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Layered dilute magnetic semiconductors are expected as promising candidates for next-generation electric devices, however, the low saturation magnetization limits their applications. Doping of semiconductors can effectively tune the magnetic and optical properties, which further influence on spintronic and optoelectronic applications. The discovery of layered materials opens a new door for spintronic application due to their unique properties. Here, the layered Gd3+ doped SnO crystals are synthesized via a simple hydrothermal method, with morphologies ranging from square shapes to four-pointed star shapes. We investigated the UV–vis absorption spectra, photoluminescence spectra and magnetic characteristics of the samples. The as-obtained Gd3+ doped SnO crystals show robust ferromagnetism at room temperature. From the first-principles calculations results, the substitution Gd dopants and the O vacancies work together to introduce the ferromagnetism. Our results demonstrate the Gd3+ doping tunability of SnO, a ferromagnetic layered material, as a functional material for spintronics and optoelectronics. [ABSTRACT FROM AUTHOR]

In this work, the optical properties including the up-conversion of Pr3+ doped Ca 2 (Lu,Gd) Hf 2 Al 3 O 12 are presented. The change in optical properties of trivalent praseodymium as a function of the gadolinium concentration was investigated by gradually replacing the lutetium cations by Gd3+. The presence of single-phase samples was proven by PXRD. Additionally, reflection spectroscopy, as well as excitation and emission measurements under X-ray and VUV excitation were recorded. Finally, decay curves were taken to determine the dependence of the decay constants from the chemical composition. • Optical Garnets. • Photoluminescence. • Praseodymium. • Gadolinium. • Up-conversion. [ABSTRACT FROM AUTHOR]

To investigate the effect of rare earth ions on the excitation energy redistribution between the UV and visible photoluminescence, the Gd 3+ doped ZnO nanocrystals prepared through Sol-Gel method were studied. Different structural characterizations and spectroscopic studies were carried out to establish a correlation between the structural effect and the photoluminescence. Our study indicates that the incorporation of Gd 3+ in ZnO nanocrystals prepared through this synthesis takes place predominantly on the surface up to 0.18 mole fraction of Gd 3+ . This is manifested by the observed lattice contraction due to the presence of Gd 3+ on the surface. This structural defect introduces various defects that modifies the photoluminescence properties. For these modifications in crystal system, the A 1 symmetry phonon modes of wurtzite structure are found to be gradually more Raman active than the other modes as the Gd 3+ concentration is increased while the E modes are suppressed. These doping induced modification of phonon spectrum strongly influences the exciton phonon coupling and thereby the photophysical properties. Resulting crystal imperfections strongly enhance the defect band luminescence. It is shown that energy transfer from selectively excited Gd 3+ centers to surface states can be effectively exploited for the sensitization of defect band luminescence in various fields such as bio imaging, light emitting devices etc. [ABSTRACT FROM AUTHOR]

Gd 3+ doped Bi 2 MoO 6 nanoplate crystals were fabricated by solvothermal combined calcination method. The effects of Gd 3+ doping with different concentrations on the texture, crystal and optical properties of Bi 2 MoO 6 were investigated by N 2 physical adsorption, X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR) and ultraviolet–visible diffuse reflection spectrum (UV–vis DRS), photoluminescence (PL) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Under simulated solar light irradiation, the influences of Gd 3+ doping on photocatalytic activity of Bi 2 MoO 6 were evaluated by photocatalytic degradation of Rhodamine B. The characterization results showed that with Gd 3+ doping, a contraction of lattice and a decrease in crystallite size occurred. Meanwhile, an increase in surface area over Gd 3+ doped Bi 2 MoO 6 was observed. Moreover, Gd 3+ doping could obviously enhance the visible light harvesting of Bi 2 MoO 6 and promoted the separation of photogenerated electrons and holes. With optimum Gd 3+ (6 wt%) doping, Gd/Bi 2 MoO 6 exhibited the best activity and stability in degradation of Rhodamine B. [ABSTRACT FROM AUTHOR]

CdS and Gd 3+ ions doped CdS nanoparticles have been prepared at two reaction temperatures 90 and 120 °C in aqueous medium in presence of cationic surfactant cetyltrimethylammonium bromide. X-ray diffraction study revealed predominant formation of zinc blend CdS and Gd:CdS at 90 °C, while at 120 °C, phase pure wurtzite CdS and Gd:CdS were formed. From EDX spectra and ICP-OES analysis, successful doping of Gd 3+ ions in CdS host has been proved. Fourier transform infrared spectroscopy results show the interaction of CTAB through headgroup at the nanoparticles surface. In the transmission electron microscopy images, it has been observed that the reaction temperature and Gd 3+ doping played critical role on size and shape of nanocrystals. In UV–visible absorption as well as photoluminescence emission spectra, size and shape-dependent quantum confinement effect has been observed. On Gd 3+ doping, surface states related emission peak shifted to higher wavelength, while intensity of peaks increased on increasing temperature. [ABSTRACT FROM AUTHOR]

In the present article, the pure PbS and different concentrations of Gd doped PbS (Gd:PbS) films were developed using the spray pyrolysis route by growing thin films on the glass substrate. The estimated crystallite sizes were found from 15.5 to 20.8 nm for as-deposited films. The spherical shape morphology of grains was observed by FESEM. The obtained average grain sizes varied from 52.8 to 108.2 nm were obtained from the grain size distributions for 0.0, 0.5, 1.5, and 2.5 wt % Gd: PbS films, respectively. Extinction coefficients of as-deposited films were measured from 0.04 to 0.12 in the range of wavelength 200–2500 nm. Refractive indices of films were obtained from 5.4 to 1.22 in range of 200–2500 nm wavelength. The band gaps of 2.75, 2.64, 2.45, and 3.10 eV for 0.0, 0.5, 1.0 and 2.5 wt % Gd thin films were estimated using Tauc's relation respectively. The values of the dielectric constant, dielectric loss, and optical conductivity were recorded in the range of 1.32–29.6, 0.30–0.61, and 2.34 × 1014–3.08 × 1013 between 200 and 2500 nm wavelengths for as-deposited thin films respectively. The optimum values of linear susceptibility, non-linear susceptibility and refractive index were recorded in the range of 1.23–2.93, 5.21 × 10−10 - 120 × 10−10, 3.54 × 10−9 – 74.2 × 10−9 (esu) between 1.46 and 0.52 eV respectively for as-deposited thin films. The Gd: PbS thin films improve the physical properties and therefore, it becomes suitable candidature for the applications in optoelectronic devices. • Fabrication of PbS and Gd:PbS films on glass by nebulizer spray pyrolysis is reported. • Spherical grains with highly packed structure of PbS and Gd:PbS thin films. • Homogeneous doping of Gd in ZnO was detected by EDX/SEM mapping. • The band gaps is noticed in range of 2.45–3.10 eV for PbS and Gd:PbS thin films. • Values of linear/non-linear susceptibilities, and non-linear refractive index of Gd: PbS decreases as compared to pure. [ABSTRACT FROM AUTHOR]

