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J. Manam

Bio: J. Manam is an academic researcher from Indian Institute of Technology Dhanbad. The author has contributed to research in topics: Photoluminescence & Phosphor. The author has an hindex of 14, co-authored 25 publications receiving 521 citations.

Papers
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TL;DR: In this article, the structural and optical properties of europium doped magnesium orthosilicate nanophosphor were investigated by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscope (FESEM), High resolution Transmission electron microscopy (HRTEM), Diffuse Reflectance Spectra (DRS), and Photoluminescence spectra (PL) together with decay time.

71 citations

Journal ArticleDOI
TL;DR: The photometric characterizations and corresponding calculations indicated the suitability of the phosphor for display devices, and divalent ions introduced radiative defect centers, which enhances the PL intensity significantly.

63 citations

Journal ArticleDOI
TL;DR: In this article, the synthesis of terbium doped zinc oxide (ZnO:Tb3+) nanorods via room temperature chemical co-precipitation was explored and their structural, photoluminescence (PL) and thermoluminecence (TL) studies were investigated in detail.
Abstract: Here in, the synthesis of the terbium doped zinc oxide (ZnO:Tb3+) nanorods via room temperature chemical co-precipitation was explored and their structural, photoluminescence (PL) and thermoluminescence (TL) studies were investigated in detail. The present samples were found to have pure hexagonal wurtzite crystal structure. The as obtained samples were broadly composed of nanoflakes while the highly crystalline nanorods have been formed due to low temperature annealing of the as synthesized samples. The diameters of the nanoflakes are found to be in the range 50–60 nm whereas the nanorods have diameter 60–90 nm and length 700–900 nm. FTIR study shows Zn O stretching band at 475 cm−1 showing improved crystal quality with annealing. The bands at 1545 and 1431 cm−1 are attributed to asymmetric and symmetric C O stretching vibration modes. The diffuse reflectance spectra show band edge emission near 390 nm and a blue shift of the absorption edge with higher concentration of Tb doping. The PL spectra of the Tb3+-doped sample exhibited bright bluish green and green emissions at 490 nm (5D4 → 7F6) and 544 nm (5D4 → 7F5) respectively which is much more intense then the blue (450 nm), bluish green (472 nm) and broad green emission (532 nm) for the undoped sample. An efficient energy transfer process from ZnO host to Tb3+ is observed in PL emission and excitation spectra of Tb3+-doped ZnO ions. The doped sample exhibits a strong TL glow peak at 255 °C compared to the prominent glow peak at 190 °C for the undoped sample. The higher temperature peaks are found to obey first order kinetics whereas the lower temperature peaks obey 2nd order kinetics. The glow peak at 255 °C for the Tb3+ doped sample has an activation energy 0.98 eV and frequency factor 2.77 × 108 s−1.

54 citations

Journal ArticleDOI
TL;DR: In this article, the effect of Li+ co-doping was systematically studied by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), UV-Vis-NIR reflectance, and Thermoluminescence (TL) studies.

45 citations

Journal ArticleDOI
TL;DR: In this article, the structural, optical and photometric characterization of yttrium gadolinium orthovanadates (Y1−xGdxVO4) doped with Dy3+ for white emission in solid state lighting was reported.
Abstract: This paper reports on the structural, optical and photometric characterization of yttrium gadolinium orthovanadates (Y1−xGdxVO4) doped with Dy3+ for white emission in solid state lighting. A series of orthovanadates were prepared through a low temperature co-precipitation method and further post annealed. The as synthesized phosphor particles revealed a single phase tetragonal structure with space group I41/amd(141). The infrared spectra confirmed the presence of characteristic vibrational bands of orthovanadates. The microscopic images showed elongated particles after annealing and the particle sizes were estimated in the range of 10–50 nm. The band gap of the prepared phosphors, calculated from the corresponding diffuse reflectance spectra was observed to be 3.75 eV and 3.57 eV for YVO4 and GdVO4 respectively. Y1−xGdxVO4:Dy3+ phosphors, illuminated with ultraviolet light exhibited characteristic blue and yellow luminescence corresponding to 4F9/2 → 6H15/2, 4F9/2 → 6H13/2 transitions of Dy3+ ion. The emission spectra showed the variation in the intensity ratio (Y/B) with Gd3+ ion variation. Furthermore the thermal quenching property, decay analysis and photometric characterizations were also studied in detail and the results indicated the suitability of these phosphors in solid state lighting.

45 citations


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Journal ArticleDOI
TL;DR: The present paper reviews the state of the art of materials and methods used to take advantage of downconversion processes in solar cells as well as the main characteristics of the materials utilized.

179 citations

Journal ArticleDOI
TL;DR: The effects of rare-earth dopant on morphology and optical properties of the prepared materials were studied and discussed in this paper, where it was found that the presence of rare earth ion in crystal structure of ZnO can change the morphology and band gap of the nanostructures.

139 citations

Journal ArticleDOI
01 Feb 2019-Vacuum
TL;DR: In this article, a mixed phase of titanium dioxide and zinc oxide nanocomposite powder was used for degradation of organic methyle blue dye under the influence of visible light and the photodegradation was increased from 75 to 90% with the varying of x from 1.0 to 0.4.

135 citations

Journal ArticleDOI
TL;DR: In this article, the effect of copper acetate concentration and the functional properties of nanocomposites was investigated and the synergistic photocatalytic mechanism was proposed based on the photodegradation results.

124 citations

27 Oct 2013
TL;DR: In this article, the authors summarize QD properties and advantages in LED backlit LCDs relative to other competitive downconversion materials, as well as compare and contrast the three primary geometries that will likely be explored during the pursuit of a potentially dominant design.
Abstract: Quantum dots (QDs) are now on the verge of widespread adoption in display applications, after 25 years of scientific research and over a decade of commercialization efforts. This is the result of a combination of industry trends such as liquid crystal displays (LCDs) and light emitting diode (LED) backlight units (BLUs), combined with improvements in QD performance and manufacturing that have taken place across the growing QD ecosystem of Universities, National Labs, and private and public companies. As QDs emerge as a viable choice as downconversion materials in LED backlit LCD displays, they have the potential to be employed in several geometries within these otherwise similar display systems. In all geometries, QD LCDs will provide the broadest available color gamut to the user, in addition to potential benefits in power efficiency, brightness, and contrast. This work will summarize QD properties and advantages in such LED backlit LCDs relative to other competitive downconversion materials, as well as compare and contrast the three primary geometries that will likely be explored during the pursuit of a potentially dominant design.

123 citations