Shyam Singh Thakur

Bio: Shyam Singh Thakur is an academic researcher from Government Post Graduate College. The author has contributed to research in topics: Crystallite & Coercivity. The author has an hindex of 3, co-authored 3 publications receiving 62 citations.

Investigation of structural, optical, magnetic and electrical properties of tungsten doped NiZn nano-ferrites

Abstract: Tungsten substituted nickel-zinc ferrite nanoparticles with chemical composition of Ni0.5Zn0.5WxFe2-xO4 (x = 0.0, 0.2, 0.4, 0.6, 0.8 & 1.0) were successfully synthesized by a chemical co-precipitation method. The prepared ferrites were pre sintered at 850 °C and then annealed at 1000 °C in a muffle furnace for 3 h each. This sintered powder was inspected by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and vibrating sample magnetometer (VSM) to study the structural, optical, and magnetic properties. XRD measurement revealed the phase purity of all the nanoferrite samples with cubic spinel structure. The estimated crystallite size by X-ray line broadening is found in the range of 49–62 nm. FTIR spectra of all the samples have observed two prominent absorption bands in the range 400–700 cm−1 arising due to tetrahedral and octahedral stretching vibrations. Vibrating sample magnetometer experiments showed that the saturation magnetizations ( M S ) decreased with an increase in non-magnetic tungsten ion doping. The electrical resistivity of tungsten doped Ni Zn nano ferrites were examined extensively as a function of temperature. With an increase in tungsten composition, resistivity was found to decrease from 2.2 × 105 Ω cm to 1.9 × 105 Ω cm which indicates the semiconducting behavior of the ferrite samples. The activation energy also decreased from 0.0264 to 0.0221 eV at x = 0.0 to x = 1.0. These low coercive field tungsten doped Ni Zn ferrites are suitable for hyperthermia and sensor applications. These observations are explained in detail on the basis of various models and theories.

Synthesis of barium ferrite nanoparticles using rhizome extract of Acorus Calamus: Characterization and its efficacy against different plant phytopathogenic fungi

Abstract: A green technology for producing barium ferrite (BaFe12O19) nanoparticles (BFNP’s) using Acorus Calamus rhizome extract was realized. To confirm the phase of magnetoplumbite structure without any impurities, the method of powder X-ray diffraction was performed using the Rietveld analysis and the FullProf program with the P63/mmc (No. 194) space group. Unit cell parameters were a = 5.8902(2) A and c = 23.2103(7) A. According to Scherrer’s calculations, the average crystallite size was from ∼ 32 to ∼ 35 nm. The results of scanning electron microscopy confirmed that synthesized BFNP’s are tightly packed and have an average grain size of ∼ 70 nm. Raman and IR active modes predicted by group theory are observed at ∼ 175 cm−1 and ∼ 677 cm−1, which corresponds to the presence of a spinel structure and trigonal pyramidal position in barium hexaferrite. It was established that the spontaneous magnetization is ∼ 52 emu/g and coercive force is ∼ 440 mT at room temperature. In vitro studies were performed to evaluate the antifungal activity of BFNP’s against various plant pathogenic fungi, namely: Fusarium oxysporum, Alternaria alternata, Colletotrichum gloeosporioides and Marssonina rosae. The antifungal effect of BFNPs was determined for different phytopathogenic fungi at a multiple dose of 200 mg/L, 300 mg/L, 400 mg/L, 500 mg/L and 600 mg/L. The maximum inhibition of mycelial growth (76.67%) was detected at 600 mg/L against the growth of Fusarium oxysoporum mycelium. The data obtained show that BFNP’s synthesized using Acorus Calamus rhizome extract can be applied as a potential antifungal agent.

Nanomaterial Fungicides: In Vitro and In Vivo Antimycotic Activity of Cobalt and Nickel Nanoferrites on Phytopathogenic Fungi

Abstract: Recent advances in engineering lead to the fabrication of nanomaterials with unique properties targeted toward specific applications. The use of nanotechnology in agriculture, in particular for plant protection and production, is an under-explored area in the research community. Fungal diseases are one of the leading causes of crop destruction and, in this context, the antifungal effect of nanoparticles of cobalt and nickel ferrite against phytopathogenic fungi is reported here. As a proof of concept, it is also shown how such nanoparticles can be used as fungicides in plants. The developed cobalt and nickel ferrite nanoparticles (CoFe2O4 and NiFe2O4) are successfully tested for antimycotic activity against three plant-pathogenic fungi: Fusarium oxysporum, Colletotrichum gloeosporioides, and Dematophora necatrix. In addition, it is also observed that these ferrite nanoparticles reduce the incidence of Fusarium wilt in capsicum. The study suggests that nanoparticles of CoFe2O4 and NiFe2O4 can be used as an effective fungicide in plant disease management.