Carbon quantum dots (CQDs) are a novel class of material that grabbed many engrossments as a promising light-emitting material. In the present work, environmentally friendly, non-toxic, and fluorescent CQDs were synthesized using organic plant-based extracts, such as Brassica juncea (mustard seeds), Citrus limon (lemon juice), Cuminum cyminum (cumin seeds) and Mangifera indica (mango leaves) by following a hydrothermal route. The powder X-ray diffraction (PXRD) studies revealed a peak at 28.7 degrees corresponding to the (002) plane confirming the formation of CQDs. The transmission electron microscope (TEM) images for the synthesized CQDs revealed their average particle size of similar to 3 nm. The optical energy band gap of the prepared CQDs was found to be in the range of similar to 3.67 - 3.99 eV. The fluorescence emission spectra revealed an intense and broad peak centered at similar to 462 nm (blue fluorescence), which is attributed to electronic pi-pi* transition (CC bond) and n-pi* transition (CO bond) on the surface of the CQDs. The lemon juice-sourced CQDs showed a prominent fluorescence intensity as compared to other carbon sources due to the existence of the surface emissive trap state on the surface. The photoluminescence (PL) lifetime of the prepared Citrus limon-based CQDs was similar to 8.9 ns. The latent fingerprints (LFPs) were visualized using optimized Citrus limon sourced CDs on various porous and non-porous substrate surfaces and found type I, type II, and type III fingerprint details with high sensitivity, selectivity, and without any background hindrance, which, owing to prepared fine powder adheres to the only ridges of the fingerprints. The aforementioned results specifically navigate the applicability of the prepared CQDs in the forensic science field.

Covalent organic frameworks (COFs) are an important class of compounds having exceptional long-range ordered structures with porosity and crystallinity. In the present study, 6-chloropyrimidine 2, 4-diamine and terephthalaldehyde were made to react in ethanol solvent at reflux conditions using the solvothermal method resulting in the formation of pyrimidine based covalent organic frameworks (PyCOFs). The synthesized PyCOFs were then functionalized with cerium (Ce) and obtained as Ce@PyCOFs. The crystal structure, microstructure, purity, and optical properties of the synthesized PyCOFs and Ce@PyCOFs were confirmed by X-ray diffraction (XRD), field emission scanning microscope (FESEM), Fourier transform infrared spectroscopy (FT-IR), and UV-visible analytical techniques. Optical studies of PyCOFs and Ce@PyCOFs revealed redshift in maximum absorbance bands with decreased the optical band gap (Eg). The mean Zeta potential of PyCOFs, and Ce@PyCOFs varies between 15.60 mV and 37.84 mV. Room temperature photoluminescence (RTPL) studies of PyCOFs and Ce@PyCOFs unveiled broad yellow-green emission peaks centered at 567.9 nm, 571.3 nm, 380 nm, 559 nm and few weak sharp emission bands at various excitation wavelengths. Further, visible light photocatalytic dye degradation studies of PyCOFs and Ce@PyCOFs against methylene blue (MB) and methyl red (MR) dyes showed degradation efficiency of 73.50 %, 78.99 % and 89.18 %, 87.34 % in 140 min and 180 min of irradiation. Further, the effect of pH on photocatalysis showed the basic medium (pH = 11) necessary for the degradation of MB dye while the acidic medium (pH = 4) was necessary for the degradation of MR dyes. The effective dosage of the catalysts was found to be 0.04-0.06 g/L. The Ce@PyCOFs showed better photocatalytic degradation efficiency than PyCOFs. Further, PyCOFs and Ce@PyCOFs showed non-linear electrical susceptibility with the involvement of rotational diffusion anisotropy (xi). The PyCOFs and Ce@PyCOFs showed dielectric loss (tan delta) at higher applied frequency. The real (Z ') and imaginary parts (Z '') of the impedance decrease monotonically with an increase in applied frequency and become linear. Cole-Cole studies for PyCOFs showed Nyquist behavior with non-linear electrical susceptibility and change in the phase angle (theta). The resistance (R) decreases with an increase in applied frequency. However, Ce@PyCOFs, showed linear variation in complex impedance spectra indicating no change in the phase angle (theta) and the voltage (V)/current (I) varies linearly with applied frequency. The synthesized Ce@PyCOFs can be utilized for photonics, optoelectronics and photocatalytic device constructions and related applications.

