Increase Of Gd3 Research Articles

G-C3N4 modified natural low-grade dolomite-palygorskite: Removal capacity and adsorption mechanism for Gd3+

Rare earth elements (REEs) pose significant environmental challenges due to the wastewater generated during their extraction. Developing efficient adsorbents with simple, economical and eco-friendly methods for removing and recovering REEs from wastewater is highly demanded but full of challenges. This study creates a novel adsorbent (g-C3N4/0.5DPal) for efficient REEs removal and recovery by integrating the low-grade mineral dolomite-palygorskite with g-C3N4 through a "one-pot" calcination method. Characterization techniques including SEM, XRD, FT-IR, XPS, etc., were employed to analyze the structure of the g-C3N4/0.5DPal composite. Batch adsorption experiments focusing on Gd3+ from among the REEs were conducted to evaluate the adsorption performance. The results reveal a remarkable 3.34 times increase in Gd3+ adsorption capacity of g-C3N4/0.5DPal (192.46 mg/g) compared to raw dolomite-palygorskite (57.62 mg/g) at 298 K, highlighting the effectiveness of the modification. The adsorption mechanism involves electrostatic interactions, surface complexation, and cation-π interactions. It is worth noting that g-C3N4 facilitates the conversion of dolomite to calcite during the preparation process, enhancing the Gd3+ adsorption of g-C3N4/0.5DPal. This work offers a promising solution for the removal and recovery of REEs and the high-value utilization of low-grade minerals, addressing both environmental concerns and resource sustainability.

X-ray/gamma radiation attenuation and cytotoxic properties of Gadolinium doped Maghemite nanoparticles

In the present work, Gadolinium doped (1–6 mol%) Maghemite nanoparticles (NPs) were synthesized via solution combustion method using Sapodilla fruit extract as a reducing agent followed by calcination at 500 °C and characterized with different techniques. The Bragg reflections consists of (hkl) planes corresponding to γ-Fe2O3 (Maghemite). Addition to this, few planes corresponding to α-Fe2O3 and Gd2O3 were also observed. The estimated crystallite size and direct energy band gap was found to decrease with increase in Gd3+ concentration. Cytotoxic properties were examined on cervical cancer cell lines HeLa cells as the Gadolinium dopant concentration increases, cell death decreases, eventually toxicity is going to reduced. Because of the non-toxicity, these NPs might be used as a drug carrier and also in the biochemical modification process called PEGylation. Theoretically, X-ray/Gamma ray attenuation parameter such as mass attenuation coefficient is studied in detail which is an essential parameter in radiation dosimetry. Gamma attenuation ion properties are increased by increase in the dopant concentration of Gadolinium. Compared to other concentrations, Gadolinium at 6 mol% shows maximum cytotoxic and mass attenuation coefficient. Thus, the present synthesized material might finds an application in biomedical field as well as in radiation dosimetry.

Structural and magnetic properties of gadolinium substituted Mn0.6Zn0.4GdxFe2−xO4 (x = 0–0.1) spinel ferrite

Soft magnetic ferrites Mn0.6Zn0.4GdxFe2-xO4 (x = 0, 0.02, 0.04, 0.06, 0.08 and 0.1) have been synthesized using a solvothermal method. X-ray diffraction analysis revealed the structure of Gd3+ doped Mn-Zn ferrite was spinel structure. In response to an increase in Gd3+ content, the lattice constant of the sample increased and then decreased, and the largest lattice constant was 8.452 Å with x = 0.04. The crystallite size varied between 14.7 and 18 nm. M−H data revealed that all samples are soft magnetic and characterized by the larger saturation magnetization, low remnant magnetization and coercively. We found that the Gd3+ ions substituted into Fe3+ ion sites and resulted an increase in Gd3+ content from x = 0 to x = 0.1, which lead to the saturation magnetization first increased then decreased. The maximum saturation magnetization value of Mn0.6Zn0.4GdxFe2-xO4 was 90.1 emu/g with x = 0.04, which suggested the Mn0.6Zn0.4Gd0.04Fe1.96O4 was magnetically responsive, and could be used in hyperthermia tumor applications.

