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Raunak Kumar Tamrakar - One of the best experts on this subject based on the ideXlab platform.
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structural characterization of gd 2 o 3 phosphor synthesized by Solid State Reaction and combustion method using x ray diffraction and transmission electron microscopic techniques
IEEE\ OSA Journal of Display Technology, 2016Co-Authors: Raunak Kumar Tamrakar, D P Bisen, Kanchan Upadhyay, Ishwar Prasad Sahu, Manjulata SahuAbstract:The combustion synthesis and conventional Solid-State Reaction method was used to synthesize Gadolinium oxide (Gd 2O3) phosphor. Nanoranged Gd2O3 was successfully synthesized by ignition of gadolinium nitrate followed by combustion in the presence of urea, and for the Solid-State Reaction method, boric acid was used as a flux at high temperature of 1400 °C monoclinic and cubic phase gadolinium oxide (Gd2 O3) phosphor was obtained for combustion and Solid-State Reaction method, respectively. Samples prepared by both the methods were characterized by using X-ray diffraction (XRD) spectroscopy, and transmission electron microscopy (TEM). The crystallite size and grain size of these phosphors are compared by using XRD profile analysis as well as by TEM. Other physical parameters such as strain, stress, and deformation energy density are also estimated precisely for the prominent XRD peaks of Gd2O3 powder in the range $2 \theta$ by using a modified Williamson–Hall analysis assuming uniform deformation model.
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luminescence properties of dysprosium doped calcium magnesium silicate phosphor by Solid State Reaction method
Journal of Alloys and Compounds, 2015Co-Authors: Ishwar Prasad Sahu, D P Bisen, Nameeta Brahme, P Chandrakar, R N Baghel, Raunak Kumar TamrakarAbstract:Abstract Dysprosium doped calcium magnesium silicate (CaMgSi2O6:Dy3+) white light emitting phosphor was synthesized by Solid State Reaction process. The crystal structure of sintered phosphor was monoclinic structure with space group C2/c. Chemical composition of the sintered CaMgSi2O6:Dy3+ phosphor was confirmed by EDX. The prepared CaMgSi2O6:Dy3+ phosphor was excited from 352 nm and their corresponding emission spectra were recorded at blue (470 nm), yellow (570 nm) and red (675 nm) line due to the 4F9/2 → 6H15/2, 4F9/2 → 6H13/2, 4F9/2 → 6H11/2 transitions of Dy3+ ions. The combination of these three emissions constituted as white light confirmed by the Commission Internationale de L'Eclairage (CIE) chromatic coordinate diagram. The possible mechanism of the white light emitting long lasting CaMgSi2O6:Dy3+ phosphor was also investigated. Investigation on afterglow property show that phosphor held fast and slow decay process. The peak of mechanoluminescence (ML) intensity increases linearly with increasing impact velocity of the moving piston. Thus the present investigation indicates that the local piezoelectricity-induced electron bombardment model is responsible to produce ML in prepared CaMgSi2O6:Dy3+ phosphor.
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luminescence properties of dysprosium doped calcium magnesium silicate phosphor by Solid State Reaction method
Journal of Alloys and Compounds, 2015Co-Authors: Ishwar Prasad Sahu, D P Bisen, Nameeta Brahme, P Chandrakar, R N Baghel, Raunak Kumar TamrakarAbstract:Abstract Dysprosium doped calcium magnesium silicate (CaMgSi2O6:Dy3+) white light emitting phosphor was synthesized by Solid State Reaction process. The crystal structure of sintered phosphor was monoclinic structure with space group C2/c. Chemical composition of the sintered CaMgSi2O6:Dy3+ phosphor was confirmed by EDX. The prepared CaMgSi2O6:Dy3+ phosphor was excited from 352 nm and their corresponding emission spectra were recorded at blue (470 nm), yellow (570 nm) and red (675 nm) line due to the 4F9/2 → 6H15/2, 4F9/2 → 6H13/2, 4F9/2 → 6H11/2 transitions of Dy3+ ions. The combination of these three emissions constituted as white light confirmed by the Commission Internationale de L'Eclairage (CIE) chromatic coordinate diagram. The possible mechanism of the white light emitting long lasting CaMgSi2O6:Dy3+ phosphor was also investigated. Investigation on afterglow property show that phosphor held fast and slow decay process. The peak of mechanoluminescence (ML) intensity increases linearly with increasing impact velocity of the moving piston. Thus the present investigation indicates that the local piezoelectricity-induced electron bombardment model is responsible to produce ML in prepared CaMgSi2O6:Dy3+ phosphor.