By pre-treating and component design of the ceramic powders, cubic (Lu,Gd) 2 O 3 :Eu solid-solution ceramics with high optical quality were achieved by the solid-state reaction method combined with vacuum sintering. The effects of Gd3+ doping (x = 0.05–0.6) on powder characteristics, phase compositions, microstructures and optical performances of the (Lu 0.95- x Gd x Eu 0.05) 2 O 3 ceramics were systematically investigated to obtain the optimum Gd3+ content. The results indicated that the incorporation of moderate amounts of Gd3+ (5–50 mol%) effectively promoted mass diffusion and grain growth during sintering. The 50 mol% Gd3+-doped Lu 2 O 3 :Eu transparent ceramic (using the powder calcined at 1200 °C) sintered at 1750 °C for 5 h exhibited the optimum transmittance of 77.0 % in the visible spectral region (∼1 mm in thickness), which was significantly higher than the reported transmittance of vacuum sintered (Lu,Gd) 2 O 3 :Eu ceramics (less than 65.0 %). Owing to the lower electronegativity of Gd3+ relative to Lu3+, the bandgap energies of the final ceramics decreased gradually with increasing Gd3+ substitution, and the redshift of the CTB centre was observed with more Gd3+ addition. Under CTB excitation, the incorporation of Gd3+ enhanced the red emission intensity and shortened the fluorescence lifetime. • Highly transparent (Lu,Gd) 2 O 3 :Eu ceramics were achieved by pre-treating and component design of ceramic powders. • Gd3+ doping promotes mass diffusion and grain growth during sintering. • The (Lu 0.45 Gd 0.5 Eu 0.05) 2 O 3 ceramic exhibits the transmittance of 77.0 % in the visible range. • Incorporation of Gd3+ results in enhanced luminescence intensity and shortened lifetime. [ABSTRACT FROM AUTHOR]

In this study, un-doped MgO–MgAl2O4 and Gd3+-doped MgO–MgAl2O4 nanocomposites have been synthesized via co-precipitation method. The effects of Gd3+ contents on the structureal and optical properties of MgO–MgAl2O4 nanocomposites were investigated using scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM), X-ray diffraction, Fourier-transform infrared and UV–VIS spectroscopies. HRTEM shows that MgO–MgAl2O4 powder are uniform spherical shape nanoparticles. The XRD shows that the nanocomposites consist of face-centered cubic MgAl2O4 and MgO crystal structures. The average crystallite sizes of MgO–MgAl2O4 nanocomposites are in the range of 8–40 nm. The quantitative elemental analysis by EDX illustrates that the nanocomposite samples are nearly stoichiometric MgO–MgAl2O4 48 to 52%, respectively. Scanning electron microscopy was used to study the surface morphology of MgO–MgAl2O4 nanocomposites that reveals the existence of both the individual nanoparticles and their aggregates. The optical bandgap was decreased with the presence of Gd3+ from 4.85 to 3.66 eV for 0.0 and 3% of Gd3+ content, respectively. The photoluminescence of un-doped and Gd-doped MgO–MgAl2O4 nanocomposite showed a green emission in the range (545–565 nm). [ABSTRACT FROM AUTHOR]

Gd3+-doped quantum dots (QDs) have been widely used as small-sized bifunctional contrast agents for fluorescence/magnetic resonance (FL/MR) dual-modality imaging. However, Gd3+ doping will always compromise the FL of host QDs. Therefore, balancing the Gd3+ doping and the optical properties of QDs is crucial for constructing high-performance bifunctional nanoprobes. Additionally, most paramagnetic QDs are synthesized in the organic phase and need to be transferred to the aqueous phase for bioimaging. Herein, ingeniously designed shell-doped Cu-In-S/ZnS:Gd3+ QDs have been prepared in the aqueous phase. It has been demonstrated that isolating paramagnetic Gd3+ from fluorescent Cu-In-S core via doping Gd3+ into ZnS shell not only avoided the decrease of FL quantum yield (QY), but also ensured the water accessibility of paramagnetic Gd3+ ions, by which the FL QY and r 1 relaxivity of Cu-In-S/ZnS:Gd3+ QDs achieved as much as 15.6% and 15.33 mM-1·s-1, respectively. These high-performance QDs with excellent stability, low biotoxicity, and good tumor permeability were successfully applied for in vivo tumor FL/MR dual-modality imaging, and have shown significant potential in the precision detection and diagnosis of diseases. [Display omitted] • The effects of Gd3+-doped region on the properties of core/shell QDs are investigated. • Isolating Gd3+ from fluorescent Cu-In-S core via doping Gd3+ into ZnS shell. • A facile aqueous synthesis of fluorescent and paramagnetic bifunctional QDs is proposed. • The hydrodynamic diameter of shell-doped Cu-In-S/ZnS:Gd3+ QDs is very small. [ABSTRACT FROM AUTHOR]

In this study, hydroxyapatite powder Ca10(PO4)6(OH)2 (HAp) doped with gadolinium (Gd3+) (HAp:Gd3+) in different mole percentage of between 0.1 and 1.6 was synthesized by sol−gel method at 900°C. The reaction was carried out by hydrolysis of Ca(OH)2 and DCPD (CaHPO4.2H2O) in aqueous solution and then analyzed through XRD, SEM, FTIR, TGA and Four-Point Probe method (custom-made). The results show that Gd3+ has been successfully doped into the hydroxyapatite structure. Then, the photoluminescence, thermal and electrical properties of pure and Gd3+ doped hydroxyapatite were studied and compared with the pure hydroxyapatite. In conclusion, the emission band of Ca10-xGdx(PO4)6(OH)2 was observed at 263, 278, 294, 312 nm) under excitation with 185 nm. The Stokes shift of HAp:Gd3+ was calculated to be 16.031 cm−1. On the other hand, the electrical and thermal conductivity of HAp increased with the increase in Gd3+ concentration due to Ca2+ cation vacancies caused by Gd3+doping. [ABSTRACT FROM AUTHOR]

Micro-size and nano-size samples of (GdxY3−xFe5O12; x = 0, 0.25, 0.5, 0.75, and 1) garnet ferrites were prepared by the standard ceramic method (CER) and the coprecipitation (COP) method. The influences of Gd3+ doping and preparation methods on the optical and dielectric properties were compared for these micro-size and nano-size compositions for the first time. X-ray diffraction data confirmed the formation of a single phase of the garnet cubic structure for all samples. It was found that there is a good agreement between the theoretical and experimental lattice parameter estimated values. The Fourier transform infrared spectroscopy was used to study the cation distributions among the different crystallographic sites. Moreover, values of energy gap (Eg) for the investigated samples were determined from the diffused reflectance spectroscopy measurements. These values were found to be higher for (COP) samples than for (CER) ones and slightly increased by increasing Gd3+ content in both series prepared via the two techniques. Furthermore, resistivity (ρac), dielectric constant (ε′), and dielectric loss (ε″) showed a decrease with increasing frequency (f) for all samples. For the samples prepared by (CER) method, ρac increases with increasing Gd3+ content while for the samples prepared by (COP) method, ρac increases for 0 ≤ x ≤ 1 except for the sample x = 0.5. Values of ρac for samples prepared by (COP) method are higher than those prepared by (CER) method. Both ε′ and ε″ had the reverse behavior of ρac. Obtained results were explained according to different models. [ABSTRACT FROM AUTHOR]

This study focuses on the facile combustion synthesis of highly luminescent Y2O3:Sm3+, Gd3+ nanophosphors, bringing down the thermal budget to a minimum of 500 K. When Sm3+ ions are doped in the Y2O3 cubic crystal system of bandgap 5.6 eV and studied under a down-conversion excitation of 260 nm, the emission spectra offered an intense vermilion color at 608 nm due to the 4G5/2 → 6H7/2 transition within the Sm3+ ions. The Y2O3:2wt%Sm3+ matrix is co-doped with 3wt%Gd3+, highlighting 100% pure vermilion emission 4.21 times higher than doped samples, which is a perfect choice for domestic lightening owing to better eye compatibility. Further, post-annealing is performed to improve the structural parameters and luminescence properties, creating sufficient alterations in the crystal lattice. It is professed that Y2O3:Sm3+, Gd3+ nanophosphors can be effectively used in optoelectronic devices, owing to their enhanced crystallinity and photoluminescence properties resulting from the Gd3+ → Sm3+ energy transfer efficiency of 75.15%. [ABSTRACT FROM AUTHOR]

