Effect of Gd~(3+)-,Pr~(3+)-or Sm~(3+)-substituted cobalt-zinc ferrite on photodegradation of methyl orange and cytotoxicity tests

Gd~(3+)-,Pr~(3+)-or Sm~(3+)-doped Co-Zn(Co_(0.5)Zn_(0.5)Fe_2 O_4) magnetic ferrites(i.e.,Co_(0.5)Zn_(0.5)Gd_(0.1)Fe_(1.9)O_4,Co_(0.5)Zn_(0.5)Pr_(0.1)Fe_(1.9)O_4 and Co_(0.5)Zn_(0.5)Sm_(0.1)Fe_(1.9)O_4) were prepared using a facile sol-gel approach,and the structure,surface morphology and chemical composition of the products were studied by means of scanning electron microscopy(SEM),energy dispersive X-ray analysis(EDX),X-ray diffraction(XRD),UVvisible diffuse reflectance spectroscopy(DRS),photoluminescence(PL) spectroscopy,Fourier transform infrared spectroscopy(FT-IR) and vibrating sample magnetometer(VSM) spectroscopy.XRD patterns show the Co-Zn product is composed of cubic spinel phases with few impurities or secondary phases,and the average crystallite sizes of the samples are determined to be approximately～51—80,～99—181,～68—103 and～83—133 nm.Also the coercivity and remnant and saturation magnetizations,evaluated by vibrating sample magnetometer(VSM),are found to increase linearly with the incorporation of Gd3+,Pr3+and Sm3+in the product formulation.The CO_(1-x)Zn_xFe_(2-y)R_yO_4 photocatalyst sample is found to display a red shift in its absorption,and exhibits outstanding photocatalytic effects in the degradation of MO under ultraviolet(UV) light.This is attributed to the reduction of the band gap of cobalt-zinc ferrite due to the presence of rare earth ions.Further in vitro evaluations of the cytotoxic effects of the synthesized nanoparticles were performed on a HeLa cell line.     

Influence of A-site doping barium on structure,magnetic and microwave absorption properties of LaFeO3 ceramics powders

In this paper, the effect of Ba²⁺ ions A-site doping LaFeO₃ on structure, magnetic properties and microwave absorption properties was investigated by the sol–gel method. According to the TEM and FullProf refinement results, the structure of LaFeO₃ changes from orthogonal (SG: Pnma) to cubic (SG: Pm-3m) when the Ba doping amount is x = 0.4. The SEM image shows that the particles size tends to decrease with the increase of Ba content. The production of weak ferromagnetism indicates that Ba doping has a significant effect on the magnetic properties of LaFeO₃. The Neel temperature (T_N) decreases significantly with the increase of Ba doping amount. An appropriate amount of Ba doping can effectively increase the dielectric and magnetic loss of LaFeO₃ ceramics powders. The increase permittivity (ε′ and ε″) may be attributed to the hopping of the electrons between the Fe³⁺ and Fe⁴⁺ ions with the Ba²⁺ ions doping. The minimum reflection loss (RL_min) of La_0.9Ba_0.1FeO₃ at 6.72 GHz reaches ?30.04 dB, its effective bandwidth (RL ≤ ?10 dB) is 2.1 GHz, and the matching thickness is only 3.2 mm. These results indicate that Ba doping can effectively control the microwave absorption properties of LaFeO₃, especially in the C-band.     