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down conversion luminescence property of er3 and yb3 co doped gd2o3 crystals prepared by combustion synthesis and Solid State Reaction method
Superlattices and Microstructures, 2015Co-Authors: Raunak Kumar Tamrakar, D P Bisen, Kanchan Upadhyay, Nameeta BramheAbstract:Abstract Monoclinic and cubic Gd 2 O 3 phosphor co doped with Er 3+ and Yb 3+ were prepared by using combustion synthesis and Solid State Reaction methods. The emission spectra were recorded as the function of Er 3+ concentration, Yb 3+ concentration, and also as the function of excitation wave length. The optical properties and the morphologies of the phosphors prepared by both the methods have been compared. Average crystal size for the phosphors yielded by both the synthesis routes were in nanometer range, which were confirmed by using XRD, TEM and SEM technique . The morphological studies shows that the phosphors prepared by Solid State Reaction method is more homogenous and the particle size of these phosphors are larger than the phosphor synthesized by combustion synthesis method. The luminescence intensity of the phosphor prepared by Solid State Reaction method is more than the phosphor prepared by combustion synthesis method at a particular excitation.
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photoluminescence properties of europium doped di strontium magnesium di silicate phosphor by Solid State Reaction method
Journal of Radiation Research and Applied Sciences, 2015Co-Authors: Ishwar Prasad Sahu, Nameeta Brahme, D P Bisen, Raunak Kumar TamrakarAbstract:Abstract Europium doped di-strontium magnesium di-silicate phosphor namely (Sr 2 MgSi 2 O 7 :Eu 3+ ) was prepared by the traditional high temperature Solid State Reaction method. The phase structure of sintered phosphor was akermanite type structure which belongs to the tetragonal crystallography with space group P 42 ¯ 1 m , this structure is a member of the melilite group and forms a layered compound. The EDX and FTIR spectra confirm the present elements in Sr 2 MgSi 2 O 7 :Eu 3+ phosphor. Photoluminescence measurements showed that the phosphor exhibited strong emission peak with good intensity, corresponding to 5 D 0 → 7 F 2 (613 nm) red emission and weak 5 D 0 → 7 F 1 (590 nm) orange emission. The excitation spectra monitored at 613 nm show broad band from 220 to 300 nm ascribed to O–Eu charge-transfer band (CTB) centered at about 269 nm, and the other peaks in the range of 300–400 nm originated from f–f transitions of Eu 3+ ions. The strongest band at 395 nm can be assigned to 7 F 0 / 5 L 6 transition of Eu 3+ ions due to the typical f–f transitions within Eu 3+ of 4f 6 configuration.
Ishwar Prasad Sahu - One of the best experts on this subject based on the ideXlab platform.
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structural characterization of gd 2 o 3 phosphor synthesized by Solid State Reaction and combustion method using x ray diffraction and transmission electron microscopic techniques
IEEE\ OSA Journal of Display Technology, 2016Co-Authors: Raunak Kumar Tamrakar, D P Bisen, Kanchan Upadhyay, Ishwar Prasad Sahu, Manjulata SahuAbstract:The combustion synthesis and conventional Solid-State Reaction method was used to synthesize Gadolinium oxide (Gd 2O3) phosphor. Nanoranged Gd2O3 was successfully synthesized by ignition of gadolinium nitrate followed by combustion in the presence of urea, and for the Solid-State Reaction method, boric acid was used as a flux at high temperature of 1400 °C monoclinic and cubic phase gadolinium oxide (Gd2 O3) phosphor was obtained for combustion and Solid-State Reaction method, respectively. Samples prepared by both the methods were characterized by using X-ray diffraction (XRD) spectroscopy, and transmission electron microscopy (TEM). The crystallite size and grain size of these phosphors are compared by using XRD profile analysis as well as by TEM. Other physical parameters such as strain, stress, and deformation energy density are also estimated precisely for the prominent XRD peaks of Gd2O3 powder in the range $2 \theta$ by using a modified Williamson–Hall analysis assuming uniform deformation model.
