Maximum Photoluminescence Intensity Research Articles

Polyaniline/reduced graphene oxide nanocomposites for electrochemical and solar cell applications

Polyaniline nanocomposites are synthesized via in situ chemical oxidation method by reinforcing reduced graphene oxide nanoparticles of various weight percentage. Structural, optical, thermal and electrochemical studies are performed to know the significance of introducing reduced graphene oxide into polyaniline and to analyse the importance of filler weight percentage in determining various properties of the nanocomposites. X-ray diffraction peak intensity is appeared to be maximum for nanocomposite doped with 2% filler. This composite shows minimum crystallite size and maximum photoluminescence intensity. Maximum ID/IG ratio obtained for 2% filler added nanocomposite from Raman spectroscopy studies proved that the presence of more surface defects and recombination of charge carriers are the reasons for enhanced photoluminescence. Thermal stability is found to be better for a nanocomposite with 1% reduced graphene oxide and obtained a mass retention of 60% even after heating up-to 600 °C. SEM images give various shapes of nanocomposite such as nanorods, spherical nanoparticles and button shaped nanocomposites for different filler weight percentage. Carbon to oxygen ratio is observed to be decreased as the filler percentage increased from 1% to 4% in SEM-EDAX analysis. Polymer nanocomposite with 1% reinforcement possess maximum UV and visible absorption and is found to be decreased as filler concentration increased from 1 to 4%. Electrochemical analysis is performed for polyaniline and 1% reduced graphene oxide reinforced polyaniline nanocomposite. Specific capacitance of the electrode is obtained as 212 F g−1 and 609 F/g for polyaniline and nanocomposite respectively at a scan rate of 0.01 V/S. Solar cell device performance study shows that power conversion efficiency is 5.54% for 1% reduced graphene oxide nanocomposite, 4.7% for 2% reinforced, 4.16% for 3% filler and 3.61% for 4% nanocomposite.

Excitation-wavelength-dependent photoluminescence in GaAs nanowires under high-pressure

GaAs nanowires (NWs) have wide application potential as near-infrared optical devices and the high-pressure strategy has been applied to modulate their crystal and electronic structures. As another typical thermodynamic parameter, temperature can also affect the optical performance of semiconductors. Here we report the excitation-wavelength-dependent photoluminescence (EWDP) in GaAs NWs under high-pressure conditions. The pressure for achieving the maximum photoluminescence (PL) intensity and bandgap transition from direct to indirect of GaAs NWs varies (1.7–2.7 GPa) with the wavelength of the incident lasers (633–473 nm). The Raman peak of GaAs NWs shifts towards higher frequency with increasing excitation wavelengths at the same high-pressure conditions, revealing the stronger heating effect induced by incident laser with the shorter wavelength. The relative temperature difference in GaAs NWs induced by two different lasers can be estimated up to 537 K, and the strong heating effect suppresses the light-emission efficiency in GaAs NWs. With increasing the pressure, the relative temperature difference presents a gradual declining trend and PL intensity presents an opposite trend, which relates to the pressure-induced suppression of nonradiative recombination in GaAs NWs. Our study provides insights into the mechanisms for the EWDP effect and an alternative route to modulate the high-pressure performance of nanodevices.

Structure and Luminescent Properties of Double‐Doped LiNbO3:Zn:Mg Crystals

The correlation between photoluminescence in the near‐IR region and point defect centers in the LiNbO3 crystals co‐doped with Zn and Mg both by homogeneous and direct methods has been studied. X‐ray diffraction (XRD) analysis shows that the LiNbO3:Zn:Mg (4.68:0.9 mol%) crystal obtained by homogeneous doping has the least number of intrinsic defects compared to the others. It has been established that ZnLi defects stimulate photoluminescence (PL) in the near‐IR region of the luminescence spectrum in the LiNbO3:Zn:Mg crystals obtained by homogeneous doping. The LiNbO3:Zn:Mg (4.68:0.90 mol%) crystal has the maximum PL intensity and the LiNbO3:Zn:Mg (3.83:0.97 mol%) crystal has the minimum. Both crystals are doped homogeneously. Such defects as niobium vacancies (VNb) and niobium in the empty octahedron (Nboct) are suggested as luminescence quenchers in the co‐doped crystals.

