Starch-Assisted Sol-Gel Auto-combustion Method Research Articles

Cation Migration-Induced Crystal Phase Transformation in Copper Ferrite Nanoparticles and Their Magnetic Property

Impact of crystal phase evolution on structural and magnetic properties of copper ferrite nanoparticles is studied and reported. The copper ferrite nanoparticles were synthesized by starch-assisted sol-gel auto-combustion method and further annealed at 200, 500, 800, and 1100°C. The X-ray diffraction study indicated phase evolution from cubic to tetragonal with increase of annealing temperature. Raman spectroscopy and Fourier transform infrared spectroscopy study revealed the impact of phase transformation and cation redistribution in copper ferrite nanoparticles with increase of annealing temperature. X-ray photoelectron study revealed the cation migration with annealing temperature, which is responsible for structural phase evolution. The field emission-scanning electron microscopy (FE-SEM) study revealed that the ferrite nanoparticles at a lower annealing temperature (200, 500, and 800°C) were agglomerated spherical and elongated particles in the grain size range 10–100 nm. However, at a higher annealing temperature (1100°C), it was hexagonal plate-like particles in the grain size range 50–200 nm. The increase in saturation magnetization (Ms) from 11.60 emu/g (200°C) to 25.48 emu/g (1100°C) with grain growth and crystal phase evolution (i.e., increase of c/a ratio and cation redistribution in CuFe2O4 mixed spinel ferrite) was noticed. In addition, a crystal phase evolution from cubic to tetragonal and a grain growth as a function of annealing temperature both cause also an increase in coercivity (Hc) value from 132.56 Oe (200 °C) to 1442.50 Oe (800 °C) Furthermore, the decrease of coercivity (Hc) value from 1442.50 Oe (800°C) to 218.06 Oe (1100°C) with increase of annealing temperature was due to the “pinning” effect of domain wall at the grain boundary.

Erratum to: Magnetic Properties of Dysprosium Doped Cobalt Ferrite Nanoparticles Synthesized by Starch-Assisted Sol-Gel Auto-combustion Method

Erratum to: Magnetic Properties of Dysprosium Doped Cobalt Ferrite Nanoparticles Synthesized by Starch-Assisted Sol-Gel Auto-combustion Method

Erratum to: Structural, Cation Distribution and Magnetic Properties of CoFe2O4 Spinel Ferrite Nanoparticles Synthesized Using a Starch-Assisted Sol-Gel Auto-Combustion Method

Erratum to: Structural, Cation Distribution and Magnetic Properties of CoFe2O4 Spinel Ferrite Nanoparticles Synthesized Using a Starch-Assisted Sol-Gel Auto-Combustion Method

Erratum to: Structural and Magnetic Properties of CoFe 2−x Gd x O4(0.0 ≤ x ≥ 0.1) Spinel Ferrite Nanoparticles Synthesized by Starch-Assisted Sol-Gel Auto-combustion Method

Acknowledgment This work was supported by Project Excellent Teams (CZ.1.07/2.3.00/30.0005) and Sustainability and Development, REG LO1211, National Programme for Sustainability I (Ministry of Education, Youth and Sports) at the Materials Research Centre, Brno University of Technology, and Project Centre of Polymer Systems (Reg. Number: CZ.1.05/2.1.00/03.0111) at Tomas Bata University in Zlin, Czech Republic.

Impact of Nd3+ in CoFe2O4 spinel ferrite nanoparticles on cation distribution, structural and magnetic properties

Nd3+ doped cobalt ferrite nanoparticles have been synthesized by starch-assisted sol–gel auto-combustion method. The significant role played by Nd3+ added to cobalt ferrite in changing cation distribution and further in influencing structural and magnetic properties, was explored and reported. The crystal structure formation and crystallite size were studied from X-ray diffraction studies. The microstructural features were investigated by field emission scanning electron microscopy and transmission electron microscopy that demonstrates the nanocrystalline grain formation with spherical morphology. An infrared spectroscopy study shows the presence of two absorption bands related to tetrahedral and octahedral group complexes within the spinel ferrite lattice system. The change in Raman modes in synthesized ferrite system were observed with Nd3+ substitution, particle size and cation redistribution. The impact of Nd3+ on cation distribution of Co2+ and Fe3+ at octahedral and tetrahedral sites in spinel ferrite cobalt ferrite nanoparticles was investigated by X-ray photoelectron spectroscopy. Room temperature magnetization measurements showed that the saturation magnetization and coercivity increase with addition of Nd3+ substitution in cobalt ferrite.

