Browsing by Author "Akanksha Maurya"
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PublicationArticle Depth exploration of gadolinium-modified bismuth iron titanate: A comprehensive investigation(Elsevier B.V., 2025) Sushil Joshi; Alok Shukla; Nitin Suresh Kumar; Akanksha Maurya; Ram Naresh Prasad ChoudharyThis study discusses the structural, dielectric, electrical, and magnetic response of gadolinium-doped bismuth iron titanate Bi0.85Gd0.15Fe0.5Ti0.5O3. It is synthesized by a high-temperature solid-state reaction method. XRD analysis shows the multiphase nature of the material consisting of three-phase symmetry, i.e., orthorhombic, cubic, and tetragonal. SEM (Scanning electron microscopy) analysis confirms a polycrystalline microstructure with a 5–6 µm average grain size, while EDX (Energy-dispersive X-ray spectroscopy) validates the stoichiometric presence of Bi, Gd, Fe, Ti, and O with appropriate atomic percentages. The dielectric studies demonstrate frequency-dependent behavior dominated by Maxwell-Wagner polarization and space charge effects, with the dielectric constant (εᵣ) decreasing with frequency and increasing with temperature. Impedance spectroscopy reveals non-Debye relaxation and contributions from grain and grain boundaries, supported by Nyquist plots and equivalent circuit modeling. AC conductivity follows Jonscher's power law and indicates that the material follows correlated barrier hopping (CBH) conduction mechanism. Magnetic measurement shows the small ferromagnetic behavior with Mr = 9.85 E-3 emu/g. Based on the compound electrical and magnetic properties; it can be used for various applications in multifunctional devices. © 2025 The AuthorsPublicationArticle Enhanced red emission from Eu3+, A+ (Li+, Na+, K+) co-doped CaZrO3 phosphor(Elsevier B.V., 2018) Akanksha Maurya; A. Bahadur; S.B. RaiThis paper reports the enhanced photoluminescence from Eu3+, A+ (Li+, Na+, K+) co-doped CaZrO3 phosphors synthesized through solid state reaction method. The X-ray diffraction (XRD) measurement reveals the orthorhombic phase of CaZrO3 crystal. The scanning electron micrographs (SEM) show that the shape of the particle is converted from polyhedron to cubic on co-doping of alkali ions. All the phosphors emit intense red emission at 613 nm corresponding to 5D0→7F2 transition of Eu3+ ion under the excitation with 266, 280, 355 and 395 nm wavelengths. The alkali ions enhance the emission intensity of Eu3+: CaZrO3 phosphor due to increase in the asymmetry in the crystal field and charge compensation. The optical band gap of Eu3+: CaZrO3 phosphor decreases and the lifetime of 5D0 level of Eu3+ ion increases in the presence of alkali ions. This material can be a potential red emitting phosphor for UV-based white LED and other display devices. © 2018 Elsevier B.V.PublicationArticle Enhanced upconversion and downshifting emissions from Tb3+, Yb3+ co-doped CaZrO3 phosphor in presence of Li+ ions(IOP Publishing Ltd, 2019) Akanksha Maurya; Amresh Bahadur; Shyam Bahadur RaiThis paper reports the enhanced green photoluminescence from Tb3+, Yb3+ co-doped CaZrO3 phosphor in the presence of Li+ ion synthesized through solid state reaction technique. The structural studies show an increase in the particle size and a shrink in crystal lattice due to Li+ co-doping in the phosphor. The phosphor sample emits intense green upconversion emission (UC) due to Tb3+ ions on excitation with 980 nm radiation which is further enhanced ∼28 times on Li+ co-doping. The lifetime of 5D4 level of Tb3+ ion decreases in the presence of Li+ ions due to increase in asymmetry in crystal field. The downshifting (DS) emission intensity monitored on 378 and 487 nm excitations is also enhanced in the presence of Li+ ions. Thus, the Tb3+, Yb3+, Li+ co-doped CaZrO3 phosphor can be a suitable candidate for UC solid state lighting. © 2018 IOP Publishing Ltd.PublicationArticle Enhanced upconversion and downshifting emissions from Tm3+, Yb3+ co-doped CaZrO3 phosphor in the presence of alkali ions (Li+, Na+ and K+)(Elsevier Ltd, 2019) Akanksha Maurya; A. Dwivedi; A. Bahadur; S.B. RaiThe Tm3+, Yb3+ co-doped CaZrO3 phosphor samples have been synthesized through solid state reaction method in the absence and presence of alkali metal ions (i.e. Li+, Na+, K+). The X-ray diffraction (XRD) study shows the formation of CaZrO3 crystal with orthorhombic phase. The Tm3+, Yb3+ co-doped CaZrO3 phosphor emits intense upconversion emission in blue (474 nm) and NIR (799 nm) regions due to 1G4 → 3H6 and 3H4 → 3H6 transitions of Tm3+ ions, respectively on excitation with 980 nm radiation. The emission intensity is significantly enhanced in the presence of alkali ions due to charge compensation and asymmetry in the crystal field. The emission intensity in the case of Na+ co-doped phosphor is maximum and at 1 W pump power, it is increased by ∼44 and ∼31 times in blue and NIR regions, respectively as compared to without alkali ions co-doped phosphor. The downshifting emission in blue region has been observed due to oxygen vacancy and Tm3+ ions on excitation with 277 and 360 nm radiations which is enhanced significantly in the presence of alkali ions. Thus, the intense blue emission by this material is suitable for blue and white light emitting phosphors. © 2019 Elsevier B.V.PublicationArticle Large enhancement in upconverted green emission intensity from Ho 3+ /Yb 3+ co-doped Y 2 Ti 2 O 7 phosphor in the presence of Zn 2+(Elsevier Ltd, 2019) P.K. Vishwakarma; A. Bahadur; Akanksha Maurya; S.B. RaiThe Ho 3+ , Yb 3+ co-doped Y 2 Ti 2 O 7 phosphor samples have been synthesized through solid state reaction method in the absence and presence of Zn 2+ ions. The X-ray diffraction (XRD) analysis show that the phase of the crystal is face centered cubic. The zinc free phosphor shows weak upconversion emission in green region due to 5 S 2 , 5 F 4 → 5 I 8 transition of Ho 3+ ion on excitation with 980 nm radiation. The emission intensity is enhanced significantly in the presence of Zn 2+ ions due to increase in crystallinity, particle size and asymmetry in the crystal field. We are reporting ˜92 times enhancement in the green emission intensity for 30 mol% co-doping of Zn 2+ ions. The lifetime of 5 S 2 level of Ho 3+ ion increases by increasing the concentration of Zn 2+ ions. The intense green emission in this material may be suitable for display and other fluorescence based devices. © 2019 Elsevier Ltd