Gd3+- free carbon dots (CDs) were synthesized by one-step solvothermal method using urea, citric acid and 3-(trifluoromethyl)aniline as precursors. Additionally, Gd3+-doped CDs were prepared by incorporating gadolinium chloride (Gd3+ ions) into the synthesis. Size selection of the purified CDs was achieved through filter membranes ranging from 3 kDa to 100 kDa. The chemical composition and optical properties of the obtained samples were characterized by Energy dispersive X-ray (EDX), Fourier-transform infrared spectroscopy (FTIR), Dynamic Light Scattering (DLS), proton relaxation time measurements, Ultraviolet–visible (UV-vis) and fluorescence spectroscopies. A comparative analysis revealed a strong size-dependent behavior in the optical properties of both Gd3+-doped and Gd3+-free CDs. Furthermore, in vitro tests confirmed the non-cytotoxicity of Gd3+-doped CDs, indicating their potential applicability in biomedicine for magnetic resonance imaging (MRI) and red fluorescence-based cell and tissue imaging. [ABSTRACT FROM AUTHOR]

• The co-precipitation method was used for the synthesis of Fe 3-x Gd x O 4 nanoparticles. • XRD results showed that the prepared particles have good crystallinity and face-centered cubic spinel structure. • TEM micrographs revealed the formation of rod-like structures along with round-shaped particles found with gadolinium doping. • The saturation magnetization and coercivity increased with increasing the Gd3+ doping concentrations. • Electrical resistivity is found to decrease two-fold with Gd3+ doping. In the present study, Fe 3-x Gd x O 4 nanoparticles (with × varying from 0 to 0.1) were synthesized using the co-precipitation method. Lattice constant and X-Ray density were determined using X-Ray Diffraction (XRD). Transmission Electron Microscopy (TEM) study revealed the formation of rod-like structures along with round-shaped particles after gadolinium doping. Selected Area Electron Diffraction (SAED) showed good crystallinity of nanoparticles. Elastic constants were calculated using FTIR and XRD data. The study of the vibrating sample magnetometer (VSM) revealed that the saturation magnetization increased with Gd3+ doping from 54.3 emu/g at x = 0.0 to 84.8 emu/g at x = 0.04. Coercivity also increased with Gd3+ doping. The value of resistivity has been observed to be 4.02 × 106 Ohm-cm for undoped samples using Keithley's two-probe method. The dc resistivity of doped samples has been decreased by two orders of magnitude as compared to the undoped sample. UV–Vis spectroscopy has been used to calculate the band gaps with the help of Tauc plots. The band gap for the undoped particle is 2.46 eV which decreases with Gd3+ doping till 2.08 eV for x = 0.03. Band gaps are correlated to electrical behavior. Young modulus, Bulk modulus, Rigidity modulus, and Poisson's ratio were found to enhance with gd doping beyond x = 0.03. The increase of elastic constants with doping indicates the strengthening of interatomic bonding. These nanoparticles could have applications as optoelectronic and magnetoelastic sensors. [ABSTRACT FROM AUTHOR]

Dilute magnetic semiconductors (DMSs) with both charge and spin degrees of freedom have emerged as promising candidates in the spintronic industry. However, the Curie temperature below room temperature and uncertainty about the origin of ferromagnetism hinder the application of DMSs. To address these issues, we explored a better SnO2-based co-doped method (Fe, V + VSn) using ab initio calculations. The calculation results show that the Sn13FeVO32 (Fe, V + VSn) has a high Curie temperature (716 K), good ferromagnetic properties, stronger covalency of bonds, and better optical transparency in the visible light range. In addition, the holes or electrons generated by the complexes in the (Fe, V + VO/VSn) co-doped system cause a spin-polarized double exchange effect in the Fe-3d, V-3d, and O-2p orbitals, which leads to magnetism of the co-doped systems. The static dielectric constant ɛ1(0) of the system increases after doping. Among them, Sn14FeVO31 (Fe, V + VO) has the largest ɛ1(0), indicating that Sn14FeVO31 has the strongest polarization ability and better photocatalytic properties. In Sn14FeVO31, the imaginary part of the dielectric function and the absorption spectrum all have new peaks in the low-energy region, which are caused by the jump of electrons from the guide band of the spin-polarized impurity energy level. This paper proposes a new method for preparing dilute magnetic semiconductors in spin electronic devices with high room temperature ferromagnetic properties and excellent optical properties through the (Fe, V + VO/VSn) co-doped SnO2. [ABSTRACT FROM AUTHOR]

Electrospun nanofibers possess a large surface area and a three-dimensional porous network that makes them a perfect material for embedding functional nanoparticles for diverse applications. Herein, we report the trends in embedding upconversion nanoparticles (UCNPs) in polymeric nanofibers for making an advanced miniaturized (bio)analytical device. UCNPs have the benefits of several optical properties, like near-infrared excitation, anti-Stokes emission over a wide range from UV to NIR, narrow emission bands, an extended lifespan, and photostability. The luminescence of UCNPs can be regulated using different lanthanide elements and can be used for sensing and tracking physical processes in biological systems. We foresee that a UCNP-based nanofiber sensing platform will open opportunities in developing cost-effective, miniaturized, portable and user-friendly point-of-care sensing device for monitoring (bio)analytical processes. Major challenges in developing microfluidic (bio)analytical systems based on UCNPs@nanofibers have been reviewed and presented. [ABSTRACT FROM AUTHOR]

The glass system of B2O3-SiO2-TeO2-Bi2O3-ZnO-BaO doped with Gd2O3 (x = 0, 1, 2, 3, and 4 mol%) (BiTeGd-x) was prepared by using the melt-quench technique. The density of glasses increased from 5.323–5.579 g cm−3 for 0–4 mol% with an increase in Gd2O3 concentration. The simulation results obtained using Photon Shielding and Dosimetry (PSD) software (Phy-X version) produced the maximum mass attenuation coefficient (MAC) and minimum half-value layer (HVL) in the entire photon energy spectrum 0.015–15 MeV, suggesting the highest potential of BiTeGd-4 glass to act as a shield against low and high-energy radiation photons. [ABSTRACT FROM AUTHOR]

Gd3+ (gadolinium)-doped ZnSe thin films (1 to 5 mol%) are grown onto indium-doped tin oxide (ITO) glass substrate by single-step electrochemical deposition process. X-ray diffraction analysis confirms the formation of hexagonal wurtzite structure with preferred growth orientation along (101) plane. A new antistructural modeling for describing active surface centers for ZnSe:Gd system is discussed for the first time. The new antistructural modeling shows that the dissolution of Gd cations increases the concentration of surface active centers GdZn• and VZn′′, which are located in the cationic sublattice. The surface morphology of thin films investigated using scanning electron microscopy reveals some agglomeration of grains with significant changes in particle size with varying Gd3+ concentrations. UV-vis and photoluminescence studies indicate a blue shift due to the incorporation of Gd3+ into ZnSe host lattice. Electrochemical impedance spectroscopy and photoelectrochemical measurements reveal that the 3 mol% Gd3+-doped ZnSe thin film possesses low charge transfer resistance (25.42 Ω) and faster migration of photoinduced electrons, resulting in high conductivity. Therefore, the optimum doping concentration, 3 mol% Gd3+-doped ZnSe, offers a positive synergistic effect for photoelectrochemical devices. [ABSTRACT FROM AUTHOR]

Bismuth silicate (Bi4Si3O12, BSO) crystal, as a nonlinear optical material with excellent optical properties, has a wide range of applications in laser technology, optical communication, and optical information processing. In order to further improve its performance, this study adopts a first principles calculation method based on density functional theory (DFT), selects Gd3+ as the dopant, and calculates and explores the changes in optical properties of BSO crystals after doping with 1/12, 1/6, and 1/3Gd3+. The calculation results show that the doping of Gd3+ changes the electronic structure of BSO crystals, which is manifested in the emergence of new light absorption and emission characteristics, an increase in carrier concentration, an improvement in conductivity, and an enhancement of crystal polarization ability in optical properties. In addition, doping with Gd3+ increases the light transmission rate and reduces energy loss of BSO crystals, while releasing more energy during electron band transitions, effectively improving the luminescence performance of BSO crystals. The theoretical research in this article provides an important theoretical basis for understanding the influence of Gd3+ doping on the optical properties of BSO, and by optimizing the ratio of Gd3+, the optical properties of BSO can be further regulated, opening up new possibilities for its application in optoelectronic devices.

