Double perovskite Sm2CoFeO6 (SCFO) compound has been synthesized by the conventional solid-state reaction route for the first time. The Rietveld refinement has been carried out using the X-ray diffraction data; it confirms the single-phase formation of orthorhombic structure with the Pnma space group. UV-DRS results show that SCFO was observed in semiconducting behavior. Spin–phonon coupling of SCFO was observed from Raman spectroscopy investigation. The Raman analysis and group theory confirms that the IR and Raman active modes of SCFO. The amount of Sm, Co, Fe and O elements in the SCFO compound was examined by energy-dispersive spectroscopy (EDS) with the assistance of field emission scanning electron microscopy (FE-SEM) analysis. The photoluminescence excitation and emission spectra of SCFO were examined. The results show that the phosphor is excited in the region from 320 to 500 nm, and it emits orange at 607 nm, due to the resultant of 4G5/26H7/2 transitions. The SCFO compound exhibited ferromagnetic behavior, which is confirmed by VSM analysis. The obtained results demonstrated that SCFO double perovskite is extensive for application of spintronic devices and LED’s.
@article{Dhilip2022,author={Dhilip, M. and Punitha, J. Stella and Rameshkumar, R. and Rameshkumar, S. and Karuppasamy, P. and Pandian, Muthu Senthil and Ramasamy, P. and Kumar, K. Saravana and Anbarasu, V. and Elangovan, K.},title={A novel double perovskite oxide Sm2CoFeO6 phosphor for orange LEDs structural, magnetic and luminescence properties},journal={Applied Physics A},year={2022},month=mar,day={20},volume={128},number={4},pages={324},issn={1432-0630},doi={10.1007/s00339-022-05446-8},url={https://doi.org/10.1007/s00339-022-05446-8},}
2021
JMSME
Synthesis and characterization of phase-stabilized Gd2FeMnO6 double-Perovskite compound
J. Stella Punitha, A. Nataraj, V. Anbarasu, and
2 more authors
Journal of Materials Science Materials in Electronics Mar 2021
In the recent past, a series of double-perovskite compounds with the molecular formula of A2BB’O6 have gained keen interest among other inorganic compounds. It is due to the fact that the exhibition of large variety of physical properties pertaining to the elements accommodated at A, B and B’ sites. In connection to the preparation of Gd2FeMnO6, a novel single-phased double perovskite compound has been carried out using conventional solid-state reaction route. Rietveld refinement of powder XRD patterns reveals that the compound crystallizes in orthorhombic crystal structure with a space group Pbnm. X-ray photoelectron spectroscopy analysis confirms the presence of Mn and Fe ions in +3 oxidation state. The field emission scanning electron micrograph reveals the granular growth morphology, having grains with irregular shape with the average grain size of about 5–10 µm. Room-temperature magnetization measurement reveals the dominant antiferromagnetic behaviour with weak ferromagnetic interactions. Deconvoluted Raman spectra using Lorentzian function confirm the first and second orders of Raman modes of the prepared compound. The activation energy value of Ea = 0.16 eV obtained from the Arrhenius plot indicates the dielectric stability of the material. The photoluminescence study shows the excitation by the light from ultraviolet region (350 to 450 nm), exhibiting blue (355 nm) to 8S7/2 → 6P3/2 transition, which may provide new applications in the field of modern electronics.
@article{Punitha2021,author={Punitha, J. Stella and Nataraj, A. and Anbarasu, V. and Dhilip, M. and Kumar, K. Saravana},doi={10.1007/s10854-021-05682-3},isbn={1085402105682},issn={1573482X},issue={8},journal={Journal of Materials Science Materials in Electronics},pages={10266-10276},publisher={Springer US},title={Synthesis and characterization of phase-stabilized Gd2FeMnO6 double-Perovskite compound},volume={32},url={https://doi.org/10.1007/s10854-021-05682-3},year={2021},}
2020
JMSME
Structural properties, optical, electrical and magnetic behavior of bismuth doped Gd3Fe5O12 prototype garnet
N. Aparnadevi, K. Saravana Kumar, M. Manikandan, and
3 more authors
Journal of Materials Science Materials in Electronics Feb 2020
The co-existence of magnetism and semi-conducting property in a material around room temperature has potential for application in the field of spintronics. The rare-earth iron garnets with high Curie temperature can be tuned by doping them with suitable elements to have properties useful for device applications. In this context, the structural, optical, electrical, and magnetic properties of bismuth doped Gd3−xBixFe5O12 (x\thinspace=\thinspace0.05 & 0.09), synthesized from ball milled stoichiometric oxide precursors, are studied. Structural deformation due to doping is not prominent from the Rietveld refinement of X-ray diffractograms. A minimal increase in the band gap is observed with increase in Bi concentration. A shift in the Curie point towards the high temperature region is observed, ascribed to the stabilizing effect of Bi ion on magnetic ordering. The P–E loops show low coercivity dictating their linear capacitive behavior.
@article{Aparnadevi2020,author={Aparnadevi, N. and Kumar, K. Saravana and Manikandan, M. and Santhosh Kumar, B. and Stella Punitha, J. and Venkateswaran, C.},title={Structural properties, optical, electrical and magnetic behavior of bismuth doped Gd3Fe5O12 prototype garnet},journal={Journal of Materials Science Materials in Electronics},year={2020},month=feb,day={01},volume={31},number={3},pages={2081-2088},issn={1573-482X},doi={10.1007/s10854-019-02729-4},url={https://doi.org/10.1007/s10854-019-02729-4},}
AIP Conf. Proc.