Role of Gd3+ on the magnetocaloric properties of lanthanum-strontium manganite

In this work, the role of magnetic ion Gd3+ in the crystal structure, magnetic and magnetocaloric properties of doped lanthanum-strontium manganite (La0.7-xGdxSr0.3MnO3 varying x from 0 to 0.2) synthesized by high-energy ball milling assisted with annealing, is discussed. Furthermore, the interplay between the magnetic and crystal structure in co-doped manganites is proposed. The X-ray diffraction patterns confirm the complete formation of lanthanum manganite showing different crystal structures regarding the gadolinium content. The Sr2+/Gd3+ doped lanthanum manganites with Gd3+ concentration lower than 0.1 mol show rhombohedral crystal structure (R-3cH). Higher gadolinium concentrations promote a phase transition from rhombohedral to orthorhombic crystal structure. The Curie temperature of the manganites decreases with an increase in Gd3+ content, from 376 K to 257 K, for un-doped and x = 0.2 Gd3+, respectively, attributed to a weakening in the double exchange interaction. Close interaction of the lattice parameters such as bond distances, bond angles, and symmetry-related with the mixed magnetic interactions was observed. The maximum magnetocaloric effect (MCE) calculated using Maxwelĺs ratio was observed around the paramagnetic to ferromagnetic ordering, at 311 K, for gadolinium content of 0.15 mol, measured through the entropy change. The Sr2+/Gd3+ doped lanthanum manganite shows a magnetically induced entropy change (|ΔSM|) in the range from 2.4 to 3.69 Jkg-1K−1 under 18 kOe, for 0.10 and 0.15, respectively, doing this manganite a suitable material for refrigeration applications at room temperature.

Fabrication luminescence and radiation shielding properties of Gd2O3–La2O3–ZnO–B2O3–Sm2O3 glasses

The purpose of developing high transparency radiation shielding materials and luminescence materials with stoichiometric ratio of xGd2O3:10La2O3:10ZnO:(79-x) B2O3: 1Sm2O3 where x = 0, 5, 10, 15, and 20 mol% using melt quenching technique. The physio-optical properties such as molar volume, density, concentration of rare-earth ions, polaron radius, inter-ionic radius, optical basicity, average distance between rare-earth ions, and optical packing density of the present glasses has been evaluated. The glass samples obtained show high density which is vital factor for radiation shielding. The absorption spectra show significant of bands Sm3+ ions. The FTIR results of Gd-La-Zn-B-Sm (Gd-1Sm) glass samples show signature borate BO3 and BO4 vibrational units in Gd-1Sm glass samples. The μ, μm, HVL, TVL, and MFP were evaluated and showed that the values decrease with increasing X-ray energy whereas increase with an increase in Gd2O3 content suggesting their potential use in X-ray diagnosis regions. The HVL value was compared with commercial windows, concrete, Serpentine and X-ray windows and found that the glasses doped with 10 mol%, 15mol%, and 20 mol% Gd2O3 content showed better results than X-Ray windows at 10 kVp. The emission and excitation spectra of glass samples were studied and emission spectra show orange emission bands. The experimental lifetime analysis shows that the glass samples show decreasing trend from 1.161 to 1.128 ms with an increase in Gd3+ ions exhibiting single exponential nature.

Influence of Gd3+ doping concentration on the properties of Na(Y,Gd)F4:Yb3+, Tm3+ upconverting nanoparticles and their long-term aging behavior

We present a systematic study on the properties of Na(Y,Gd)F4-based upconverting nanoparticles (UCNP) doped with 18% Yb3+, 2% Tm3+, and the influence of Gd3+ (10–50 mol% Gd3+). UCNP were synthesized via the solvothermal method and had a range of diameters within 13 and 50 nm. Structural and photophysical changes were monitored for the UCNP samples after a 24-month incubation period in dry phase and further redispersion. Structural characterization was performed by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) as well as dynamic light scattering (DLS), and the upconversion luminescence (UCL) studies were executed at various temperatures (from 4 to 295 K) using time-resolved and steady-state spectroscopy. An increase in the hexagonal lattice phase with the increase of Gd3+ content was found, although the cubic phase was prevalent in most samples. The Tm3+-luminescence intensity as well as the Tm3+-luminescence decay times peaked at the Gd3+ concentration of 30 mol%. Although the general upconverting luminescence properties of the nanoparticles were preserved, the 24-month incubation period lead to irreversible agglomeration of the UCNP and changes in luminescence band ratios and lifetimes.

