Search

The present article inspects the structural and optical properties of Dy3+ activated SrNb2O6 phosphors for solid state lighting applications. The structural properties are studied by XRD, FTIR, XPS and Raman spectroscopies. XRD data are further utilized to perform Rietveld refinement and model the structure. The band gap of the samples is evaluated to ensure the utility and found to decrease upon incorporation of the Dy3+ ions. The photoluminescence excitation spectra recorded at an emission wavelength of 572 nm shows several excitation peaks in the near-UV region. Afterward, the excitation wavelengths of 350, 366 and 387 nm are utilized to excite the sample, and emission spectra are recorded. The luminescence intensity is optimized in terms of Dy3+ concentration and the optimum luminescence is derived at 4 mol% Dy3+ concentration. The calculated decay times are evaluated for different energy levels and are observed to reduce on increasing doping concentration. Photometric studies reveal the CIE color coordinates in the yellowish–white region and CCT values less than 5000 K. The derived outcomes recommend the utilization of prepared phosphor materials as a single-phase warm white light emitting candidate for solid-state lighting for indoor appliances and display devices. [ABSTRACT FROM AUTHOR]

In recent years, the growth of luminescent materials for optical thermometry applications has gained substantial attention due to their non-invasive and contactless nature. This research article presents the synthesis, characterization, and potential application of SrWO4:Ho3+/Yb3+ phosphors as temperature-sensitive materials. The inspection of the structural properties is done by X-ray diffraction and Raman and FTIR spectroscopy. The X-ray diffraction signifies the single tetragonal phase of the materials without any impurity or secondary phase. Nine Raman active modes are detected in the Raman spectra of pure SrWO4 and 10 Raman active bands are present in the doped samples. The morphology and elemental composition are visualised by field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) spectroscopy. The spectral properties of these phosphors are evaluated by down-conversion and up-conversion photoluminescence, signifying their suitability for solid state lighting and optical thermometry in various temperature regimes. The phosphors can generate green and yellow light under blue and near-infrared radiation, respectively. The sensitivity of 3.19 × 10−3 K−1 ensures the promising prospects of SrWO4:Ho3+/Yb3+ phosphors for precise and reliable temperature sensing in diverse fields. [ABSTRACT FROM AUTHOR]

The present article reports the up- and down-conversion photoluminescence studies of Er3+-activated SrWO4 (SWO) phosphors. The synthesized samples are characterized by different characterization instruments. The phase formation and particle morphology are ensured through X-ray diffractogram, Field emission scanning electron microscopy (FESEM), and Transmission electron microscopy (TEM). Fourier Transform Infrared spectroscopy (FTIR) is used to gather chemical and structural information through the identification of vibrational bands of the sample. The elemental compositions and their oxidation states are determined using X-ray photoelectron spectroscopy (XPS). Diffuse reflectance spectroscopy is used to analyze the reflectance spectra and obtain the optical bandgap of the material. The photoluminescence down-conversion (DC) and up-conversion (UC) emissions are obtained in the green region under near-ultraviolet (UV) excitation of 379 nm and near-infrared excitation of 980 nm, respectively. Bright green LED is fabricated by coating the prepared phosphor on a 365 nm UV LED chip. Temperature-dependent UC is conducted to explore the temperature sensing performance of the material. The material exhibits excellent thermal stability and temperature sensing sensitivity of 7.8 ⋅ 10− 3 K− 1 under UC study. The proposed material can be developed as a near-UV excited green phosphor for white-LED and non-contact optical temperature sensor. [ABSTRACT FROM AUTHOR]

The reported article covers the down-conversion (DC) and up-conversion (UC) photoluminescence properties of BaWO4 (BWO): Er3+ phosphors, prepared via solid-state reaction route. The prepared samples were subjected to various characterization tools and spectroscopic techniques such as XRD, FESEM, EDX, XPS, PL, FTIR and UV–Vis-NIR for structural and optical characterizations. Intense green emission was achieved from both down-conversion and up-conversion emission spectra under UV excitation of 378 nm and near-infrared excitation of 980 nm, respectively. Green LED is fabricated using a 365 nm UV chip to ensure the performance of the material. The luminescence quenching was observed above 0.5 mol% doping of Er3+, governed by dipole–quadrupole interaction. Decay curves of all samples follow single exponential behavior and the average decay time reduces with the increase of Er3+ concentration. Temperature-dependent UC emission spectra were recorded within 300–500 K. The emission intensity was maintained at 82% at 147 °C compared to the intensity at room temperature, suggesting the good thermal stability of the BWO: Er3+ phosphors. The change in the fluorescence intensity ratio (FIR) between two thermally coupled energy levels of Er3+ ion with temperature has been utilized to investigate the temperature-sensing properties of the reported phosphors. The maximum relative temperature sensitivity was found to be 9.97 × 10–3 K−1 at 300 K. Obtained efficient green emission and comparatively good sensitivity make the proposed phosphor material a promising candidate for the color mixing component of phosphor-converted WLED and temperature-sensing applications. [ABSTRACT FROM AUTHOR]

A multicolor BaAl2O4:Eu2+,Dy3+/dye encapsulated in mesoporous SiO2 composite long persistent phosphor is developed based on a radiative energy transfer process. Multicolor long persistence luminescence is achieved through radiative energy transfer from BaAl2O4:Eu2+,Dy3+ to rhodamine 6G or rhodamine B dye encapsulated in mesoporous silica nanoparticles. BaAl2O4:Eu2+,Dy3+ (BAO) is a cyan-emitting long persistent phosphor with high brightness and a long afterglow time. For color tuning, rhodamine 6G dye encapsulated in mesoporous silica (MSNP-Rh6G) or rhodamine B dye encapsulated in mesoporous silica (MSNP-RhB) nanoparticles are mixed with BAO phosphor in different weight ratios to afford BAO/MSNP-Rh6G and BAO/MSNP-RhB composite phosphors. BAO/MSNP-Rh6G shows a long persistent emission with colors varying from cyan to yellow, with similar color tuning observed for BAO/MSNP-RhB. A possible afterglow mechanism is described. The multicolor long persistent phosphors are potentially applicable in displays, bio-imaging, and luminous paints. [ABSTRACT FROM AUTHOR]

In recent years, the growth of luminescent materials for optical thermometry applications has gained substantial attention due to their non-invasive and contactless nature. This research article presents the synthesis, characterization, and potential application of SrWO 4 :Ho 3+ /Yb 3+ phosphors as temperature-sensitive materials. The inspection of the structural properties is done by X-ray diffraction and Raman and FTIR spectroscopy. The X-ray diffraction signifies the single tetragonal phase of the materials without any impurity or secondary phase. Nine Raman active modes are detected in the Raman spectra of pure SrWO 4 and 10 Raman active bands are present in the doped samples. The morphology and elemental composition are visualised by field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) spectroscopy. The spectral properties of these phosphors are evaluated by down-conversion and up-conversion photoluminescence, signifying their suitability for solid state lighting and optical thermometry in various temperature regimes. The phosphors can generate green and yellow light under blue and near-infrared radiation, respectively. The sensitivity of 3.19 × 10 -3 K -1 ensures the promising prospects of SrWO 4 :Ho 3+ /Yb 3+ phosphors for precise and reliable temperature sensing in diverse fields.