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luminescence properties of dysprosium doped calcium magnesium silicate phosphor by Solid State Reaction method
Journal of Alloys and Compounds, 2015Co-Authors: Ishwar Prasad Sahu, D P Bisen, Nameeta Brahme, P Chandrakar, R N Baghel, Raunak Kumar TamrakarAbstract:Abstract Dysprosium doped calcium magnesium silicate (CaMgSi2O6:Dy3+) white light emitting phosphor was synthesized by Solid State Reaction process. The crystal structure of sintered phosphor was monoclinic structure with space group C2/c. Chemical composition of the sintered CaMgSi2O6:Dy3+ phosphor was confirmed by EDX. The prepared CaMgSi2O6:Dy3+ phosphor was excited from 352 nm and their corresponding emission spectra were recorded at blue (470 nm), yellow (570 nm) and red (675 nm) line due to the 4F9/2 → 6H15/2, 4F9/2 → 6H13/2, 4F9/2 → 6H11/2 transitions of Dy3+ ions. The combination of these three emissions constituted as white light confirmed by the Commission Internationale de L'Eclairage (CIE) chromatic coordinate diagram. The possible mechanism of the white light emitting long lasting CaMgSi2O6:Dy3+ phosphor was also investigated. Investigation on afterglow property show that phosphor held fast and slow decay process. The peak of mechanoluminescence (ML) intensity increases linearly with increasing impact velocity of the moving piston. Thus the present investigation indicates that the local piezoelectricity-induced electron bombardment model is responsible to produce ML in prepared CaMgSi2O6:Dy3+ phosphor.
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luminescence properties of dysprosium doped calcium magnesium silicate phosphor by Solid State Reaction method
Journal of Alloys and Compounds, 2015Co-Authors: Ishwar Prasad Sahu, D P Bisen, Nameeta Brahme, P Chandrakar, R N Baghel, Raunak Kumar TamrakarAbstract:Abstract Dysprosium doped calcium magnesium silicate (CaMgSi2O6:Dy3+) white light emitting phosphor was synthesized by Solid State Reaction process. The crystal structure of sintered phosphor was monoclinic structure with space group C2/c. Chemical composition of the sintered CaMgSi2O6:Dy3+ phosphor was confirmed by EDX. The prepared CaMgSi2O6:Dy3+ phosphor was excited from 352 nm and their corresponding emission spectra were recorded at blue (470 nm), yellow (570 nm) and red (675 nm) line due to the 4F9/2 → 6H15/2, 4F9/2 → 6H13/2, 4F9/2 → 6H11/2 transitions of Dy3+ ions. The combination of these three emissions constituted as white light confirmed by the Commission Internationale de L'Eclairage (CIE) chromatic coordinate diagram. The possible mechanism of the white light emitting long lasting CaMgSi2O6:Dy3+ phosphor was also investigated. Investigation on afterglow property show that phosphor held fast and slow decay process. The peak of mechanoluminescence (ML) intensity increases linearly with increasing impact velocity of the moving piston. Thus the present investigation indicates that the local piezoelectricity-induced electron bombardment model is responsible to produce ML in prepared CaMgSi2O6:Dy3+ phosphor.
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photoluminescence properties of europium doped di strontium magnesium di silicate phosphor by Solid State Reaction method
Journal of Radiation Research and Applied Sciences, 2015Co-Authors: Ishwar Prasad Sahu, Nameeta Brahme, D P Bisen, Raunak Kumar TamrakarAbstract:Abstract Europium doped di-strontium magnesium di-silicate phosphor namely (Sr 2 MgSi 2 O 7 :Eu 3+ ) was prepared by the traditional high temperature Solid State Reaction method. The phase structure of sintered phosphor was akermanite type structure which belongs to the tetragonal crystallography with space group P 42 ¯ 1 m , this structure is a member of the melilite group and forms a layered compound. The EDX and FTIR spectra confirm the present elements in Sr 2 MgSi 2 O 7 :Eu 3+ phosphor. Photoluminescence measurements showed that the phosphor exhibited strong emission peak with good intensity, corresponding to 5 D 0 → 7 F 2 (613 nm) red emission and weak 5 D 0 → 7 F 1 (590 nm) orange emission. The excitation spectra monitored at 613 nm show broad band from 220 to 300 nm ascribed to O–Eu charge-transfer band (CTB) centered at about 269 nm, and the other peaks in the range of 300–400 nm originated from f–f transitions of Eu 3+ ions. The strongest band at 395 nm can be assigned to 7 F 0 / 5 L 6 transition of Eu 3+ ions due to the typical f–f transitions within Eu 3+ of 4f 6 configuration.
