Mrinal Kanti Adak; Prasanta Dhak; Atreyee Kundu; Debasis Dhak
Abstract
In this present work, nanocrystalline Co 2+ and Ta 5+ substituted barium bismuth niobate Ba0.5Co0.5Bi2NbTaO9 was synthesized by chemical process. Room temperature single phase, tetragonal structure was confirmed using X-ray diffraction (XRD) study. Average crystallite and particle sizes were found to ...
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In this present work, nanocrystalline Co 2+ and Ta 5+ substituted barium bismuth niobate Ba0.5Co0.5Bi2NbTaO9 was synthesized by chemical process. Room temperature single phase, tetragonal structure was confirmed using X-ray diffraction (XRD) study. Average crystallite and particle sizes were found to be 33 nm and 40 nm, when analyzed through XRD and transmission electron microscopy (TEM) respectively. Field emission scanning electron microscopy (FESEM) was used for micro-structural investigation of samples sintered at 950?C for 4h. The investigation revealed that the material was exhibiting high dielectric constant value of 1017 at Curie temperature (Tc), 500?C when measured at 10 kHz. Impedance spectroscopy analysis showed that above 425?C, the material exhibited both bulk and grain boundary conductivities which were evidenced from FESEM studies. Density of states, minimum hoping distance, binding energy etc. were studied along with other electrical properties from impedance analysis. Hysteresis behavior was also investigated using polarization study.
Prasanta Dhak; A. Kundu; K. Pramanik; P. Pramanik; D. Dhak
Abstract
Small amounts of Cu and Al-K substitution on the A and B site of BaTiO3, respectively resulting a solid solution of the type Ba1-xCuxTi1-x(AlK)xO3 (BCTAK) [x = 0.05, 0.10, 0.15, 0.20] have been investigated. The compositions have been prepared in the nanocrystalline range by chemical route. X-ray diffraction ...
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Small amounts of Cu and Al-K substitution on the A and B site of BaTiO3, respectively resulting a solid solution of the type Ba1-xCuxTi1-x(AlK)xO3 (BCTAK) [x = 0.05, 0.10, 0.15, 0.20] have been investigated. The compositions have been prepared in the nanocrystalline range by chemical route. X-ray diffraction revealed the tetragonal (P4/mmm) phase. Average crystallite size and particle size were found to be in the range between 25 nm and 35 nm which were analyzed through X-ray diffraction and transmission electron microscopy respectively. A dielectric study of these compounds as a function of temperature suggested that with increasing substitution concentration the dielectric constant decreased and the Curie temperature shifted towards the lower temperature side. Discontinuous grain growth accompanied with excellent dielectric diffuseness was found with increasing concentration of substitution. The dielectric diffuseness γ was found to be maximum to 1.91 at the substitution of BCTAK x = 0.20. The activation energy, Ea was found to decrease along with an increase in conductivity with increasing substitution concentration in BCTAK.
Tanmay K. Ghorai; Prasanta Dhak
Abstract
Mesoporous titania adapted chromium-niobate nanocatalysts CrxNbxTi1-2xO2-x/2 (x = 0.01-0.2) were synthesized by a new synthetic approach, using N,N,N',N'-tetrakis(2-hydroxyethyl)ethylenediamine (edteH4) precursors and their photocatalytic activities were investigated. TiO2 nanomaterials have ...
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Mesoporous titania adapted chromium-niobate nanocatalysts CrxNbxTi1-2xO2-x/2 (x = 0.01-0.2) were synthesized by a new synthetic approach, using N,N,N',N'-tetrakis(2-hydroxyethyl)ethylenediamine (edteH4) precursors and their photocatalytic activities were investigated. TiO2 nanomaterials have continued to be highly active in photocatalytic applications because these are useful to break down the organic molecules in water for endorsing the diffusion of reactants and products. CrxNbxTi1-2xO2-x/2 (x = 0.01)(CNT1) nanoparticles with the smaller particle sizes 12±1 nm and have mesoporous characteristics (SBET = 162 m 2 g −1 ). The energy band gap of CNT1 was found 1.85 eV obtained from optical emission spectrum. The XRD peaks revealed a mixture of anatase and rutile phases in the synthesized powders. EPR spectroscopy showed the characteristic features of Nb 5+ ions, whose existence was confirmed by XPS. The CNT1 powders display good (2.5 times greater) photocatalytic activity for degradation of Rhodamine B (RhB) as opposed to pure anatase TiO2 and other compositions of CrxNbxTi1-2xO2-x/2.