The impact of the varying Dy3+ (1-9 mol %) rare earth ion concentration on the structural and luminous characteristics of La2O3 phosphors was studied via solution combustion synthesis. Structure formation, photoluminescence (PL) effectiveness, optical properties, and energy transfer mechanisms were examined in detail. All the synthesised samples exhibits hexagonal structure, which is supported by X-ray diffraction patterns (space group: P-3 mL (16 4)). Scanning electron microscope analysis shows irregular particle size and shapes of the synthesised materials. The presence of prominent and dominant Dy3+ ion peaks in the excitation spectrum of the ideal sample material, correlate to the Dy3+ ion's absorption peaks, supports the existence of considerable energy transfer among La3+ and Dy3+ ions. The PL emission wavelengths at 486 and 570 nm assigned to the Dy3+ ions transitions 4F9/2 -* 6H15/2 and 4F9/2 -* 6H13/2 respectively owing to the charge-transfer between La3+ and Dy3+ ions. PL emission intensity increases up to 3 mol% and afterwards it starts to decrease due to concentration quenching caused by non-radiative interactions. Photometric properties were investigated to check the possible utilization of La2O3:Dy3+ phosphor in white light emitting diodes application with CIE (x- 0.3468, y- 0.3986), CCT (0.1957, 0.5060), and colour purity (23.8 %). Aforementioned findings suggest that the synthesized phosphor is a viable option for making w-LEDs using NUV chips serving as the source of excitation.

Combustion synthesis was used to synthesise the undoped and Fe3+ ions incorporated ZrO2 nanostructures using Tamarind indica extract. The synthesised ZrO2 nanoparticles with a tetragonal phase and a particle size <45 nm were found by structural investigation. Fe doping causes the optical band gap of ZrO2 nanostructures to decrease. Due to the hybridization of the host and dopant orbitals, the energy band gap value of the resulting nanoparticles considerably become smaller (from 5.35 eV to 4.18 eV) towards the visible range. By studying PL measurements of the synthesised samples, it is confirmed that the presence of oxygen vacancies was observed. The size and phase purity of the nanoparticles are responsible for the intriguingly high dielectric constant increase of up to 9.7 x 10(4) with very little loss following the integration of Fe into the ZrO2 medium. The high value of dielectric constant and uniform nanoparticles produced have applications in high-frequency devices and technologies such as spintronics as multifunctional applications.

The envisaged design and development of individual materials to excavate a broader spectrum of desired properties and offer multiple applications are highly necessitating. Keeping this in mind, a series of forsterite-structured Mg2GeO4:Eu3+ (1 mol%-9 mol%) nanophosphors was synthesized via a solution combustion method using oxalyl dihydrazide as a fuel. The X-ray diffraction patterns confirm the orthorhombic crystal system with a Pnma space group. Morphological results clearly show irregularly shaped cluster-like structures with aggregation of the particles. Employing diffuse reflectance spectra, the optical energy band gap of the Mg2GeO4:Eu3+ (1 mol%-9 mol%) nanophosphors was estimated and obtained to be similar to 4.12-4.32 eV. The photoluminescence emission spectra exhibit intense peaks at similar to 579, 589, 610, 661, and 707 nm, which are due to characteristic D-5(0) -> F-7(0), D-5(0) -> F-7(1), D-5(0) -> F-7(2), D-5(0) -> F-7(3) and D-5(0) -> F-7(4) transitions of Eu3+ ions, respectively. The Commission International de L'Eclairage color coordinates are gradually tuned from pale red (0.5980, 0.4012) to a pure red (0.6385, 0.3611) region. Thermoluminescence glow peaks showcase excellent super -linear response at low doses of gamma-irradiations, indicating that the prepared phosphor can be used in thermoluminescent personal dosimetry which is a biological tissue equivalent. The aforementioned results demonstrate that the prepared Mg2GeO4:Eu3+ (1 mol%-9 mol%) nanophosphors are considered an excellent candidate for dual applications, i.e., red component in future generation white-light-emitting diodes (WLEDs) and personal dosimetric applications.