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dysprosium doped di strontium magnesium di silicate white light emitting phosphor by Solid State Reaction method
Displays, 2014Co-Authors: Ishwar Prasad Sahu, D P Bisen, Nameeta BrahmeAbstract:Abstract Dysprosium doped di-strontium magnesium di-silicate namely Sr 2 MgSi 2 O 7 :Dy 3+ phosphor was prepared by the Solid State Reaction method. The phase structure, surface morphology, particle size, elemental analysis was analyzed by using XRD, TEM, EDX and FTIR techniques. The EDX and FTIR spectra confirm the present elements in Sr 2 MgSi 2 O 7 :Dy 3+ phosphor. The optical properties of Sr 2 MgSi 2 O 7 :Dy 3+ phosphor was investigated utilizing thermoluminescence (TL), photoluminescence (PL), long lasting phosphorescence and mechanoluminescence (ML). Under the ultraviolet excitation, the emission spectra of Sr 2 MgSi 2 O 7 :Dy 3+ phosphor are composed of a broad band and the characteristic emission of Dy 3+ peaking at 470 nm (blue), 575 nm (yellow) and 678 nm (red), originating from the transitions of 4 F 9/2 → 6 H 15/2 , 4 F 9/2 → 6 H 13/2 and 4 F 9/2 → 6 H 11/2 . CIE color coordinates of Sr 2 MgSi 2 O 7 :Dy 3+ are suitable as white light emitting phosphor. Decay graph indicate that this phosphor also contains fast decay and slow decay process. The peak of ML intensity increases linearly with increasing impact velocity of the moving piston. The possible mechanism of this white light emitting long lasting phosphor is also investigated.
D P Bisen - One of the best experts on this subject based on the ideXlab platform.
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structural characterization of gd 2 o 3 phosphor synthesized by Solid State Reaction and combustion method using x ray diffraction and transmission electron microscopic techniques
IEEE\ OSA Journal of Display Technology, 2016Co-Authors: Raunak Kumar Tamrakar, D P Bisen, Kanchan Upadhyay, Ishwar Prasad Sahu, Manjulata SahuAbstract:The combustion synthesis and conventional Solid-State Reaction method was used to synthesize Gadolinium oxide (Gd 2O3) phosphor. Nanoranged Gd2O3 was successfully synthesized by ignition of gadolinium nitrate followed by combustion in the presence of urea, and for the Solid-State Reaction method, boric acid was used as a flux at high temperature of 1400 °C monoclinic and cubic phase gadolinium oxide (Gd2 O3) phosphor was obtained for combustion and Solid-State Reaction method, respectively. Samples prepared by both the methods were characterized by using X-ray diffraction (XRD) spectroscopy, and transmission electron microscopy (TEM). The crystallite size and grain size of these phosphors are compared by using XRD profile analysis as well as by TEM. Other physical parameters such as strain, stress, and deformation energy density are also estimated precisely for the prominent XRD peaks of Gd2O3 powder in the range $2 \theta$ by using a modified Williamson–Hall analysis assuming uniform deformation model.
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luminescence properties of dysprosium doped calcium magnesium silicate phosphor by Solid State Reaction method
Journal of Alloys and Compounds, 2015Co-Authors: Ishwar Prasad Sahu, D P Bisen, Nameeta Brahme, P Chandrakar, R N Baghel, Raunak Kumar TamrakarAbstract:Abstract Dysprosium doped calcium magnesium silicate (CaMgSi2O6:Dy3+) white light emitting phosphor was synthesized by Solid State Reaction process. The crystal structure of sintered phosphor was monoclinic structure with space group C2/c. Chemical composition of the sintered CaMgSi2O6:Dy3+ phosphor was confirmed by EDX. The prepared CaMgSi2O6:Dy3+ phosphor was excited from 352 nm and their corresponding emission spectra were recorded at blue (470 nm), yellow (570 nm) and red (675 nm) line due to the 4F9/2 → 6H15/2, 4F9/2 → 6H13/2, 4F9/2 → 6H11/2 transitions of Dy3+ ions. The combination of these three emissions constituted as white light confirmed by the Commission Internationale de L'Eclairage (CIE) chromatic coordinate diagram. The possible mechanism of the white light emitting long lasting CaMgSi2O6:Dy3+ phosphor was also investigated. Investigation on afterglow property show that phosphor held fast and slow decay process. The peak of mechanoluminescence (ML) intensity increases linearly with increasing impact velocity of the moving piston. Thus the present investigation indicates that the local piezoelectricity-induced electron bombardment model is responsible to produce ML in prepared CaMgSi2O6:Dy3+ phosphor.