Tetragonal structure and dielectric behaviour of rare-earth substituted La0.8Co0.16-xEu0.04GdxTiO3 (x = 0.04–0.16) nanorods

La0.8Co0.16-xEu0.04GdxTiO3 (LCEGT) (x = 0.04–0.16) nanorods were synthesized via low temperature hydrothermal process. The X-ray diffraction studies revealed that the formation of tetragonal structure along with the secondary phases of α-Eu2TiO3. The lattice parameters, unit cell volume were observed to be decreased with the increase of Gd3+ from 0.04 to 0.16, and X-ray density increased from 11.01 to 11.67 g/c.c. with the Gd3+ composition. FESEM and TEM images confirmed the formation of mixed morphology consisting of nanorods and nanospheres in all samples. The dielectric analysis studied in-between frequencies 10 kHz–8 MHz discovered that the dielectric constant decreases from 4653 to 306 with the increase of Gd3+ composition from 0.04 to 0.12. The dielectric loss at 1 MHz was observed to be decreased from 223 to 28 with the increase of Gd3+ in the sample. The ac-conductivity increases from 0.0015 to 0.0223 S/cm with the increase of frequency from 10 kHz to 8 MHz for the Gd3+ = 0.04 sample. The impedance and dielectric modulus formalism were studied as a function of composition and frequency. The conduction process is through the grains in place of grain boundaries and non-Debye type of relaxations revealed from Cole-Cole plots. The studied properties of LCEGT nanorods indicate that the material is suitable for dielectric absorber and charge stored capacitor applications.

Synthesis of Gd+3 doped hydroxyapatite ceramics: optical, thermal and electrical properties

ABSTRACT 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.

Effect of Gd2O3 on the radiation shielding, physical, optical and luminescence behaviors of Gd2O3–La2O3–ZnO–B2O3–Dy2O3 glasses

The present work focuses on lead-free glasses, their shielding behavior, and other optical studies. The glass composition with xGd2O3+10La2O3+10ZnO+(79-x) B2O3+1Dy2O3, x = 0, 5, 10, 15, 20 mol% were prepared to the characterization on physical, absorption spectra, photo-, radioluminescence, and radiation shielding properties. In the experimental results, the density of Gd-1Dy glass samples increases with the increase of Gd3+ ions concentrations. The ten-strong peak in the 5Gd-1Dy glass of absorption spectra in UV–Vis–NIR regions. The white photoluminescence spectra base of Gd-1Dy glass samples can be generated under excitation at 351 nm makes the strongest emission of Dy3+ ions and excitation through energy transfer from Gd3+ in Gd-1Dy glass samples with 275 and 351 nm. This strong white emission of Dy3+ ions also strong in x-ray luminescence and performs the integral scintillation efficiency of 33% when compared with BGO crystal. The radiation shielding properties in the diagnostic medicine energies region are correlated, the values of glass samples better than commercial windows, bricks, and concrete. The HVL values of glass sample at 15 and 20 mol% of Gd2O3 has been found better than X-ray windows. The corollaries of Gd-1Dy glass samples can be a candidate for radiation detector and lead-free radiation shielding materials in future.

Study of gadolinium substitution effects in hexagonal yttrium manganite YMnO3

In the present work, gadolinium substitution effects on the properties of yttrium manganite YxGd1−xMn0.97Fe0.03O3 (x from 0 to 1 with a step of 0.2) synthesized by an aqueous sol–gel method have been investigated. Partial substitution of Mn3+ by 57Fe3+ in the manganite was also performed in order to investigate deeper the structural properties of synthesized compounds applying Mössbauer spectroscopy. It was demonstrated that substitution of Y3+ by Gd3+ ions leads to the changes of structural, magnetic and morphological properties of investigated system. The crystal structure gradually transformed from hexagonal to orthorhombic with an increase of Gd3+ content in the crystal lattice. The mixed phase was obtained when x = 0.6, whereas other compounds were determined to be monophasic. Magnetization measurements revealed paramagnetic behavior of all specimens, however magnetization values were found to be dependent on chemical composition of the samples. Solid solutions with orthorhombic structure revealed higher magnetization values compared to those of hexagonal samples. The highest magnetization was observed for pure GdMn0.97Fe0.03O3. Structural properties were investigated by powder X-ray diffraction, Mössbauer, FTIR and Raman spectroscopies. Morphological features of the synthesized specimens were studied by scanning electron microscopy (SEM).

Selective delivery of remarkably high levels of gadolinium to tumour cells using an arsonium salt.

The use of a triphenylarsonium vector for tumour cell-targeting leads to a dramatic increase in Gd3+ uptake in human glioblastoma multiforme cells by up to an order of magnitude over the isosteric triarylphosphonium analogue, with significant implications for 'theranostic' applications involving delivery of this important lanthanoid metal ion to tumour cells.