In the present study, cesium oxide(x)@cobalt oxide (Cs2Ox@Co3O4) (x = 5, 10 and 12 wt%) nanostructures (NS) were successfully synthesized by chemical precipitation method and characterized by XRD (X-ray diffraction), SEM (scanning electron microscope), EDX (energy dispersive X-ray), XPS (X-ray photoelectron spectroscopy), BET (Brunauer-Emmett-Teller), Raman, and UV-visible analytical techniques. XRD studies revealed the formation of the mixed phase of orthorhombic/monoclinic crystal structure. Disc shaped morphology of the cesium oxide(x)@cobalt oxide NS was noticed from SEM images. Redshift in optical absorbance and decrease in optical band gap (E-g) resulted in increase in Cs1+ concentration. Room temperature photoluminescence (RTPL) studies of cesium oxide(x)@cobalt oxide NS at various excitation wavelengths showed sharp and broad emission peaks located at 668.2 nm (red), 675.1 nm (red), 561.8 nm (yellow-green), 834.5 nm (near infrared region), 594 nm (yellow). Steady state photoluminescence (SSPL) studies revealed a sharp emission peak at similar to 428.0 nm (violet) with large stoke's shift (21.1 to 590.0 eV). The zeta potential studies showed a decrease in conductance from 62 to 57 mu s with an increase in mobility of the charge carriers (0.4 to 1.08 mu/s V/cm) and an increase in zeta potential (31.90 to 82.92 mV). AC resistance studies at various temperatures showed inducting coupling phenomenon in cesium oxide(x)@cobalt oxide NS with DC resistance of cesium oxide(5 wt.%)@cobalt oxide was found to be 8.2 x 10(-4) Sm-1. The relaxation frequency of cesium oxide(12 wt.%)@cobalt oxide NS was found be 1.2 x 10(5) Hz. The synthesized NS is a promising candidate for optoelectronics and photonic applications.

In the current study, an extract from Moringa Oleifera (MO) leaves was utilized for synthesis nanoparticles (ZnO) in an easy-to-use and ecologically friendly manner. Different ratios of MO leaf extraction (1:1, 1:3, 1:5, and 1:7, 1:9) were used to synthesize the nanostructured ZnO. The synthesized ZnO NPs were examined using an array of analytical methods, including energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV-Vis absorption spectroscopy, and antibacterial investigations. The synthesized MOL: ZnO NPs confirmed the hexagonal wurtzite structure, as demonstrated by XRD analysis. FT-IR demonstrated that the presence of distinct functional groups was required for the reduction of the metal ion into MOL: ZnO NPs. High purity and crystalline EDX has been used to identify the intense and narrow measurements of the zinc and oxygen found in the MOL: ZnO NPs. After being examined for antibacterial activity, the produced MOL: ZnO NPs showed the highest zones of inhibition against both gram negative Pseudomonas and gram positive Bacillus. The results show that ZnO-based NPs aided by leaf extract of Moringa Oleifera are the promising materials for a variety of applications such as food package applications and advanced forensic applications.