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luminescence properties of dysprosium doped calcium magnesium silicate phosphor by Solid State Reaction method
Journal of Alloys and Compounds, 2015Co-Authors: Ishwar Prasad Sahu, D P Bisen, Nameeta Brahme, P Chandrakar, R N Baghel, Raunak Kumar TamrakarAbstract:Abstract Dysprosium doped calcium magnesium silicate (CaMgSi2O6:Dy3+) white light emitting phosphor was synthesized by Solid State Reaction process. The crystal structure of sintered phosphor was monoclinic structure with space group C2/c. Chemical composition of the sintered CaMgSi2O6:Dy3+ phosphor was confirmed by EDX. The prepared CaMgSi2O6:Dy3+ phosphor was excited from 352 nm and their corresponding emission spectra were recorded at blue (470 nm), yellow (570 nm) and red (675 nm) line due to the 4F9/2 → 6H15/2, 4F9/2 → 6H13/2, 4F9/2 → 6H11/2 transitions of Dy3+ ions. The combination of these three emissions constituted as white light confirmed by the Commission Internationale de L'Eclairage (CIE) chromatic coordinate diagram. The possible mechanism of the white light emitting long lasting CaMgSi2O6:Dy3+ phosphor was also investigated. Investigation on afterglow property show that phosphor held fast and slow decay process. The peak of mechanoluminescence (ML) intensity increases linearly with increasing impact velocity of the moving piston. Thus the present investigation indicates that the local piezoelectricity-induced electron bombardment model is responsible to produce ML in prepared CaMgSi2O6:Dy3+ phosphor.
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down conversion luminescence property of er3 and yb3 co doped gd2o3 crystals prepared by combustion synthesis and Solid State Reaction method
Superlattices and Microstructures, 2015Co-Authors: Raunak Kumar Tamrakar, D P Bisen, Kanchan Upadhyay, Nameeta BramheAbstract:Abstract Monoclinic and cubic Gd 2 O 3 phosphor co doped with Er 3+ and Yb 3+ were prepared by using combustion synthesis and Solid State Reaction methods. The emission spectra were recorded as the function of Er 3+ concentration, Yb 3+ concentration, and also as the function of excitation wave length. The optical properties and the morphologies of the phosphors prepared by both the methods have been compared. Average crystal size for the phosphors yielded by both the synthesis routes were in nanometer range, which were confirmed by using XRD, TEM and SEM technique . The morphological studies shows that the phosphors prepared by Solid State Reaction method is more homogenous and the particle size of these phosphors are larger than the phosphor synthesized by combustion synthesis method. The luminescence intensity of the phosphor prepared by Solid State Reaction method is more than the phosphor prepared by combustion synthesis method at a particular excitation.
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photoluminescence properties of europium doped di strontium magnesium di silicate phosphor by Solid State Reaction method
Journal of Radiation Research and Applied Sciences, 2015Co-Authors: Ishwar Prasad Sahu, Nameeta Brahme, D P Bisen, Raunak Kumar TamrakarAbstract:Abstract Europium doped di-strontium magnesium di-silicate phosphor namely (Sr 2 MgSi 2 O 7 :Eu 3+ ) was prepared by the traditional high temperature Solid State Reaction method. The phase structure of sintered phosphor was akermanite type structure which belongs to the tetragonal crystallography with space group P 42 ¯ 1 m , this structure is a member of the melilite group and forms a layered compound. The EDX and FTIR spectra confirm the present elements in Sr 2 MgSi 2 O 7 :Eu 3+ phosphor. Photoluminescence measurements showed that the phosphor exhibited strong emission peak with good intensity, corresponding to 5 D 0 → 7 F 2 (613 nm) red emission and weak 5 D 0 → 7 F 1 (590 nm) orange emission. The excitation spectra monitored at 613 nm show broad band from 220 to 300 nm ascribed to O–Eu charge-transfer band (CTB) centered at about 269 nm, and the other peaks in the range of 300–400 nm originated from f–f transitions of Eu 3+ ions. The strongest band at 395 nm can be assigned to 7 F 0 / 5 L 6 transition of Eu 3+ ions due to the typical f–f transitions within Eu 3+ of 4f 6 configuration.
Thomas Graule - One of the best experts on this subject based on the ideXlab platform.
