Doped Gd2O3 Research Articles

Eu3+ activated gadolinium oxide quantum dots: Biocompatible red luminescent phosphor for photonic, latent fingerprint imaging, and anticancer therapy

In this study, we employed a straightforward chemical reduction method to synthesize Gd2O3 quantum dots (QDs) doped with Eu3+ ions, yielding a remarkable red emission. X-ray diffraction (XRD) analysis confirmed the cubic structure of both pristine and Eu3+ doped Gd2O3 QDs. Characterization of particle size and elemental composition was accomplished through Transmission Electron Microscope (TEM) and X-ray photoelectron spectroscopy (XPS), respectively. Photoluminescence analysis under UV excitation revealed a blue emission at 436 nm for the undoped Gd2O3 QDs. Furthermore, room temperature photoluminescence analysis was conducted on the undoped Gd2O3 quantum dots (QDs) with a UV excitation source. While Gd2O3 QDs emitted a blue light at 436 nm under 396 nm illumination, the Eu3+ doped Gd2O3 QDs exhibited a striking red luminescence under the same 394 nm wavelength. The red luminescence was notably enhanced in Gd2O3 QDs containing 0.5 mol% Eu3+ ions, although concentration quenching was observed when the concentration exceeded this level. A transfer of energy from pristine Gd2O3 QDs to Eu3+ ions was observed, leading to color purity exceeding 80.8% in the optimized sample. Notably, the 0.5 mol% Eu3+-doped Gd2O3 QD phosphor displayed non-cytotoxicity on C2C12 muscle myoblast cells while demonstrating remarkable cytotoxicity against MDA-MB-231 human breast cancer cells. This versatile material holds great promise for applications in latent fingerprinting, security coding, labeling, anticancer therapies, bio-imaging, and the advancement of lanthanide-doped QD phosphors for a wide range of photonic and biomedical applications.

Synthesis and Characterization of White Light Emission of Dy3+ Doped Gd2O3 Phosphors

Dy3+ ion doped Gd2O3 phosphors with varying concentrations were synthesized successfully by hydrothermal process. The XRD patterns and TEM images of prepared samples were well-studied. Upon the emission at λem = 573 nm, the excitation spectra consist of several peaks which denote the characteristic lines of the 4f-4f or 4f-5d intra-configurational transition of Gd3+ and Dy3+ ions. In the emission spectrum obtained by excitations at 234 nm and 273 nm, consist of two characteristic band obtained at 485 and 573 nm, which are attributed to 4F9/2→6H15/2 (blue) and 4F9/2→6H13/2 (yellow) transitions of Dy3+ ion, repectively. The photoluminescence lifetime are found to be at around 0.599-1.200 ms. The CIE Chromaticity coordinates showed the prepared samples could be used as a white light emitting phosphor applied in near UV region.

Multiphonon assisted upconversion thermal enhancement for optical temperature sensing and high penetration depth

Thermal quenching that the upconversion (UC) luminescence intensities decrease with increasing temperature limits the application of UC luminescence materials in the field of optical temperature sensing. Herein, we report that Tm3+/Yb3+ doped Gd2O3 phosphors achieve thermal enhancement of UC luminescence with the multiphonon assisted process. Significantly, a possible mechanism of Yb3+ ions in thermal enhancement and multiphonon assisted UC luminescence process is proposed. Based on the luminescence intensity ratio technique of non-thermally coupled energy levels, research shows that thermal enhancement can effectively improve the optical temperature sensing absolute sensitivity. Owing to the near-infrared excitation and strong near-infrared emission, the UC luminescence of the Gd2O3: Tm3+/Yb3+ phosphors can penetrate 12 mm pork tissue and achieve UC thermal enhancement in 287-314 K after penetrating 6 mm pork tissue, which shows its potential in vivo application. The results not only provide a pathway to realize the thermal enhancement of UC luminescence and the improvement of the temperature sensing sensitivity, but also promote the understanding and utilization of the UC luminescence thermal enhancement.