Optical activation of praseodymium ions implanted in gallium nitride after ultra-high pressure annealing

Lanthanide (Ln)-implanted gallium nitride (GaN) semiconductors have a variety of potential applications as light-emitting devices and quantum light sources, but their optical properties are not well understood. In this study, we investigate the room temperature optical properties of praseodymium (Pr) ion implanted single-crystal GaN and their changes upon ultrahigh pressure annealing (UHPA) up to 1480 °C. Photoluminescence (PL) spectra, luminescence transition lifetime, and excitation cross section of the implanted Pr ions are analyzed. In addition, the recovery of implantation-induced damage and the thermal diffusion of implanted Pr ions by UHPA are investigated by X-ray diffraction, Raman spectroscopy, and secondary ion mass spectrometry. The results show that the implantation damage is recovered by annealing at temperatures above 1200 °C, but Pr ions thermally diffuse to the surface as the annealing temperature increases. The annealing temperature at which a maximum PL intensity is obtained increases with increasing the implantation dose. However, the PL intensity decreases in all cases after annealing at 1480 °C, indicating that a quenching factor is dominant in this temperature range.

Structural and optical characteristics of α-Bi2O3/ Bi2O(3-x):Ho3+ thin films deposited by pulsed laser deposition for improved green and near-infrared emissions and photocatalytic activity

Pulsed laser deposited films on glass substrate deposited at different substrate temperatures (Ts) and partial pressures of oxygen, Ho3+-doped Bi2O3 films were produced. The degradation capability of the Rhodamine B dye using the Bi2O3:Ho3+ films was explored. The impact of the Bi2O3:Ho3+ content on the dye degradation performance was analyzed. The X-ray powder diffraction patterns showed that the films deposited at 400 °C had an α-Bi2O3 phase. The impacts of various Ts and O2 partial pressures were correlated with the surface morphology and the thickness of the films using results of field emission scanning electron microscope. The thin films deposited at a low O2 partial pressure of 5–20 mTorr at Ts = 400 °C exhibited nano-needles with an average size of 80 nm and a length of ∼750 nm. The estimated band gap of the prepared films was found to vary between 2.6 and 3.0 eV. The photoluminescence (PL) of the Bi2O3:Ho3+ thin films excited at 450 nm showed an intense green band emission observed at 548 nm, and the feeble emissions at 654 and 753 nm were ascribed to the transitions of Ho3+. The nano-needle particles of the α-Bi2O3:Ho3+ exhibited a maximum PL intensity for the 20 mTorr O2 partial pressure thin film. The films prepared in vacuum and with an O2 partial pressure of 5 mTorr exhibited a 41 % dye degradation efficiency during a duration of 270 min of the photocatalysis experiment.

Study on photoluminescence of integrated nano-calcium carbonate (CaCO3) enhanced with dysprosium (Dy) doped calcium borophosphate (CBP) phosphor