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the fe k edge x ray absorption characteristics of la sub 1 x sr sub x feo sub 3 delta prepared by Solid State Reaction
Materials Research Bulletin, 2009Co-Authors: Ulrich Vogt, Wonsub Yoon, Christian Soltmann, Xiaoqing Yang, Artur Braun, Thomas GrauleAbstract:Perovskites of the composition La{sub 1-x}Sr{sub x}FeO{sub 3-{delta}} (x = 0.0, 0.1, 0.5, 0.9, 1.0) were prepared by the conventional Solid State Reaction route. The single phase behaviour was assessed by XRD analysis, the electronic properties were investigated by Fe K-edge X-ray absorption spectroscopy. The work is focused on the valence State of iron and the oxygen vacancies of the perovskites investigated. The XRD measurements revealed that the Solid State Reaction yields cubic perovskites for x = 1, 0.9, rhombohedral perovskites for x = 0.5, and orthorhombic perovskites for x = 0, 0.1. The X-ray absorption data are discussed in detail with respect to Fe K-edge shift, white-line intensity, pre-edge features, and the EXAFS data. The first peak in the Fourier transform of the Chi x k{sup 3} and Chi x k{sup 2} functions was simulated for a detailed analysis of scattering contributions from the first oxygen shell to evaluate the Fe-O bond length. The substitution of lanthanum by strontium leads to a corresponding increase of the iron valence State and thus to the formation of the Jahn-Teller Fe{sup 4+} ion. This is causing disorder in the first coordination shell and thus an increase of the Debye-Waller factor with increasingmore » x. The Fe-O bond length obtained from XRD and especially from X-ray absorption data are consistent with {delta}-values close to zero.« less
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the fe k edge x ray absorption characteristics of la1 xsrxfeo3 δ prepared by Solid State Reaction
Materials Research Bulletin, 2009Co-Authors: O. Haas, Wonsub Yoon, Ulrich Vogt, Christian Soltmann, Xiaoqing Yang, Artur Braun, Thomas GrauleAbstract:Abstract Perovskites of the composition La 1− x Sr x FeO 3− δ ( x = 0.0, 0.1, 0.5, 0.9, 1.0) were prepared by the conventional Solid State Reaction route. The single phase behaviour was assessed by XRD analysis, the electronic properties were investigated by Fe K-edge X-ray absorption spectroscopy. The work is focused on the valence State of iron and the oxygen vacancies of the perovskites investigated. The XRD measurements revealed that the Solid State Reaction yields cubic perovskites for x = 1, 0.9, rhombohedral perovskites for x = 0.5, and orthorhombic perovskites for x = 0, 0.1. The X-ray absorption data are discussed in detail with respect to Fe K-edge shift, white-line intensity, pre-edge features, and the EXAFS data. The first peak in the Fourier transform of the Chi × k 3 and Chi × k 2 functions was simulated for a detailed analysis of scattering contributions from the first oxygen shell to evaluate the Fe–O bond length. The substitution of lanthanum by strontium leads to a corresponding increase of the iron valence State and thus to the formation of the Jahn-Teller Fe 4+ ion. This is causing disorder in the first coordination shell and thus an increase of the Debye-Waller factor with increasing x . The Fe–O bond length obtained from XRD and especially from X-ray absorption data are consistent with δ -values close to zero.
