Peaks In Visible Region Research Articles

NIR-II Conjugated Electrolytes as Biomimetics of Lipid Bilayers for In Vivo Liposome Tracking.

Liposomes serve as promising and versatile vehicles for drug delivery. Tracking these nanosized vesicles, particularly in vivo, is crucial for understanding their pharmacokinetics. This study introduces the design and synthesis of three new conjugated electrolyte (CE) molecules, which emit in the second near-infrared window (NIR-II), facilitating deeper tissue penetration. Additionally, these CEs, acting as biomimetics of lipid bilayers, demonstrate superior compatibility with lipid membranes compared to commonly used carbocyanine dyes like DiR. To counteract the aggregation-caused quenching effect, CEs employ a twisted backbone, as such their fluorescence intensities can effectively enhance after a fluorophore multimerization strategy. Notably, a "passive" method was employed to integrate CEs into liposomes during the liposome formation, and membrane incorporation efficiency was significantly promoted to nearly 100%. To validate the in vivo tracking capability, the CE-containing liposomes were functionalized with cyclic arginine-glycine-aspartic acid (cRGD) peptides, serving as tumor-targeting ligands. Clear fluorescent images visualizing tumor site in living mice were captured by collecting the NIR-II emission. Uniquely, these CEs exhibit additional emission peak in visible region, enabling in vitro subcellular analysis using routine confocal microscopy. These results underscore the potential of CEs as a new-generation of membrane-targeting probes to facilitate the liposome-based medicine research.

NIR‐II Conjugated Electrolytes as Biomimetics of Lipid Bilayers for In Vivo Liposome Tracking

AbstractLiposomes serve as promising and versatile vehicles for drug delivery. Tracking these nanosized vesicles, particularly in vivo, is crucial for understanding their pharmacokinetics. This study introduces the design and synthesis of three new conjugated electrolyte (CE) molecules, which emit in the second near‐infrared window (NIR‐II), facilitating deeper tissue penetration. Additionally, these CEs, acting as biomimetics of lipid bilayers, demonstrate superior compatibility with lipid membranes compared to commonly used carbocyanine dyes like DiR. To counteract the aggregation‐caused quenching effect, CEs employ a twisted backbone, as such their fluorescence intensities can effectively enhance after a fluorophore multimerization strategy. Notably, a “passive” method was employed to integrate CEs into liposomes during the liposome formation, and membrane incorporation efficiency was significantly promoted to nearly 100%. To validate the in vivo tracking capability, the CE‐containing liposomes were functionalized with cyclic arginine‐glycine‐aspartic acid (cRGD) peptides, serving as tumor‐targeting ligands. Clear fluorescent images visualizing tumor site in living mice were captured by collecting the NIR‐II emission. Uniquely, these CEs exhibit additional emission peak in visible region, enabling in vitro subcellular analysis using routine confocal microscopy. These results underscore the potential of CEs as a new‐generation of membrane‐targeting probes to facilitate the liposome‐based medicine research.

Fabrication of Ag–TiO2 nanocomposite employing dielectric barrier discharge plasma for photodegradation of methylene blue

Ag nanoparticles have been incorporated in TiO2 to form Ag–TiO2 nanocomposite. The purpose was to enhance the photocatalytic activity of TiO2 in visible region. Ag–TiO2 nanocomposites were prepared using Dielectric Barrier Discharge Plasma operated at 14, 16 and 20 kV. XRD depicts the formation of cubic Ag with tetragonal geometry of TiO2. FTIR confirms the presence of Ag–O, Ti–O and Ag–O–Ti vibrations. UV-VIS shows that the TiO2 and pristine AgTiO2 do not have any absorption peaks in visible region. However, for 16 and 20 kV plasma treated samples, an absorption peak in visible region (580–720 nm) is observed. Evolution of this peak is because of the bandgap tuning from 3.15 to 2.31 eV. Ag–TiO2 based Photodegradation of methylene blue under UV, Plasma, and sunlight reveals that 16 kV Plasma treated Ag–TiO2 is the best under sunlight (93%). It is concluded that plasma treatment has activated Ag–TiO2 for photo degradation in the visible region.