Purpose There is a strong inducement to develop new inorganic materials to substitute the current industrial pigments, which are known for their poor ultraviolet absorbent and low photoluminescence (PL) properties. The purpose of this paper is to invent a better rare-earth-based pigment material as a spectral modifier with good luminescence properties to enhance the spectral response for photovoltaic panel application. Design/methodology/approach Different phosphor samples made of nano-calcium carbonate (CaCO3) with varied wt.% of the dopant Dysprosium doped calcium borophosphate (CBP/Dy) as (W0 – 0%, W1 – 3,85%, W2 – 7.41%, W3 –10.71% and W4 –13.79%) were prepared via the solid-state diffusion method at 600 °C for 6 h using a muffle furnace. The structural, morphological and luminescence properties of the CaCO3:CBP/Dy powder samples were examined using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and PL test. Findings The XRD, SEM and FTIR results verified the crystalline formation, morphological behaviour and vibration bonds of synthesized CBP/Dy-doped CaCO3 powder samples. XRD pattern revealed that the synthesized powder samples exhibit crystalline structured materials, and SEM results showed irregular shape and porous-like structured morphologies. FTIR spectrum shows prominent bands at 712, 874 and 1,404 cm−1, corresponding to asymmetric stretching vibrations of CO32− groups and out-of-plane bending. PL characterization of CBP/Dy-doped CaCO3 (sample W) shows emission at 427 nm (λmax) under the excitation of 358 nm. The intensity of PL emission spectra drops due to the concentration quenching effect, while the maximum PL intensity is observed in the W3 phosphor powder system. Research limitations/implications This phosphor powder is expected to find out the potential application such as a spectral modifier which is applied to match the energy of photons with solar cell bandgap to improve spectral absorption and lead to better efficiency. Originality/value The introduction of a nano-CaCO3:CBP/Dy hybrid powder system with good luminescence properties to be used as spectral modifiers for solar cell application has been synthesized in the lab, which is a novel attempt.

Investigation of the synthesis of nanostructures with increased photoluminescence obtained by depositing ultrathin layers of ZnO to the surface of porous silicon

Determining the features of the formation of hierarchical structures based on the interactions of elementary particles is a promising area of research. The deposition of 20 and 25 layers of zinc oxide by spray pyrolysis on the Si surface with stepped porosity led to the formation of ZnO particles of various sizes. X-ray fluorescence spectroscopy revealed zinc-containing compounds in thin formed layers. The maximum photoluminescence intensity and peaks characteristic of nanosized zinc oxide were found for a sample with 25 film layers. The mechanism of nanocrystal formation includes the capture of charges on oxygen vacancies.

Preparation and Characterization of Polyvinyl Alcohol (PVA)/ZrO2 Composite Membranes

Nanocomposite membranes of ZrO2‐doped polyvinyl alcohol (PVA) with varying amounts of ZrO2 nanoparticles (5, 9, and 13 wt%) have been prepared via a solution casting technique. The ZrO2 nanoparticles are used as a filler synthesized by sol–gel technique. Effects of ZrO2 nanoparticles doping on composites’ morphological, optical, luminescence, and structural characteristics have been analyzed using atomic force microscopy, X‐ray diffraction (XRD), UV–visible spectroscopy, photoluminescence (PL) spectroscopy, Fourier transform infrared spectroscopy, X‐ray photo electron spectroscopy, and field emission scanning electron microscopy. The XRD studies confirm the successful incorporation of ZrO2 into the PVA matrix and showed improved crystallinity following the doping of ZrO2 in PVA. The average size of ZrO2 nanoparticles calculated by XRD agrees well with the particle size measured by transmission electron microscopy. The UV–visible studies of nanocomposite membranes show an enhancement in absorption intensity and a slight red shift in peak positions as the ZrO2 concentration increases. The enhancement in absorption intensity suggests the potential applications in filters and solar cells. The maximum PL intensity observed for 5 wt% of ZrO2 in the PVA/ZrO2 composite membrane suggests that this concentration is most suitable for optoelectronic applications.