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the fe k edge x ray absorption characteristics of la1 xsrxfeo3 delta prepared by Solid State Reaction
Materials Research Bulletin, 2009Co-Authors: O. Haas, Wonsub Yoon, Ulrich Vogt, Christian Soltmann, Xiaoqing Yang, Artur Braun, X Q Yang, Thomas GrauleAbstract:Perovskites of the composition La{sub 1-x}Sr{sub x}FeO{sub 3-{delta}} (x = 0.0, 0.1, 0.5, 0.9, 1.0) were prepared by the conventional Solid State Reaction route. The single phase behaviour was assessed by XRD analysis, the electronic properties were investigated by Fe K-edge X-ray absorption spectroscopy. The work is focused on the valence State of iron and the oxygen vacancies of the perovskites investigated. The XRD measurements revealed that the Solid State Reaction yields cubic perovskites for x = 1, 0.9, rhombohedral perovskites for x = 0.5, and orthorhombic perovskites for x = 0, 0.1. The X-ray absorption data are discussed in detail with respect to Fe K-edge shift, white-line intensity, pre-edge features, and the EXAFS data. The first peak in the Fourier transform of the Chi x k{sup 3} and Chi x k{sup 2} functions was simulated for a detailed analysis of scattering contributions from the first oxygen shell to evaluate the Fe-O bond length. The substitution of lanthanum by strontium leads to a corresponding increase of the iron valence State and thus to the formation of the Jahn-Teller Fe{sup 4+} ion. This is causing disorder in the first coordination shell and thus an increase of the Debye-Waller factor with increasingmore » x. The Fe-O bond length obtained from XRD and especially from X-ray absorption data are consistent with {delta}-values close to zero.« less
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the fe k edge x ray absorption characteristics of la1 xsrxfeo3 δ prepared by Solid State Reaction
Materials Research Bulletin, 2009Co-Authors: O. Haas, Wonsub Yoon, Ulrich Vogt, Christian Soltmann, Xiaoqing Yang, Artur Braun, Thomas GrauleAbstract:Abstract Perovskites of the composition La 1− x Sr x FeO 3− δ ( x = 0.0, 0.1, 0.5, 0.9, 1.0) were prepared by the conventional Solid State Reaction route. The single phase behaviour was assessed by XRD analysis, the electronic properties were investigated by Fe K-edge X-ray absorption spectroscopy. The work is focused on the valence State of iron and the oxygen vacancies of the perovskites investigated. The XRD measurements revealed that the Solid State Reaction yields cubic perovskites for x = 1, 0.9, rhombohedral perovskites for x = 0.5, and orthorhombic perovskites for x = 0, 0.1. The X-ray absorption data are discussed in detail with respect to Fe K-edge shift, white-line intensity, pre-edge features, and the EXAFS data. The first peak in the Fourier transform of the Chi × k 3 and Chi × k 2 functions was simulated for a detailed analysis of scattering contributions from the first oxygen shell to evaluate the Fe–O bond length. The substitution of lanthanum by strontium leads to a corresponding increase of the iron valence State and thus to the formation of the Jahn-Teller Fe 4+ ion. This is causing disorder in the first coordination shell and thus an increase of the Debye-Waller factor with increasing x . The Fe–O bond length obtained from XRD and especially from X-ray absorption data are consistent with δ -values close to zero.
Nameeta Brahme - One of the best experts on this subject based on the ideXlab platform.
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luminescence properties of dysprosium doped calcium magnesium silicate phosphor by Solid State Reaction method
Journal of Alloys and Compounds, 2015Co-Authors: Ishwar Prasad Sahu, D P Bisen, Nameeta Brahme, P Chandrakar, R N Baghel, Raunak Kumar TamrakarAbstract:Abstract Dysprosium doped calcium magnesium silicate (CaMgSi2O6:Dy3+) white light emitting phosphor was synthesized by Solid State Reaction process. The crystal structure of sintered phosphor was monoclinic structure with space group C2/c. Chemical composition of the sintered CaMgSi2O6:Dy3+ phosphor was confirmed by EDX. The prepared CaMgSi2O6:Dy3+ phosphor was excited from 352 nm and their corresponding emission spectra were recorded at blue (470 nm), yellow (570 nm) and red (675 nm) line due to the 4F9/2 → 6H15/2, 4F9/2 → 6H13/2, 4F9/2 → 6H11/2 transitions of Dy3+ ions. The combination of these three emissions constituted as white light confirmed by the Commission Internationale de L'Eclairage (CIE) chromatic coordinate diagram. The possible mechanism of the white light emitting long lasting CaMgSi2O6:Dy3+ phosphor was also investigated. Investigation on afterglow property show that phosphor held fast and slow decay process. The peak of mechanoluminescence (ML) intensity increases linearly with increasing impact velocity of the moving piston. Thus the present investigation indicates that the local piezoelectricity-induced electron bombardment model is responsible to produce ML in prepared CaMgSi2O6:Dy3+ phosphor.