Effects of annealing temperature variation on the evolution of structural and magnetic properties of NiFe2O4 nanoparticles synthesized by starch-assisted sol–gel auto-combustion method

Evolution of the structural and magnetic properties of NiFe2O4 nanoparticles synthesized by starch-assisted sol–gel auto-combustion method, and exposed to further annealing at 200°C, 400°C, 600°C, 800°C and 1000°C, was evaluated in detail and correlation of these properties explored. The ferrite nanoparticles were characterized by X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy, Raman Spectroscopy, Fourier Transform Infrared Spectroscopy, X-ray Photoelectron Spectroscopy and Vibrating Sample Magnetometer. The X-ray diffraction patterns demonstrated single phase formation of NiFe2O4 spinel ferrite nanoparticles at different annealing temperature 200°C, 400°C, 600°C, 800°C and 1000°C. The change in crystallite size with increase of annealing temperature is observed. The FE-SEM analysis also indicated an increase of particle size with increase of higher annealing temperature. The change in Raman modes and infrared absorption bands were noticed with change of particle size. The X-ray photoelectron spectroscopy revealed the presence of Ni2+ and Fe3+ at octahedral and tetrahedral sites in NiFe2O4 nanoparticles. The representative sample NiFe2O4 nanoparticles annealed at 400°C, have mixed cation distribution (Ni0.23+2Fe0.52+3)[ Ni0.77+2Fe1.48+3]O4. The highest value of coercivity 62.35Oe and saturation magnetization 34.10erg/g were obtained at annealing temperature 600°C and 1000°C, respectively.

Magnetic Properties of Dysprosium-Doped Cobalt Ferrite Nanoparticles Synthesized by Starch-Assisted Sol-Gel Auto-combustion Method

Dysprosium-substituted cobalt ferrite nanoparticles with composition of CoFe2−x Dy x O4 (x = 0 − 0.1 in a step of 0.025) were synthesized by starch-assisted sol–gel auto-combustion method. The effect of Dy3+ cation substitution on structural and magnetic properties of cobalt ferrite nanoparticles was investigated. Powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), Raman spectroscopy, infrared spectroscopy (IR), X-ray photoelectron spectroscopy and vibrating sample magnetometer (VSM) were employed to characterize the physical properties of these ferrite nanoparticles. XRD pattern reveals the formation of cubic spinel ferrite with the signature of DyFeO3 phases for x ≥ 0.05. An infrared spectroscopy study shows the presence of two absorption bands in the frequency range around 560 cm−1 (ν 1) and around 380 cm−1 (ν 2), which indicate the presence of tetrahedral and octahedral group complexes, respectively, within the spinel ferrite nanoparticles. FE-SEM analysis indicated the formation of nanosized particles (5 −15 nm) with spherical morphology. Vibrating sample magnetometer was employed to probe the magnetic properties of the samples at room temperature. It was observed that rare earth ion dopant, crystallite size and foreign phase DyFeO3 affect the magnetic properties of cobalt ferrite nanoparticles.