Effect of Annealing Temperature on Excitonic Binding Energy and Other Optical Properties of Mn-Ni Co-Doped Transparent ZnO Thin Films

In this work, low cost sol-gel spin coating technique was successfully employed to deposit Mn-Ni co-doped ZnO (MNZO) thin films on glass substrates. Structural, topographical and optical properties of MNZO thin films were studied in the light of XRD spectra, Raman spectroscopy, SEM, AFM, UV-visible spectroscopy and photoluminescence spectroscopy. XRD study revealed that all annealed ZnO thin films have hexagonal wurtzite structure with (002) preferred orientation along c-axis. Hexagonal wurtzite structure for all films has been confirmed by Raman spectra which show optical phonon modes. Grain size, micropores and RMS surface roughness showed an increasing trend with the rise in annealing temperature as revealed by SEM and AFM images. The experimental data of absorption coefficient was analysed in the light of hydrogenic excitonic model to estimate excitonic binding energy (R) and other optical parameters of the prepared thin films. The excitonic binding energy decreased from 71.55 to 49.2 meV on increasing annealing temperature from 200° to 500°C. Peaks corresponding to UV, violet, green, yellow and orange were clearly observed in photoluminescence spectra for all annealed thin films. The ultraviolet peak shifted towards lower wavelength (blue-shifted) as the annealing temperature was increased. All the peaks in visible region were attributed to transition between complex intrinsic and extrinsic defects. Such films can be a potential candidate for efficient lasers and LEDs and for variety of optoelectronic device applications.

Sustainable synthesis of silver nanoparticles using fruit waste and its antibacterial activity

Herein we have employed efficient, inexpensive and eco-friendly green synthesis process to produce well-defined geometries of silver nanoparticles at room temperature by utilizing fruit extracts (Punica granatum and Artocarpus heterophyllus) having unique optical, antibacterial and catalytic property. Reducing or anti-oxidant properties of phytochemicals present in fruit waste are typically responsible for reduction of metal precursor into their respective nanoparticles.Occurrence of surface plasmon resonance (SPR) peak in visible region (around 420 nm) as characterized by UV–Vis spectroscopy indicates formation of silver nanoparticles further confirmed via Transmission electron microscopy (TEM) measurements. The average size and stability are detected by dynamic light scattering (DLS), zeta potential analysis and TEM measurements. Crystallinity and face-centered cubic (fcc) structure of formed silver nanoparticles are examined via selected electron area diffraction (SEAD) pattern. Antibacterial sensitivity of formed silver nanoparticles against the bacteria E Coli is also determined.

Investigation of spectroscopic and photoluminescence properties of Erbium doped phosphate (P2O5-K2O3-Al2O3) glasses

Erbium (Er) doped P2O5-K2O3-Al2O3:Er2O3 glasses (KPEr) with different contents of Er3+ ions were fabricated by famous melt-quenching technique. The fabricated samples were characterized by using physical, X-ray photoelectron spectroscopy (XPS), photoluminescence, absorption, and J-O analysis techniques. The XRF analyses were performed in order to know the change in elemental composition of fabricated glasses, while using the various concentrations of Er3+ ions. Three emission peaks were observed, two peaks in visible regions of 526 nm (2H11/2→4I15/2) and 550 nm (4S3/2→4I15/2) and one peak in near infrared (NIR) region of 1545 nm (4I13/2→4I15/2). Nine peaks were observed in absorption spectra in the range of 390–1800 nm. The trend of JO parameters for the present KPEr6 glass sample is Ω2> Ω4> Ω6. Higher values of stimulated emission cross-section σemi(λ), full wave half maxima FWHM and (FWHM x σemi (λ)), for KPEr6 indicate that the present glass has potential candidate to be used for broadband amplification in telecommunication. The McCumber theory is used to study absorption and emission cross-section for 4I13/2→4I15/2 transition. The luminescence colors of these samples were almost entirely fall in the yellow-green (Y-G) region (x = 0.33, y = 0.64) in the CIE 1931 diagram. The calculated CCT values for our prepared glasses were found to be 5554 K. The present study suggest that KPEr glass samples have potential candidate for broadband amplification in telecommunication, green LED and display devices.