Characterization of the structural, magnetic and raman properties of 6f - 4d double perovskite compound
J. Stella Punitha, K. Saravana Kumar, M. Dhilip, and
2 more authors
The structure and vibrational properties of Pr2FeMnO6 double perovskite are explored in this paper. The compound issynthesized using high temperature solid-state reaction method in airatmosphere. Rietveld analysis of X-ray powder diffraction pattern confirms that the material has orthorhombic structure of space group Pbnm.Room temperature SEM micrograph exhibits the grain size of the particles in the range of 1-5µm.Raman Spectroscopy analysis indicates the strong coupling in two/multi-phonon modes, that are aligned in four strong bands1170,1356, 1609 and 1838 cm-1.Magnetization study at room temperature reveals the Paramagnetic nature of the material with a saturation magnetization of 18.43 emu/g at the maximum applied field.
@article{StellaPunitha2020,author={Punitha, J. Stella and Kumar, K. Saravana and Dhilip, M. and Anbarasu, V. and Nataraj, A.},doi={10.1063/5.0016644},isbn={9780735420250},issn={15517616},issue={November},journal={AIP Conference Proceedings},keywords={Double perovskite,Paramagnetic,Raman spectroscopy,Rietveld analysis,Structure,X-ray diffraction},pages={5-9},title={Characterization of the structural, magnetic and raman properties of 6f - 4d double perovskite compound},volume={2265},year={2020},}
Mat. Chem. Phys.
Synthesis and characterization of nanostructured La-doped BaSnO3 for dye-sensitized solar cell application
Nandarapu Purushothamreddy, M. Kovendhan, Reshma K. Dileep, and
3 more authors
Nanostructured pure and lanthanum (La) doped (0.01%, 0.03% and 0.05%) perovskite BaSnO3 materials were synthesized by hydrothermal method and annealed at 1000 °C/2 h in air. Rietveld refinement of the XRD data indicated single-phase nature of the samples with cubic crystallographic structure. The morphology of pure and La-doped BaSnO3 (La–BSO) studied using scanning electron microscopy indicated the formation of distinct rod-like structures. Upon doping with La, the BSO nanorods disintegrated and tend towards a mixed nanorods-nanoparticle like morphology as confirmed from the TEM measurements. The XPS data confirmed La to be in 3+ oxidation state. The 0.03% La–BSO was found to have a higher value of band-gap. A maximum power conversion efficiency of 1.23% with a higher short circuit current density of 2.57 mA/cm2 was obtained for the DSSC fabricated using 0.03% La–BSO nanostructured material as a photoanode.
@article{Purushothamreddy2020,author={Purushothamreddy, Nandarapu and Kovendhan, M. and Dileep, Reshma K. and Veerappan, Ganapathy and Kumar, K. Saravana and Joseph, D. Paul},doi={10.1016/j.matchemphys.2020.123137},issn={02540584},issue={May},journal={Materials Chemistry and Physics},keywords={Dye-sensitized solar cell (DSSC),La doped BaSnO3,Nanostructure,Perovskite},pages={123137},publisher={Elsevier B.V.},title={Synthesis and characterization of nanostructured La-doped BaSnO3 for dye-sensitized solar cell application},volume={250},url={https://doi.org/10.1016/j.matchemphys.2020.123137},year={2020},}
2019
Vacuum
Conventional synthesis and characterization of cubically ordered La2FeMnO6 double perovskite compound
M. Dhilip, N. Aparna Devi, J. Stella Punitha, and
2 more authors
The cubically ordered double perovskite compound, La2FeMnO6, has been synthesized using high temperature solid-state reaction method. Rietveld refinement of powder X-ray diffraction data indicates the formation of La2FeMnO6 compound, having cubic structure with space group Pm-3m. It is also inferred that the LaFeO3 perovskite structure accommodates the Mn3+ ions to stabilize the double perovskite La2FeMnO6 structure. The scanning electron micrograph reveals the uniform distribution of crystallites without any segregation. Energy dispersive spectra confirms the presence of La, Fe, Mn and O elements in the prepared compound. The existence of higher order Raman active vibrational modes confirms the phase purity of the prepared sample, where higher-order phonon modes may be related to the strong spin-lattice coupling arising from the interaction between the adjacent magnetic sublattices. The magnetic exchange interactions between transition metal ions influences the anti-ferromagnetic ordering (AFM) existing in the La2FeMnO6 compound. The magnetization measurement confirms the dominant exchange interactions between Fe3+ and Mn3+ ions in the material which provides a complex environment for the competition between ferri-magnetism (FIM) and AFM interactions. Hence, a phase pure double perovskite La2FeMnO6 compound prepared at high temperature is characterized for its structural, optical and magnetic properties.
@article{Dhilip2019,author={Dhilip, M. and Devi, N. Aparna and Punitha, J. Stella and Anbarasu, V. and Kumar, K. Saravana},doi={10.1016/j.vacuum.2019.05.028},issn={0042207X},issue={March},journal={Vacuum},keywords={Double perovskites,Raman spectroscopy,Rietveld refinement,VSM},pages={16-20},publisher={Elsevier},title={Conventional synthesis and characterization of cubically ordered La2FeMnO6 double perovskite compound},volume={167},url={https://doi.org/10.1016/j.vacuum.2019.05.028},year={2019},}
AIP Conf. Proc.
Coexistence of two phases in Sr2TiFeO6 double perovskite
J. Stella Punitha, M. Dhilip, V. Anbarasu, and
2 more authors
In the present study, the structure and magnetic properties of Sr2TiFeO6 have been investigated. This compound is synthesized using standard solid state route and its physical properties are analysed by X-ray diffraction, Raman spectroscopy and room temperature magnetic measurements. Rietveld refinement of X-ray powder diffraction pattern reveals co-existence between cubic and tetragonal phases with Pm3m space group. The scanning electron micrograph exhibits heterogeneous grain distribution with average grain size of 1μm to 5μm. Raman spectra of Sr2TiFeO6 reveals six characteristic bands that are in accordance with the group theoretical predictions. Furthermore, the magnetic measurement at room temperature exhibits weak ferromagnetic ordering.
