文摘

Nanoporous Ni0·5Zn0·5Fe2O4 particles of diameter, ~ 9·5?nm, were synthesized by citric acid assisted thermal decomposition in an autoclave. The BET surface area measured was 80?m2?g??- and the average pore diameter was 2·5?nm. By soaking the particles in a suitable precursor solution and then subjecting them to a heat treatment at 923?K for 3?h, Pb(Zr0·52Ti0·48)O3 was grown within the nanopores. X-ray and electron diffraction studies confirmed the presence of both these phases. The nanocomposites showed ferromagnetic behaviour over the temperature range 2-00?K. No ferroelectric hysteresis loop could be found which was consistent with the earlier theoretical prediction of loss of ferroelectricity below a critical thickness of 2·4?nm. Good magneto-dielectric response of the order of 7% at a magnetic field of 9?kOe was recorded for the present system. This is believed to arise due to a negative magnetostriction coefficient of Ni0·5Zn0·5Fe2O4 which exerted a compressive strain on Pb(Zr0·52Ti0·48)O3 thereby lowering the tetragonality in its crystal structure.