Spectroscopic analysis of Dy3+ ions activated borosilicate glasses for photonic device applications

Abstract A new series of optically translucent borosilicate glasses activated with varying concentrations of Dy3+ ions were fabricated by employing melt quenching method. Spectral investigations were conducted by recording the absorption, photoluminescent (PL) excitation and PL emission for Dy3+ activated borosilicate glasses. The absorption spectral information was exposed to Judd-Ofelt (J-O) analysis to calculate various radiative properties such as transition probability, total transition probability, branching ratios and radiative lifetimes of the as synthesized glasses. The excitation spectrum recorded under 483 nm emission wavelength possess a sharp peak at 348 nm in 0.1 mol% of Dy3+ ions doped borosilicate glass. Emission spectra recorded for all the Dy3+ ions activated borosilicate glasses under 348 nm intense excitation wavelength exhibit two potential peaks in visible region at 483 nm (4F9/2 → 6H15/2) and 575 nm (4F9/2 → 6H13/2). The emission centered at 483 nm is most prominent. Radiative properties measured from the absorption spectral feature were correlated with emission spectral information to estimate emission cross-section, gain bandwidth and optical gain parameters to understand the utility of the as synthesized glasses as photonic devices. The CIE coordinates measured for all the titled glasses are in good proximity with the white light coordinates of CIE 1931 diagram.

Impact of vacancy defects on optoelectronic and magnetic properties of Mn-doped ZnSe

Based on first principles calculations, we have investigated the electronic, magnetic and optical properties of Mn-doped ZnSe with and without vacancy defects. We find that the incorporation of Mn at Zn site changes the non-magnetic ground state of ZnSe to magnetic ground state with total magnetic moment 5 μB. From the investigation of magnetic coupling, it is found that the interaction between Mn spins in Mn-doped ZnSe is AFM which can be explained in term of super-exchange mechanism. The effect of vacancy defects such as Zn or Se vacancy on magnetic coupling between Mn spins were also analyzed and we found that Zn-vacancy promotes double exchange interaction which stabilizes the ferromagnetic state and room temperature ferromagnetism is expected while Se-vacancy doesn’t change magnetic ground state from AFM to FM states. The magnetic interactions in Mn-doped ZnSe system with and without Zn vacancy were explained using phenomenological band structure model. Moreover, optical absorptions for all systems were investigated at their stable magnetic states and we found that Mn doping causes the red shifted in absorption edge which is due to the spin forbidden d-d transitions (4T1-6A1) in Mn ions. The new peak in low energy range is related to the acceptor states introduced by Zn-vacancy in Mn-doped ZnSe system. The Se-vacancy generates peaks in visible region which is attributed to the donor states caused by Se-vacancy. Finally, the d-d transition (4T1-6A1) in FM and AFM coupled Mn ions were also studied and we found that the d-d transition peaks in AFM and FM coupled Mn ions are blue and red shifted respectively. Similarly, the blue and red shift in the energy bandgap of ZnSe are also observed in AFM and FM coupled Mn ions which support the agreement between the experimental and theoretical observations.

Magnetic and Optical Properties of Ag‐CoFe Nanohybrids Prepared by a Sequenced Microfluidic Process

AbstractMetal‐based magnetic nanoparticles (NPs) with hybrid structures are currently attracting extensive attention due to the synergistic effects among constructing components. Their unique physicochemical properties endow them with widespread applications in catalysis, optics, magnetic separation and magnetic resonance imaging contrast agents. However, the formation of nanohybrids (NHs) is usually difficult due to the incompatibility of components, especially for NHs of core‐shell structures with mismatched crystal lattices. In this study, NHs containing Ag core and CoFe alloy surface layer (Ag‐CoFe NHs) with varieties of hybrid structures were successfully synthesized by a sequenced microfluidic process. The hybrid structure formation mechanism was discussed according to the crystal plane matching theory, and their related optical and magnetic properties were investigated. When compared to Ag NPs, Ag‐CoFe NHs presented a distinct red shifted and broader absorption peak in visible region. This may be attributed to the changes in dielectric constant caused by different CoFe shells and the diversity of hybrid structures. Moreover, due to the interface pinning effects and magnetoelectric coupling effect between Ag cores and CoFe shells, the superparamagnetic properties of Ag‐CoFe NHs still existed at room temperature although its block temperature was much higher than that of CoFe NPs. Based on these characteristics, the Ag‐CoFe NHs show great potential in magneto‐optics, multi‐mode nanomedicines and other related fields.