Effect of dopant concentration on photoluminescence properties of Dy3+ doped Gd2O3 nanophosphors under different excitation wavelengths

In this work, the role of dopant Dy3+ concentration and excitation wavelength on luminescence properties of Dy3+ doped Gd2O3 nanophosphors prepared by chemical precipitation method were studied. The phosphors were characterized by X-ray diffraction (XRD), Energy dispersive analysis of X-ray (EDAX) and photoluminescence spectroscopy. The crystallite sizes of the phosphors were found to be in the range of 11–17 nm. The profile of the emission spectra for the phosphors was independent of dopant concentration as well as excitation wavelengths. The photoluminescence emission peaks were observed at 486 nm and 574 nm corresponding to 4F9/2-6H15/2 and 4F9/2-6H13/2 transitions respectively. The optimum concentration of Dy3+ for maximum emission intensity was found to be 2 at.% of Dy3+ which was independent of excitation wavelength. The emission intensity of all prepared phosphors under 234 nm excitation wavelength was found to be stronger than that of 278 nm. This showed the energy transfer due to host absorption was more efficient. The color emission of different concentration of Dy3+ doped Gd2O3 nanophosphors under different excitation wavelengths were studied from calculated CIE coordinates and was found to be shifted towards the blue region with the increase of dopant concentration.

The influence of lithium ion incorporation on the luminescence enhancement of Gd2O3:Pr3+ nanophosphors for lighting applications

In this study, nanosized Gd2O3: Pr3+ and Li+ co-doped Gd2O3: Pr3+ were synthesised by solution combustion method for analysing the structural, morphological and optical properties. X-ray diffraction patterns of as-prepared Gd2O3:Pr3+ indicated the existence of multiphase crystallites and it transformed to pure cubic phase upon annealing. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) images confirmed that the particles are spherical. Upon 321 nm excitation, Gd2O3: Pr3+ phosphor exhibits characteristic emission bands at 613 nm, 529 nm and 439 nm. The photoluminescence emission intensity was found maximum for 2 wt% Pr3+ doped Gd2O3 powders. Li+ ions were co-doped into this Gd2O3:Pr3+ phosphor and were found to induce a considerable enhancement in PL emission intensity. Lithium co-doped samples crystallize in cubic structure. Raman spectra of the Li+ co-doped phosphors revealed characteristic Ag+ Fg mode of the cubic phase of Gd2O3, apart from other independent modes. The maximum emission intensity was obtained for 0.5 wt% Li+ co-doped samples, with an improved intensity of about 2.87 times that of Gd2O3:Pr3+. The new composition Gd2O3: Pr3+: Li+ with enhanced luminescence properties can be employed as a red light emitting phosphor for white light emitting diodes (WLEDs).

Enhancement of photoacoustic and upconversion emission in Mg2+/Zn2+ codoped Gd2O3: Er3+/Yb3+ phosphor using 980 nm excitation.

In this work, Er3+/Yb3+ doped Gd2O3 phosphor samples were synthesized through a combustion method and then characterized through X-ray diffraction and FE-SEM techniques. The sample was studied for photoacoustic spectroscopy (PAS) and upconversion (UC) emission spectroscopy techniques using a frequency modulated 980 nm excitation source. A correlation between PA signal (produced due to non-radiative transitions) and UC emission intensity (produced due to radiative transition) is made in order to optimize the sample for both these properties. The phosphor was codoped with Mg2+ and Zn2+ ions to see enhancement in upconversion emission intensity and these ions have enhanced the upconversion emission. Studies show that the present phosphor is appropriate for producing strong upconversion emission intensity along with a strong photoacoustic signal which is beneficial for upconversion-imaging as well as photothermal therapy. The present sample has also shown its potential for detection of fingerprints.