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luminescence properties of dysprosium doped calcium magnesium silicate phosphor by Solid State Reaction method
Journal of Alloys and Compounds, 2015Co-Authors: Ishwar Prasad Sahu, D P Bisen, Nameeta Brahme, P Chandrakar, R N Baghel, Raunak Kumar TamrakarAbstract:Abstract Dysprosium doped calcium magnesium silicate (CaMgSi2O6:Dy3+) white light emitting phosphor was synthesized by Solid State Reaction process. The crystal structure of sintered phosphor was monoclinic structure with space group C2/c. Chemical composition of the sintered CaMgSi2O6:Dy3+ phosphor was confirmed by EDX. The prepared CaMgSi2O6:Dy3+ phosphor was excited from 352 nm and their corresponding emission spectra were recorded at blue (470 nm), yellow (570 nm) and red (675 nm) line due to the 4F9/2 → 6H15/2, 4F9/2 → 6H13/2, 4F9/2 → 6H11/2 transitions of Dy3+ ions. The combination of these three emissions constituted as white light confirmed by the Commission Internationale de L'Eclairage (CIE) chromatic coordinate diagram. The possible mechanism of the white light emitting long lasting CaMgSi2O6:Dy3+ phosphor was also investigated. Investigation on afterglow property show that phosphor held fast and slow decay process. The peak of mechanoluminescence (ML) intensity increases linearly with increasing impact velocity of the moving piston. Thus the present investigation indicates that the local piezoelectricity-induced electron bombardment model is responsible to produce ML in prepared CaMgSi2O6:Dy3+ phosphor.
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photoluminescence properties of europium doped di strontium magnesium di silicate phosphor by Solid State Reaction method
Journal of Radiation Research and Applied Sciences, 2015Co-Authors: Ishwar Prasad Sahu, Nameeta Brahme, D P Bisen, Raunak Kumar TamrakarAbstract:Abstract Europium doped di-strontium magnesium di-silicate phosphor namely (Sr 2 MgSi 2 O 7 :Eu 3+ ) was prepared by the traditional high temperature Solid State Reaction method. The phase structure of sintered phosphor was akermanite type structure which belongs to the tetragonal crystallography with space group P 42 ¯ 1 m , this structure is a member of the melilite group and forms a layered compound. The EDX and FTIR spectra confirm the present elements in Sr 2 MgSi 2 O 7 :Eu 3+ phosphor. Photoluminescence measurements showed that the phosphor exhibited strong emission peak with good intensity, corresponding to 5 D 0 → 7 F 2 (613 nm) red emission and weak 5 D 0 → 7 F 1 (590 nm) orange emission. The excitation spectra monitored at 613 nm show broad band from 220 to 300 nm ascribed to O–Eu charge-transfer band (CTB) centered at about 269 nm, and the other peaks in the range of 300–400 nm originated from f–f transitions of Eu 3+ ions. The strongest band at 395 nm can be assigned to 7 F 0 / 5 L 6 transition of Eu 3+ ions due to the typical f–f transitions within Eu 3+ of 4f 6 configuration.
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dysprosium doped di strontium magnesium di silicate white light emitting phosphor by Solid State Reaction method
Displays, 2014Co-Authors: Ishwar Prasad Sahu, D P Bisen, Nameeta BrahmeAbstract:Abstract Dysprosium doped di-strontium magnesium di-silicate namely Sr 2 MgSi 2 O 7 :Dy 3+ phosphor was prepared by the Solid State Reaction method. The phase structure, surface morphology, particle size, elemental analysis was analyzed by using XRD, TEM, EDX and FTIR techniques. The EDX and FTIR spectra confirm the present elements in Sr 2 MgSi 2 O 7 :Dy 3+ phosphor. The optical properties of Sr 2 MgSi 2 O 7 :Dy 3+ phosphor was investigated utilizing thermoluminescence (TL), photoluminescence (PL), long lasting phosphorescence and mechanoluminescence (ML). Under the ultraviolet excitation, the emission spectra of Sr 2 MgSi 2 O 7 :Dy 3+ phosphor are composed of a broad band and the characteristic emission of Dy 3+ peaking at 470 nm (blue), 575 nm (yellow) and 678 nm (red), originating from the transitions of 4 F 9/2 → 6 H 15/2 , 4 F 9/2 → 6 H 13/2 and 4 F 9/2 → 6 H 11/2 . CIE color coordinates of Sr 2 MgSi 2 O 7 :Dy 3+ are suitable as white light emitting phosphor. Decay graph indicate that this phosphor also contains fast decay and slow decay process. The peak of ML intensity increases linearly with increasing impact velocity of the moving piston. The possible mechanism of this white light emitting long lasting phosphor is also investigated.
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comparison of photoluminescence properties of gd2o3 phosphor synthesized by combustion and Solid State Reaction method
Journal of Radiation Research and Applied Sciences, 2014Co-Authors: Raunak Kumar Tamrakar, D P Bisen, Nameeta BrahmeAbstract:In this paper, we presented a comparison of Photoluminescence (PL) studies of Gd2O3 phosphor prepared by two synthesis methods, high temperature (1400°C) Solid State Reaction and low temperature co...