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Dielectric studies were carried out on Nd 2 CuTiO 6 samples prepared by high temperature solid-state reaction followed by annealing under different oxygen partial pressures. X-ray diffraction studies revealed that the orthorhombic (Pnma) structure of Nd 2 CuTiO 6 is retained in all the samples. The room temperature permittivity at 100Hz was found to be about 200 in the air-annealed sample, and it increased considerably to about 3000 upon annealing in argon atmosphere. The electrical conductivity in the argon-annealed compound was found to be an order of magnitude higher than that for the air-annealed sample. On annealing in oxygen, both permittivity and electrical conductivity of the sample were found to be significantly reduced. The variation in dielectric properties could be attributed to the induction or annihilation of mixed valence state of copper and oxygen vacancies, which was supported by X-ray photoelectron and diffuse reflectance spectroscopy data. The analysis of temperature and frequency dependent conductivity and dielectric data showed that the overlapping large polaron tunnelling (OLPT) mechanism is responsible for the observed dielectric relaxations and conduction. The observed systematic dependence of properties on the oxygen partial pressure of the annealing environment suggests a simple method to tune the electrical properties of Nd 2 CuTiO 6. • Annealing conditions affect dielectric properties in rare-earth double perovskite. • Crystalline structure remains unchanged. • Changes in mixed valence of copper and oxygen vacancies. • Dielectric properties may be tuned by varying synthesis conditions. • Conduction due to overlapping large polaron tunnelling. [ABSTRACT FROM AUTHOR]

Low electric and magnetic moment features are the main drawbacks that restrict the practical utilities of bismuth ferrite. Successfully, we have substituted Li+ and W6+ in Sb3+ and Fe3+ sites to eliminate further confinements of bismuth ferrite (referred as BFO/BiFeO 3). A new lead-free perovskite compound of (SbLi) 1/2 (Fe 2/3 W 1/3)O 3 (symbolized as SLFWO) has been produced through ceramic processing (high temperature) route. The calcination temperature of said compound is confirmed from the thermogravimetric analysis. The structural, microstructural, magnetic and electrical (dielectric constant/loss, impedance, modulus, conductivity) features of the said material have been studied over an extensive range of frequency (100 Hz-1 MHz) and temperature (RT-400 °C). The finding of reflection indices and crystal parameters approve the development of polycrystalline nature with orthorhombic symmetry of the compound. The impedance analysis confirms the existence of non-Debye type relaxation trend. The frequency-temperature dependence of ac-conductivity studies proves the nature and conduction mechanism in the compound. At specific peak frequency, the modulus spectrum movements of the charge carrier vary from wide array to narrow array. The peak frequencies increase with temperature signifying the thermally activated relaxation process. The value of leakage current rises with the temperature that established the NTCR trend of the compound. The observed values of remanent magnetization, saturation magnetization and coercivity of SLFWO are 0.5647 emu/g, 0.04953 emu/g, and 104.242 Oe respectively. • The material is quite new considering its application point of view. • The structural, thermal, impedance and magnetic properties with in-depth understanding are explained well in this manuscript. • The material has an excellent electrical and magnetic property. [ABSTRACT FROM AUTHOR]