Nanomaterials have emerged as an active area of research. This is because of their broad spectrum of applications such as sensors, white light emitting diodes (LEDs), electronic displays, and other optoelectronic devices in the optics and electronic industries owing to their size- and shape-dependent properties. The synthesis technique plays a crucial role in tuning the size and shape of the materials. Herein, we briefly describe these nanomaterials' fundamental aspects, properties, and applications. Various nanomaterial synthesis methods are discussed. Their advantages and disadvantages are highlighted in conjunction with the criteria for selecting a synthesis method. The principle underlying the sonochemical method and its applicability in synthesizing diverse sub-15 nm size nanoparticles (NPs) are presented. The main objective of this article is to review recent studies on lanthanide-doped nanophosphors and the various parameters that play key roles in achieving optimum luminescence emission. Both down-conversion and up-conversion mechanisms are discussed. The importance of the combinations and concentrations of the synthesizer/activator, color tuning, and host material are emphasized.

Magnesium oxide nanostructured particles (NP) were prepared using a simple solution combustion technique using different leaf extracts such as Mangifera indica (Mango - Ma), Azadirachta indica (Neem—Ne), and Carica papaya (Papaya—Pa) as surfactants. The highly crystalline phase of MgO nanostructures was confirmed by PXRD and FTIR studies for 2 h 500°C calcined samples. To analyze the characteristics of obtained material–MaNP, NeNP, and PaNP for dosimetry applications, thermoluminescence (TL) studies were carried out for Co-60 gamma rays irradiated samples in the dose range 10–50 KGy; PaNP and NeNP exhibited well-defined glow curve when compared with MaNP samples. In addition, it was observed that the TL intensity decreases, with increase in gamma dose and the glow peak temperature is shifted towards the higher temperature with the increase in heating rate. The glow peak was segregated using glow curve deconvolution and thermal cleaning method. Kinetic parameters estimated using Chen’s method, trap depth (E), and frequency factor (s) were found to be 0.699, 7.408, 0.4929, and 38.71, 11.008, and 10.71 for PaNP, NeNP, and MaNP respectively. The well-resolved glow curve, good linear behavior in the dose range of 10–50, KGy, and less fading were observed in PaNP as compared with MaNP and NeNP. Further, the antibacterial activity was checked against human pathogens such as Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. A visible zone of clearance was observed at 200 and 100 μg/mL by the PaNP and NeNP, indicating the death of colonies by the nanoparticles. Therefore, PaNP nanomaterial is a potential phosphor material for dosimetry and antibacterial application compared to NeNP and MaNP.

Research & Development in Material Science Advances in Solid-State Lighting: A Review Kartik1, DV Sunitha1* and TP Jyothi1,2 1Department of Physics, School of Applied Sciences, REVA University, Bengaluru 560064, India 2Govt First Grade College, KR Puram, Bengaluru, 560036, India *Corresponding author:DV Sunitha, Department of Physics, School of Applied Sciences, REVA University, Bengaluru 560064, India Submission: June 12, 2023;Published: July 12, 2023 DOI: 10.31031/RDMS.2023.19.000956 ISSN: 2576-8840 Volume 19 Issue 2

In our work, a novel series of europium (III) (Eu3+) (5, 10 and 15 wt

Novel solution combustion technique was equipped for the synthesis of ZnO:Co2+ (1–11 mol%) nanostructures using mimosapudica (MP) leaf extract as a fuel. The prepared sample exhibits highly crystalline structure showing mushroom like morphological features. This might be due to the experimental reaction took place at the time of synthesis and evident that morphology was highly dependant on concentration of leaf extract. The obtained product of ZnO:Co2+ through MP leaf extract was examined through several characterization techniques. The packing diagram obtained using Rietveld refinement data shows the formation of hexagonal wurtzite structure having crystallite size 43–68 nm, cell volume ∼ 47.58 Å3 and density of atoms ∼ 8.42 × 1022 atoms percm3. From FTIR spectra the absorption peak in the range 500–650 cm−1exhibits the Zn-O stretching frequency having the high orientation of ZnO wurtzite structure. The energy band gap increases with Co2+ ion concentration in ZnO. The Photoluminescence (PL) emission spectra was observed in blue and green region at 422–435 & 524 nm respectively due to the presence of Zinc and oxygen vacancies. The CIE coordinate value reflecting in blue and green region confirms that the ZnO:Co2+ can be used as a one of the component in production of artificial white light LEDs/solid state display applications.