Band gap and pseudocapacitance of Gd2O3 doped with Ni0.5Zn0.5Fe2O4

Herein, we present a detailed study of the structural, optical, and electrochemical responses of Gd2O3 doped with nickel zinc ferrite nanoparticles. Doping of Ni0.5Zn0.5Fe2O4 nanoparticles to Gd2O3 powder was done through thermal decomposition at 1000 °C. The average grain size of the mixture was determined to be approximately 95 nm, and phases of cubic Gd2O3, GdO, and orthorhombic prisms of GdFeO3 were identified. The focused ion beam energy dispersive x-ray spectrum (FIB-EDX) mapping results clearly show the morphology of the particles with Gd and Fe as the dominant elements. The structural data were compared with the spectroscopic measurements confirming the formation of multiple phases of oxides and ferrites. The measured optical band gap is significantly redshifted to 1.8 eV and is close to that of nitride compounds of gadolinium metal. The measured specific capacitance was almost 7 Fg−1 at a current density of 1 Ag−1, showing a small drop of 27% when the current density is increased to 10 Ag−1. Cyclic voltammetry (CV) plots of the ferrite doped Gd2O3 electrode at a scan rate of 5 to 100 mV s−1 indicate the pseudocapacitive nature of the material.

Redshift of the optical gap in ferrite doped Gd2O3

We report the measurement of the optical bandgap in ferrite doped Gd2O3. Doping of the nickel zinc ferrite (Ni0.5Zn0.5Fe2O4) nanoparticles to Gd2O3 powder was done through thermal decomposition of the mixture at 1000 °C. The average grain size of the thermally decomposed mixture was determined to be around 95 nm and contained phases of cubic Gd2O3, GdO, and orthorhombic prisms of GdFeO3. The imaginary part of the complex dielectric function was calculated from the absorbance measurements that showed an optical bandgap at 1.8 eV. The observed value of the fundamental energy gap is on average 4.0 eV smaller than suggested by early experiments. A model for the ferrite doped Gd2O3 was constructed to suggest that the Ni, Zn, and Fe atoms occupy Gd sites in the Gd2O3 lattice. A new band at Γ point is formed due to the hybridization of the atomic orbitals of dopant and Gd3+ that shifts the fundamental absorption edge to the red part of the photon energy spectrum. Despite having a high density of negatively charged carriers contributed by the dopant, the onset of the direct interband transitions is clearly resolved.

Color tunable Gd2O3:Dy3+ nanophosphors under different excitation wavelengths

Undoped and 2 at.% Dy3+ doped Gd2O3 nanophosphor were synthesized using chemical precipitation method. The crystallite sizes of the samples were found to be in nanometer range. The luminescent properties of the samples were studied under different excitation wavelength namely 234 nm and 278 nm. The photoluminescence emission peaks of doped samples were observed at 486 nm and 574 nm corresponding to 4F9/2-6H15/2 and 4F9/2-6H13/2 transitions respectively in both cases. The emission intensity due to 234 nm excitation wavelength was much stronger which showed the energy transfer due to host absorption was more efficient. The change in color emission of 2 at.% Dy3+ doped Gd2O3 nanophosphor under different excitation wavelength were observed from calculated CIE coordinates and CCT values.

Synthesis and studies of optical properties of Eu3+ doped Gd2O3 phosphor prepared via hydrothermal process

Synthesis and studies of optical properties of Eu3+ doped Gd2O3 phosphor prepared via hydrothermal process

Frequency upconversion, paramagnetic behavior and biocompatibility of Gd2O3:Er3+/Yb3+ nanorods

A facile base-catalyzed hydrothermal method is used to synthesize a bifunctional luminomagnetic Er3+/Yb3+ doped Gd2O3 nanorods material. The as-synthesized nanorods material is investigated for structural/microstructural, upconversion, and magnetic properties. The intense emission bands at 520 nm, 540 nm, and 654 nm are observed upon excitation with a 980 nm solid state laser. The effect of Yb3+, Er3+ doping concentrations and incident laser power on the upconversion emission properties are also investigated, and the mechanism for the upconversion process is proposed. We further investigated the magnetic properties by room temperature M-H and M-T measurements in the temperature range of 2-300 K by standard ZFC-FC protocols. Cytotoxicity analysis of these bifunctional luminomagnetic nanorods in established cell lines did not show considerable cytotoxicity.