@article{Punitha2019a,author={Punitha, J. Stella and Dhilip, M. and Anbarasu, V. and Nataraj, A. and Kumar, K. Saravana},doi={10.1063/1.5114590},isbn={9780735418578},issn={15517616},issue={June},journal={AIP Conference Proceedings},keywords={Ferromagnetic ordering,Raman spectroscopy,Structure,X-ray diffraction},pages={1-5},title={Coexistence of two phases in Sr2TiFeO6 double perovskite},volume={2117},year={2019},}
AIP Conf. Proc.
Structural and magnetic properties of Fe, Mn based double perovskite La2FeMnO6 compound
J. Stella Punitha, M. Dhilip, V. Anbarasu, and
1 more author
The double perovskite materials provide flexible selection of ions and the combination of La, Fe and Mn provide an interesting prospect. The double perovskite La2FeMnO6 (LFMO) was synthesized using conventional high temperature solid-state reaction method. Rietveld refinement of powder X-ray diffraction pattern confirms the formation of LaFeMnO6 phase. From the Raman spectroscopic analysis, it was identified that the La2FeMnO6 compound six Raman active modes and the modes at higher frequency region reveals the existence of ferromagnetic ordering in the material. The soft ferromagnetic behavior of the prepared compounds was revealed by the magnetization analysis. Hence, structural stable double perovskite La2FeMnO6 compound has been reported for possible opto-magnetic device applications.
@article{Punitha2019,author={Punitha, J. Stella and Dhilip, M. and Anbarasu, V. and Kumar, K. Saravana},doi={10.1063/1.5113307},isbn={9780735418516},issn={15517616},issue={July},journal={AIP Conference Proceedings},keywords={Ferromagnetism,Raman spectroscopy,Rietveld Refinement,Structure},pages={6-9},title={Structural and magnetic properties of Fe, Mn based double perovskite La2FeMnO6 compound},volume={2115},year={2019},}
J. Elec. Mat.
Intrinsic Magnetic and Ferroelectric Behaviour of Non-magnetic Al3+ Ion Substituted Dysprosium Iron Garnet Compounds
M. Dhilip, K. Saravana Kumar, R. Ramesh Kumar, and
1 more author
Synthetic garnets are a group of oxide materials that play a vital role in the development of solid state lasers, magnetic and optic-electronic devices. The analysis on the solubility of rare-earth elements in the well-crystallized system has led to the discovery of peculiar oxide materials with multifunctional properties. By following the above importance, Aluminium ion (Al3+) substituted Dysprosium Iron Garnet compounds with the chemical formula of Dy3Fe5−xAlxO12 (x = 0–0.5) have been synthesized by the solid state reaction method and the effect of substitution of non-magnetic ions into the magnetic sub-lattices have been analyzed. The Rietveld refinement of powder x-ray diffraction patterns confirms that the pure Dy3Fe5O12 compound crystallizes with cubic (Space group Ia3d) superstructure whereas all the Al3+ substituted samples exhibit the coexistence of cubic (Ia3d) and trigonal Fe2O3 (R3c) phases. The energy gap values of the prepared compounds is found to be around 1.6 eV which reveals the semiconducting nature and the decreasing trend of band gap values may be due to the growth factor of crystallites, structural disorder and distortion introduced into the crystal lattice. From the Micro-Raman analysis, it is found that the substituted Al3+ ions starts filling into both tetrahedral and octahedral positions and the assignments of vibrational modes observed from Raman spectra confirm the incorporation of Al3+ ions into the Dy3Fe5O12 garnet structure. From the magnetization analysis, it is found that the response of super-exchange interaction between Fe3+ ions in the a and d sites of Dy3Fe5O12 compound leads to net magnetic moment and the substitution of Al3+ ions preferably replaces Fe3+ ions in d sites and suggests the decrease in net magnetization values. From the photoluminescence studies, it is noticed that the luminescence behavior of Al3+ ions substituted Dy3Fe5−xAlxO12 compounds are due to the superposition of a broad emission band and reveals the variation in concentration of Al3+ ions in the prepared compounds. An interesting point to note is that, a well saturated “soft” ferroelectric hysteresis loop is obtained in both pure and Al3+ substituted Dy3Fe5−xAlxO12 compounds, and the observed electric hysteresis loops are found to be influenced by the factors such as capacitance nature, resistivity effects and leakage current of the compounds. Hence, the study on effect of trivalent non-magnetic ion substitution in a hard magnetic Dy3Fe5O12 system leads to interesting intrinsic magnetic and ferroelectric properties and found suitability for the fabrication of energy storage and optoelectronic devices.
@article{Dhilip2019b,author={Dhilip, M. and Kumar, K. Saravana and Kumar, R. Ramesh and Anbarasu, V.},doi={10.1007/s11664-019-07675-9},issn={1543186X},issue={12},journal={Journal of Electronic Materials},keywords={Raman spectroscopy,Rare-earth iron garnet,Rietveld analysis,ferroelectric,photoluminescence,solid state reaction},pages={8243-8253},title={Intrinsic Magnetic and Ferroelectric Behaviour of Non-magnetic Al3+ Ion Substituted Dysprosium Iron Garnet Compounds},volume={48},year={2019},}
JMSME
Synthesis of SrCoO3 perovskite as W-based double perovskite and its structural properties
M. Dhilip, M. Manikandan, S. Ramesh Kumar, and
3 more authors
Journal of Materials Science Materials in Electronics Feb 2019
The double-perovskites, (AA′)(BB′)O 6 , are gaining importance due to their flexibility in the choice of ions, and the wide application potential in magnetic, electrical, optical and thermal applications. Especially, the tungsten-based double-perovskites been explored for their optical properties. Hence, the double perovskite oxide, Sr 2 CoWO 6 , was synthesized using conventional solid-state reaction method. The Rietveld refinement data derived from powder X-ray diffraction pattern confirms the single-phase formation of Sr 2 CoWO 6 compound. The deconvolution of Raman’s spectra exhibits first-order Raman’s modes of Sr 2 CoWO 6 . The observed phonon modes found to be in good agreement with the corresponding theoretical predictions for the space group of I4/m. The phosphor could be excited by the UV light region from 350 to 450 nm, and it exhibits blue (390 nm) to 4A2 → 2T2 transition. The compound is stable with antiferromagnetic ordering, as evident from the magnetization loop and theoretical calculations. Band structure calculations for tetragonal Sr 2 CoWO 6 predict an energy gap in both spin-up and spin-down configurations.