Cupper oxide (CuO) nano structured material has been synthesized by using eco-friendly simple solution method using plant leaf extracts(Mangifera indica, Carica papaya and Azadirachta indica) as a reducing agent. The obtained material is subjected to calcination at 500 °C for further studies. Powder X-ray diffraction (PXRD) and Fourier transmittance Infrared spectroscopy (FTIR) was performed for the structural confirmation of the calcined CuO samples.The CuO prepared by using Mangifera indica, Carica papaya and Azadirachta indica leaf extracts exhibited flake shape, irregular and spherical structures respectively in scanning electron microscope (SEM) micrographs.In addition, the UV-Visible absorption spectrum was recorded and the energy gap determined by using Tauc relation was 3.5, 3.75 and 3.9eV for Mangifera indica, Carica papaya and Azadirachta indica respectively.

Herein, carbon quantum dots (CQDs) are anchored on reduced graphene oxide (rGO) sheets by sonochemical assisted method. The developed carbon quantum dots/reduced graphene oxide (CQDs/rGO) catalyst shows enhancement in the photocatalytic degradation of methylene blue and methyl orange under visible light compared to that of individual CQDs and rGO components. The improved performance of the CQDs/rGO catalyst has been attributed to efficient separation of photogenerated charge carriers as studied by photoluminescence studies and to increase in the surface area as studied by Brunauer-Emmett-Teller method. The photocatalytic degradation is studied in detail by varying catalyst loading, dye concentration and the rate constant is determined by first order kinetics. The enhancement in photocatalytic activity of CQDs/rGO catalyst is validated by first principles density functional theory (DFT) calculations which shows the enrichment in density of states thereby decreasing the work function.

Solution combustion synthesis (SCS) is employed for the synthesis of SrTiO3:Sm3+ (0-11 mol%) nanophosphors. The Powder X-ray diffraction (PXRD) confirms the formation of highly crystalline SrTiO3:Sm3+ nanophosphor assigned to the which was athe standard JCPDs number card 350734. Further, the synthesized samples are irradiated by 9 MeV electron beam (10-50 kGy) and analysed using Fourier Transform Infrared (FTIR) spectroscopy and Raman spectroscopic studies to understand the change in chemical properties. PL spectra of pristine sample exhibits emission peaks at 552, 607 and 732 nm wherein irradiated samples 552 and 732 nm peaks vanishes due to loss of crystallinity by irradiation. Further, two TL glow peaks are observed at 192 and 358 degrees C in E-beam irradiated samples which shows linear L response with dose. The linear TL response is attributed to release of more number of charge carriers and trap density. The kinetic parameters estimated shows simple trap distribution making SrTiO3: Sm3+(3 mol %) nano phosphor good material for radiation dosimetry applications.

Nanostructures of V2O5, doped with Dy3+ ions of different concentrations were prepared though solution combustion technique using Cymbopogon citrates extract as a fuel for its application towards white light LEDs (WLEDs). The characterization tools such as PXRD, FTIR, Raman spectroscopy, DRS, SEM, TEM, EDS and SAED was employed to study the structural and morphological features of the V2O5: Dy3+ nanostructures. Positron annihilation lifetime spectroscopy (PALS) is a non-destructive technique carried out to find out the type of defects evolved during Dy3+ ion doping into the host matrix, which has greater influence on the photoluminescence properties of the V2O5 nanostructures. The positron lifetime annihilation spectrum was analyzed with tau(1), tau(2) the lifetime components, tau(1) is the shortest and attributes to the free positrons. tau(2) was found to be longer and arises due to trapped positrons at the grains, grain boundaries and their interface. As the Dy3+ ion concentration increases positron annihilation lifetime increases due to development of strain gradient in host matrix.