Synthesis, characterization and effect of dopant on magnetic hyperthermic efficacy of Gd2O3 nanoparticles

Rare-earth oxides are paramagnetic materials and their high magnetic susceptibility in the bulk makes them potentially promising materials, but the magnetic properties of their nanoparticles remain incompletely characterized. We explore the effect of dopant (Tb3+ and Eu3+) in Gd2O3 host lattice as a heating agent for magnetic hyperthermia application. The structural, optical, and magnetic properties of the pristine, Gd2O3:Tb3+ and Gd2O3:Eu3+ nanocrystals were studied by XRD, HR-TEM, FTIR, and VSM. XRD analysis revealed the presence of mixed-phase (cubic and monoclinic) in pristine, and doped Gd2O3 nanoparticles. The morphological information has been observed with the help of HRTEM and the calculated inter-planar spacing is in well agreement with JCPDS data. Particles are nearly spherical and diameter ∼15 nm, estimated from HRTEM image. FTIR spectroscopic analysis confirms the presence of Gd-O-Gd stretching at 583cm−1. We confirmed the paramagnetic nature for all samples using VSM analysis. The self-heating capability of prepared samples are investigated by performing the induction heating experiment and it is assessed through calculated SAR and ILP values with help of Box-Lucas fitting model where 10% Tb3+ doped Gd2O3 has maximum values.

A review: X-ray excited luminescence of gadolinium based optoelectronic phosphors.

X-ray excited fluorescence tomography is an emerging field in the application of bio-imaging and computer tomography. Some rare-earth doped inorganic phosphors like gadolinium oxide (Gd2 O3 ), yttrium oxide (Y2 O3 ), zinc tungstate (ZnWO4 ), cesium fluoride (CsF), barium fluorochloride (BaFCl), lanthanum oxybromide (LaOBr) are shown outstanding applications for X-ray excited phosphors. Gadolinium (Gd)-based inorganic phosphors show extraordinary applications in the field of X-ray chromatography and computer chromatography. In this review article, we discussed the general information about X-ray excited luminescence (XEL) phosphor. Further, we discussed importance, synthesis, structural and photoluminescence (PL) properties of rare-earth (Europium (Eu)) doped Gd2 O3 . To elaborate the scope of the review, we have discussed synthesis, structural and optical properties of lithium (Li) doped Gd2 O3 :Eu. At the end of the review, synthesis, structural and optical properties of Eu doped lutetium oxide (Lu2 O3 ) have been discussed and the results compared with Eu doped Gd2 O3 . The comparison provided the understanding of structural and optical peak position of host and the dopant (Eu).

Effect of oxygen pressure on stoichiometric transfer in laser ablation of Pr3+ doped Gd2O3–Ga2O3 binary system

Three different compounds, cubic Gd2O3, orthorhombic GdGaO3, and cubic Gd3Ga5O12 doped with Pr3+ ions were fabricated as waveguiding films by pulsed laser deposition from the same target material, Pr3+ doped Gd3Ga5O12 (Pr:GGG) single crystal. All of them were deposited at the same substrate temperature of 800 °C. The different crystalline phases obtained depend only on the ambient oxygen pressure and the substrate type (YAG or YAP single crystals). The structural and texture properties of the films were analyzed by x-ray diffraction. Pr3+ fluorescence properties were found to be similar to those of the bulk crystals. The refractive indices and waveguiding properties of the films were determined. The fluorescence properties of Pr3+ doping ions and the refractive index of the film are presented. The oriented crystalline Pr:GdGaO3 and Pr:GGG films show waveguiding propagation with attenuation around 2.5 and 1 dB/cm, respectively.

