STRUCTURAL AND PHOTOLUMINESCENCE PROPERTIES OF THE (Ni,Zn) Fe2O4-BaTiO3 MULTIFERROIC COMPOSITE NANOPOWDERS

Abstract

Ferroics and multiferroics are among the most attractive multifunctional materials. In recent years, multiferroic composite consisted of two or more ferroic orders, such as ferroelectric, ferromagnetic, or ferroelastic, in which coupling between these phases can produce magnetoelectric effect, has been drawing significant attention. Besides others, (Ni, Zn)Fe2O4-BaTiO3 composites have attracted considerable attention not only due to fundamental research of magneto-electric effect, but also for the potential applications in many electronic devices such as drug delivery, heterogeneous catalysis, levitated railway system, magnetic-refrigeration, microwave devices, antennas, memory devices, etc. In this composite, (Ni,Zn)Fe2O4(NZF) possesses magnetic behavior, and the ferroelectricity is due to the presence of BaTiO3 (BT). In the present work, it was investigated the structural and photoluminiscence properties of NZF-BT composite nanopowders prepared by auto-combution method and the different ratio of NZF/BT was explored. XRD indicated well cristallized powders but with small presence of secondary phases respecting to BT. By FE-SEM analyses was noticed the agglomerates with wide particles size distribution, as well as the difference of the particles morphology between (Ni,Zn)Fe2O4 and BaTiO3. FT-IR spectra display interactions between metal-oxygen around 500-600 cm-1. The different ratio of NZF/BT effects on the optical band gap values indicating the formation of intermediary levels modifying the Fermi level. Photoluminescence (PL) analysis provides important information about the materials structures, however the PL behavior of these composites is not very well known. The presence of PL emission suggests that the structures of the materials are medium range disordered. All samples showed a broad band emission centered around 450 nm, being a region characteristic of resultant emission from the presence of shallow defects in materials structures. This behavior is reinforced by deconvolution of PL bands, which shows the contribution of tree sub bands to emission (blue, green and yellow emission), being that the largest area of spectra is occupied by a band correspondent to blue emission.