Host sensitization of luminescence of lanthanide activators in NaBi(WO4)2

The synthesis and luminescence of a series of NaBi(WO4)2 activated with trivalent lanthanides Tb, Sm and Nd using the solid-state reaction method is reported. All samples were characterised by X-ray diffraction (XRD), scanning electron microscope (SEM) and photoluminescence (PL). The XRD study confirmed the tetragonal phase without any secondary phase. Particles of irregular shape ranging between 5 and 20 µm were observed. Elemental composition was obtained from EDAX and results were found consistent with the formula NaBi(WO4)2. The formation of single-phase NaBi(WO4)2 was again confirmed through these results. Elemental mapping indicated that all elements were uniformly distributed. The band gap was evaluated using Tauc’s. formula and was found from 5.6 eV to 5.91 eV which is higher than reported values (3.6 eV). For NaBi(WO4)2:Tb, excitation was monitored for 545 nm emission. Emission spectra upon excitation by 488 nm showed prominent lines around 545 and 549 nm. These are due to the transition 5D4 7F5. 5 mol.% Tb yielded maximum PL intensity. When 405 nm excitation is used for Sm3+ doped phosphor, lines can be seen in three groups around 564, 600 and 647 nm. The highest emission intensity is observed for Sm3+ concentration of 5 mol.% and quenching was observed for high values. A weak band could be seen in the excitation spectra which is distinct from the f-f lines. The position of this band is close to that observed in the reflectance spectra. Hence it is proposed that there is host sensitization, even though weak, of the lanthanide luminescence in this host. Sensitization is most probably due to Bi3+ Ln3+ energy transfer.

Creation and repair of luminescence defects in hexagonal boron nitride by irradiation and annealing for optical neutron detection

Hexagonal boron nitride (hBN) is promising for applications in neutron detection and quantum sensing. Here we created spin-dependent luminescence defects in hBN using 50 keV helium ion beam. The irradiated hBN flakes with a dose around 2 × 1014–1 × 1015/cm2 have the maximum photoluminescence (PL) intensity. The PL spectra are in the range of 700–1000 nm with a peak around 818 nm at 297 K after irradiation with a dose of less than 2 × 1014/cm2, which can be eliminated by high temperature annealing at 1097 K due to defects repair according to Raman spectra. However, the PL peaks exhibit a redshift from 818 nm to 830 nm when the irradiation dose is no less than 1 × 1015/cm2. Combining with constrained density functional theory calculations, it is found that high dose irradiation can cause local lattice swelling and further induce the redshift of PL spectra by 12 nm/0.33% strain. Furthermore, we proposal a novel optical neutron detection method by recording the intensity and position of PL signal of luminescence defects induced by neutron-10B nuclear reaction daughter particles. This work would be helpful to create luminescence defects in hBN for quantum sensing, and develop a novel neutron detector.

Near infrared photoluminescence of Si1–xGex quantum dots fabricated by double hot Ge+/Si+ implantation into SiO2 layer

In this study, we developed very simple and ULSI (ultra large scale integration) compatible fabrication processes for group-IV (Si1–xGex and Si) semiconductor quantum dots (QDs) to apply hybrid ULSIs with photonic and electron devices, using double Ge+/Si+ hot-ion implantation into a SiO2 layer with larger bandgap EG and the post-furnace annealing. We successfully demonstrated the near-infrared (IR) photoluminescence (PL) from Si1–xGex-QDs. Transmission electron microscopy observations of single-crystallized Si1–xGex-QDs revealed that the diameter and the QD density were 3.6 ± 0.9 nm and (2.6 ± 0.4) × 1012 cm−2, respectively. In addition, Ge atoms were detected in the Si1–xGex-QDs by the energy dispersive x-ray spectroscopy analysis, and the Ge fraction of Si1–xGex-QDs was varied from 0.06 to 0.26 by changing the Ge ion dose. The increase in the PL intensity by forming gas annealing was attributed to the dangling-bond reduction by the H-atom termination method. The PL spectrum of Si1–xGex-QDs was fitted by PL components of two QD structures containing Si1–xGex and Si materials. The PL intensity and PL-peak photon energy of Si1–xGex-QDs strongly depended on the Ge fraction. The Si1–xGex-QDs achieved the maximum PL intensity at x ≈ 0.13. High PL-peak photon energy (∼1.31 eV) of Si1–xGex-QDs is attributed to the quantum confinement effect of carriers in QDs. Consequently, group-IV semiconductor QDs including Si1–xGex, Si, SiC, and C, through the simple hot-ion implantation into the SiO2 layer, exhibited a wide range of PL emissions from the near-IR to ultraviolet regions.