@article{Dhilip2019a,author={Dhilip, M. and Manikandan, M. and Kumar, S. Ramesh and Jayalakshmi, V. and Anbarasu, V. and Kumar, K. Saravana},doi={10.1007/s10854-019-00718-1},isbn={0123456789},issn={1573482X},issue={4},journal={Journal of Materials Science Materials in Electronics},pages={4270-4278},publisher={Springer US},title={Synthesis of SrCoO3 perovskite as W-based double perovskite and its structural properties},volume={30},url={http://dx.doi.org/10.1007/s10854-019-00718-1},year={2019},}
2018
AIP Conf. Proc.
Study of crystal structure and unique photoluminescence properties of Eu2-xFexO3 (x = 0 - 0.5) orthoferrites
M. Dhilip, V. Anbarasu, K. Saravana Kumar, and
1 more author
A series of Europium orthoferrites, Eu2-xFexO3 (x = 0 - 0.5) are successfully prepared by employing solid state reaction technique. The structural analysis through powder X-Ray diffraction technique reveals the multiphase formation of all the prepared compounds. Further, the unit cell visualization of all the prepared compounds confirms the change of crystal structure from cubic to orthorhombic phase. The crystal structure analysis confirms the typical framework of Eu - Fe - O chains with unprecedented ratio of Eu3+ and Fe3+ ions. The optical properties of prepared compounds are investigated using photoluminescence (PL) analysis. Upon excitation at 495 nm wavelength, the emission spectrum of prepared compounds exhibits a broad band in the range of 500-700nm with maximum intensity peak at 548 nm (Blue - 2.26eV). Hence, the substitution of Fe3+ ion yields with intrinsic blue photoluminescence (5D0 → 7F0) of Eu3+ and is easily shielded by the substitution of Fe3+ which may be due to the closer conduction band gap of Eu3+ (2.26 eV) with Fe3+ (2.67 eV). The schematic energy level diagram for Fe3+ in the Eu3+ host matrix has been proposed for the better understanding of photoluminescence processes. The variation of intensity of PL peak between 500 and 700 nm for the substitution of Fe in the range of x = 0 - 0.5 yields with interesting optical properties for exploring new phosphor materials for optoelectronic device fabrications.
@article{Dhilip2018,author={Dhilip, M. and Anbarasu, V. and Kumar, K. Saravana and Sivakumar, K.},doi={10.1063/1.5029063},isbn={9780735416345},issn={15517616},journal={AIP Conference Proceedings},keywords={Europium Orthoferrite,Photoluminescence,multiphase},pages={3-7},title={Study of crystal structure and unique photoluminescence properties of Eu2-xFexO3 (x = 0 - 0.5) orthoferrites},volume={1942},year={2018},}
2017
JMSME
Effect of transition metal ion substitution on structural and magnetic properties of Eu2O3 sesquioxide system
V. Anbarasu, M. Dhilip, K. Saravana Kumar, and
1 more author
Journal of Materials Science Materials in Electronics Feb 2017
The effect of trivalent transition metal ion (Fe3+) substitution in Eu2O3 system has been carried out. The ceramic compounds of Eu2−xFexO3 (where x = 0–0.5) are prepared by solid-state reaction technique. The crystal symmetries of synthesized materials have been calculated from powder X-ray diffraction patterns through Rietveld refinement process. The Rietveld refinement confirms that the pure Eu2O3 compound exhibits multiphase structure (monoclinic and cubic) of space group (c 1 2/m 1) and (I a -3). The incorporation of Fe3+ ion in the rare earth site (Eu3+) leads with change of cubic crystal symmetry to orthorhombic multiphase (monoclinic and orthorhombic) of space group (c 1 2/m 1) and (p b n m). The field emission scanning electron microscopic images of the samples reveals the substitutional effect of transition metal ion with the increasing grain growth and grain boundaries. The energy dispersive analysis confirms the increasing concentration of Fe3+ ion in to the host Eu2O3 system. From the Raman spectra, it is observed that most of intense Raman resonance peaks are dully assigned with cubic phase Eu2O3 compound. Further, it is noticed that the major intensity Raman signal of Eu2O3 compound at 109 cm−1 assigned with Fg mode is goes on decreasing with respect to increasing concentration of Fe which evident the change of crystal structure from cubic phase to Orthoferrite phase in Eu2−xFexO3 compounds The diffused reflectance study confirms the semiconducting nature of all the prepared compounds. Magnetization analysis reveals that due to substitution of transition metal ion in rare earth site leads with decreasing trend of magnetic moment which is due to the fact of substituting lower ionic radii element (Fe3+) in non-magnetic Eu3+ ion leads with change in position of atoms in their crystal structure by variation in bond length and bond angles between RE–O and induces co-linearity in magnetic exchange interactions. Hence even the partial substitution of ferromagnetic Fe3+ ions in Eu3+ lattice site induces change in magnetic sub-lattices due to the variation in crystallographic position of atoms and results in paramagnetic ordering with lower magnetic moment than the parent compound.
