Chemical characterization of BiFeO3 obtained by Pechini method

Abstract

Este trabalho descreve a síntese e a caracterização de BiFeO 3 obtido a partir da rota Pechini, utilizando-se nitrato de bismuto e nitrato de ferro como precursores. Os pós foram calcinados a 800 °C em ar durante 2 h. Os difratogramas de raios X mostraram que o material apresenta duas fases, BiFeO 3 (95%) e α-Bi 2 O 3 (5%). A transição de fase ferroelétrica da amostra em 821 °C foi detectada por análise térmica diferencial. Os resultados das análises por microscopia eletrônica de varredura (SEM), espectroscopia de energia dispersiva (EDS) e fluorescência de raios X por dispersão de energia (EDX) mostraram que a amostra é quimicamente homogênea. As imagens de microscopia eletrônica de transmissão revelaram que a amostra é uniforme e apresenta partículas com formato esférico e tamanho médio de 30 nm.This work describes the synthesis and characterization of BiFeO 3 obtained by the Pechini route using bismuth nitrate and iron nitrate as precursors. The powders were annealed at 800 °C in air for 2 h. X-ray diffraction patterns showed that the material presents two phases, BiFeO 3 (95%) and α-Bi 2 O 3 (5%). The ferroelectric transition of the sample at 821 °C was detected by differential thermal analysis. Results of analyses by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and energy dispersive X-ray fluorescence (EDX) showed that the sample is chemically homogeneous. Transmission electron microscopy images revealed that the sample is uniform and contains spherical particles with an average size of 30 nm. Keywords:Pechini method, X-ray diffraction, ferroelectricity, magnetic properties IntroductionMultiferroic magnetoelectric materials are known to exhibit magnetic (ferro, anti, or ferri) and electric (ferro) ordering simultaneously at room temperature, 1 as well as interesting physical properties with possible practical applications, as in new memory devices whose polarization and magnetization states and coupling can be simultaneously exploited.2-6 BiFeO 3 is one of these few materials, along with YMnO 3 and BiMnO 3 , that have all the potential applications of both their parent ferroelectric and ferromagnetic materials.Bismuth ferrite, BiFeO 3 , belongs to the perovskite class of materials with a rhombohedrally distorted unit cell. It has the polar R3c space group, whose ions are displaced along the [111] direction relative to the ideal centrosymmetric positions.7,8 Detailed structural investigations of BiFeO 3 can be found elsewhere.9,10 The interest in this compound is due to its ferroelectric behavior with a high Curie temperature (T C ca.1100 K) and its antiferromagnetic behavior with a relatively high Néel temperature (T N ca. 650 K).7,11 Both BiFeO 3 thin films and ceramics have been intensively investigated in the last years. 11-19Multiferroic BiFeO 3 was discovered in the 1960s and its properties have been extensively studied. However, the electrical properties of pure BiFeO 3 have rarely been reported on and it has no commercial applications due to its room-temperature low resist...

Structural, optical and transport properties of Al3+ doped BiFeO3 nanopowder synthesized by solution combustion method

“…This leads to disorders in both the coordination number and bond length and this degradation in crystal symmetry is responsible for the shifting in IR active modes [13]. The IR results are in good agreement with those reported earlier in literature [14][15][16].…”

Nonlinear optical and magnetic properties of BiFeO3 harmonic nanoparticles

“…23,34,35 However, these approaches remain undemonstrated for producing large amounts of material and a reduction of Fe 3þ by oxidation of the polyol was also observed. 36 On the other hand, widely used methods for the preparation of nanocrystalline BFO are sol-gel reactions like chelate assisted or Pechini reactions with citric acid 37 or tartaric acid. 38,39 As described in the original patent, 40 the Pechini method needs an annealing step to decompose the amorphous organic precursor and to promote crystallization.…”

Defect driven multiferroicity in Gd doped BiFeO3 at room temperature

“…BFO belongs to the ABO 3 type perovskite class of materials with rhombohedrally distorted unit cell structure [11,12]. Its multiferroics behavior was discovered in 1960 and its properties were extensively studied [11] to understand underlying physics associated with this system [3,6].…”