Luminescence Properties of Fe2+:ZnSe Single Crystals Grown via a Traveling Heater Method

The luminescence properties of iron-doped ZnSe (Fe2+:ZnSe) single crystals grown via a traveling heater method have been studied via photoluminescence (PL). Nine emission bands were identified in the PL spectra of Fe2+:ZnSe single crystals and their origins were also discussed. The near-infrared emission bands seen at 820 nm and 978 nm can be attributed to the emission bands formed by the background Fe or other impurity-related defect complexes in Fe2+:ZnSe single crystals, rather than by doped transition-metal-related defects. With the increase in temperature, the PL intensity increased slightly and reached a maximum near room temperature for bound excitons (430–490 nm), but the PL intensity decreased significantly for impurity-defect emission bands (500–720 nm), indicating the occurrence of a thermal quenching effect. The excitation wavelength-dependent PL spectra showed that PL intensity first increased and then decreased with an increase in the excitation wavelengths, and the maximum PL intensity of the bound excitons was obtained at 364 nm. In addition, the X-ray photoelectron spectroscopy (XPS) results showed that both bivalent and trivalent iron ions were found, but bivalence was the dominant charge state for iron atoms in the iron-doped ZnSe single crystals, meaning that they are suitable for developing mid-infrared gain medium applications.

Photoluminescence and lifetime studies of C-dot decorated CdS/ZnFe2O4 composite designed for photoelectrochemical applications

Cadmium sulphide (CdS) is a well-known material for photoelectrochemical water splitting as a photoanode. The valence and conduction band edges are well suited for both hydrogen and oxygen evolution reactions. However, a major drawback in the case of cadmium sulphide is its photocorrosion. In this regard, formation of a Type II heterostructure helps in well separation of the photogenerated charge carriers and reduces photocorrosion. Herein, we have incorporated a carbon dot layer (high conductivity) in between a CdS/ZnFe2O4 Type II composite heterostructure to further enhance the photoelectrochemical performance of the material. Steady state photoluminescence (PL) study revealed that maximum PL intensity is observed in the case of bare CdS while minimum intensity in the case of ternary composite after the incorporation of carbon dots. The inflation of PL intensity revealed the overall increase in the conductivity and enhanced charge separation at the interface after composite formation. The time-resolved photoluminescence (TRPL) decay dynamics have also been studied. The lifetime of the charge carriers for the ternary composite was found to be 2.41 ns, which is much higher than the bare (0.78 ns) and binary composite (0.85 ns), indicating the improved charge separation and the stability after composite formation (CdS/C-dot/ZnFe2O4). This further aids in the enhancement of photocurrent generation. The photocurrent density is enhanced by approximately 50 times compared to the bare material (CdS) and 5 times compared to the binary composite (CdS/ZnFe2O4).

Effect of Interfacial Schemes on the Optical and Structural Properties of InAs/GaSb Type-II Superlattices.

