Solution combustion synthesis and characterization of nanosized bismuth ferrite
V. Sesha Sai Kumar1, K. Venkateswara Rao*1, T. Krishnaveni1, A. Shiva Kishore Goud1, P.Ranjith Reddy2 1
Centre for Nano Science and Technology, I.S.T, Jawaharlal Nehru Technological University- Hyderabad, Hyderabad-500 085 2 Dept of Physics,JNTU College of Engineering,JNT University-Hyderabad, Hyderabad-500 085 *Email:
[email protected] (corresponding author) Abstract. The present paper describes a simple method of nanosized BiFeO3 by the solution combustion synthesis using bismuth and iron nitrates as oxidizers and the combination fuel of citric acid and ammonium hydroxide, with fuel to oxidizer ratio (Ψ = 1) one. The X-ray Diffraction results indicated rhombohedral phase (R3m) with JCPDS data card no: 72-2035. The ferroelectric transition of the sample at 8310C was detected by differential thermal analysis. Thermal analysis was done by Thermal gravimetric-Differential thermal analyzer and obtained results were presented in this paper.
Keywords: Solution Combustion Synthesis, X-Ray Diffraction (XRD), Scanning electron microscopy (SEM), Thermal gravimetric-Differential thermal analysis (TG-DTA). PACS: 81.07.Bc ; 81.16.Be; 78.40.-q; 82.60.Qr
INTRODUCTION Multiferroic materials are known to exhibit magnetic and electric ordering simultaneously at room temperature [1]. Recent interest in these materials is driven by their potential applications in memory devices and sensors. Bismuth ferrite is one of the very few multi ferroics materials with a simultaneous coexistence of ferroelectric (TC ~ 1103K) and antiferromagnetic (TN ~ 643K) order parameters in perovskite structures. Several ways for the preparation of BiFeO3 were informed [2-4]. In this paper, we report the synthesis of nanosized bismuth ferrite by a solution combustion synthesis[5], using Bi (NO3)3.5H2O and Fe (NO3)3.9H2O as oxidizers and citric acid as a fuel with the combination of ammonium hydroxide.
EXPERIMENTAL Bismuth ferrite nanocrystalline powder was synthesized by a solution combustion synthesis. 0.1M Bi (NO3)3.5H2O and 0.1M Fe (NO3)3.9H2O were dissolved in 2N nitric acid. Citric acid with the combination of ammonium hydroxide is added to the above metal nitrates in 1:1 molar ratios. Usually any fuel (citric acid, glycine, and urea) ends up in combustion products with the traces of carbon. So ammonium hydroxide, which acts as an extra oxidizer was used along with citric acid. This solution was then heated on a hot plate until all the liquid is evaporated.
The solution containing the above redox mixture boils, foams, catches fire and burns with a smoldering flame leaving a fluffy brown mass at the base of the beaker. After the combustion the fine crystalline powder was further dried in an oven at 1200C for 30min. 4Bi (NO3)3(aq) + 4Fe (NO3)3(aq) + 5C6H8O7 (aq) + 4BiFeO3 (s) + 17N2 (g) + 10NH4OH(aq) 45H2O (l) + 30CO2 (g)
RESULTS AND DISCUSSION X-ray Diffraction From Fig 1 X-ray diffraction pattern of the as-prepared BFO sample synthesized by solution combustion synthesis. The XRD pattern is in accord with the powder data of JCPDS Card No: 72-2035 thus indicating the formation of single phase BiFeO3. Also the XRD pattern suggests the formation of highly crystalline BiFeO3 (R3m space group) with rhombohedral perovskite structure with lattice parameters a= 5.5 Ao and c= 13.35 Ao.
FIGURE 1. bismuth ferrite
XRD Pattern of nanocrystalline
Thermal Gravimetric Analysis Fig 2. shows the TG-DTA analysis of BFO nanopowder. On the DTA curve, an exothermic peak around 4190C can be assigned to the decomposition of trapped nitrates and carbonaceous matters [6]. DTA studies also indicated that there is an endothermic peak around 9810C which is most probably due to the melting point of BFO [6]. It also reveals an endothermic peak around 831oC which is attributed to ferroelectric to paraelectric phase transformation in BFO. The Curie temperature of 8310C is in good agreement with a few references [7].
dilute nitric acid in the solution plays a key role in the synthesis of BiFeO3. The synthesis of nano sized BiFeO3 through solution combustion method resulted in the formation of highly crystalline nano sized BiFeO3 perovskite, with good homogeneous distribution. The X-ray Diffraction results indicated rhombohedral phase (R3m) with JCPDS data card no: 72-2035. Scanning electron microscopy analysis confirmed the chemical homogeneity of the BFO sample. DTA analysis indicated ferroelectric phase transition at 8310C which is Curie’s temperature of the BFO sample.
ACKNOWLEDGMENTS The author wants to thank Dr .D. Jaya Prakash, Director, Centre for Analytical Facility, Osmania University-Hyderabad for his help in doing Scanning Electron Microscopy.
REFERENCES 1.
Nicola A. Hill, Why are There so Few Magnetic Ferroelectrics? J. Phy. Chem. B Vol 104, No 29, (2000) 6694-6709.
2.
J. K. Kim, S.S Kim, W.J Kim, Sol-gel synthesis and properties of multi ferroic BiFeO3. Mat. Lett Vol 59, (2005) 4006-4009.
3.
I. Szafranik, M.Polomska, B. Hilczer, A. Pietraszko, L. Kepinski, Characterization of nanopowder obtained by BiFeO3 mechanochemical synthesis. J. Eur. Ceram. Soc. Vol 27, (2007) 4399-4402.
4.
S. Ghosh, S, Dasgupta, A. Sen, H. S. Maiti, Low temperature synthesis of bismuth ferrite nanoparticles by a ferrioxalate precursor method. Mat. Res. Bull. Vol 40, (2005) 20732079.
5.
K. C. Patil, S. T. Aruna, S. Ekambaram , Combustion synthesis, Curr Opin Solid State Mater Sci Vol 2 (1997) 158–165.
6.
Monica Popa, Daniel Crespo, and Jose M. Calderon-Moreno, Silviu Preda and Victor Fruth, “Synthesis and Structural Characterization of Single-Phase BiFeO3 Powders from a Polymer Precursor”, J. Am. Ceram. Soc., Vol 90, No 9, (2007) 2723–2727.
7.
Xiong Wang, Yange Zhang, Zhibin Wu, “Magnetic and optical properties of multiferroic bismuth ferrite nanoparticles by tartaric acidassisted sol–gel strategy”, Materials Letters, Vol 64 (2010) 486–488.
FIGURE 2. Thermal gravimetric analysis of nanosized Bismuth ferrite
Scanning Electron Microscopy Even if the particles are very small (at nanometric scale) so that the average particle size cannot be estimated by SEM, however this method provides useful information about the aggregation of the powders. Fig 3. exhibits a SEM micro structural image of the phase pure Bismuth ferrite (BFO) nanopowders. The SEM images showed in fig 3. at different magnifications reveal the presence of BFO nanoparticles. SEM studies also indicated the spherical morphology of the particles with high tendency of agglomeration.
FIGURE 3. SEM images of the nanosized Bismuth Ferrite
CONCLUSIONS In this present study, nanocrystalline BiFeO3 is prepared by solution combustion synthesis. Citric acid with the combination of ammonium hydroxide and