Structural and optical studies of cerium doped gadolinium oxide phosphor

This research aims to study the influence of variation of doping concentration on various properties of Ce3+ doped Gd2O3 phosphor. The phosphors (Gd1−xCex)2O3 (0 ≤ x ≤ 0.15) were successfully synthesized by the solution combustion method. The structural and optical properties of the prepared phosphors were studied. Rietveld refinement confirms the formation of the cubic phase. Fourier transform infrared spectra further confirm the formation of the phosphor. It is found that an enhancement in doping concentration of Ce3+ results in the expansion of the crystal lattice, leading to a reduction in crystallite size as well as in the optical band gap. Photoluminescence emission spectra are studied, and the exact emission colour is confirmed using 1931 Commission Internationale de l’Eclairage (CIE) chromaticity coordinates. The prepared phosphor exhibits bluish green emission corresponding to 5d–4f transitions of the trivalent cerium ion and can be used as a promising candidate in optical display applications and LED applications.

Gd2O3:Er3+ embedded PMMA/PC nanocomposites: A luminescent nanocomposite

Gd2O3:Er3+ nanophosphor powders were synthesized by the solution combustion method and then embedded into neat Poly(methyl methacrylate) (PMMA) polymer solution and Poly carbonate (PC) polymer solution via the solvent casting method to obtain Polymer-Phosphor nanocomposites. This method is widely used due to certain advantages like uniform dispersion of the filler being added and ease of the preparation procedure. Different samples (0.5–2.0 wt %) of Er3+ doped Gd2O3 nanophosphors were prepared by the combustion method. The samples were then characterized by FTIR, XRD, SEM techniques. The particle size was evaluated by Debye Scherrer's formula and was found to be 12 nm using urea as fuel. XRD analysis revealed crystalline nature and monoclinic phase of the synthesized phosphor. On incorporation of the synthesized nanophosphor into the neat polymer solution, neat dispersion of the powder in the film was observed and also at higher phosphor loading (2 wt %), agglomeration was observed. XRD diffractogram of the nanocomposite films confirmed the incorporation of the nanophosphor into the polymer matrix. The emission spectra monitored at 275 nm excitation wavelength, similar emission bands as that of the nanophosphor at 552, 590 and 605 cm−1 were observed with slight shifts. TGA analysis revealed the thermal stability of the polymer. The CIE chromaticity diagram confirmed the emission color of the nanocomposite films, and the tuning of color by changing Er3+ concentration was also studied.

Warm white broadband emission and tunable long lifetimes in Yb3+ doped Gd2O3 nanoparticles

Upconversion luminescence materials have stimulated growing attention in photovoltaic cell owning to the ability of converting a few low-energy photons into a single high-energy photon. However, there still remains a daunting challenge to achieve upconversion emission covering the entire visible spectrum in a single material. Here, an incandescent broadband white upconversion emission covering the entire visible region is realized in a single Gd2O3:Yb3+ nanoparticles by utilization of adverse multiphonon relaxation. Importantly, tunable long fluorescence lifetime can be synchronously implemented in the single material, where the lifetime range spans one order of magnitude. Furthermore, benefiting from the broadband emission, the luminescence intensity achieves 482-fold improvement as the power increase from 0.53 W to 1.51 W. These broadband emissions are enabled by engineering the pathways of nonradiative de-excitation via multiphonon relaxation. Based on the kinetic analysis and mechanism research, the photon avalanche is demonstrated to play an important role for broadband emission. The warm white emission together with its tunable long lifetime provides a new avenue for developing single emitter-based white-light-emission materials for next-generation display and lighting technologies.

