Effect of Cr3+ substitution on properties of nano-ZnFe2O4

Kumari, Naveen; Kumar, Vinod; Singh, Satbir

doi:10.1016/j.jallcom.2014.10.083

Cited by 37 publications

(7 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is observed that as Zn 2+ substitution increases from 0.3 to 0.7, a exp values increase from 8.402 to 8.424 Å. This can be explained based on cation radii of ions; Zn 2+ ions (0.74 Å) have larger ionic radii than Mg 2+ (0.66 Å) and Fe 3+ ions [20,21]. Using the cation distribution given in Table 1, the average cationic radius at A (r A ) and B (r B ) sites can be given using Eqs.…”

Section: Xrd Analysismentioning

confidence: 93%

Zn2+ substituted superparamagnetic MgFe2O4 spinel-ferrites: Investigations on structural and spin-interactions

2020

Self Cite

View full text Add to dashboard Cite

Nano-magnetic ferrites with composition Mg1−xZnxFe2O4 (x = 0.3, 0.4, 0.5, 0.6, and 0.7) have been prepared by coprecipitation method. X-ray diffraction (XRD) studies showed that the lattice parameter was found to increase from 8.402 to 8.424 Å with Zn2+ ion content from 0.3 to 0.7. Fourier transform infrared (FTIR) spectra revealed two prominent peaks corresponding to tetrahedral and octahedral at around 560 and 430 cm−1 respectively that confirmed the spinel phase of the samples. Transmission electron microscopy (TEM) images showed that the particle size was noted to increase from 18 to 24 nm with an increase in Zn content from x = 0.3 to 0.7. The magnetic properties were studied by vibrating sample magnetometer (VSM) and electron paramagnetic resonance (EPR) which ascertained the superparamagnetic behavior of the samples and contribution of superexchange interactions. The maximum magnetization was found to vary from 23.80 to 32.78 emu/g that increased till x = 0.5 and decreased thereafter. Further, X-ray photoelectron spectroscopy (XPS) was employed to investigate the chemical composition and substantiate their oxidation states.

show abstract

Section: Xrd Analysismentioning

confidence: 93%

Zn2+ substituted superparamagnetic MgFe2O4 spinel-ferrites: Investigations on structural and spin-interactions

2020

Self Cite

View full text Add to dashboard Cite

show abstract

“…11 The following arguments are presented to support this interpretation. 14,28 In a recent study on the effect of Cr 3+ -substitution at the B-sites of nanocrystalline ZnFe 2 O 4 , Kumari et al 29 had reported about the lattice contraction and size reduction of the crystallites and also the change in dielectric properties but had possibly not observed the structural inversion due to the very limited range of substitution, i.e., from x ¼ 0.1 to x ¼ 0.5 only. 10,25 The purpose of this experiment was to explore such a possibility when ions at the B-sites are replaced by other cations.…”

Section: Resultsmentioning

confidence: 99%

“…An identical effect but from inverse to normal spinel transformation had been earlier observed in the case of Cr 3+substitution at the sites of Fe 3+ in CoFe 2 O 4 . 14,28 In a recent study on the effect of Cr 3+ -substitution at the B-sites of nanocrystalline ZnFe 2 O 4 , Kumari et al 29 had reported about the lattice contraction and size reduction of the crystallites and also the change in dielectric properties but had possibly not observed the structural inversion due to the very limited range of substitution, i.e., from x ¼ 0.1 to x ¼ 0.5 only. With the broader range of substitution undertaken in this study, the effect of inversion could be highlighted as it dominates over the competing process of lattice contraction in directly inuencing the positron annihilation parameters.…”

Section: (A) and (B)mentioning

confidence: 99%

Cr³⁺-substitution induced structural reconfigurations in the nanocrystalline spinel compound ZnFe₂O₄ as revealed from X-ray diffraction, positron annihilation and Mössbauer spectroscopic studies

et al. 2015

View full text Add to dashboard Cite

In an earlier work, the substitution of Zn 2+ ions at the tetrahedral sites of nanocrystalline zinc ferrite (ZnFe 2 O 4 ) by Ni 2+ ions had been observed to cause a transformation from the normal spinel structure to the inverse one. The present study has been undertaken to explore the possibility of a similar change when the Fe 3+ ions at the octahedral sites are replaced by Cr 3+ ions. Concomitant lattice contraction and a steady decrease of the sizes of the nanocrystallites preceded and then resulted into the inversion of ZnFe 2Àx Cr x O 4 from normal spinel to inverse at x $ 0.8. Positron lifetime and coincidence Doppler broadening spectroscopic studies were carried out on the samples and a distinct third positron lifetime component emerged in the range of Cr 3+ concentration 0.8 # x # 1.6. The new positron trapping sites were the result of the inversion of the spinel structure wherein the Cr 3+ ions which substituted the Fe 3+ ions at the octahedral sites got shifted to the tetrahedral sites, interchanging their positions with the Zn 2+ ions. The incomplete success of inversion led to the generation of vacancy-type defects, which significantly trapped the positrons and the changes in their lifetimes indicated the occurrence of the process. The continued lattice contraction ensured an inverted spinel structure even for the final ZnCr 2 O 4 , which in coarse-grained form and at room temperature is a normal spinel. M} ossbauer spectroscopic studies also supported the idea of spinel inversion above x ¼ 0.8 through definite changes in the isomer and quadrupole shifts.

