Browsing by Author "Manish Kumar Verma"

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Dielectric and electrical properties measurement of BCTO and Co & V-doped BCTO synthesized via semi-wet route method
(Springer, 2023) Anup Kumar; Vinod Kumar; Manish Kumar Verma; Vishnu Shankar Rai; Dinesh Prajapati; Biswajit Jena; Dipendra Kumar Verma; Poonam Kumari; D. Tiwary; K.D. Mandal
Bi2/3Cu3Ti4O12 (BCTO) and Bi2/3Cu3Ti3.95Co0.025V0.025O12 (BCTCVO) Ceramic was synthesized by using a cost-effective novel semi-wet route method. The phase formation was confirmed by XRD analysis with traces of TiO2 and CuO phases of BCTO and BCTCVO ceramic. The average crystallite sizes of BCTO and BCTCVO ceramic were found to be 40.49 and 39.72 nm, respectively. XPS studies confirm the oxidation state of each elements in appropriate oxidation state. Elemental analysis was performed by EDS. It was observed that the maximum dielectric constant values of BCTO and BCTCVO ceramic were 3372 and 1663 at 523 K and at 1 kHz. The value of dielectric constant was observed very low at higher frequency. Tangent loss values of BCTO and BCTCVO ceramic were found 3.67 and 2.39 at 523 K and 1 kHz, respectively. © 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
Emergence of Dielectric Properties by Doping of Semi-Transition Metal in Semiconductor Complex Perovskite Oxide
(John Wiley and Sons Inc, 2023) Vishnu Shankar Rai; Dinesh Prajapati; Manish Kumar Verma; Vinod Kumar; Atendra Kumar; Tapas Das; Kedar Sahoo; Narsingh Bahadur Singh; Kamdeo Mandal
The effect of zinc substitution at the Cu2+ site and germanium substitution at the Ti4+ site in bismuth copper titanate, Bi2/3Cu3Ti4O12, is investigated. Composition with x = 0.05 is synthesized by semi-wet route in the system Bi2/3Cu3Ti4−xGexO12 (BCTGO) and Bi2/3Cu3−xZnxTi4−xGexO12 (BCZTGO) that are sintered at 1123 K for 8 h. Crystal structure has remained cubic. The phase formations of these ceramics are confirmed by the X-ray diffraction. The microstructural analysis of the samples is done by scanning electron microscopy and tunneling electron microscopy. Elemental analysis is performed by energy dispersive X-ray spectroscopy. X-ray photoelectron spectroscopy suggests that all elements present in these ceramics are in proper oxidation states. The dielectric constant is found high for BCTGO-0.05 ceramic. The specific capacitances of BCTGO-0.05 and BCZTGO-0.05 are found to be 13.05 and 15.7 F g−1, respectively. Optical band gap values (Eg) of BCTGO-0.05 and BCZTGO-0.05 ceramics are found as 1.77 and 1.91 eV. © 2023 Wiley-VCH GmbH.
Studies of multifunctional Bi12GeO20 compound synthesized by chemical route
(SPIE, 2024) Anup Kumar; Manish Kumar Verma; Biswajeet Jena; Dhanesh Tiwary N.B. Singh; K.D. Mandal
Increasing water pollution poses a serious threat to both humankind and animals in the current situation. Low cost optical especially photocatalytic material is of utmost relevance to improve situation and meet the global energy demand with little environmental damage. The aim of this study is to develop low-cost low temperature reproducible method to synthesize multifunctional material suitable for degradation of a very dangerous water contaminant dye under visible light exposure. A semiwet chemical route was used to synthesize a multifunctional Bi12GeO20 compound suitable for photocatalytic activity for the degradation of Rhodamine B (RhB) dye under visible light exposure. Bi12GeO20 (BGO) ceramic with polycrystalline structure was prepared successfully e using a low temperature chemical process. X-ray powder diffraction reveals that single-phase BGO ceramic was formed. Nanosized BGO ceramic particles that had been stabilized, XRD and TEM to showed particle sizes in the 60-10 nm range. Due to the favorable band gap (2.72 eV) and the sillenite type Bi12GeO20 exhibits strong photocatalytic activity for the degradation of Rhodamine B (RhB) dye under visible light exposure. © 2024 SPIE.
The Effect of Rare Earth Metal Doping in Bi2/3Cu3Ti4O12 Ceramic on Microstructure, Dielectric and Electrical Properties
(Korean Institute of Electrical and Electronic Material Engineers, 2023) Dinesh Prajapati; Vishnu Shankar Rai; Vinod Kumar; Manish Kumar Verma; Atendra Kumar; N.B. Singh; K.D. Mandal
An Aurivillius oxide, Bi(2/3)-xGdxCu3Ti4O12 (x = 0.05, 0.10, and 0.20) ceramic designated as BGCTO-0.05, BGCTO-0.1 and BGCTO-0.2 has been fabricated by modified solid-state route resemble with semi wet route and characterized by using various techniques including XRD, SEM, EDX, TEM and XPS for getting information about phase formation, morphology, particle size distribution and oxidation state of elements of synthesized ceramics. X-ray diffraction pattern confirmed the single-phase formation of BGCTO ceramic. The crystalline nature of BGCTO ceramic for few selected compositions, x = 0.05, 0.10, and 0.20 were observed by TEM analysis. Further, particle size was determined with the help of Image J software and found to be 90.85 ± 5 nm, 75.35 ± 5 nm and 72.43 ± 5 nm, respectively for BGCTO-0.05, BGCTO-0.1 and BGCTO-0.2 ceramic. The dielectric permittivity (εr) as well as tangent loss (tan δ) was observed at room temperature and 1 kHz for all synthesized ceramics. The electrical behaviour of BGCTO ceramic revealed the presence of semiconducting grain separated by grain boundaries. © 2023, The Korean Institute of Electrical and Electronic Material Engineers.
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.