Browsing by Author "Navneet Yadav"

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The emergence of Griffiths phase in CaCu3Ti(4−x)Mn xO12 (CCTMO, x = 1, 2 and 3) geometrically frustrated antiferromagnetic complexes perovskite
(Springer, 2024) Vinod Kumar; Anup Kumar; Shruti Singh; Krishna Kumar; Manish Kumar Verma; Vishnu Shankar Rai; Gurudeo Nirala; Shail Upadhyay; Navneet Yadav; N.B. Singh; Dhanesh Tiwary; K.D. Mandal
In this work, we have reported the rare coexistence of a Griffiths phase (GP) in a complex perovskite oxide with geometrically frustrated antiferromagnetism. We have achieved this by substituting Manganese (Mn) in the titanium site of CaCu3Ti(4−x)MnxO12 (CCTMO, x = 1, 2 and 3). The occurrence of a Griffiths phase is observed when a strong contest between antiferromagnetic transition (TN) and paramagnetic (PM) occurs in the magnetic domain. As we increased the molar concentration of Manganese while substituting at titanium site in CaCu3Ti4O12, we observed the appearance of a step-like Griffiths phase. Manganese (Mn)-substituted materials exhibit paramagnetic (PM) to ferromagnetic (FM) phase transitions below CaCu3Ti3Mn1O12 (CCTM1O), CaCu3Ti2Mn2O12 (CCTM2O), and CaCu3Ti1Mn3O12 (CCTM3O), marked by a rapid step-like change in the magnetic moment due to spin ordering. The deviation of inverse magnetic susceptibility (χ−1) from Curie–Weiss behavior occurs in the temperature ranges of 75 to 190 K, 80 to 200 K, and 150 to 280 K, respectively. The emergence of the Griffiths phase before the actual PM–FM transition indicates that the inhomogeneous phase above the Curie temperature (T C), which can be defined as a Griffiths phase, is dominated by ferromagnetic interactions rather than antiferromagnetic ones. The presence of a Griffiths-like phase beyond its Curie temperature (T C) is indicated by low-field DC magnetization of the nanostructures, showing abnormal magnetic behavior. The presence of short-range magnetic correlations and ferromagnetic clusters in the system due to the size decrease is linked to this unexpected behaviour. © 2024, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
Trimetallic Au/Pt/Ag based nanofluid for enhanced antibacterial response
(Elsevier Ltd, 2018) Navneet Yadav; Aashit Kumar Jaiswal; Kajal Kumar Dey; Virendra Bahadur Yadav; Gopal Nath; Avanish Kumar Srivastava; Raja Ram Yadav
The antimicrobial activity of trimetallic Au/Pt/Ag nanoparticle based nanofluids were studied and compared with that of monometallic Au and bimetallic Au/Pt nanofluid. The trimetallic nanofluid was prepared by green microwave assisted successive chemical reduction method and characterized by UV–Vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The metallic nanofluids were tested for antibacterial properties using agar disc diffusion test method against various micro-organisms and their minimum inhibitory concentration (MIC) values were calculated. The trimetallic nanofluid exhibited efficient antibacterial activity and were found to be better agent than bimetallic and single metallic nanofluid at a very low metal concentration. These results of trimetallic nanofluids may be utilized in the field of many applications such as medical research, pharmaceutical industries and environmental sciences. © 2018 Elsevier B.V.