@article{Anbarasu2017a,author={Anbarasu, V. and Dhilip, M. and Kumar, K. Saravana and Sivakumar, K.},doi={10.1007/s10854-017-7035-y},issn={1573482X},issue={16},journal={Journal of Materials Science Materials in Electronics},pages={12197-12206},publisher={Springer US},title={Effect of transition metal ion substitution on structural and magnetic properties of Eu2O3 sesquioxide system},volume={28},year={2017},}
JMSME
Effect of trivalent transition metal ion substitution in multifunctional properties of Dy2O3 system
V. Anbarasu, M. Dhilip, K. Saravana Kumar, and
1 more author
Journal of Materials Science Materials in Electronics Feb 2017
The present work describes the systematic study on inducing multiferroic properties in non-magnetic Dy2O3 system. The ceramic compounds of Dy2−xFexO3 (where x = 0.1–1.5) have been prepared by solid state reaction method. The powder X-ray diffraction patterns of all the prepared compounds reveal the strong influence of transition metal ion (Fe) in the Dy2O3 crystal structure. By Rietveld analysis, it is determined that with respect to increasing concentration of Fe3+ ion at Dy3+ site leads to transformation of crystal structure from Cubic to Orthorhombic with varying concentration of DyFeO3 phase and further increase in Fe3+ concentration leads to the formation of Garnet phase in Dy2−xFexO3 compounds. The scanning electron microscopic images of the samples confirm the change in surface morphology with increasing grain boundaries and porosity due to the substitution of Fe in Dy2O3 system which may effects on the electrical transport properties of the materials and increasing concentration of Fe in Dy2O3 system is also analyzed by energy dispersive analysis spectra. By Raman spectral analysis, it is identified that the strong absorption band of Cubic Dy2O3 compound at 373 cm−1 is gradually shifted to 257 cm−1 which indicates the molecular stretching motion of RE–O bond in REO6 octahedra and the large deviation in position of intense Raman bands below 300 cm−1 confirms the incorporation of Fe3+ ion in the host Dy2O3 lattice and imparting large polarizability in the prepared compounds due to translational motions of ReO6 octahedrons by variation in bond length and reduced mass of the bonding atoms. Diffused reflectance spectroscopy analysis implies the semiconducting nature of all the prepared compounds. It is also identified that the energy gap values goes on decreasing till DyFeO3 and then starts increasing due to change in crystal structure by cubic to orthorhombic and then orthorhombic to garnet phase. From the magnetization studies, it is found that till even substitution of Fe (i.e. x = 0.1–0.9) in Dy2−xFexO3 system, the compounds exhibits paramagnetic nature whereas from x = 1.0 i.e. DyFeO3, the samples exhibits ferromagnetic nature. The variation of magnetization behaviour from paramagnetic to ferromagnetic in higher concentration of Fe explicit the feasibility of attaining ferroic behaviour in Garnet mixed phase ceramic compounds. The electric polarization analysis reveal that while substituting Fe3+ ion in Dy3+ site by more than 50% of molecular ratio, the compounds exhibits non-zero remanance and coercivity values with respect to applied d.c. electric field and evident peculiar ferroelectric characteristic of those compounds. The maximum saturation polarization achieved in Dy0.6Fe1.4O3 compound is 0.2 µC/cm2 and found comparable with the results observed from Bismuth Ferrite related compounds.
@article{Anbarasu2017,author={Anbarasu, V. and Dhilip, M. and Kumar, K. Saravana and Sivakumar, K.},doi={10.1007/s10854-017-6628-9},isbn={1085401766},issn={1573482X},issue={12},journal={Journal of Materials Science Materials in Electronics},pages={8976-8985},publisher={Springer US},title={Effect of trivalent transition metal ion substitution in multifunctional properties of Dy2O3 system},volume={28},year={2017},}
2016
J. Appl. Phy.
Room temperature dual ferroic behaviour of ball mill synthesized NdFeO3 orthoferrite
N. Aparnadevi, K. Saravana Kumar, M. Manikandan, and
2 more authors
Phase pure NdFeO3 has been achieved using high energy ball milling of oxide precursors with subsequent sintering. It is established that structural arrangement of NdFeO3 regulates the multifunctional feature of the material. Rietveld refinement of the room temperature X-ray diffraction pattern shows that the Fe-O-Fe bond angle significantly favors the super exchange interaction, which is predominantly antiferromagnetic in nature. Magnetization measurement illustrates antiferromagnetic behaviour with a weak ferromagnetic component caused by the canted nature of the Fe3+ spins at room temperature. Absorption bands in the visible ambit, apparent from the UV-Vis diffuse reflectance studies, is found due to the crystal ligand field of octahedral oxygen environment of Fe3+ ions. The direct band gap is estimated to be 2.39 eV from the diffuse reflectance spectrum. The lossy natured ferroelectric loop having a maximum polarization of 0.23 μC/cm2 at room temperature is found to be driven by the non-collinear magnetic structure with reverse Dzyaloshinskii-Moriya effect. Magnetic field has influence on the dielectric constant as evident from the impedance spectroscopy, indicating the strong coupling between ferroelectric and the magnetic structure of NdFeO3.
@article{Aparnadevi2016,author={Aparnadevi, N. and Kumar, K. Saravana and Manikandan, M. and Joseph, D. Paul and Venkateswaran, C.},doi={10.1063/1.4954842},issn={10897550},issue={3},journal={Journal of Applied Physics},pages={0-8},title={Room temperature dual ferroic behaviour of ball mill synthesized NdFeO3 orthoferrite},volume={120},url={http://dx.doi.org/10.1063/1.4954842},year={2016},}
2015
Pss(a). AMS.
Hopkinson effect and temperature-dependent dielectric properties of single domain SrFe12O19 particles
M. Manikandan, K. Saravana Kumar, N. Aparnadevi, and
1 more author
Physica Status Solidi (A) Applications and Materials Science Feb 2015
Strontium hexagonal ferrite particles having single domain nature were prepared by initial ball milling followed by sintering. Effect of the synthesis method on structural, magnetic, and electrical properties were analyzed using various characterization techniques. XRD pattern reveals the formation of hexagonal phase SrFe12O19. XPS study indicates the presence of Fe3+ in different crystallographic environments. SEM image suggests the size of particles in the range of single domain. VSM studies; M-H loop illustrates the ferrimagnetic nature and the initial magnetization behavior demonstrates the typical behavior of single domain particles. Temperature-dependent magnetization shows a Hopkinson peak before transition. Conductivity study shows two different conduction process with the activation energy values of 0.2 and 0.95 eV. The variation in the dielectric behavior with respect to frequency and temperature are explained using the grain-grain boundary and polarization contributions. The hard ferrimagnetism and good dielectric response renders this material suitable for magneto-electronic devices.
