Effect of Gd and Nb on dielectric and magnetic transition temperature of BaTiO3- Li0.5Fe2.5O4 composites

The Gd and Nb doped 90 BaTiO3- 10 Li0.5Fe2.5O4 composites are prepared using solid state technique. The structural, functional, dielectric, magnetic and magneto-electric properties of Gd and Nb doped 90 BaTiO3-10Li(0.5)Fe(2.5)O(4) have been studied using X-ray diffraction, FTIR, dielectric spectrometer, vibrating sample magnetometer and DSP lock-in amplifier respectively. The XRD peaks indicate the absence of impurities in the undoped and doped BLF composite which confirms the high crystalline nature of all the composites. The FTIR spectrum reveals a strong absorption bands at 468 cm(-1) and 853 cm(-1). The transition temperature of BLF decreases slightly and the dielectric constant of all composites is maximum for different temperatures at fixed frequency due to mechanical strain in the grains and inhomogeneous distribution of Gd and Nb ions in place of Ti. The dielectric dissipation (tan delta) of BLF decreases with increase in the concentration of Gd and Nb in BLF which indicates the less number of defects like oxygen vacancies in BLF. The magnetic transition increases with increase in the concentration of Gd and Nb in BLF composites and this increase of the magnetic transition may due to the presence of exchange interaction between Fe3+ and Gd3+, Nb5+ ions through neighboring octahedrons. The M-E coefficient of BLF decreases after doping Gd, Nb in BLF which may be due to the resistivity of ferroelectric phase greater than ferrite phase.