Fabrication and characterization of novel excellent thermal-protection Gd2Zr2O7/ZrO2 composite ceramic fibers with different proportions of Gd2Zr2O7

Three kinds of Gd2Zr2O7/ZrO2 (GZC) composite fibers with different proportions of Gd2Zr2O7 were prepared by electrospinning method through changing the amount of Gd3+ in precursor solutions. The thermal decomposition, crystallization process, high temperature stability and heat-conducting properties of GZC fibers were fully characterized. The results showed that there were three crystalline phases, tetragonal phase ZrO2, cubic phase ZrO2 and defect fluorite phase Gd2Zr2O7 in all the GZC fibers. The content of Gd2Zr2O7 increased gradually with the increase of Gd3+ in precursor solutions which led to the gradual slowing down of grain growth rate, the decrease of thermal conductivity and the increase of high temperature stability of the obtained composite fibers. The thermal conductivities of all the GZC fiber sheets were lower than that of 7YSZ fiber sheet. The sheets of all the GZC fibers could keep the high temperature stability up to 1300 °C.

Gd-doping effect on crystallization behaviour and valence state of Ce-bearing zirconolite glass-ceramic

Zirconolite-based glass-ceramic is a waste matrix used for incorporating high-level waste (HLW) which is rich in minor actinides. In this study, Ce-bearing zirconolite glass-ceramics were prepared via a traditional two-step thermal treatment method, and gadolinium was selected as the trivalent actinide residual to investigate co-doping effects. Co-doped samples were then characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy (XPS). The XRD results indicated that zirconolite was the sole crystalline phase synthesized from a SiO2–B2O3–Na2O–CaO–ZrO2–TiO2–Al2O3–CeO2–Gd2O3 system. A slight lattice expansion in the Ce-bearing zirconolite was also found after Gd doping. However, the average size of zirconolite particles obtained empirically via SEM remained constant (~1.8 μm) and was within the error range. A progressive decrease of the volume fraction of zirconolite was also observed after doping. In addition, XPS results confirmed that the Ce3+ fraction incorporated into zirconolite decreased with the increase in Gd3+, while it still dominated the Ce species, even for a Gd-doping concentration of as much as 1.0 wt%. This study aimed to advance the current understanding of the immobilization of actinide residuals in zirconolite glass-ceramics as well as provide some basic technical data for the deep geological disposal of HLW.

The crystallographic, magnetic, and electrical properties of Gd3+-substituted Ni–Cu–Zn mixed ferrites

Polycrystalline Ni0.48Cu0.12Zn0.40GdxFe2-xO4 (where x = 0.00, 0.02, 0.04, 0.08, and 0.10) was synthesized by the conventional solid-state reaction technique. The structure and surface morphology were studied by X-ray diffraction (XRD) and high-resolution optical microscopy, respectively. The XRD patterns indicated that the compositions formed a cubic spinel structure for a small amount of Gd3+ substitution. With increasing Gd3+ concentration, a gradual rise in the intensity of the extra peaks was observed, and those peaks were identified as corresponding to GdFeO3 (orthoferrite). Rietveld refinement was performed on the XRD data of Gd3+-substituted Ni0.48Cu0.12Zn0.40 ferrite samples for further verification, and the results were found to be in good agreement with results reported in the literature. Variation of the lattice constant obeyed Vegard's law. Microstructural studies showed that the average grain diameter increases as the Gd3+ content increases up to an optimum concentration and then it decreases. Magnetic properties were characterized by the complex initial permeability (100 Hz–100 MHz). The real part of the complex initial permeability (μi′) increases with Gd3+ concentration up to x = 0.04 and then decreases. Ni0.48Cu0.12Zn0.40Gd0.04Fe1.96O4 shows the highest value of μi′ (at the optimum sintering temperature), which is more than eight times that of the parent sample. Conversely, magnetic loss is reduced remarkably in this composition. The Néel temperature was determined from the temperature-dependent initial complex permeability, which showed a decreasing trend with increase in Gd3+ concentration owing to the weakening of the A-B interaction. DC magnetizations as a function of the applied magnetic field were evaluated with a vibrating-sample magnetometer at room temperature. The magnetization increased with increasing Gd3+ content up to x = 0.04 owing to the variation of cation distribution and then reduced because of the possibility of noncollinear spin arrangement with further increase of Gd3+ content. The number of Bohr magnetons (nB) and the Yaffet-Kittel angle (αY-K) were evaluated. The calculated αY-K values were a minimum for x = 0.04, while the nB variation showed the opposite trend. Because of the reduction of electron exchanges between Fe2+ and Fe3+ at the octahedral site, the room temperature dielectric constant and the dielectric loss were reduced with increasing Gd3+ content. There was an exceptional increase in the dielectric constant for x = 0.02 sample. The AC conductivity spectrum exhibited two regions, and the conductivity was found to decrease with the addition of Gd3+. Impedance spectroscopy studies indicated a non-Debye-type relaxation process. Ferroelectric transition temperatures, TC, were also determined from measurement of the temperature-dependent dielectric constant.