Strain-tuned optical property in magnetoelectric LiFe5O8 thin film

Based on the density-functional theory, we investigated the energy band structure and optical property of LiFe5O8 thin film with different biaxial strains using the first-principles calculations for ferrimagnetic (FI) and ferromagnetic (FM) states. The calculations indicated that a great magnetostriction exists in LiFe5O8 films, and both FI and FM LiFe5O8 films have the strong and wide absorption peak in visible region. The investigations found that, different from the other semiconductor photovoltaic material, both tensile strain and compressive strain decrease the band gap of LiFe5O8 whether it’s in FM or FI state. The FI LiFe5O8 possesses the direct band gap that can be adjusted from 1.33 to 1.47 eV under −3% biaxial strain, while the FM ones are of relative smaller indirect band gaps with 0.61∼0.82 eV in these strains. Furthermore, by comparing the variations of carrier effective mass and concentration, as well as the electronic and optical band gaps in different strains, we found that the effects of compressive strain on broadening optical absorption and increasing carrier concentration of LiFe5O8 thin films is obviously more helpful than those of the tensile strain, particular in FM state. These results indicated that the strain-tuned LiFe5O8 films possess the extensively application prospects in magnetoelectric photovoltaic fields.

Synthesis of ZnO/ZnS core/shell microsphere and its photocatalytic activity for methylene blue and eosin dyes degradation

In this paper, ZnO/ZnS photocatalyst was synthesized by a relatively simple method. The synthesized ZnO/ZnS microspheres have a nice core-shell structure. The structure of ZnO/ZnS composites was studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The diameter of the microsphere was about 800 nm, and the shell structure was 200 nm. The structure and composition of the composites were studied by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The absorption intensity of ZnO and ZnO/ZnS in UV-Vis region was compared by UV–vis diffuse reflectance spectroscopy. ZnO/ZnS has absorption peaks in visible region, while ZnO does not. The photocatalytic experiment of ZnO/ZnS photocatalyst proves that the photocatalyst has good degradation effect on methylene blue (MB) and eosin under visible light irradiation. This is a great improvement in the treatment of various organic pollutants in water.

Down-conversion characteristics of Eu3+ doped M2Y2Si2O9 (M = Ba, Ca, Mg and Sr) nanomaterials for innovative solar panels

Down-conversion properties of Eu3+ doped M2Y2Si2O9 (M = Ba, Ca, Mg, Sr) phosphors have been investigated in detail. These phosphors were synthesized via the simple, fast and cost-effective sol-gel technique at a temperature of 950 °C. Color coordinates and emission color can be altered by the varying concentration of dopant ion in Ca2Y2Si2O9 phosphor. Optimum luminescence intensity was obtained when doping 0.03 mol of Eu3+ ion. Using the excitation wavelength of 395 nm, these silicates showed strong red color, pure and sharp spectral peaks in visible region due to 5D0→7F1-3 transitions of Eu3+ present in the lattice. Effect of reaction temperature on luminescence was also analyzed for these phosphors. The sharp peaks in the X-ray diffraction pattern indicated the high crystallinity of prepared phosphors. Ca2Y2Si2O9 has shown an orthorhombic crystal structure. The FTIR results confirmed the metal-oxygen vibrational modes available in the range of 400–1600 cm−1. Transmission electron microscopy images have revealed that the variation of alkaline earth metal provided a very different crystal structure. Excellent down conversion response of these phosphor materials can provide a great significance in the application of the coming solar devices.

Study of the extrinsic properties of Copper doped Cadmium Sulfide Thin Film by Hydrothermal assisted CBD Method

Cadmium sulphide (CdS) and Cu doped CdS film were deposited onto commercially available FTO glass substrate by the hydrothermal assisted chemical bath deposition (HACBD). The effect of doping on the properties of CdS films were investigated. Optical, morphological, structural and photoluminescence properties of deposited films were investigated using UV–vis spectroscopy, SEM, FTIR, x-ray diffraction and photoluminescence spectroscopy (PL). Lower value of the bandgap energy was observed for the Cu doped CdS films as compared to those of the undoped CdS films. XRD patterns revealed a cubic and hexagonal crystal structure phase with (1 1 1) and (0 0 2) as the preferential orientation having an average crystallite size of 18 nm. SEM images revealed a change in the morphology of CdS and Cu-CdS thin films from spherical to disclike structures. PL spectra showed strong emission peak in visible region for both doped and undoped films. The associated chemical bonds were investigated using FTIR spectroscopy.

