D GURUVAMMAL
@mdthinducollege.org
Assistant professor and Physics
The Madurai Diraviyam Thayumanavar Hindu College, Tirunelveli, Tamil Nadu, India
i have been working as a assistant professor of Physics in The Madurai Diraviyam Thayumanavar Hindu College, Tirunelveli, Tamil Nadu, India for last 14 years.
EDUCATION
i had completed M.Phil in physics at 2003 in Manonmaniam sundaranar University, Tirunelveli, Tamil Nadu, India. i have submitted my Ph.D thesis entitled "synthesis and characterization of II-VI semiconductor nanocrystals" to Manonmaniam sundaranar University, Tirunelveli, Tamil Nadu, India.
RESEARCH INTERESTS
Nanoscience, Nanotechnology, Crystal growth, Metal Oxides
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
D. Guruvammal, S. Selvaraj, and S. Meenakshi Sundar
Springer Science and Business Media LLC
Abstract.This paper presents the influence of replacing divalent Zn2+ ions of the ZnO by trivalent Cr3+ ions on their structural, optical and magnetic properties. Samples of Zn1-xCrxO (where $ x=0.001$x=0.001-0.004) are synthesized using the microwave irradiated solvothermal method. The X-ray diffraction pattern confirms the single-phase wurtzite hexagonal structure of ZnO nanoparticles and the average size of the samples is found to be 10.3-19nm. The morphology and chemical composition of the samples are found out using Scanning electron microscopy with energy dispersive X-ray analysis. Transmission electron microscopy results show the formation of quasi-hexagonal nanoparticles whereas Fourier transform infrared spectroscopy studies identify the presence of a functional group in the samples. The ultra-violet-visible spectrum shows a blue shift in the absorption edge. The presence of oxygen related defects in the samples is confirmed by photoluminescence spectroscopy studies. Defect related bands are identified from the value of Lande splitting factor “g ” with the help of electron spin resonance spectroscopy studies. Vibrating sample magnetometer studies exhibit room temperature ferromagnetic properties for all samples. Due to the existence of oxygen-related defects, the saturation magnetization increases with increasing in Cr concentrations.
D. Guruvammal, S. Selvaraj, and S. Meenakshi Sundar
Elsevier BV
Abstract Microwave irradiation method is employed to synthesis of Zn1−xCoxO (x = 0.001–0.004) nanoparticles and investigate their structural, optical and magnetic properties using various characterization techniques. Structural studies reveal single phase hexagonal structure with average crystallite size 18–28 nm. FTIR study identifies the functional group present in the samples. The incorporation of Co2+ ions into the ZnO lattice is confirmed through XRD and UV–Vis studies. PL spectra exhibit a strong emission peak in UV region and a defect related visible emission peak in orange red region. These peaks are attributed to near band edge emission and the presence of oxygen related defects in the samples respectively. The blue shift observed in the UV emission peak shows an increase in the carrier concentration caused by the interstitial incorporation of ions into the ZnO lattice. The oxygen related defect is also confirmed through a peak obtained around g factor 1.9933 in ESR studies. Further, the number of spin contributing the ESR signal demonstrates the dependence of the strength of ferromagnetism on the concentration of oxygen ion vacancies. The VSM, ESR and PL measurements confirm the origin of RTFM of Co doped ZnO nanoparticles from the exchange interaction between the localized spin moments resulting from oxygen vacancies. The reason for the obtained super paramagnetic nature for x = 0.002 and x = 0.003 may be either due to some of nanoparticles or due to the weakly coupled Co ions in the Zn2+ site in the ZnO lattice. Further, the ferromagnetic behavior arises again for x = 0.004 due to the incorporation of Co2+ ions in the interstitial positions.
D. Guruvammal, S. Selvaraj, and S. Meenakshi Sundar
Elsevier BV
Abstract In this paper, the effect of nickel doping on structural, optical and magnetic properties of ZnO: Ni particles synthesized by solvothermal route using microwave oven is investigated. XRD, SEM with EDAX, TEM and FTIR spectroscopy studies confirm the existence of single phase hexagonal wurtzite structure. UV–Vis spectroscopy shows a shift in band edge towards lower energy. PL spectroscopy measurements illustrate UV emission centered at 390 nm and red emission at 626 nm due to the near-band-edge (NBE) emission and defect related emission of ZnO respectively. VSM studies reveal that the super exchange interaction between the neighboring Ni2+ with Ni2+ ions is responsible for room temperature ferromagnetic behavior in our samples.