Inhibition of Tolaasin Hemolytic Activity by Increase in GD3+-Induced Membrane Rigidity

Tolaasin molecule multimerizes and forms a membrane pore, causing brown blotch disease of the cultivated mushrooms. The peptide is a pore-forming bacterial toxin produced by Pseudomonas tolaasii. The pores destroy plasma membrane by interrupting cellular osmotic pressure. Cytotoxicity of tolaasin can be evaluated by measuring hemolytic activity using erythrocytes and blotch formations on the mushroom tissue. Previous studies showed that divalent cations, such as Zn2+, Ni2+, and Cd2+, inhibit tolaasin-induced hemolysis. In this study, Gadolinium ion, Gd3+, known to inhibit the mechanosensitive ion channels, also inhibits the tolaasin activity as a dose-dependent manner. The inhibition of tolaasin-induced hemolysis was observed at 200 μM Gd3+ and completed at 1 mM. Mechanism of Gd3+ action has not been clearly demonstrated; however, it has been known that Gd3+ decreases membrane fluidity. Inhibition of hemolytic activity by Gd3+ was reversible similar to that of Zn2+, but the action mechanisms of these two ions seem to be very different. Although Zn2+ inhibits the ion channel by plugging into the entrance of tolaasin pore, Gd3+ may inhibit the formation of tolaasin channel by changing membrane fluidity. To investigate the effect of Gd3+ on the plasma membrane of erythrocyte, a fluorescent probe, 1,6-diphenyl-1,3,5-hexatriene (DPH), was inserted into the membrane and the changes in fluorescence intensity were measured. The maximum fluorescence intensity of DPH was measured at 360 nm in excitation and at 456 nm in emission. In the presence of Gd3+, the fluorescence intensity of DPH was increased, suggesting that Gd3+ made the membrane more rigid. Therefore, the Gd3+-mediated increase in membrane rigidity reduces the rate of molecular diffusion in the membrane and may inhibit the multimerization and orientation of tolaasin molecules requiring for membrane pore formation.

A ratiometric optical thermometer with tunable sensitivity and superior signal discriminability based on Eu2+/Eu3+ co-doped La1-yGdyAlO3 phosphors

The La1-0.03-yGdyAlO3: 0.03Eu (y = 0.2–0.8) phosphors are prepared via solid phase method. The normal thermal quenching of Eu2+ ion and abnormal thermal quenching of Eu3+ ion in La1-0.03-yGdyAlO3: 0.03Eu (y = 0.2–0.8) phosphors are explained by the configuration coordinate system and energy transfer process. Considering the fluorescence intensity ratio temperature measurement technology, the temperature sensitivity values of the phosphors increase with the increase of Gd3+ ion concentration. When Gd3+ ion concentration is 0.8, the maximal Sa and Sr can even reach 0.084 K-1 and 3.233% K−1. Moreover, the excellent separation of emission peaks of Eu2+ and Eu3+ ions also provides good signal discriminability for temperature measurement. These results indicate that the La1-0.03-yGdyAlO3: 0.03Eu phosphors can be used as the superior non-contact optical thermometry materials.

Correlations between microstructural and magnetic properties of Gd3+-doped spinel ferrite nanoparticles

We report the effect of rare-earth Gd3+ doping in Ni–Zn ferrite nanoparticles with a generic formula Zn0.2Ni0.8GdxFe2–xO4 (x = 0.00, 0.05, 0.10 and 0.15), synthesized using chemical co-precipitation technique. The cubic spinel phase formation and phase purity were confirmed using X-ray diffraction with crystallite size in the range of 16 ± 7 nm obtained from Scherrer’s formula and Williamson–Hall (W–H) plots analysis. The lowering of octahedral cubic symmetry was also observed from Raman spectra with increasing Gd3+ ions content. Increase in Gd3+ ions concentration results in enhancement of A–O–B superexchange magnetic interaction, confirmed by hysteresis curves at 5 K. The room temperature M–H plots showed superparamagnetic behavior due to small particle size. The blocking temperature was found to decrease with increase in Gd3+ ions concentration in Ni–Zn ferrite nanoparticles, which makes it a potential candidate for biomedical applications such as targeted drug delivery and hyperthermia.