Structural, Cation Distribution, and Magnetic Properties of CoFe2O4 Spinel Ferrite Nanoparticles Synthesized Using a Starch-Assisted Sol–Gel Auto-Combustion Method

In this article, cobalt ferrite nanoparticles were synthesized using a starch-assisted sol–gel auto-combustion route. The significant role played by further annealing temperatures of 300, 500, 700, 900 and 1100 °C on particle size and magnetic properties of ferrite nanoparticles was explored and reported. The prepared nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, using a vibrating sample magnetometer. The X-ray diffraction patterns demonstrated singlephase formation of CoFe2O4 spinel ferrite nanoparticles at different annealing temperatures. The FESEM analysis indicated a change of particle size and morphology at higher annealing temperature. The change in Raman modes and infrared absorption bands was observed with change of particle size and cation distribution. The highest value of coercivity (1091.2 Oe) and the saturation magnetization (54.76 erg g−1) were obtained at annealing temperatures of 900 and 1100 °C, respectively. X-ray photoelectron spectroscopy revealed the presence of Co2+ and Fe3+ at octahedral and tetrahedral sites in CoFe2O4 nanoparticles. Further, the cation redistribution with change of particle size was confirmed by X-ray photoelectron spectroscopy.

Structural and Magnetic Properties of CoFe2−x Gd x O4 (0.0 ≤ x ≥ 0.1) Spinel Ferrite Nanoparticles Synthesized by Starch-Assisted Sol–Gel Auto-combustion Method

In this present article, CoFe2−x Gd x O4 (0.0 ≤ x ≥ 0.1) nanoparticles were synthesized by starch-assisted sol–gel auto-combustion method. Powder X-ray diffraction patterns revealed the formation of cubic spinel ferrite with the signature of GdFeO3 phase at higher Gd3+ concentration. The field emission scanning electron microscopy study demonstrated the spherical nanoparticle in the size range 4–10 nm. Raman and Fourier transform infrared spectra supported the formation of the spinel ferrite structure in the nanocrystalline form. The X-ray photoelectron spectroscopy (XPS) analysis confirmed the presence of Co2+ and Fe3+ at the octahedral site as well as the tetrahedral site in CoFe2−x Gd x O4 (x = 0.05) nanoparticles. The distribution of Fe3+ ions was obtained to be about 73 % in the octahedral sites and about 27 % in the tetrahedral sites. The distribution of Co2+ ions at the octahedral and tetrahedral sites were 78 and 22 %, respectively. The increase in saturation magnetization and coercivity from 14.59 emu/g (x = 0.00) to 16.11 emu/g (x = 0.025) and 51.75 Oe (x = 0.00) to 92.86 Oe (x = 0.050), respectively, in CoFe2−x Gd x O4 nanoparticles were observed.

Magnetic properties of Co 1−x Zn x Fe 2 O 4 spinel ferrite nanoparticles synthesized by starch-assisted sol–gel autocombustion method and its ball milling

In this article, Co1−xZnxFe2O4 (x=0.0 and 0.5) spinel ferrite nanoparticles were achieved at 800 °C by starch-assisted sol–gel autocombustion method. To further reduce the particle size, these synthesized ferrite nanoparticles were ball-milled for 2 h. X-ray diffraction patterns demonstrated single phase formation of Co1−xZnxFe2O4 (x=0.0 and 0.5) spinel ferrite nanoparticles. FE-SEM analysis indicated the nanosized spherical particles formation with spherical morphology. The change in Raman modes and relative intensity were observed due to ball milling and consequently decrease of particle size and cationic redistribution. An X-ray Photoelectron Spectroscopy (XPS) result indicated that Co2+, Zn2+ and Fe3+ exist in octahedral and tetrahedral sites. The cationic redistribution of Zn2+ and consequently Fe3+ occurred between octahedral and tetrahedral sites after ball-milling. The change in saturation magnetization (Ms) and coercivity (Hc) with decrease of nanocrystalline size and distribution of cations in spinel ferrite were observed.