Er3+-substituted W-type barium ferrite: preparation and electromagnetic properties

Er3+-substituted W-type barium ferrites Ba1-xErx(Zn0.3Co0.7)2Fe16O27(x=0.00,0.05,0.10,0.15,0.20)were synthesized by polymer adsorbent combustion method.Samples were characterized by X-ray diffraction analysis(XRD),X-ray fluorescence(XRF),scanning electron microscopy(SEM)and network analyzer to investigate the relationships among Er3+concentration,crystal structure,surface mcrphology and electromagnetic properties.All the XRD patterns showed pure phase of W-type barium ferrite when x≤0.15,while the impurity phase of ErFeO3 appeared when x=0.20.The pure W-type barium ferrite showed a hexagonal flake shape.In addition,the microwave electromagnetic properties of samples were analyzed in the frequency range of 2-18 GHz.It was indicated that the electromagnetic properties were significantly improved when Er3+doping content was 0.10.The reasons were also discussed using electromagnetic theory.The optimized ferrite exhibited excellent microwave absoption performance.The maximum of reflection loss(RL)reached about-27.4 dB and RL was below-10dB at the frequency range from 8.4 GHz to 18 GHz,when the thickness was 2.6 mm.     

Enhanced afterglow performance of CaAl_2O_4:Eu~(2+),Nd~(3+) phosphors by co-doping Gd~(3+)

In order to effectively improve the afterglow properties of CaAl_2 O_4:Eu~(2+),Nd~(3+) phosphors,a series of Ca_(0.982-x)Al_2 O_4:0.012 Eu~(2+),0.006 Nd~(3+),xGd~(3+)(x=0,0.012,0.024,0.036,0.048,0.060 mol) phosphors were prepared by a high-temperature solid-phase approach.Crystalline composition and microstructure were characterized by XRD,TEM,HRTEM,and XPS,luminescence properties were systematically analyzed by fluorescence spectra,afterglow decay curves and TL glow curve.Results show that all of Ca_(0.982-x)Al_2 O_4:0.012 Eu~(2+),0.006 Nd~(3+),xGd~(3+)phosphors belong to monoclinic CaAl_2 O_4,without other cystalline phase.The blue emission at 442 nm is observed,which is assigned to the 4 f~65 d→4 f~7 transition of Eu~(2+) ions.Doping with appropriate amount of Gd~(3+) ions(x=0.036 mol) significantly improves the afterglow properties of phosphors,but the excessive doping of Gd~(3+) induces the fluorescent quenching.The doping of moderate Gd3+changes the traps states,the trap depth varies from 0.598 to 0.644 eV and the trap concentration is also greatly improved,thus significantly improving afterglow performance.     

Synthesis and luminescent properties of Ba3Y3.88Gd0.12O9:Eu3+ phosphors with enhanced red emission

In this work, the Gd³⁺/Eu³⁺ activated Ba₃Y₄O₉ (BYO) phosphors were successfully synthesized via coprecipitation method at 1400 °C. The precursor composition, crystal structure stability, microscopic morphology, photoluminescence (PL)/photoluminescence excitation (PLE) spectra and fluorescence attenuation analysis of the phosphors are discussed in detail. The chemical composition of the precursor was determined by Fourier transform infrared spectroscopy (FT-IR) and thermogravimetry (TG) analysis; According to field emission-scanning electron microscopy (FE-SEM) analysis, it is found that the particle size of phosphor is uniform and the agglomeration is few. According to PL/PLE spectra analysis, Ba₃Y_3.28Eu_0.6Gd_0.12O₉ phosphors has the strongest excitation band at 260 nm and the strongest emission band at 614 nm, and the fluorescence intensity of Ba₃Y_3.28Eu_0.6Gd_0.12O₉ is higher than that of Ba₃Y_3.4Eu_0.6O₉. The quenching concentration of Eu³⁺ in Ba₃Y_3.88–4xEu_4xGd_0.12O₉ phosphors is x = 0.15 and the mechanism of quenching concentration of Eu³⁺ is electric dipole-quadrupole type interactions. The lifetime value of Ba₃Y_3.88–4xEu_4xGd_0.12O₉ (x = 0.15) phosphors is 0.686 ms and decreases with the increase of Eu³⁺ content. In addition, the CIE chromaticity diagram of Ba₃Y_3.28Eu_0.6Gd_0.12O₉ phosphors is (0.66, 0.34). Finally, the lamp beads assembled with Ba₃Y_3.28Eu_0.6Gd_0.12O₉ phosphors have an ideal luminous effect. Therefore, the Ba₃Y_3.88–4xEu_4xGd_0.12O₉ phosphors designed in this work may hopefully meet the requirements of various lighting and optical display applications.     