A series of Yttrium (Y)-doped Bi2MoO6 composites with calcined mussel shell powder (CMS) as supports were synthesized using a solvothermal method. The as-prepared samples were analyzed using multiple techniques to investigate their microscopic morphology, composition structure, and optical properties. The photocatalytic performance of the as-prepared samples was assessed via examining their capacity to degrade Rhodamine B (RhB) under visible-light irradiation. The photocatalytic data showed that the Y-doped Bi2MoO6/CMS composites exhibited better photocatalytic activity compared to pure Bi2MoO6 and undoped Bi2MoO6/CMS samples. Among the samples, the 0.5%Y-doped Bi2MoO6/CMS (0.5%Y-BC) showed the highest photocatalytic activity, achieving a maximum degradation rate of 99.7% within 60 min. This could be attributed to highly reactive sites due to Y doping, a narrower band gap, and a lower recombination rate of photoinduced electron–hole pairs. Additionally, the 0.5%Y-BC photocatalyst exhibited excellent stability and reusability properties even after four cycles, making it suitable for practical applications. The findings provided a feasible synthesis of nanocomposite photocatalysts with outstanding properties for organic pollutant removal from the solution system. [ABSTRACT FROM AUTHOR]

In this study, the synthesized rare earth Ce3+ ion doped Mg-Ni-Cu ferrites with composition formula Mg0.5Ni0.3Cu0.2CexFe2-xO4 (0.0 ≤ X ≤ 0.1) using solution gel auto-combustion method. Synthesized ferrite samples were systematically investigated for their structural, morphology, optical, and dielectric properties at varying temperatures and magnetic properties at room temperature. X-ray diffraction analysis confirms the formation of the cubic spinel phase with the Fd-3 m space group, and reviled the development of a secondary phase of cerium oxide CeO2 from the cerium concentration was increased to X = 0.04. The FESEM micrographs of our prepared ferrites show the nano-pores surface and spherical shape grains. EDX confirms the presence of all desired elements. FTIR studied supports the XRD finds. UV–vis spectra showing the blue shift along all samples, and Tauc plots giving the highest band gap energy of 2.54 eV were obtained for the X = 0.06 sample, and the lowest for X = 0.02 is 2.38 eV. VSM instrument was adopted to evaluate the magnetic behaviour of our prepared ferrites at room temperature. The magnetic hysteresis loop confirmed the ferromagnetic behaviour. Ce3+ substitution remarkably affected prepared material coercivity, and magnetic saturation was found between 15.22 emu/g and 22.41 emu/g. The squareness ratio of prepared material was found between 0.19 and 0.26, and it is known that the squareness ratio values fall in the range of multi-domine sates (0.05–0.5). Dielectric properties of synthesized ferrites were produced with normal ferrite plots with higher dielectric constant values. Most significantly, observed very low dielectric loss tangent values. The impedance analysis confirms the dominance of grain boundary resistance with only one semi-circle. [ABSTRACT FROM AUTHOR]

Tb3+ complexes with β-ketocarboxylic acid as main ligand and heterocyclic systems as auxiliary ligand were synthesized and analyzed to assess their prospective relevance as green light emitting material. The complexes were characterized via various spectroscopic techniques and were found to be stable up to ≈ 200 ℃. Photoluminescent (PL) investigation was performed to assess the emissive nature of complexes. Longest luminescence time of decay (1.34 ms) and highest intrinsic quantum efficiency (63.05%) were fetched for complex T5. Color purity of complexes was found to be in range 97.1 – 99.8% which demonstrated the aptness of these complexes in green color display devices. NIR Absorption spectra were employed to evaluate Judd–Ofelt parameters to appraise the luminous performance and environment encircling Tb3+ ions. The JO parameters were found to follow the order: Ω2 > Ω4 > Ω6 and suggested the higher covalence character in complexes. Theoretical branching ratio in the range 65.32 – 72.68%, large stimulated emission cross section and narrow FWHM for 5D4 → 7F5 transition unlocked the relevance of these complexes as a green color laser media. Band gap and Urbach analysis were consummated via enforcing nonlinear curve fit function on absorption data. Two band gaps with values in between 2.02 – 2.93 eV established the prospective use of complexes in photovoltaic devices. Energies of HOMO and LUMO were estimated employing geometrically optimized structures of complexes. Investigation of biological properties accomplished via antioxidant and antimicrobial assays which communicated their applicability in biomedical domain. [ABSTRACT FROM AUTHOR]

Based on density functional theory (DFT), theoretical models of three kinds of lanthanide rare earth metal ion-doped γ-Bi2MoO6 were constructed (Ln-BMO (Ln=Gd, Ho, Yb)). The geometric structure, electronic structure, and optical properties of the model were calculated, and the influence of doped Ln3+ ions on the structures and properties of the system was analyzed. The results revealed that the substitution of smaller ionic radius Ln3+ ions for Bi3+ ions caused a contraction of the lattice parameters. At the same time, the contribution of the [Ln]4d near valence band and conduction band reduced the bandwidth of γ-Bi2MoO6, forming the Ln-O ionic bond with different strengths to obtain higher charge conductivity and charge-separation ability. Secondly, Ln3+ ions have a strongly ionic charge, which leads to the appearance of optical absorption bands in the infrared region and part of the visible region. This reduces the reflection in the visible region, improves the utilization rate, delays the loss of electron energy, and promotes phase matching in the visible region. And the Gd3+-doped system has better photocatalytic activity than the other Ln3+-doped system. This research provides theoretical insights into doped lanthanide rare earth ions and also provides strategies for the modification of γ-Bi2MoO6 nanomaterials. [ABSTRACT FROM AUTHOR]

The luminescence and charge transport properties of inorganic CsPbX3 perovskite nanocrystals (NCs) make them attractive candidates for various optoelectronic applications, such as lasing, X-ray imaging, light communication, and light-emitting diodes (LEDs). However, to realize cutting-edge device performance, high-quality NCs with high photoluminescence quantum yields (PLQYs) are essential. Therefore, substantial efforts and progress have been made to attain superior design/engineering and optimization of the inorganic NCs with a focus on surface quality, reduced nonradiative charge carrier recombination centers, and improved colloidal stabilities. Metal-ion doping has been proven to have a robust influence on the electronic band structure, PL behavior, and charge carrier recombination dynamics. Thus, in this perspective, we summarize the recent progress of the significant impact of metal cation doping on the optical properties, including the PL enhancement of CsPbCl3, CsPbBr3, and CsPbI3 perovskite NCs. Moreover, we shed light on the mechanism behind such improved properties. We conclude by recommending possible aspects and strategies to be further explored and considered for better utilization of these doped NCs in thin-film optoelectronic and energy conversion devices. [ABSTRACT FROM AUTHOR]