@article{Manikandan2015,author={Manikandan, M. and Kumar, K. Saravana and Aparnadevi, N. and Venkateswaran, C.},doi={10.1002/pssa.201532229},issn={18626319},issue={10},journal={Physica Status Solidi (A) Applications and Materials Science},keywords={Hopkinson effect,ferrimagnetism,hexagonal ferrite,semiconductivity},pages={2179-2185},title={Hopkinson effect and temperature-dependent dielectric properties of single domain SrFe12O19 particles},volume={212},year={2015},}
Mat. Res. Bull.
Structural, magnetic and electrical properties of BiFeO3 co-substituted with Pr-Mn
K. Saravana Kumar, J. Ayyappan, and C. Venkateswaran
Samples of stoichiometry Bi1 - xPrxFe1 - xMnxO3 (x = 0, 0.10, 0.15, 0.20) have been synthesized by solid-state reaction method. Fe is found to be in the mixed and single oxidation states for pure and substituted samples, respectively. Mn is in +3 state, as inferred from XPS. XRD analysis indicates the formation of stoichiometric phase with control over the Bi and Fe rich secondary phases. The x = 0.10 sample shows thermal stability and characteristic ferroelectric-paraelectric transitions are observed in all the samples, from the thermal studies. Effect of substitution on the grain size distribution is not observed in the SEM picture. Magnetization values from the hysteresis curves obtained at the maximum applied field, increases with substitution indicating the effect of Pr-Mn in BiFeO3. The substituted samples show different response in resistivity and dielectric behaviour than the pure sample, as understood from impedance spectroscopy data. Defects, and charge carriers resulting from Pr-Mn substitution are responsible for this change in conductivity.
@article{Kumar2015,author={Kumar, K. Saravana and Ayyappan, J. and Venkateswaran, C.},doi={10.1016/j.materresbull.2014.12.077},issn={00255408},journal={Materials Research Bulletin},keywords={A. Ceramics,B. Chemical synthesis,C. Photoelectron spectroscopy,C. XRD,D. Electrical properties,D. Magnetic properties},pages={224-230},publisher={Elsevier Ltd},title={Structural, magnetic and electrical properties of BiFeO3 co-substituted with Pr-Mn},volume={65},url={http://dx.doi.org/10.1016/j.materresbull.2014.12.077},year={2015},}
Sol. St. Sci.
Phase stabilization of Fe substituted NdMn2O5 ceramics and their properties
An oxide of stoichiometry, NdFeMnO5, has been synthesized using a two-step process. First the precursor oxides are high-energy ball milled and the as-milled powders are then sintered to obtain the NdFeMnO5 phase. Rietveld refinement of the XRD pattern, by replacing the Mn3+ sites with Fe3+, shows the formation of stoichiometric NdFeMnO5. Nd & Mn are found to be in +3 and +4 states, respectively from the XPS study. Agglomeration of fine grains is evident from the electron micrographs. Fe3+ has a magnetic moment higher than Mn3+, and hence affects the magnetic property. Thermo-magnetization measurements show the existence of magnetic ordering below 290 K. An increase in magnetization at low temperature is also observed due to ordering of R3+ moments in addition to Fe and Mn spin moments. A linear increase in conductivity and stable dielectric response is observed from impedance study at high temperature.
@article{SaravanaKumar2015a,author={Kumar, K. Saravana and Venkateswaran, C.},doi={10.1016/j.solidstatesciences.2015.05.003},issn={12932558},journal={Solid State Sciences},keywords={High-energy ball milling,Magnetic study,NdMn2O5,Spectroscopy,X-Ray Photoelectron},pages={1-6},publisher={Elsevier Masson SAS},title={Phase stabilization of Fe substituted NdMn2O5 ceramics and their properties},volume={46},url={http://dx.doi.org/10.1016/j.solidstatesciences.2015.05.003},year={2015},}
JMMM
Multiferroicity in polar phase LiNbO3 at room temperature
M. Manikandan, K. Saravana Kumar, N. Aparnadevi, and
2 more authors
Journal of Magnetism and Magnetic Materials Feb 2015
Abstract LiNbO3, prepared by ball milling assisted ceramic method, exhibits weak ferromagnetism and ferroelectricity at room temperature. X-ray diffraction pattern reveals the rhombohedral phase of LiNbO3 with hexagonal unit cell symmetry. The weak ferromagnetic behavior, obtained using VSM, has been explained using Dzyaloshinskii-Moriya interaction caused by the ferroelectric distortion in its magnetic order. The P-E loop measurement shows lossy natured ferroelectric loop. Electrical and dielectric properties analyzed using impedance spectroscopy show two thermally activated conduction processes, derived from the Arrhenius plot. A gradual increase in the dielectric constant below 493 K and a rapid increase above 493 K reveals the contribution of polarization components and Lithium ion hopping.
@article{Manikandan2015a,author={Manikandan, M. and Kumar, K. Saravana and Aparnadevi, N. and Shanker, N. Praveen and Venkateswaran, C.},doi={10.1016/j.jmmm.2015.04.099},issn={03048853},journal={Journal of Magnetism and Magnetic Materials},keywords={Ferroelectricity,Multiferroics,Weak ferromagnetism},pages={156-160},publisher={Elsevier},title={Multiferroicity in polar phase LiNbO3 at room temperature},volume={391},url={http://dx.doi.org/10.1016/j.jmmm.2015.04.099},year={2015},}
Tr. Ind. Ins. Met.
