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RISS 인기검색어
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- 저자 : Rani Geeta (검색결과 4 건)
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Photoluminescence characterizations in phase transition alumina with boehmite nanostructures
Rani Geeta 한국세라믹학회 2021 한국세라믹학회지 Vol.58 No.6
The phase transition alumina γ, ẟ, θ, α with boehmite nanostructure have been prepared, and a relative study between the crystal structure, annealing temperature, and photoluminescence properties are reported in this paper. The eff ects of diff er- ent temperatures up to 1600 on the boehmite nanostructure revealed diff erent phases of alumina which are characterized using X-ray diff raction (XRD) technique. The evolution of crystal micrographs and grain size during the transformation are studied using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The emission spectra of the obtained samples are investigated using photoluminescence (PL) spectroscopy in which the traces of inherent impuri- ties of Cr 3+ are detected in the α-Al 2 O 3 without any doping. The XRD and SEM/TEM analysis show that with increasing temperature, the transformation of boehmite into a well-crystallized α-Al 2 O 3 and the micrographs from nanoplatelets with spindle-like edges to vermicular structure take place. Thus, this paper reports an important role of temperature in the phase transition, morphologies, and in the photoluminescence properties of the obtained samples. The optical properties investi- gate the defects associated with each phase of alumina in the transition alumina material system. The considerable sign of the crystal phase found that the emission band spectra of the corresponding phase vary greatly due to the presence of traces of uncontrolled impurity like Cr 3+ found in the sample. The most prominent peak corresponding to the ruby laser has been found due to these Cr 3+ ions in the most stable phase, α-Al 2 O 3 which is the final product.
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Singh, Sanjay,Rani, Geeta Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.7
The two chelates based on calix[4]arene and thiacalix[4]arene have been synthesized and used as neutral ionophores for preparing PVC based membrane sensor selective to $Ho^{3+}$ ion. The addition of potassium tetrakis(4-chlorophenyl)borate (KTpClPB) and various plasticizers, viz., NDPE, o-NPOE, DOP, TEP and DOS have been found to improve significantly the performance of the sensors. The best performance was obtained with the sensor no. 6 having membrane of $L_2$ with composition (w/w) ionophore (2%): KTpClPB (4%): PVC (37%): NDPE (57%). This sensor exhibits Nernatian response with slope $21.10{\pm}0.3mV/decade$ of activity in the concentration range $3.0{\times}10^{-8}-1.0{\times}10^{-2}M\;Ho^{3+}\;ion$, with a detection limit of $1.0{\times}10^{-8}M$. The proposed sensor performs satisfactorily over a wide pH range of 2.8-10, with a fast response time (5 s). The sensor was also found to work successfully in partially non-aqueous media up to 25% (v/v) content of methanol, ethanol and acetonitrile, and can be used for a period of 4 months without any significant drift in potential. The electrode was also used for the determination of $Ho^{3+}$ ions in synthetic mixtures of different ions and the determination of the arsenate ion in different water samples.
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Sanjay Singh,Geeta Rani 대한화학회 2012 Bulletin of the Korean Chemical Society Vol.33 No.7
The two chelates based on calix[4]arene and thiacalix[4]arene have been synthesized and used as neutral ionophores for preparing PVC based membrane sensor selective to Ho3+ ion. The addition of potassium tetrakis(4-chlorophenyl)borate (KTpClPB) and various plasticizers, viz., NDPE, o-NPOE, DOP, TEP and DOS have been found to improve significantly the performance of the sensors. The best performance was obtained with the sensor no. 6 having membrane of L2 with composition (w/w) ionophore (2%): KTpClPB (4%): PVC (37%): NDPE (57%). This sensor exhibits Nernatian response with slope 21.10 ± 0.3 mV/decade of activity in the concentration range 3.0 × 10−8 – 1.0 × 10−2 M Ho3+ ion, with a detection limit of 1.0 × 10−8 M. The proposed sensor performs satisfactorily over a wide pH range of 2.8-10, with a fast response time (5 s). The sensor was also found to work successfully in partially non-aqueous media up to 25% (v/v) content of methanol, ethanol and acetonitrile, and can be used for a period of 4 months without any significant drift in potential. The electrode was also used for the determination of Ho3+ ions in synthetic mixtures of different ions and the determination of the arsenate ion in different water samples.
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Certain Models of the Lie Algebra 𝒦<sub>5</sub> and Their Connection with Special Functions
Yadav, Sarasvati,Rani, Geeta Department of Mathematics 2018 Kyungpook mathematical journal Vol.58 No.4
In this paper, we discuss the connection between the 5-dimensional complex Lie algebra ${\mathcal{K}} _5$ and Special functions. We construct certain two variable models of the irreducible representations of ${\mathcal{K}}_5$. We also use an Euler type integral transformation to obtain the new transformed models, in which the basis function appears as $_2F_1$. Further, we utilize these models to get some generating functions and recurrence relations.
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