The gadolinium effect on crystallization behavior and luminescence of β‐NaYF4:Yb,Er phase

AbstractSingle phase β‐NaY0.8‐xGdxYb0.18Er0.02F4 nanoparticles with different concentrations of gadolinium ions were prepared via PVP‐assisted solvothermal treating at 200°C (PVP‐ polyvinylpyrrolidone). With the increase in Gd3+ concentration, size of the nanoparticles decreased. The up‐converting spectra recorded upon 980 nm irradiation showed the green (510‐560 nm) and red (640‐690 nm) emissions, due to 2H11/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions, respectively. The strongest up‐conversion luminescence was detected in 15 mol% Gd3+‐doped nanoparticles obtained after 20 hours of solvothermal treating. With the rise of Gd3+ content up‐conversion emission decreased due to increased defect concentration in the NaYF4 matrix. Fourier transform infrared spectroscopy proved in situ generation of hydrophilic nanoparticles as a result of PVP ligands retention at the particle surface.

Thermostability and reliability properties studies of transparent Ce:GdYAG ceramic by Gd substitution for white LEDs

Yttrium Aluminum Garnet transparent ceramics with different Gd3+ concentrations ((Ce0.001GdxY0.999-x)3Al5O12) ceramics were prepared by the conventional solid state reaction technology and vacuum sintering method, and the ceramic-based LEDs with blue LED were prepared by flip chips and Chip on board package. The extreme circumstance of −40 °C and 150 °C alternate environments, high humidity and high temperature as well as xenon lamp aging test for a long time are mentioned to explore the reliability of phosphor ceramics, respectively. And the thermostability and the effect of Gd3+ doping on the PL properties of ceramics were also investigated. What is more, the effects on the optical performance of the ceramic-based LEDs have been also investigated. As Gd3+ concentration added from 0 to 0.5, the PL spectra peaks of phosphor shifted from 542 nm to 575 nm under the excitation of 460 nm. It can be summarized that the increase of Gd3+ concentration could not improve the thermostability, but enhance the reliability when the x value is x is not greater than 0.4. What is more, the ceramics-based LED of x = 0.3 instead of x = 0.4 has the best reliability after the xenon lamp aging and thermal cycling test. And the ceramics-based LED of x = 0.45 has the best reliability after the high humidity and high temperature test. Compared with Ce:YAG and Ce:LuAG ceramics, although the increase of Gd3+ concentration decreases the thermostability and luminous efficiency, the Gd substitution can enhance the reliability and solve the lack of red light in the spectrum of Ce:YAG and Ce:LuAG ceramics, which has improved the performance of Ce:GdYAG ceramics for high-power warm white LEDs.

Influences of Gd3+ doping modification on the crystal microstructure and electrochemical performance of Li1.20[Mn0.52Ni0.20Co0.08]O2 as cathode for Lithium-ion batteries

ABSTRACT The Li1.20[Mn0.52-xGdxNi0.20Co0.08]O2 (x = 0, 0.01, 0.02, 0.03) cathode materials have been synthesized by using the combination of co-precipitation with high temperature sintering method. The XRD, SEM, TEM and galvanostatic charge-discharge tests were carried out to study the influence of Gd3+ doping on the crystal structural, morphology and electrochemical properties of Li1.20[Mn0.52Ni0.20Ni0.08]O2. The XRD result revealed the Gd3+ doping modification could decrease the cation mixing degree. The galvanostatic charge-discharge tests results showed the improved electrochemical properties were obtained through the Gd3+ doping modification. With the increase of Gd3+ doping content, the capacity retentions enhanced from 88.1% to 90.3% and then decrease to 87.0% after 100 cycles with x = 0.01, 0.02 and 0.03, respectively, while the un-doped sample delivered the capacity retention of 85.1%. The Li1.20[Mn0.50Gd0.02Ni0.20Co0.08]O2 exhibited a discharge capacity of 115.5 mAh g−1 at 5C rate, much larger than that (85.1 mAh g−1) of the un-doped Li1.20[Mn0.52Ni0.20Co0.08]O2. The cyclic voltammetric analysis has proved that the Gd3+ doping modification can keep the stability of the cathode layer structure and further hold the high working voltage.