Dr. G. Gowri, Assistant Professor, Research Centre and PG Department of Physics,
The Madura College, Madurai- 625 011
Mobile: 99445 68916,
Email: [email protected]
Ph.D. topic:
Synthesis, characterization and charge density of multiferroic materials
Date of Registration : 19/12/2015 Registration no. : P4287 Date of Colloquium Presentation : 13/05/2021 Date of Thesis submission : 01/07/2021 Date of viva voce examination : 09/01/2023 Date of Convocation : 26/10/2023
About the research work:
The research work focuses on the Synthesis, characterization and charge density of multiferroic material. Since the magnetic and electric properties coexist in the multiferroic material, it will be of interest to synthesis and characterize it. The structural, optical, magnetic and the electric properties of the multiferroic material can be altered by doping divalent or trivalent or tetravalent ions at the host lattice site.
The pure and doped LaFeO3 multiferroic materials such as i) La1-xAlxFeO3 ii) La1-xCexFeO3 iii) La1-xSrxFeO3 have been synthesized through high temperature solid state reaction method and La1-xZnxFeO3 has been synthesized by chemical co-precipitation method.
Characterization techniques such as, powder X-ray diffraction (PXRD), Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), UV-Vis spectra and dielectric measurement have been used to analyze the effect of various dopants (Zn2+, Sr2+, Al3+, and Ce4+) on structural, surface morphological, elemental composition, optical and polarization properties. The structural analysis has been done through Rietveld refinement process using JANA2006 software. The charge density and interatomic bonding analysis in the unit cell have been investigated through high resolution maximum entropy method (MEM) by employing the softwares PRIMA and VESTA. The magnetic and electric properties have been investigated by recording the magnetization–magnetic field (M-H) hysteresis loop and the polarization–electric field (P–E) hysteresis loop, using VSM and P-E loop tracer. The optical behavior, polarization behavior, magnetic ordering and electric ordering have been correlated separately with the experimental charge densities which have not been done so far.
Multiferroic materials:
The coexisting states of coupled magnetic and ferroelectric ordering in multiferroic materials makes them interesting for the researchers. The material lanthanum orthoferrite (LaFeO3) is one of the most important multiferroic material due to the simultaneous presence of coupled (ferro/antiferro) magnetic and (ferro/antiferro) electric ordering in that system. LaFeO3 is a ABO3 – typed perovskite like structure, which crystallizes in an orthorhombic phase at room temperature. The perovskite oxide LaFeO3 is known to be a canted G-type wide-gap antiferromagnetic insulator at room temperature with high Néel temperature (TN~740°C). In LaFeO3, La3+ ions are at the corners of the unit cell and the Fe3+ ion lies at the centre of octahedron formed by six O2- ions.
The structure, size, physical and chemical properties of LaFeO3 are strongly influenced by the choice of synthesis method along with the substitution of divalent or trivalent or tetravalent ions at the La site of host lattice in LaFeO3. Since LaFeO3 exhibits significant physical and chemical properties, it is of great importance to be used in many branches of modern technologies such as solid oxide fuel cells, photocatalyst, chemical sensors, non-volatile magnetic memory devices, ultrasensitive magnetic read heads of modern hard disk drives, novel spintronic devices, and multistate memories etc.,. To understand the physical and chemical properties of LaFeO3, the electronic distribution and the nature of chemical bonding between the atoms in the unit cell are essential. Therefore, this research work is aimed at synthesis, characterization and charge density distribution analysis of pure and doped LaFeO3 multiferroic materials such as i) La1-xAlxFeO3 ii) La1-xCexFeO3 iii) La1-xSrxFeO3 and iv) La1-xZnxFeO3 . The multiferroics La1-xAlxFeO3, La1-xCexFeO3, La1-xSrxFeO3 have been synthesized through high temperature solid state reaction method and La1-xZnxFeO3 has been synthesized by chemical co-precipitation method.
The structural analysis of the synthesized multiferroics has been done through Rietveld refinement process using JANA2006 software. The charge density and interatomic bonding analysis have been done through high resolution maximum entropy method (MEM) by employing the softwares PRIMA and VESTA. The optical behaviour, polarization behaviour, magnetic ordering and electric ordering have been correlated separately with the experimental charge densities which have not been done so far.
Materials of Interest:
Ceramic materials, multiferroic materials, dielectric and magnetic materials
La1-xCexFeO3 (x=0.00, 03, 0.06, 0.09 and 0.12) (LCFO)
La1-xZnxFeO3 (x=0.00, 0.05, 0.15 and 0.25) (LZFO)
La1-xAlxFeO3 (x=0.05, 0.15 and 0.25) (LAFO)
La1-xSrxFeO3 (x= 0.05, 0.10, 0.15 and 0.20) (LSFO)
List of Publications: 1. Charge Density of Al Doped Lanthanum Orthoferrites, Novel Ceramic materials R. Saravanan, G. Gowri Materials Research Forum, LLC, Materials Research Foundation, USA, Chapter 9, Vol. 2, 108 - 127, (2016), ISBN : 978-1-945291-02-9. 2. Bonding in La0.9Zn0.1FeO3 multiferroic material, Contemporary dielectric materials G. Gowri, R. Saravanan, R. Pradeepa, M. Raja Rajeswari, K. Abirami Materials Research Forum, LLC, Materials Research Foundations, USA, Chapter 6, Vol.7, 63-78, (2017), ISBN: 978-1-945291-12-8. 3. Interatomic bonding and charge ordering in superpramagnetic La0.8Zn0.2FeO3 multiferroic G. Gowri, R. Saravanan International Journal of Latest Trends in Engineering and Technology, Special Issue - International Conference on Nanotechnology: The Fruition of Science-2017, pp.144-150, (2017). 4. Exchange bias effect, ferroelectric property, primary bonding and charge density analysis in La1-xCexFeO3 multiferroics G.Gowri, R.Saravanan, S.Sasikumar, I.B.ShameemBanu Materials Research Bulletin, 118, 110512, (2019) MRB - 2019 (Materials Research Bulletin - Info) (Impact Factor = 4.091) 5. Interatomic chemical bonding and charge correlation of optical, magnetic and dielectric properties of La1-xSrxFeO3 multiferroics synthesized by solid state reaction method G.Gowri, R.Saravanan, S.Sasikumar, M.Nandhakumar, R.Ragasudha Journal of Materials Science : Materials in Electronics, 30, 4409-4426, (2019) JMSE - 2019 (Journal of Materials Science : Materials in Electronics - Info) (Impact Factor = 2.195) 6. Investigation on interatomic chemical bonding and charge-related optical, multiferroic properties of La1−xZnxFeO3 bulk ceramics. G.Gowri, R.Saravanan, N.Srinivasan, O.V.Saravanan, S.Sonai Materials Chemistry and Physics (Elsevier), 267, 124652 (2021) (https://doi.org/10.1016/j.matchemphys.2021.124652) (Impact Factor = 3.408) 7. Probing the effects of Al dopant over the structure and charge-related optical, magnetic, and electrical properties of Al3+-doped LaFeO3 bulk multiferroic materials G.Gowri, R.Saravanan, N.Srinivasan, K.Karunya, P.Jeyasheela, M.Uthra Chemical Papers (Springer) (Accepted - In Press) (2021) https://doi.org/10.1007/s11696-021-01672-1 (Impact Factor = 1.680) Colloquium (Viva-Voce Video link) Viva Photos