Incorporating an intentional strain compensating InSb interface (IF) layer in InAs/GaSb type-II superlattices (T2SLs) enhances device performance. But there is a lack of studies that correlate this approach's optical and structural quality, so the mechanisms by which this improvement is achieved remain unclear. One critical issue in increasing the performance of InAs/GaSb T2SLs arises from the lattice mismatch between InAs and GaSb, leading to interfacial strain in the structure. Not only that but also, since each side of the InAs/GaSb heterosystem does not have common atoms, there is a possibility of atomic intermixing at the IFs. To address such issues, an intentional InSb interfacial layer is commonly introduced at the InAs-on-GaSb and GaSb-on-InAs IFs to compensate for the strain and the chemical mismatches. In this report, we investigate InAs/GaSb T2SLs with (Sample A) and without (Sample B) InSb IF layers emitting in the mid-wavelength infrared (MWIR) through photoluminescence (PL) and band structure simulations. The PL studies indicate that the maximum PL intensity of Sample A is 1.6 times stronger than that of Sample B. This could be attributed to the effect of migration-enhanced epitaxy (MEE) growth mode. Band structure simulations understand the impact of atomic intermixing and segregation at T2SL IFs on the bandgap energy and PL intensity. It is observed that atomic intermixing at the IFs changes the bandgap energy and significantly affects the wave function overlap and the optical property of the samples. Transmission electron microscopy (TEM) measurements reveal that the T2SL IFs in Sample A are very rough compared to sharp IFs in Sample B, indicating a high possibility of atomic intermixing and segregation. Based on these results, it is believed that high-quality heterostructure could be achieved by controlling the IFs to enhance its structural and compositional homogeneities and the optical properties of the T2SLs.

Manufacturing a high-transmittance quantum-dot pixel frame using magnetic field and vibration field composite stamping

A simple way to complement full-color micro-light-emitting diode (micro-LED) displays is to employ ultraviolet or blue micro-LEDs with quantum dot (QD) converters. A pixel frame is essential for precisely locating the QD converter on a micro-LED chip and to limit the optical cross-talk effect. The limitations of pixel frames prepared by the commonly-used lithography technique, such as shallow depth and high dependence on high-transmittance substrates, have not been resolved in previous studies. In this study, we propose a magnetic-vibration composite stamping (MVCS) process to prepare a high-aspect-ratio and high-transmittance QD pixel frame. Magnetic extinction particles were employed, regulated, and converged into the wall of the pixel frame under the combined function of magnetic and vibration fields. Compared with the pixel frame prepared by the traditional stamping process, the pixelated QD converter achieved a 4.5-fold increase in the maximum photoluminescence intensity. Combining the micro-LED and pixelated QD converters in the pixel frame prepared by MVCS provides an alternative and practical approach for full-color micro-LED displays.

Investigation of Annealing and Crystallite Size on the Photoluminescence Properties of Ca2Al2SiO7: Eu Phosphors Prepared by Spray Pyrolysis

Crystalline gehlenite (Ca2Al2SiO7) phosphor, doped with Eu ions, was successfully synthesized by the spray pyrolysis method followed by annealing temperature. The crystallite size and photoluminescence characterization were investigated as function of the annealing temperature. The X-ray diffraction pattern indicates that all peaks could be ascribed to the tetragonal Ca2Al2SiO7 phase in which the dopant could not affect the crystal structures. All annealed powders emitted red luminescence at 613 nm under excitation of 394 nm. However, at 1300°C annealing temperature for Ca2Al2SiO7 doped with Eu ions, the maximum photo luminescent intensity has been obtained.

Temperature-dependent Photoluminescence Properties of Eu2+-doped CaMgSi2O6 Phosphors

The solid-state reaction method was used to synthesize 0.025Eu2+-doped CaMgSi2O6 (Eu-CaMgSi2O6) powder in the reduction atmosphere of 5% H2 + 95% N2 at 1300oC with a duration of 4 h. The reduction atmosphere was removed when the temperature was down to 800oC. The XRD pattern showed that only the CaMgSi2O6 phase was observed in synthesized 0.025Eu2+-doped CaMgSi2O6 powder. Room-temperature photoluminescence excitation (PLE) and photoluminescence (PL) spectra of Eu-CaMgSi2O6 phosphors were recorded by using the Hitachi F-4500 fluorescence spectrophotometer at wavelength ranges of 200–430 and 350–600 nm, respectively. A new important finding is that the synthesized Eu-CaMgSi2O6 phosphor has three important PLE wavelengths. Therefore, Eu-CaMgSi2O6 phosphors are measured from 25oC (room temperature) to 200oC under three different PLE wavelengths to find the effect of temperature on the variations of maximum photoluminescence intensities (PLmax). All the PL spectra show that only one emission band with a central wavelength of 449 nm is found, which is independent of the PLE wavelengths and is caused by the transition of 4f7 → 4f65d1. Another important finding is that the different PLE wavelengths have an apparent effect on the PLmax value of the Eu-CaMgSi2O6 phosphor. Finally, the decay-time curves of Eu-CaMgSi2O6 phosphor under three PLE wavelengths are also investigated.

