral sites are occupied by B ions and the remaining six sites by A ions, and the compound is generally represented by the formula Journal of Advanced Ceramics 2014, 3(1): 1–6
Summary
Due to the structural versatility of vanadiumcontaining compounds, some vanadates have attracted much attention of the researchers to work in such new compounds. They have the ability to act as intercalation, ion-exchange, magnetism, cathode, and nonlinear optical (NLO) materials [1,2,3,4,5,6,7]. If the binary system is composed of A and B oxides, we could only find one A5B10O30 TB type where six A sites are occupied by five ions; this is a typical TB structure. In view of the importance of materials within this family, we have attempted to study the synthesis, structure and electrical properties (impedance parameters) of Na2SmV5O15 (NSV) ceramics by the substitutions of Na at the A site and V at the B site of the TB structure
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