Magnetic Properties of ZnFe2O4 Nanoparticles Synthesized by Starch-Assisted Sol–Gel Auto-combustion Method

In this paper, ZnFe2O4 spinel ferrite nanoparticles with different grain sizes at different annealing temperatures have been synthesized using the starch-assisted sol–gel auto-combustion method. The synthesized nanoparticles were characterized by conventional powder X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, and vibrating sample magnetometer. The X-ray diffraction (XRD) patterns demonstrated that the ZnFe2O4 nanoparticles consist of single-phase spinel structure with crystallite sizes 4.81, 8.72, 12.06, 29.32, and 72.60 nm annealed at 400, 600, 800, 1000, and 1200 °C, respectively. Field emission scanning electron microscopy reveals that particles are of spherical morphology at lower annealing temperature and hexagonal-like morphology at higher temperature. An infrared spectroscopy study shows the presence of two principal absorption bands in the frequency range around 525 cm−1 (ν 1) and around 350 cm−1 (ν 2), which indicate the presence of tetrahedral and octahedral group complexes, respectively, within the spinel ferrite nanoparticles. Raman spectroscopy study also indicated the change in octahedral and tetrahedral site-related Raman modes in zinc ferrite nanoparticles with change of particle size. The nanocrystalline ZnFe2O4 samples (4.81, 8.72, 12.06, 29.32 nm) show ferrimagnetic behavior, and bulk sample (72.60 nm) shows paramagnetic behavior. This change in magnetic behavior is due to change of cation distribution in ZnFe2O4 nanoparticles with decrease of particle size.

Structural and Magnetic Properties of CoFe2O4 Nanoparticles Synthesized by Starch-Assisted Sol–Gel Auto-Combustion Method in Air, Argon, Nitrogen and Vacuum Atmospheres

In the present work, structural and magnetic properties of CoFe2O4 nanoparticles synthesized by starch-assisted sol–gel auto-combustion method in air, argon, nitrogen and vacuum atmospheres were investigated. The particle size, shape, crystal structure and magnetic properties of synthesized ferrite nanoparticles were investigated by powder X-ray diffractometer (XRD), field emission scanning electron microscopy (FE-SEM), Raman spectrometer, Fourier transform infrared spectroscopy (FTIR) and a vibrating sample magnetometer (VSM). The FE-SEM micrographs indicate the octahedron-like cobalt ferrite nanoparticles formation in air atmosphere; however, spherical nanoparticles were formed in argon, nitrogen and vacuum atmospheres. An infrared spectroscopy study showed the presence of two absorption bands in the frequency range around 560 cm−1 (ν 1) and around 340 cm−1 (ν 2) which indicated the presence of tetrahedral and octahedral group complexes, respectively, within the spinel lattice. Room temperature magnetization measurements showed that the saturation magnetization (M s) and coercivity (H c) were influenced by cobalt ferrite formation atmosphere, i.e., air, argon, nitrogen and vacuum.

Effect of Pr 3 + Substitution on Structural and Magnetic Properties of CoFe 2 O 4 Spinel Ferrite Nanoparticles

In this paper, CoFe2−xPrx O4 (x = 0.00 to 0.1 in step of 0.025) nanoparticles were synthesized by starch-assisted sol-gel auto-combustion method. Powder X- ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, infrared spec- troscopy and vibrating sample magnetometer (VSM) were employed to characterize these synthesized CoFe2−xPrxO4 nanoparticles. The structural phase purity, crystallite size, and lattice parameter of synthesized CoFe2−xPrx O4 ferrite nanoparticles were estimated from X-ray diffraction stud- ies. XRD patterns reveal the formation of cubic spinel ferrite with the signature of PrFeO3 phase at higher Pr 3+ con- centration. FE-SEM images endorse that the synthesized nanoparticles are of spherical morphology with size in the range of 5-20 nm. Raman and Fourier transform infrared (FTIR) spectra support the formation of the spinel Co- Fe-Pr ferrite structure in the nanocrystalline form. Room temperature magnetic measurement shows increase in sat- uration magnetization and coercivity, from 13.96 emu g −1 (x = 0.0) to 19.34 emu g −1 (x = 0.075) and 52.30 Oe (x = 0.0) to 546.94 Oe (x = 0.075), respectively, in CoFe2−xPrx O4 nanoparticles synthesized by starch-assisted sol-gel auto-combustion method