show abstract

“…The electron will hardly transfer before the alternating field reverses and as a result probability of electrons reaching the grain boundary becomes very less. Consequently, the contribution of space charge polarization decreases causing the dielectric constant value to decrease [37]. Further, it is observed that dielectric constant decreases with increasing x in Mn 0.5 Zn 0.5 Gd x Fe 2-x O 4 .…”

Section: Dielectric Constant Studymentioning

confidence: 91%

Structural, thermomagnetic, and dielectric properties of Mn0.5Zn0.5GdxFe2−xO4 (x = 0, 0.025, 0.050, 0.075, and 0.1)

Phor

Kumar

2020

J Adv Ceram

Self Cite

View full text Add to dashboard Cite

In this paper, effect of Gd 3+ was investigated on structural, magnetic, and dielectric properties of Mn 0.5 Zn 0.5 Gd x Fe 2-x O 4 (x = 0, 0.025, 0.050, 0.075, and 0.1) nanoparticles prepared by facile coprecipitation method. X-ray diffraction (XRD) studies confirmed the single cubic spinel phase for all the samples and showed that lattice parameter (a exp) was found to increase from 8.414 to 8.446 Å with the substitution of Gd 3+ ions due to their larger ionic radii than the replaced Fe 3+ ions. Shape and size of developed nanoparticles were studied using transmission electron microscopy (TEM) and found that particle size decreased from 31.06 to 21.12 nm for x = 0-0.1. Magnetic properties showed that maximum magnetization decreased from 39.21 to 23.59 emu/g, and Curie temperature decreased from 192 to 176 ℃ with increase in x from 0 to 0.1 due to weakening of superexchange interaction. Dielectric parameters like dielectric constant (  and  ), dielectric loss (tanδ), AC conductivity (σ ac), and impedance (Z  and Z ) as a function of frequency and composition were analyzed and discussed. It was found that   ,   , σ ac , and tanδ values decreased with Gd substitution, which has been explained based on Maxwell-Wagner theory and hopping mechanism of electrons between Fe 3+ and Fe 2+ ions at octahedral sites. Nyquist plots for all the developed compositions showed single semi-circular arc which indicate the dominant effect of grain boundaries.

show abstract

Effect of Cr3+ substitution on properties of nano-ZnFe2O4

Cited by 37 publications

References 33 publications

Zn2+ substituted superparamagnetic MgFe2O4 spinel-ferrites: Investigations on structural and spin-interactions

Zn2+ substituted superparamagnetic MgFe2O4 spinel-ferrites: Investigations on structural and spin-interactions

Cr³⁺-substitution induced structural reconfigurations in the nanocrystalline spinel compound ZnFe₂O₄ as revealed from X-ray diffraction, positron annihilation and Mössbauer spectroscopic studies

Structural, thermomagnetic, and dielectric properties of Mn0.5Zn0.5GdxFe2−xO4 (x = 0, 0.025, 0.050, 0.075, and 0.1)

Contact Info

Product

Resources

About

Effect of Cr3+ substitution on properties of nano-ZnFe2O4

Cited by 37 publications

References 33 publications

Zn2+ substituted superparamagnetic MgFe2O4 spinel-ferrites: Investigations on structural and spin-interactions

Zn2+ substituted superparamagnetic MgFe2O4 spinel-ferrites: Investigations on structural and spin-interactions

Cr3+-substitution induced structural reconfigurations in the nanocrystalline spinel compound ZnFe2O4 as revealed from X-ray diffraction, positron annihilation and Mössbauer spectroscopic studies

Structural, thermomagnetic, and dielectric properties of Mn0.5Zn0.5GdxFe2−xO4 (x = 0, 0.025, 0.050, 0.075, and 0.1)

Contact Info

Product

Resources

About

Cr³⁺-substitution induced structural reconfigurations in the nanocrystalline spinel compound ZnFe₂O₄ as revealed from X-ray diffraction, positron annihilation and Mössbauer spectroscopic studies