Twisted donor substituted simple thiophene dyes retard the dye aggregation and charge recombination in dye-sensitized solar cells

Abstract Two novel thiophene 3,4-disubstituted organic dyes with double acceptors at 2,5-position framework photosensitizers were carefully designed and synthesized for the dye sensitized solar cell (DSSC) application. In this submission, the influence of carbazole (Cz) and triphenylaime (NPh3) units substitution at 3,4-position of thiophene is studied. Both the planar structure of carbazole based dyes and three dimension structure of triphenylamine based dyes are found to effectively inhibit the I − /I 3 − and Co +2 /Co +3 electrolyte on TiO 2 surface. The results show that varying the donor position in dyes also effectively works for DSSC application, even if it does not broaden the absorption peak in visible region (for both the dyes) due to the blocking of electron delocalization at 2,5-positions by acceptor units. With two twisted donors at 3,4-position in Cz-Th-Dye, NPh3-Th-Dye the dye aggregation and charge recombination retarded. The optical, electrochemical, density functional theory and TRPL studies were used to estimate the photovoltaic properties of the dyes. The dye having two acceptors on both sides (2,5-position) of thiophene moiety showed efficient electron extraction from the electron donor part. Without using any additives, Cz-Th dye and NPh3-Th dye in presence of cobalt (II/III) redox shuttle, resulted in the power conversion efficiency (η, PCE) of ∼3.4% and 3.1% respectively. By replacing one acceptor with any other donor, these thiophene moiety can effectively work as a new π-spacer in DSSC application.

Long afterglow in hexagonal SrAl2O4:Eu2+, Dy3+ synthesized by crystallization of glass and solidification of supercooled melts

High temperature phase of hexagonal SrAl2O4:Eu2+,Dy3+ crystals were synthesized via two paths; (1) heat-treatment on glass (a conventional glass crystallization technique), and (2) solidification of supercooled melts in melt-cooling process with non-contact process, where a levitation melting technique was used to obtain precursor glass and ceramics beads. Hexagonal SrAl2O4 (βʹ-phase) were formed in both samples, not stable phase of monoclinic phase (α-phase), which is well known as one of the best afterglow material. Both samples with hexagonal phase showed brighter broad green emission, higher intensity of PLE peak in visible region (λ=400–500nm), and longer duration of afterglow compared to monoclinic SrAl2O4:Eu2+,Dy3+ sintered by solid-state reaction.

Effect of Mn doping on the structural, magnetic, optical and electrical properties of ZrO2–SnO2 thin films prepared by sol–gel method

Manganese doped ZrO2–SnO2 (ZrO2–SnO2: Mn) nanocomposite thin films were prepared using sol – gel dip coating technique. The structural, morphological, magnetic, optical and electrical properties of the films were studied for undoped and different (15 mol %) manganese doping concentrations. X-ray diffraction pattern (XRD) of films showed the formation of tetragonal phase of SnO2 and orthorhombic ZrSnO4. Decrease in crystallinity with increase of Mn concentration was observed for the films. Scanning electron microscopy (SEM) showed the formation of grain growth with an increase in Mn concentration. X-ray photo electron spectroscopy (XPS) confirmed the presence of Zr4+, Sn4+ and Mn2+ ion in ZrO2–SnO2: Mn films. Vibrating sample magnetometer (VSM) measurements reveal the presence of magnetic properties in Mn doped nanocomposite thin films. Antiferromagnetic interactions were observed for 5 mol % Mn doping. An average transmittance >80% (UV - Vis region) was observed for all the films. Band gap of the films decreased from 4.78 to 4.41 eV with increase in Mn concentration. Photoluminescence (PL) spectra of the films exhibited emission peaks in visible region of the electromagnetic spectra. Conductivity of the film increased up to 3 mol % Mn doping and then decreased.

Fabrication of chiral-molecular@ nanoparticle complex materials with great chiroptical effect in visible region

Chirality plays a key role in biochemical reaction and the self-assembled mechanism of life. The detection of chiral molecules is one crucial issue in biology, clinic, pharmacy and food security fields, which usually refers to the detectable chiroptical effect, i.e. circular dichroism (CD) and optical rotatory dispersion (ORD) Gansel et al. (2009), Quake and Scherer (2000), Pendry (2004), Zhang et al. (2009), Kastel et al. (2007) [1–5]. However, the chiroptical effect from chiral molecules in nature (such as proteins and DNAs) is usually very small and located in ultraviolet spectral region. This limits the detection sensitivity of chiral molecules and their ability to control electromagnetic wave. In this paper, we report a scalable fabrication of a new kind of chiral molecule@nanoparticle complex materials, which are composed of an achiral nano-cup array and a pair of chiral molecules (l-/d-cysteine). The nano-cup array with localized surface plasmonic response peak of 630nm is obtained with the micro-sphere assembly technique, which is a kind of scalable, low-cost and material-independent fabrication method. After coating a layer of chiral molecules on the surface of the nano-cup array, a clear induced-CD peak in visible region is demonstrated from the l/d-cysteine@nano-cups complex materials, the intensity of which can be much greater than the existing results [9–16]. Full-wave electromagnetic simulation method has been performed to get insight into the mechanism of the induced chiroptical effect. The simulation results indicate that this giant induced CD signal should be attributed to the electromagnetic interaction between chiral molecules and plasmonic nanostructures, especially for the wave at the plasmonic resonance peak. These results indicate the potential application prospect of these newly-fabricated complex chiral materials.