Structural, compositional and luminescence studies of Y2O3:Eu3+ nanophosphor synthesized by sol-gel method

Europium doped Yttrium oxide (Y2O3) nanophosphors with different doping concentrations were synthesized by simple and efficient sol-gel method. The structural, morphological and compositional study was carried out by using XRD, FE-SEM, TEM, EDS, XPS, etc. Results demonstrated that the material is highly crystalline with cubic (body centered) structure and the particles apparently are of spherical shape with particle size around ∼10–20 nm. EDS results show the presence of Eu-impurity evenly distributed. Optimization of luminescence properties of the material by varying the concentration and annealing temperature show maximum thermoluminescence (TL) sensitivity at 1600 °C for 10.0 M% of Eu, however, maximum photoluminescence (PL) intensity was achieved after annealing the nanophosphor at 1200 °C. It exhibits a strong red emission with a sharp peak at 612 nm under excitation with UV and visible light (λex = 260, 393, 466 nm). TL studies showed four peaks at 100, 117, 139, and 301 °C. However, the first peak fades completely in a day (apparently due to low peak temperature) but the other three peaks are quite stable. The TL response was found to be linear from 120 Gy to 1.0 kGy but becomes sub-linear later in the dose range 1.0–100 kGy.

Effect of the Synthesis Conditions on the Morphology, Luminescence and Scintillation Properties of a New Light Scintillation Material Li2CaSiO4:Eu2+ for Neutron and Charged Particle Detection

In the present article, the influence of the activator concentration and impurity content of raw materials on the luminescence and scintillation properties of Li2CaSiO4 was studied. Polycrystalline powder material was obtained by the sol–gel method. It was shown that europium had limited solubility in the host lattice with a limiting concentration proximate to 0.014 formula units. The maximum intensity of photoluminescence was observed with a divalent europium concentration of 0.002 formula units; the light yield under alpha-particle excitation was measured to be 21,600 photons/MeV for ~200 μm of coating, and under neutron excitation, it was calculated to be 103,800 photons/n, the scintillation kinetics was characterized by an effective decay time of 157 ns. These properties and the transparency in the visible spectrum make it possible to produce scintillation screens with a coating of Li2CaSiO4 for detecting neutrons, alpha particles and low-energy beta radiation. The low Zeff (~15) of this compound makes it less sensitive to gamma rays. The 480 nm blue emission peak makes this material compatible with most commercial PMT photocathodes, CCD cameras and silicon photomultipliers, which have a maximum quantum efficiency in the blue–green spectral region.

Structural and luminescence studies of titanium co-doped SrY2 O4 :Eu phosphors.

Here, europium-doped (1 to 11 mol%) and titanium (1 to 5mol%)co-doped SrY2 O4 :Eu phosphors were synthesized using solid-state reaction method. The synthesized samples were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), and photoluminescence (PL) techniques for structural, morphological, functional group, and photoluminescence studies, respectively. XRD patterns confirmed the formation of pure phase SrY2 O4 at 1300°C and structural parameters were further determined using Rietveld refinement. FESEM micrographs revealed that doped and co-doped samples had different morphological features. All the samples were excited at ultraviolet light excitation and emission spectra consisted of peaks corresponding to the Eu ions. The maximum PL intensity was observed for 9mol% of Eu ions and 3mol% co-doping of Ti ions. The synthesized phosphors have potential applications in optoelectronics and display devices.