Multiple deep-level defect correlated emissions and phosphorescence in Eu3+ doped Gd2O3 compound systems

Various concentrations of Europium doped Gadolinium Oxide powders are synthesized by high temperature solid state reaction method. X-ray diffraction pattern of the compounds revealed single phase crystal formation, consistent with predominant monoclinic phase of Gd2O3. Deep level photoluminescence spectra showed multiple emissions in yellow - red region corresponding to transitions of 5D0-7F2, 5D0-7F1 and 5D0-7F0 which arise due to europium substitution. Appreciable enhancement in emission intensity is observed at higher doping concentrations. The optical band gap energies are determined from the diffuse reflectance spectra by utilizing Kubelka-Munk theory.

Upconversion luminescence of Er<SUP align="right">3+</SUP> doped Y<SUB align="right">2O<SUB align="right">3 and Gd<SUB align="right">2O<SUB align="right">3 nanophosphors

The luminescence process and mechanism of Er3+ doped Y2O3 and Gd2O3 nanophosphors are investigated with focus on their upconversion luminescence properties. Here the strong up-conversion (UC) emissions of both Y2O3:Er3+ nanoparticles prepared by combustion with EDTA and Gd2O3:Er3+ nanospheres synthesised by multistep chemical reaction using urea have been measured at room or low temperatures. The downward-conversion luminescence spectra in visible and near infrared region have been assigned from the transitions in the energy level system of Er3+ion. For Y2O3:Er3+nanoparticles, the upconversion luminescent intensity depends on excitation power at 980 nm have properly indicated the two photon process which are the calculated slope values of main transitions in Er3+ions: 2H11/2-4I15/2, 4S3/2-4I15/2and 4F9/2-4I15/2 are 2.07, 1.72, 1.87 (0.5% Er) and 2.32, 1.82 and 2.07 (Er 1.0%) respectively. The integral intensity of the red band is smaller than that of the green band in the upconversion emission of nanoparticles Y2O3 doped with Er3+ with 0.50, 1.00 and 1.50%. However it was the integral intensity of red emission bands that dominated in Gd2O3: 1% Er3+. The lifetimes of the band in green colour peaked at 562 nm upon excitation at 380 nm in Y2O3:Er3+ with 0.50, 1.00 and 1.50%, and have shown the two sequent time decay processes, the shorter and the longer, both in millisecond scale, 0.14 ms (0.5%); 0.28 ms (1.00%) and 0.13 ms (1.50%) and 4.49 ms (0.5%); 6.89 ms (1.00%) and 5.16 ms (1.50%), respectively. For the nanoparticles Gd2O3: 1% Er the intensity decrease of the upconversion emission peaked at 562 nm with only a single process with a decay time of 1.24 ms. Both nanophosphors Y2O3 and Gd2O3 doped with Er3+ are promising materials to develop multifunctional units for medical applications.

Up-conversion luminescence of Yb[formula omitted]/Er[formula omitted] doped Gd[formula omitted] phosphors for optical temperature sensing in green and red regions

In this work, the up-conversion luminescence of Yb 3+/Er3+ doped Gd2O3 phosphors for optical temperature sensing in green and red regions are investigated. The intense green (522 and 562 nm) and red emissions (660 and 682 nm) radiated from Er3+/Yb3+ tri-doped Gd2O3 phosphors are successfully realized via tuning the doping proportion of Er3+ and Yb3+. To evaluate their potential ability of optical thermometry in green light range and the first biological window, the temperature-dependent green and red emissions are investigated. Based on the florescence intensity ratio (FIR) of 522 and 562 nm, the absolute sensing sensitivities of Gd2O3: 1 mol% Er3+/4 mol% Yb3+ and Gd2O3: 1 mol% Er3+/6 mol% Yb3+ phosphors reach 1.16 and 1.2% K−1 (523 K), respectively. In addition, the temperature sensing sensitivities based on the FIR of 660 and 682 nm reach 0.8 and 0.6% K−1 (300 K), respectively. Moreover, the changes of FIR (ΔR) are smaller than 3% within the cycling heat and cool processes. These results reveal that Gd2O3:1mol%Er/4(6)mol%Yb phosphors are promising for FIR-based temperature sensing in high temperature via green emissions and room temperature via red emissions.