Upconversion and colour tunability of Gd2O3:Er3+ phosphor prepared by combustion synthesis method

Er3+ doped Gd2O3 phosphors were prepared by using solution combustion synthesis method. The structural characterization and the luminescence behaviour of the prepared phosphors were determined and compared. Average crystal size for the phosphors yielded was in nanometre range from 6 to 48 nm, which was calculated by using XRD and confirmed by SEM and TEM technique. The compositional analysis was done by FTIR. Qualitative and quantitative information regarding the powder sample were measured using EDX spectroscopy. EDX and FT-IR spectra confirms presence of Er3+ in the Gd2O3:Er3+ phosphors For photoluminescence studies the emission spectra were recorded under 980 nm excitations. All the phosphors give emission peaks in visible region. Effect of annealing and Er3+ concentration on emission spectra has been studied for the prepared phosphor. Specific colour produced by the prepared phosphor is determined by the CIE chromaticity technique. The emitted coloured was tuned by determining the CIE coordinates for different concentrations of Er3+ ion. The CIE coordinates of prepared phosphor confirms emission of green colour.

Preparation and characteristics of ZnO nanoflowers

Unlike the general substrates such as SiO2, ITO, and AZO, the metal foil used as a substrate is rarely studied in application in the substrate, however, it has lots of advantages including cheapness, good conductivity and excellent scalability. In this paper, an acanthosphere-like structure named ZnO nanoflowers is successfully synthesized on Cu foil by using chemical vapor deposition method. The gas flows with oxygen-argon ratios ranging from 1 : 150, 1 : 200, 1 : 250 to 1 : 400, which impacted on Cu foil, and the property of the ZnO nanoflowers are carefully studied. The SEM images shown that there are lots of ZnO nanorods grown on the sphere cores, and look like flowers. The ZnO nanoflowers contains uniformly sized ZnO nanorods and morphology with best flower structure when the oxygen/argon gas flow ratio is 1 : 250. Furthermore, the length-diameter ratio of the ZnO nanorods on the ZnO nanoflowers decreases as the oxygen-argon gas flow ratio decreases. The ZnO is of hexagonal wurtzite structure indicated by XRD pattern and there exist no other diffraction peaks existence except those from the Cu foil. In addition, the photoluminescence of ZnO nanoflower changes from a wave packet into a broad peak in the visible region when the oxygen-argon gas flow ratio between decreases. Further study of the photoluminescence by fitting the peaks in visible region with gaussian function indicates that the photoluminescence relating to the oxygen vacancy defects increases, but that relating to the zinc vacancy defects decreases. Therefore, the white light emitting device may be constructed based on the ZnO nanoflowers studied shown above. Finally, a possible model of the ZnO nanoflowers grown on Cu foil is proposed based on the experimental results.

High temperature solid state synthesis and photoluminescence behavior of Eu3+ doped GdAlO3 nanophosphor

Gadolinium monoaluminate is successfully synthesized by the high solid state reaction method. The method is suitable for large scale production. The high temperature synthesis techniques have some advantages to enhance the efficiency of luminescence. Samples were prepared with variable concentration of europium (0.5–6mol%) all the prepared sample were characterized by X-ray diffraction technique (XRD) and transmission electron microscopic (TEM) technique. The particle size was evaluated by Scherer’s formula and found around 55.16nm and having orthorhombic phase. The surface morphology of prepared phosphor was determined by TEM and it shows good connectivity with grain and formation of nano sized crystal. The photoluminescence with variable concentration of europium shows very good excitation and emission spectra. The excitation spectra monitored at 612nm excitation and excitation found with broad peaks at 266nm with shoulder peak at 274nm. The emission spectra monitored at 266nm and it shows all peaks in visible region (583, 594, 599, 613 and 630nm) with intense peak at 613nm (red emission). The intensity of PL spectra increases with increasing the concentration of europium, up to 5mol% after this concentration intensity decreases due to concentration quenching occurs. The spectrophotometric determination was determined by Commission Internationale de I’Eclairage (CIE) technique.