Phase Stabilization of Fe Substituted SmMn2O5 SmFeMnO5
K. Saravana Kumar, N. Aparnadevi, A. Muthukumaran, and
1 more author
Transactions of the Indian Institute of Metals Feb 2015
The SmFeMnO5 phase has been stabilized using mechanical milling and respective high temperature sintering of the oxides in stoichiometric ratio. The crystal structure is studied by Rietveld analysis of the X-ray diffraction data obtained at room temperature. Analysis is done by considering Fe3+ ions at the Mn3+ sites in the parent SmMn2O5 structure and the results indicate the formation of SmFeMnO5. A change in bond angles and bond distances is obtained due to the reduction in the percentage of Mn3+ Jahn–Teller ions. Isothermal magnetization study at room temperature reveal ferromagnetic nature of the material with a saturation magnetization of 6.57 emu/g. A linear decrease in resistivity with temperature is obtained and the activation energy is calculated from Arrhenius plot. Impedance studies show decrease in dielectric constant values with frequency and temperature due to Fe substitution in the SmMn2O5 structure.
@article{SaravanaKumar2015,author={Kumar, K. Saravana and Aparnadevi, N. and Muthukumaran, A. and Venkateswaran, C.},doi={10.1007/s12666-014-0501-9},issn={09751645},issue={5},journal={Transactions of the Indian Institute of Metals},keywords={Frustrated magnets,Impedance spectroscopy,Mechanical milling,Multiferroic,Rietveld refinement},pages={693-698},title={Phase Stabilization of Fe Substituted SmMn2O5 SmFeMnO5},volume={68},year={2015},}
IOP Conf. Ser.
Study on the properties of Fe-substituted NdMn2O5
K. Saravana Kumar, and C. Venkateswaran
IOP Conference Series Materials Science and Engineering Feb 2015
The oxide, NdFeMnO5, has been synthesized using a two-step synthesis process. First the precursor oxides are high-energy ball milled and the as-milled powders are then sintered to obtain the NdFeMnO5 phase. X-ray diffraction confirms phase formation and the calculated pattern is obtained by the substitution of Mn3+ sites by Fe3+ sites. Agglomeration of small sized grains is observed from the scanning electron microscopy images. Room temperature magnetization measurement shows a paramagnetic behaviour. A ferrimagnetic ordering is observed to be established below ∼110 K from the thermo-magnetization measurements.
@article{Kumar2015a,author={Kumar, K. Saravana and Venkateswaran, C.},doi={10.1088/1757-899X/73/1/012031},issn={1757899X},issue={1},journal={IOP Conference Series Materials Science and Engineering},pages={2-6},title={Study on the properties of Fe-substituted NdMn2O5},volume={73},year={2015},}
J. Appl. Phy.
Mn doping instigated multiferroicity and magneto-dielectric coupling in KNbO3
M. Manikandan, K. Saravana Kumar, and C. Venkateswaran
KNb1-xMnxO3 (0 ≤ x ≤ 0.07) samples were synthesized by a two-step process, ball milling of the precursors and then sintering subsequently. Mn doping at Nb site induces a weak ferromagnetism at room temperature and it has been explained with the help of bound magnetic polaron model. Magnetization values at 15 kOe initially increase followed by a decrease with increase in the Mn concentration. Two phase transitions - orthorhombic to tetragonal and tetragonal to cubic, above room temperature were analyzed from the differential scanning calorimetry and temperature dependent dielectric studies. It elucidates the effect of Mn concentration on phase transition temperatures. All the samples exhibit a peak behaviour in the dielectric constant Vs temperature plot at phase transition temperatures. The samples also exhibit leaky ferroelectric loops at room temperature. PUND measurement reveals the true ferroelectric polarization of the samples. The probable origin of magneto-dielectric effect is discussed based on the dielectric study in the presence of variable magnetic field at a frequency of 1 kHz.
@article{Manikandan2015b,author={Manikandan, M. and Kumar, K. Saravana and Venkateswaran, C.},doi={10.1063/1.4938118},issn={10897550},issue={23},journal={Journal of Applied Physics},pages={0-6},title={Mn doping instigated multiferroicity and magneto-dielectric coupling in KNbO3},volume={118},year={2015},}
2014
Dal. Trans.
Role of oxygen vacancy and Fe-O-Fe bond angle in compositional, magnetic, and dielectric relaxation on Eu-substituted BiFeO3 nanoparticles
A. Tamilselvan, S. Balakumar, M. Sakar, and
3 more authors
@article{Tamilselvan2014,author={Tamilselvan, A. and Balakumar, S. and Sakar, M. and Nayek, Chiranjib and Murugavel, P. and Kumar, K. Saravana},doi={10.1039/c3dt52260a},issn={14779234},issue={15},journal={Dalton Transactions},pages={5731-5738},title={Role of oxygen vacancy and Fe-O-Fe bond angle in compositional, magnetic, and dielectric relaxation on Eu-substituted BiFeO3 nanoparticles},volume={43},year={2014},}
JMMM
Magnetodielectric properties of CoFe2O4-BaTiO 3 core-shell nanocomposite
M. Malar Selvi, P. Manimuthu, K. Saravana Kumar, and
1 more author
Journal of Magnetism and Magnetic Materials Feb 2014
@article{Selvi2014,author={Selvi, M. Malar and Manimuthu, P. and Kumar, K. Saravana and Venkateswaran, C.},doi={10.1016/j.jmmm.2014.06.039},issn={03048853},journal={Journal of Magnetism and Magnetic Materials},keywords={Core-shell,Magnetocapacitance,Magnetoelectric coupling susceptibility,Magnetoimpedance,Nanocomposite},pages={155-161},publisher={Elsevier},title={Magnetodielectric properties of CoFe2O4-BaTiO 3 core-shell nanocomposite},volume={369},url={http://dx.doi.org/10.1016/j.jmmm.2014.06.039},year={2014},}
JMMM
Effect of Tb-Mn substitution on the magnetic and electrical properties of BiFeO3 ceramics
K. Saravana Kumar, P. Aswini, and C. Venkateswaran
Journal of Magnetism and Magnetic Materials Feb 2014
@article{SaravanaKumar2014,author={Kumar, K. Saravana and Aswini, P. and Venkateswaran, C.},doi={10.1016/j.jmmm.2014.04.008},issn={03048853},journal={Journal of Magnetism and Magnetic Materials},keywords={Impedance spectroscopy,Magnetic study,X-ray photoelectron spectroscopy},pages={60-67},publisher={Elsevier},title={Effect of Tb-Mn substitution on the magnetic and electrical properties of BiFeO3 ceramics},volume={364},url={http://dx.doi.org/10.1016/j.jmmm.2014.04.008},year={2014},}
Phys. B Con. Mat.