Sol-gel technology has attracted attention in the fabrication of diverse luminescent materials and thin film structures, with forms that range from powders to microcavities. The optical properties of sol-gel-derived structures depend on the sol composition, deposition, and heat treatment conditions, as well as on the film thicknesses and other factors. Investigations on the upconversion luminescence of lanthanides in film structures and materials are also ongoing. In this study, we synthesized three different types of materials and film structures using the same sol, which corresponded to a Ba0.76Er0.04Yb0.20TiO3 xerogel, as follows: (a) the target form, which used the explosive compaction method for sol-gel-derived powder; (b) single-layer spin-on xerogel films annealed at 450 and 800 °C; and (c) microcavities with an undoped SiO2/BaTiO3 Bragg reflector surrounding a Ba0.76Er0.04Yb0.20TiO3 active layer. The BaTiO3:(Er,Yb)/SiO2 microcavity exhibited an enhancement of the upconversion luminescence when compared to the BaTiO3:(Er,Yb) double-layer film fabricated directly on a crystalline silicon substrate. The reflection spectra of the BaTiO3:(Er, Yb)/SiO2 microcavity annealed at 800 °C demonstrated a deviation of the maxima of the reflection within 15% for temperature measurements ranging from 26 to 120 °C. From the analyses of the transmission and reflection spectra, the optical band gap for the indirect optical transition in the single layer of the BaTiO3:(Er,Yb) spin-on film annealed at 450 °C was estimated to be 3.82 eV, while that for the film annealed at 800 °C was approximately 3.87 eV. The optical properties, upconversion luminescence, and potential applications of the BaTiO3:(Er,Yb) sol-gel-derived materials and structures are discussed in this paper. [ABSTRACT FROM AUTHOR]

New Gd3+- and Mn2+-co-doped calcium molybdato-tungstates with the chemical formula of Ca1−3x−yMny▯xGd2x(MoO4)1−3x(WO4)3x (labeled later as CaMnGdMoWO), where ▯ denotes vacant sites in the crystal lattice, 0 < x ≤ 0.2500 and y = 0.0200 as well as 0 < y ≤ 0.0667 and x = 0.1667 were successfully synthesized by high-temperature solid-state reaction method and combustion route. Obtained ceramic materials crystallize in scheelite-type structure with space group I41/a. Morphological features and grain sizes of powders under study were investigated by SEM technique. Spectroscopic studies within the UV-vis spectral range were carried out to estimate the direct band gap (Eg) and Urbach energy (EU) of obtained powders. EPR studies confirmed the existence of two types of magnetic objects, i.e., Mn2+ and Gd3+ ions, and significant antiferromagnetic (AFM) interactions among them. [ABSTRACT FROM AUTHOR]

In the present work, Al3+-Gd3+ substituted (at iron site) cubic nickel ferrite nanoparticles having the formula NiFe2-2xAlxGdxO4 (x = 0.00–0.08 in the step of 0.02) were fabricated through wet chemical, low temperature sol–gel self-ignition method. Glycine (C2H5NO2) was used as a fuel; maintaining the metal nitrite to glycine ratio as 1:4.4. The as prepared nanoparticles were annealed at 850 ºC for 5 h for removal of the moisture and other impurities. The phase purity and the structural parameters were investigated using the powder X-ray diffraction technique, which indicates the presence of principle reflections (220) and (311) along with other reflections belonging to cubic structure which proves that the prepared samples possesses mono-phase and the crystal structure have cubic spinel symmetry. The ferrite phase formation was assured with the characteristic peaks driven by intrinsic υ1 = 546 cm−1, 557 cm−1, and extrinsic vibration υ2 = 401 cm−1, 417 cm−1 studied in the FTIR spectroscopic analysis. The lattice constant (a) of NiFe2-2xAlxGdxO4 NPs was found to be increased gradually with an increasing composition of Al-Gd co-substitution under the influence of higher ionic radii. The average crystallite size (D) was estimated through Scherrer's formula varies between 20.88 and 27.82 nm. The SEM and TEM observations of typical samples have suggested the well-defined spherical grain growth with dense structure and agglomeration with a particle size of ~ 28.56 nm to ~ 47.74 nm. From the Brunauer–Emmett–Teller analysis, the surface area of the samples with x = 0.02 and 0.04, was found to be in the range of 10.6–18 m2/g. The magnetic properties such as saturation magnetization (Ms) and magneton number (nB) were decreased with an increasing Al-Gd content X. The remanence ratio (Mr/Ms) was found to be in the range of 0.25 to 0.37, indicating the multi-domain structure of the prepared samples. The Ultraviolet–Visible spectroscopy was employed to study the absorbance and determine the bandgap of the NiFe2-2xAlxGdxO4 NPs which is of the order ~ 2.80 eV. [ABSTRACT FROM AUTHOR]

Upconversion materials have numerous potential applications in light energy utilization due to their unique optical properties. The use of visible light excitation to obtain ultraviolet emission is a promising technology with broad application prospects, while relevant research is absent. A series of Pr3+, Gd3+ doped Y7O6F9 phosphors were synthesized by traditional solid–state reaction. X-ray diffraction, scanning electronic microscopy, steady-state photoluminescence spectra, a decay dynamic, and upconversion emission spectra of the samples were studied. Under the excitation of 238 nm, the energy transfer from Pr3+ to Gd3+ was realized and a strong ultraviolet B emission due to the 6P7/2→8S7/2 transition of the Gd3+ ions was achieved. Under the excitation of a 450 nm blue laser, Pr3+ absorbed two blue photons to realize the upconversion process and then transferred the energy to Gd3+ to obtain the ultraviolet B emission. [ABSTRACT FROM AUTHOR]

Solar driven semiconductor-based photoreforming of biomass derivatives, such as glycerol is a sustainable alternative towards green hydrogen evolution concerted with production of chemical feedstocks. In this work, we have investigated the influence of the pH of the hydrothermal treatment on the efficiency of Bi2WO6 as photocatalyst in the glycerol photoreforming. Bi2WO6 is pointed as a promising material for this application due its adequate band gap and the ability to promote hole transfer directly to glycerol without formation of non-selective ⋅OH radicals. Samples prepared at neutral to moderate alkaline conditions (pH = 7–9) are highly crystalline, while those prepared in acidic media (pH = 0–2) exhibit higher concentrations of oxygen vacancies. At pH = 13, the non-stoichiometric Bi(III)-rich phase Bi3.84W0.16O6.24 is formed. All samples were fully characterized towards their optical and morphological properties. UV–Vis irradiation of the photocatalysts modified with 1% m/m Pt and in the presence of 5% v/v aqueous glycerol solution leads to H2 evolution and glycerol oxidation. The sample prepared at pH = 0 exhibited the highest photonic efficiency (ξ) for H2 evolution (1.4 ± 0.1%) among the investigated samples with 99% selectivity for simultaneous formic acid formation. Similar performance was observed for the non-stoichiometric Bi3.84W0.16O6.24 sample (ξ = 1.2 ± 0.1% and 88% selectivity for formic acid), whereas the more crystalline sample prepared at pH = 9 was less active (ξ = 0.9 ± 0.1%) and leads to multiple oxidation products. The different behaviors were rationalized based on the role of oxygen vacancies as active adsorption and redox sites at the semiconductor surface, stablishing clear relationships between the semiconductor structure and its photocatalytic performance. The present work contributes for the rational development of specific photocatalysts for glycerol photoreforming. [ABSTRACT FROM AUTHOR]

In this study, hydroxyapatite powder Ca10(PO4)6(OH)2 (HAp) doped with gadolinium (Gd3+) (HAp:Gd3+) in different mole percentage of between 0.1 and 1.6 was synthesized by sol−gel method at 900°C. The reaction was carried out by hydrolysis of Ca(OH)2 and DCPD (CaHPO4.2H2O) in aqueous solution and then analyzed through XRD, SEM, FTIR, TGA and Four-Point Probe method (custom-made). The results show that Gd3+ has been successfully doped into the hydroxyapatite structure. Then, the photoluminescence, thermal and electrical properties of pure and Gd3+ doped hydroxyapatite were studied and compared with the pure hydroxyapatite. In conclusion, the emission band of Ca10-xGdx(PO4)6(OH)2 was observed at 263, 278, 294, 312 nm) under excitation with 185 nm. The Stokes shift of HAp:Gd3+ was calculated to be 16.031 cm−1. On the other hand, the electrical and thermal conductivity of HAp increased with the increase in Gd3+ concentration due to Ca2+ cation vacancies caused by Gd3+doping.