Physicochemical properties of Li3Ba2La3(MoO4)8:Eu,Tb red-emitting phosphor for solid state white lamps

In this work,combustion synthesis was used for the first time to fabricate a phosphor material with red emission for applications in solid-state white-light lamps.We synthesized a material with emission wavelength at λ_em=617 nm,excited under long UV-blue wavelength based on Eu³⁺,Tb³⁺-activated molybdates Li₃Ba₂(La_1-x-yEu_xTb_y)₃(MoO₄)₈ with 0 ≤ x ≤1 and 0 ≤ y ≤ 1.A series of pow...     

Role of composition and grain size in controlling the structure sensitive magnetic properties of Sm~(3+) substituted nanocrystalline Co-Zn ferrites

The nanocrystalline samarium substituted Co-Zn ferrites with chemical formula Co_(0.7)Zn_(0.3)SmyFe_(2-y)O_4(where y=0,0.01,0.02,0.03,0.04) were synthesized by sol-gel autocombustion route.The analysis of Xray diffractograms(XRD) reveals the formation of cubic spinel structure.The planes indexed from XRD analyses were confirmed in the selected area electron diffraction(SAED) image of the sample.Nanocrystalline nature of the particles in the ferrite samples was confirmed by TEM.The morphology was analyzed by scanning electron microscopy(SEM).Magnetic measurements show an increase in the magnetization for x ≤0.03.The decrease in magnetization due to spin canting is observed for x=0.04.The coercivity depends on Sm~(3+)doping concentration,grain size and saturation magnetization.The complex permeability of the ferrites was analyzed as the function of frequency and Sm~(3+)composition(y).The real part of complex permeability varies linearly with the grain size.     

Spectral properties and Judd–Ofelt analysis of novel red phosphors Gd2InSbO7:Eu3+ with high color purity for white LEDs

Gd₂InSbO₇:Eu³⁺ red phosphors were successfully synthesized via high-temperature solid–state reaction. The phase purity, particle size, and luminescence properties of obtained phosphors were measured and analyzed in detail. The Gd₂InSbO₇ lattice possesses cubic structure with F_d-3m (227) space group. The phosphors emit bright red emission at 628 nm under 393 nm excitation, and this phenomenon is attributed to the ⁵D₀–⁷F₂ transition. The Judd–Ofelt parameters (Ω₂, Ω₄), transition ratio, and branching ratios (β) of Eu³⁺-doped Gd₂InSbO₇ phosphor were calculated on the basis of the emission spectra and decay lifetimes. The optimal content in Gd₂InSbO₇:xEu³⁺ is identified to be 15 mol%. The thermal quenching of Gd₂InSbO₇:Eu³⁺ is found to be over 500 K, and its activation energy is 0.26 eV. The Commission Internationale de l'Eclairage (CIE) chromaticity coordinates of Gd₂InSbO₇:15%Eu³⁺ are (0.629, 0.371), which are close to ideal red chromaticity coordinates (0.670, 0.330). The fabricated w-LED exhibits good color rendering index (R_a) (86), correlated color temperature (CCT) (6997 K), and CIE chromaticity coordinates (0.302, 0.330). The obtained results demonstrate that Gd₂InSbO₇:Eu³⁺ phosphors have potential applications in white LEDs.     