Silver/Polycarbonate (Ag/PC) and Gold/Polycarbonate (Au/PC) samples were synthesized by Synchrotron X-ray radiation assisted method in single step. X-ray Diffractogram, UV-Visible spectroscopy, X-ray Photoelectron Spectroscopy and Transmission Electron Microscopic results revealed the formation of Face Centered Cubic structured Ag nanoparticles (AgNPs) and Au nanoparticles (AuNPs) having sizes 15 nm and 17 nm respectively. Rutherford Backscattering results confirmed the diffusion of AgNPs and AuNPs in PC. The prepared Ag/PC and Au/PC samples showed the enhancement in photocatalytic degradation of Methylene Blue dye due to their diffusion into the defects sites of PC. Synchrotron X-ray radiation assisted synthesis of Ag/PC and Au/PC samples may emerge as a promising method for the synthesis of nanoparticles and polymer based photocatalysts towards pollutants degradation.

Nanostructures contribute vital applications for surface-based science including latent fingerprints (LFPs) detection and reconstruction. Fingerprints are unique to an individual, matching the finger prints help to identify culprits. Vanadium Pentoxide (V2O5) nanorods were synthesized via hydrothermal method using pomegranate peel extract as fuel, towards their use in fingerprint development. PXRD patterns confirmed the formation of orthorhombic V2O5 crystal structure. Raman vibration modes at 144 cm(-1) and 994 cm(-1) signifies the characteristic orthorhombic V2O5 structural formation, FTIR spectra shows vibration bands of V2O5, UV-vis spectroscopy shows an intrinsic absorption band at similar to 418 nm corresponding to electron transitions (O-2p -> V-3d). The energy band gap (E-g) estimated from absorption spectrum was found to be similar to 2.35 eV. Formation of nanorods was observed from SEM micrographs and particle size was found to be 30 nm from TEM images. Photoluminescence emission studies were performed and yellow-orange (brown) emission was observed from CIE diagram. The characteristic brown-Yellow-orange color of V2O5 nanorods supports tracing of LFPs on many kind of surfaces in visible light which eliminates the need for illuminating source. Hence, V2O5 nanorods find potential application in Forensic sciences.

Structural and luminescence properties of SrTiO3: Pr3+: A(+) (A(+): Li, Na, K) nanophosphors were synthesized by simple sonochemical route. Prepared products were well-characterized for their optical and structural properties. Surface morphology of the prepared samples were studied with the influential parameters such as surfactant concentration, sonication time, temperature, pH and compared the effect with normal mechanical stirring. Morphology was highly dependent on the experimental parameters. The predicted growth mechanism to obtain superstructures of the samples prepared by sonochemical method was discussed. Photoluminescence (PL) studies exhibit characteristic emission peaks of Pr3+ ions in the range 500-750 nm. The highest PL intensity was obtained for 5 mol% of Pr3+ doped samples. Further, co-doping with Li+, Na+ and K+ ions into Pr3+ activated SrTiO3 phosphor led to an enhancement in luminescence intensity by reducing the parity restriction of electric dipole transitions. As a consequence of suitable local distortion of the crystal field surrounding to the Pr3+ activator ions. The maximum PL intensity was observed for Li+ (1 wt%) co-doped SrTiO3:Pr3+ (5 mol%) samples. Furthermore, Li+ ion was the best charge compensator, because of it reduced the defects emission and also increased the emission intensity of Pr3+ significantly. Prepared phosphors exhibit short lifetime, good quantum efficiency; excellent color purity which is near to the NTSC standards. Prepared fluorescent powders were used as a dusting powder for the rapid visualization of latent fingerprints under UV light of 254 nm. From the reported results it is evident that the optimized prepared samples are suitable for solid state lighting and advanced forensic investigation applications.