Development of nanotheranostic agents with near-infrared (NIR) absorption offers an effective tool for fighting malignant diseases. Lanthanide ion neodymium (Nd3+)-based nanomaterials, due to the maximum absorption at around 800 nm and unique optical properties, have caught great attention as potential agents for simultaneous cancer diagnosis and therapy. Herein, we employed an active nanoplatform based on gadolinium-ion-doped NdVO4 nanoplates (NdVO4:Gd3+ NPs) for multiple-imaging-assisted photothermal therapy. These NPs exhibited enhanced NIR absorption and excellent biocompatibility after being grafted with polydopamine (pDA) and bovine serum albumin (BSA) layers on their surface. Upon expose to an 808 nm laser, these resulting NPs were able to trigger hyperthermia rapidly and cause photo-destruction of cancer cells. In a xenograft tumor model, tumor growth was also significantly inhibited by these photothermal agents under NIR laser irradiation. Owing to the multicomponent nanostructures, we demonstrated these nanoagents as being novel contrast agents for in vivo magnetic resonance (MR) imaging, X-ray computed tomography (CT), photoacoustic (PA) imaging, and second biological window fluorescent imaging of tumor models. Thus, we believe that this new kind of nanotherapeutic will benefit the development of emerging nanosystems for biological imaging and cancer therapy. [ABSTRACT FROM AUTHOR]

Abstract: Gd-doped CdO thin films with various Gd compositions were prepared on glass and Si wafer substrates using a vacuum evaporation technique. The influence of varying Gd composition on structural, electrical, and optical properties of the prepared films were systematically investigated. Experimental data indicate that Gd3+ doping slightly stress the CdO crystalline structure and change its optoelectronic properties. The bandgap of Gd-doped CdO suffers narrowing by about 40% due to a small (0.2%) doping level. The electrical behaviours of the Gd-doped CdO films show that they are degenerate semiconductors. The 0.6% Gd-doped CdO film shows increase its mobility by about eight times, conductivity by 150 times, and carrier concentration by 20 times, relative to undoped CdO film. However, the largest mobility of 66.7cm2/Vs was obtained for 0.2% Gd-doped CdO film. From transparent-conducting-oxide point of view, the Gd is effectively suitable for CdO doping. Finally, the absorption in the NIR spectral region was studied in the framework of the classical Drude theory. [Copyright &y& Elsevier]

The impact of Gd rare earth ion on structural, magnetic, and optical properties of Ni and Co spinel ferrite nanomaterial prepared by low-cost sol–gel method has been studied in this research. The XRD measurement confirms the pure phase formation having crystallite size between 15.61–23.49 and 12.01–30.95 nm for Gd3+substituted CoFe2O4 and NiFe2O4, respectively. A slight decrement in crystallite size was found due to large size ion of rare earth elements. The lattice constants of CoFe2O4 materials displayed a decrease from 8.4477 to 8.3635 Å and an increase from 8.3565 to 8.3968 Å in NiFe2O4 materials, prepared at the same temperature. The molecular bonds between 469 and 3453 cm−1 were examined by FTIR spectroscopy. The direct bandgap (Eg) of CoFe2O4 and NiFe2O4 was between 1.63–2.41 and 1.61–1.66 eV, respectively, by UV–Visible spectroscopy. The room temperature PL studies (200 nm excitation) revealed a dominant blue emission and a weak green emission. The particle size of CoFe2O4 and NiFe2O4 was found 34 and 41.58 nm, respectively, by HRTEM which is close to the result obtained by XRD analysis. The coercivity (Hc) of pure CoFe2O4 and NiFe2O4displayed the magnitude of 1452.41 and 191.49 Oe, respectively. The saturation magnetization (Ms) was found between 30.59–57.84 and 23.99–42.11 emu/g for CoFe2O4 and NiFe2O4. The tuned optical and magnetic behavior could make them applicable in magneto-optical devices, water purification and other related uses. [ABSTRACT FROM AUTHOR]

This paper reports the spectroscopic investigation of Ba3Zr2O7 phosphors. A series of Ba3Zr2O7: Eu3+ with the different molar concentrations (0–4 mol.%) of europium (Eu3+) ion is synthesized by the solution combustion method. The synthesized powders are characterized systematically using X-ray diffraction, X-ray photoelectron spectroscopy, photoluminescence spectroscopy, and ultraviolet–visible spectroscopy. X-ray diffraction results indicate that the synthesized powder has a tetragonal crystal structure. X-ray photoelectron spectroscopy is used to study the elemental composition of the synthesized phosphor. Field emission scanning electron microscopy result reveals that non-uniform morphology is formed. Photoluminescence spectroscopy result shows several emission peaks due to electronic transitions of Eu3+ ion, and the dominant peak is observed at 613 nm due to electric dipole transition 5D0 → 7F2. CIE coordinates of Eu3+-activated Ba3Zr2O7 phosphor is found to be (x = 0.64, y = 0.36) which gives bright red emission. The optical band gap of the phosphors is obtained from the diffuse reflectance spectrum and found in the range of 4.62–4.83 eV. [ABSTRACT FROM AUTHOR]

Eu-doped calcium fluoride (CaF 2) single crystals co-doped with various concentrations of Gd3+ were grown by the Bridgman-Stockbarge method. A broad excitation band in the ultraviolet (UV) region were observed in the crystal, which is attributed to the existence of Eu2+ ions detected with the help of XPS measurements. The Gd3+ doping was found to have a significant influence on the luminescence properties of the Eu: CaF 2 , resulting in a suppression of Eu2+ luminescence and enhancement of Eu3+ emission at high Gd3+ co-doping level. The photoluminescence excitation and emission spectra of Eu2+ and Eu3+ ions were measured using luminescence spectrometer. The local site symmetry in the crystals was investigated to explain the influence of Gd3+ on suppression of Eu2+ luminescence and emission of 5D 3 →7F J (J = 1, 2, 3) in Eu3+ transition. The fluorescence emissions of the 3%Eu, 6%Eu: CaF 2 and 3%Eu, 12%Gd: CaF 2 crystals excited at 398 nm relate to the Commission internationale de I'éclairage (CIE) color coordinates of (0.6012, 0.3870) and (0.5930, 0.3953), respectively. A highest quantum yield of 40.53% and 5D 0 →7F 1 transition decay time of 9.54 ms were obtained on the 3%Eu, 6%Gd: CaF 2 crystal. This investigation suggests that Eu, Gd: CaF 2 has great potentials for optimizing solid state UV–visible converter performances through appropriate concentration tuning of dopants. • Eu2+ ions can be significantly converted into Eu3+ ions in CaF 2 crystals by the co-doping Gd method. • Different influences of optical properties and regulation of color gamut with different concentration of Gd3+. • Suppression of Eu2+ luminescence and enhancement of Eu3+ emission with higher Gd3+ co-doping level. [ABSTRACT FROM AUTHOR]