A simple experimental setup for magneto-dielectric measurements
P. Manimuthu, N. Praveen Shanker, K. Saravana Kumar, and
1 more author
@article{Manimuthu2014,author={Manimuthu, P. and Shanker, N. Praveen and Kumar, K. Saravana and Venkateswaran, C.},doi={10.1016/j.physb.2014.03.051},issn={09214526},journal={Physica B Condensed Matter},keywords={Connector setup,Impedance analyzer,Magneto-dielectric,Multiferroic,Vibrating sample magnetometer},pages={354-355},publisher={Elsevier},title={A simple experimental setup for magneto-dielectric measurements},volume={448},url={http://dx.doi.org/10.1016/j.physb.2014.03.051},year={2014},}
IJESRT
A New Approach towards Gas Sensing through A.C. Conductivity of Tin Oxide-Copper Oxide Composite
Alison Christina Fernandez, P Sakthivel, K. Saravana Kumar, and
1 more author
International Journal of Engineering Sciences & Research Technology Feb 2014
Tin oxide-Copper oxide composites were synthesized by a hydrothermal method using tin chloride dihydrate and copper nitrate trihydrate as precursors in different molar ratios. The obtained powders were characterized by X-ray diffraction and dielectric analysis. The average crystallite sizes were determined. The analysis exhibited a tetragonal phase for tin oxide and cubic phase for copper oxide. The microstructure of the composites were examined by the scanning electron microscopy. Optical properties were investigated by a UV-Vis absorption spectrophotometer. Good electrical response of the composites to cigarette smoke was observed in dielectric analysis, holding substantial promise for SnO2-CuO as a challenging material for novel sensing applications.
@article{Fernandez2014,author={Fernandez, Alison Christina and Sakthivel, P and Kumar, K. Saravana and Jesudurai, Joe},issn={2277-9655},issue={8},journal={International Journal of Engineering Sciences & Research Technology},keywords={ACConductivity,Cigarette smoke,composite,hydrothermal,morphology},pages={324-338},title={A New Approach towards Gas Sensing through A.C. Conductivity of Tin Oxide-Copper Oxide Composite},volume={3449},url={http://www.ijesrt.com},year={2014},}
2012
J. Phy. D Ap. Phy.
Mechanical milling assisted synthesis of Ba-Mn co-substituted BiFeO 3 ceramics and their properties
K. Saravana Kumar, C. Venkateswaran, D. Kannan, and
2 more authors
@article{SaravanaKumar2012,author={Kumar, K. Saravana and Venkateswaran, C. and Kannan, D. and Tiwari, Brajesh and Rao, M. S. Ramachandra},doi={10.1088/0022-3727/45/41/415302},issn={00223727},issue={41},journal={Journal of Physics D Applied Physics},title={Mechanical milling assisted synthesis of Ba-Mn co-substituted BiFeO 3 ceramics and their properties},volume={45},year={2012},}
AIP Conf. Proc.
Synthesis and study of Bi0.9Tb0.1Fe 0.9Mn0.1O3 ceramics
@article{Kumar2012,author={Kumar, K. Saravana and Venkateswaran, C.},doi={10.1063/1.4710403},isbn={9780735410442},issn={0094243X},issue={1},journal={AIP Conference Proceedings},keywords={BiFeO3,Electron Microscopy,High-Energy Ball Milling,Magnetic Material,Multiferroics},pages={1125-1126},title={Synthesis and study of Bi0.9Tb0.1Fe 0.9Mn0.1O3 ceramics},volume={1447},year={2012},}
2011
J. Phy. D Ap. Phy.
Effect of Fe substitution on the magnetic properties of BiMn 2O5
@article{Kumar2011a,author={Kumar, K. Saravana and Venkateswaran, C.},doi={10.1088/0022-3727/44/32/325001},issn={00223727},issue={32},journal={Journal of Physics D Applied Physics},title={Effect of Fe substitution on the magnetic properties of BiMn 2O5},volume={44},year={2011},}
Tr. Ind. Ins. Met.
Structural and magnetic properties of Bi0.7Gd 0.3FeO3 ceramics
K. Saravana Kumar, and C. Venkateswaran
Transactions of the Indian Institute of Metals Feb 2011
@article{SaravanaKumar2011,author={Kumar, K. Saravana and Venkateswaran, C.},doi={10.1007/s12666-011-0048-y},issn={09722815},issue={1-2},journal={Transactions of the Indian Institute of Metals},keywords={BiFeO3,high-energy ball milling,magnetization study,magnetoelectric,multiferroic,thermal study},pages={241-243},title={Structural and magnetic properties of Bi0.7Gd 0.3FeO3 ceramics},volume={64},year={2011},}
AIP Conf. Proc.
Synthesis and characterization of BiMn2O5 ceramics
K. Saravana Kumar, D. Paul Joseph, S. Philip Raja, and
2 more authors
@article{Kumar2011,author={Kumar, K. Saravana and Joseph, D. Paul and Raja, S. Philip and Manimuthu, P. and Venkateswaran, C.},doi={10.1063/1.3606273},isbn={9780735409057},issn={0094243X},issue={PART A},journal={AIP Conference Proceedings},keywords={BiMn2O5,High Energy Ball Milling,Magnetic studies,Multiferroics},pages={1155-1156},title={Synthesis and characterization of BiMn2O5 ceramics},volume={1349},year={2011},}