The structure of the host lattice has a substantial influence on the optical properties of lanthanide-doped luminescent materials. Hexagonal-phase (β-phase) NaREF4 (RE = rare earth) is the most commonly used crystal structure for lanthanide-doped upconversion nanoparticles (UCNPs) owing to its high upconversion (UC) efficiency. In this work, we report, for the first time, that more efficient cooperative sensitization upconversion (CSU) can be achieved in cubic-phase (α-phase) NaREF4 UCNPs instead of their β-phase counterparts. With the passivation of an inert shell, the UC emission intensity of α-NaYbF4:Tb40%@CaF2 is 10.5 times higher than that of β-NaYbF4:Tb40%@NaYF4. We propose that the high-symmetry crystal structure of the α phase facilitates the formations of [Yb–Yb] dimers and [Yb–Yb–Tb] clusters, which are particularly beneficial for CSU. Moreover, we prove that such Tb3+-based UCNPs are almost impervious to water quenching because of the large energy gap (∼15,000 cm−1) that existed in Tb3+ between its lowest emit-ting level (5D4) and next low-lying level (7F0). Finally, their potential application for single-nanoparticle imaging has also been demonstrated. As expected, the α-core-shell UCNPs measured at the single-nanoparticle level are estimated to be 9-fold brighter than their β-core-shell counterparts. Importantly, the α-NaYbF4:Tb40%@CaF2 UCNPs offer exciting opportunities for realizing single-nanoparticle imaging at ultralow irradiance (30 W/cm2). [ABSTRACT FROM AUTHOR]

The crystal structure, photocatalytic activity, and ferromagnetic properties of Sm-substituted (Bi1−xSmxFeO3, x = 0.05, 0.10, 0.15, 0.20) nanoparticles were systematically investigated within the entire Sm substitution region. The morphotropic phase boundary (MPB) consisting of a rhombohedral phase, orthorhombic interim phase (Pna21), and orthorhombic phase with 0.1 ≤ x ≤ 0.2 is constructed and confirmed by x-ray diffraction and Raman spectra with new vibration modes at ∼310 cm−1. The photocatalytic activity and ferromagnetism are improved around the MPB region (x = 0.10). Meanwhile, the wasp-waisted hysteresis loops are present around the MPB region. Wasp-waisted hysteresis loops have the features of low hysteresis loss in low magnetic fields and are helpful in designing some multiferroic devices. [ABSTRACT FROM AUTHOR]

Lanthanide-doped inorganic nanocrystals, possessing superior luminescence performance and photochemical stability, have attracted considerable attention due to their promising biological applications such as in bioimaging, biodetection, biotherapeutics and temperature sensing. Great progress has been made in achieving distinct and tailored optical properties for these functional nanocrystals in the past few decades. In this feature article, we summarize our recent advances in the realization of desirable and tunable luminescence for lanthanide-doped inorganic nanocrystals through local structure engineering that includes two main strategies, namely, externally morphological architecture design and intrinsically crystal structure regulation. As for the externally morphological architecture design, distinct optical performance achieved in lanthanide-doped nanocrystals with varied morphologies like core–shell, hollow and ultrasmall nanoarchitectures is summarized. With regard to the intrinsically crystal structure regulation, the tunable upconversion luminescence intensity and red-to-green ratio of Er3+ for Yb3+/Er3+-doped nanocrystals and the consequent biodegradable nanocrystals are discussed, with an emphasis on the origin underlying the crystal-structure-dependent upconversion luminescence. Multifarious biological applications, including heterogeneous biodetection based on core–shell nanocrystals, homogeneous biodetection based on ultrasmall nanocrystals, superior nanothermometer based on hollow nanocrystals and in vivo bioimaging based on biodegradable nanocrystals, are briefly reviewed. Current challenges and future opportunities for lanthanide-doped inorganic nanocrystals for biological applications are also provided in the end. [ABSTRACT FROM AUTHOR]

Transition metal such as Copper substituted Mn-Zn magnetic nano ferrite with general formula Mn0.5Zn0.5CuxFe2−xO4 (x = 0.0, 0.1, 0.2, and 0.3) were fabricated by solution combustion method and expose how significant properties of the samples are modified accordingly by dopant concentration. By FTIR spectroscopy various functional group present in Mn-Zn ferrites is studied. The optical plots revealed bandgap energy reduced from 2.42 to 1.82 eV although the electrical study shown the highest conductivity of synthesized nano ferrite is 1.93 × 10−8Scm−1. The dielectric constant as well as dielectric loss behavior recorded at room temperature and were analyzed with increasing temperature; both dielectric constant and loss tangent upsurge however with increasing frequency both are observed to reduce. Doping with Cu has the potentiality of accumulative dielectric constant and conductivity of Mn0.5Zn0.5CuxFe2−xO4 thereby improving its application for electromagnetic devices. [ABSTRACT FROM AUTHOR]

Nickel oxide (NiO) thin films were grown on glass substrates by a simplified spray pyrolysis technique using perfume atomizer at different substrate temperatures which is the novelty of this work. X-ray diffraction patterns reveal the cubic crystalline phase pure NiO film with preferential orientation along (2 0 0) plane. Thermal treatment of NiO thin films at 400 °C enables us to identify a suitable deposition temperature for obtaining good quality thin films. The average crystallite size calculated from Scherrer's formula is found to be 28 nm. The closely packed and spherical shaped grains obtained were confirmed from field emission-scanning electron microscope (FE-SEM). From FE-SEM analysis, the smooth nature of NiO thin films deposited at 400 °C enables it to use for solar cell applications, whereas the porous nature of NiO thin films deposited at 300 °C enables it to use for gas sensing applications. The mean square roughness increased with substrate temperature is confirmed from atomic force microscope analysis. The average transmittance of 75–85% demonstrates the compactness of the film except for the film N400, which is attributed to the defects. The energy band gap (Eg) is found to be 2.93, 3.63, 3.72, and 3.67 eV, respectively, for NiO thin film deposited at substrate temperature 300 °C, 350 °C, 400 °C, and 450 °C. The Raman peak at 1573 cm−1 corresponds to 2 M band antiferromagnetic state. The presence of defect states is identified from PL and EPR spectra. [ABSTRACT FROM AUTHOR]

In this paper, a CSVO3 phosphor for white LED has been successfully prepared by solid-state synthesis and has been characterized. The CsVO3 was simulated by Materials Studio software based on density functional theory (DFT). The results show that the CsVO3 sample has a direct optical transition with band gap energy of 3.143 eV. Under ultraviolet excitation in the range of 300–390 nm, the emission spectrum of CsVO3 phosphors ranges from 400 to 700 nm, and its peak emission spectrum is near 492 nm, and shows yellow color fluorescence emission. These results indicate that CsVO3 phosphor can be used as a promising white phosphor for white LED. [ABSTRACT FROM AUTHOR]

The authors in this article present the synthesis of good quality CuGaGeSe4 thin films of different thicknesses using electron beam deposition on well pre-cleaned glass substrates. X-ray diffraction patterns displayed the amorphous nature of as-prepared CuGaGeSe4 thin films. In addition, the elemental compositional analysis of these films was examined by the energy-dispersive X-ray spectroscopy technique, which showed that there is good matching between the selected and detected percentages. Transmittance and reflectance spectra of these CuGaGeSe4 samples were measured to experimentally determine the absorption coefficient and some related optical parameters. Optical band-gap energy values of samples were determined via Tauc's Plots; they are arisen owing to the indirect allowed transition. They are decreased from 1.43 to 1.29 eV by increasing the film thickness from 250 to 445 nm. The skin depth, absorption index, and refractive index of CuGaGeSe4 thin films were also obtained and extensively studied. As well as, some optoelectrical parameters of these investigated films were discussed, like optical resistivity, optical mobility, optical conductivity, the lattice dielectric constant, and the ratio of the charge carrier concentrations to the effective mass (Nopt/m*). Along with, some nonlinear optical parameters of CuGaGeSe4 films were studied employing Miller's formulas. The values of the dispersion energy, static refractive index, the static dielectric constant, the oscillator strength and others increase, while the oscillator energy and the relaxation time decrease as the film thickness increased. The obtained results showed that these CuGaGeSe4 film samples can be successfully used as absorption layers in thin-film solar cells. [ABSTRACT FROM AUTHOR]

Due to their unique photophysical properties, upconverting nanoparticles (UCNPs), i. e. particles capable of converting near‐infrared (NIR) photons into tunable emissions in the range of ultraviolet (UV) to NIR, have great potential for use in various biomedical fields such as bioimaging, photodynamic therapy and bioanalytical applications. As far as biomedical applications are concerned, these materials have a number of advantageous properties such as brilliant luminescence and exceptional photostability. Very small "stealth" particles (sub‐10 nm), which can circulate in the body largely undetected by the immune system, are particularly important for in vivo use. The fabrication of such particles, which simultaneously have a defined (ultrasmall) size and the required optical properties, is a great challenge and an area that is in its infancy. This minireview provides a concise overview of recent developments on appropriate synthetic methodologies to produce such UCNPs. Particular attention was given to the influence of both surfactants and dopants used to precisely adjust size, crystalline phase and optical properties of UCNPs. [ABSTRACT FROM AUTHOR]

This work presents the optical and structural properties of rare earth-doped and co-doped yttrium oxide nanophosphors. Europium oxide and gadolinium oxide-doped and co-doped Y2O3 phosphors were synthesized by make use of combustion method followed by annealing to different temperatures in order to obtain much more good crystallinity. The X-ray diffraction and Fourier transform infrared spectroscopy confirms the structural formation and phase purity of the compound. The diffuse reflectance spectra of doped and co-doped Y2O3 powder were analysed. It was found that there appears shifting of absorption edge towards longer wavelength region when compared to pure yttrium powder. The band gap was calculated by make use of Kubelka–Munk function. It was noticed that band gap increases with annealing temperature. The dependence of doping concentration, pH and annealing temperature on photoluminescence properties were studied in a systematic manner. The PL emission intensity was maximum for 6 wt% Eu3+-doped Y2O3 powders that results 5D0–7F2 transition within europium and emits red light at 612 nm under the excitation of 260 nm. In the case of co-dopant, maximum intensity is obtained for 7 wt% Gd3+ under the excitation of 255 nm. [ABSTRACT FROM AUTHOR]

The morphology, structure and optical properties of zinc sulfide (ZnS) thin films prepared through radio-frequency (RF) magnetron sputtering have been analyzed using atomic force microscopy (AFM), UV–Vis–NIR spectrophotometry, X-ray diffraction, and multifractal analyses. The X-ray diffraction patterns revealed that all ZnS thin films show a single peak at around 29.6°, which has been ascribed to the (111) planes of sphalerite phase, indicating that the growth direction of the films is the [111] direction. UV–Vis–NIR transmittance spectra were used to determine the refractive index of the samples, their thickness, and their band gap energy, showing the optical and semiconductor properties a clear dependence of the film thickness. Finally, ZnS thin films were characterized and analyzed by atomic force microscopy (AFM) measurements and multifractal analyses for a complex and precise interpretation of the 3-D surface microtexture characteristics. The multifractal examinations of the samples revealed a particular distribution at the nanometric level associated with multifractal surface characteristics. These experimental results are corroborated, presented, and discussed together with the essential stereometric parameters of the thin films. The combination of the different experimental information and the comprehensive stereometric and multifractal analyses provide new and deeper insight into the ZnS thin films that would be exploited to develop novel micro-topography models. [ABSTRACT FROM AUTHOR]

Well-dispersed (Gd, Al)-codoped ZnO (Zn0.96–xGdxAl0.04O) nanoparticles (NPs) with different Gd content (x = 0–0.04) were synthesized by low temperature hydrothermal method and their structural, optical, and magnetic properties were investigated. All the as-prepared Zn0.96–xGdxAl0.04O NPs exhibit a hexagonal wurtzite structure with good crystal quality and small particle size (~3 nm). With increasing Gd-doping content from 0 to 0.04, the band gap Eg of Zn0.96–xGdxAl0.04O NPs increases from 3.46 to 3.62 eV owing to the substitution of Gd ions at Zn sites. The presence of additional intrinsic defects Zn-interstitial (Zni) and/or O-vacancy (VO) induced by Gd-doping results in the enhanced PL emission and increased PL lifetime. As compared with Al-doped ZnO, the room temperature ferromagnetic behavior of (Gd, Al)-codoped ZnO system is enhanced remarkably, which is explained based on the O-vacancy mediated exchange interactions between Gd and Al ions. Highlights: Well-dispersed Zn0.96–xGdxAl0.04O (x = 0–0.04) nanoparticles were synthesized by low temperature hydrothermal method. The band gap Eg was found to increase from 3.46 to 3.62 eV as the Gd-doping content increases from 0 to 0.04. Enhanced PL intensity and longer PL lifetime confirmed the formation of more Zn-interstitial and O-vacancy defects generated by Gd doping. O-vacancy mediated exchange interactions between Gd and Al ions improved the ferromagnetic properties of (Gd, Al)-codoped ZnO NPs. [ABSTRACT FROM AUTHOR]

In current article authors aim is to present an insight on structural, opto-nonlinear-limiting properties of Cadmium sulfide (CdS) thin films affected by various concentrations of tellurium (Te) doping. Hence, the thin films of pure and Te:CdS were fabricated by spray pyrolysis technique by keeping the substrate at 300 °C. X-ray diffraction and FT-Raman spectroscopy analyses confirmed the hexagonal phase of CdS. The values of Lave, ρave and εave are found in range of 18–20 nm, 2.6–3 nm−2 and 1.7–1.9, respectively. Furthermore, the energy dispersive X-ray spectroscopy/scanning electron microscopy mapping (SEM) confirmed the presence and homogeneous doping of Te in CdS. SEM study shows that the fabricated films are free from any pin holes and possess very fine nanostructures. The optical transparency of grown films was noticed ~ 70%, which is quite impressive for colored materials. The absorption index, refractive index values are found in range of 0.04 to 0.25, 1.25 to 3.2 in 200 to 2500 nm wavelength region. The direct energy gap of CdS was noticed to be reduced from 2.44 to 2.35 eV (ΔEg = 0.09) with Te doping content. Photoluminescence emission spectra contains an intense green emission band at ~ 528 ± 4 nm. The dielectric constant and optical conductivity were noticed in range of 1.5 to 10 and 0.02 to 0.6 (× 105), respectively. The values of third order susceptibility and nonlinear refractive index was found of the order of 10−10 esu. The output power of the 532 nm laser passed from films is found to be reducing with increasing the Te content in CdS films. Hence, the deposited films of Te:CdS will be more applicable as optical limiter in sensor device protection from intense lights. [ABSTRACT FROM AUTHOR]