Fabrication and long persistent luminescence of Ce3+-Cr3+ co-doped yttrium aluminum gallium garnet transparent ceramics

Persistent luminescence (PersL) materials are widely used in safety indication, traffic and transportation signs, architectural decoration and other fields. In this paper, (Y_1?xCe_x)₃(Al_0.9995Cr_0.0005)₂Ga₃O₁₂ (x = 0.001, 0.002, 0.003, 0.005) transparent ceramics were successfully prepared by solid-state reaction method in air followed by HIP post-treatment. With the increase of Ce³⁺ doping concentration, the optical quality of the as-prepared ceramics is improved and the morphology is denser. Luminescent quenching occurs when the Ce³⁺ concentration is more than 0.2%. The as-prepared transparent ceramics were annealed in different atmospheres. From the PersL decay curves, the transparent ceramics after air annealing show the best PersL performance: luminance with 4424.0 mcd/m² and PersL duration over 865 min after ceasing 365 nm excitation, respectively. The effects of Ce³⁺ doping concentration and annealing atmospheres are also discussed in detail.     

Microwave electromagnetic and absorbing properties of Dy3+doped MnZn ferrites

Dy3+ doped Mn-Zn ferrites Mn0.3Zn0.7Fe2-xDyxO4(x=0,0.01,0.02,0.03,0.04)were prepared by the conventional solid-state reaction.The crystal structure,surface morphology and electromagnetic properties of the calcined samples were characterized by X-ray diffraction analysis(XRD),scanning electron microscopy(SEM) and network analyzer(Agilent 8722ET).All the XRD patterns showed the single phase of the spinel-type ferrite without other intermediate when x≤0.03.The average crystallite size was about 44?56 nm.The mi...     

Adsorption behavior of rare earth elements using polyethyleneglycol (phosphomolybdate and tungstate) heteropolyacid sorbents in nitric solution

A new type of crystalline sorbent was prepared by the reaction of polyethyleneglycol (PEG) with phosphomolybdic (PMo) and phosphotungstic (PW) heteropolyacids. The morphology of the obtained sorbents was studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). It has been shown that a complexing reaction occurs between PEG and the heteropolyacids. By using these sorbents, the adsorption behaviors of rare earth elements in nitric solution were studied. The effects of temperature, contact time, nitric acid and initial metal ion concentration on the adsorption were investigated. In 0.1–5.0 mol L^− 1HNO₃, the adsorption percentage decreases with the increase of acid concentration. H,PEG400,PW and H,PEG400,PMo exhibited a different selectivity for rare earth metals, with H,PEG400,PW adsorbing in the order of La³⁺ > Y³⁺ > Pr³⁺ > Gd³⁺ > Sm³⁺, and H,PEG400,PMo in the order of Y³⁺ > La³⁺ > Pr³⁺ > Gd³⁺ > Sm³⁺. The experimental maximum adsorption capacities of the sorbents are in the range of 90–225 mg g^− 1 for Y³⁺, La³⁺, Pr³⁺, Sm³⁺ and Gd³⁺. In all cases, the maximum adsorption capacities of H,PEG400,PW are near to those of H,PEG400,PMo. The equilibrium data were evaluated according to the Freundlich and Langmuir isotherms and the Langmuir equation gave a better fit and modeled the adsorption well.     

Effect of Y3＋, Gd 3＋and La3＋dopant ions on structural,optical and electrical properties of o-mullite nanoparticles

Dielectric ceramics of M(x) Al6(1–x) Si2 O13 doped mullite were synthesized via co-precipitation technique. The X-ray diffraction profiles revealed that these nanoparticles were crystallized well and the volume of mullite unit cell was increased as a function of the ionic radius of dopant ion. TEM images showed regular orthorhombic crystal morphology for the pure mullite sample. Meanwhile, the doped samples exhibited slightly distorted crystal morphology of larger particle sizes. DSC thermograms evinced that the exothermic peak temperature of mullite was shifted to the lower value with M3+ion insertion. The photoluminescence spectra were studied for mullite samples, and it was found that the intensity of the emission spectra was affected by the M3+ion type. It was found that, Y3+doped mullite achieved the minimum dielectric loss value of 0.01 in the radio wave frequency region(1 MHz). Meanwhile, Gd3+ doped mullite achieved the minimum dielectric loss value of 0.09 in the microwave frequency region(1 GHz).     

Energy transfer and luminescent properties of Pr^3＋ and/or Dy^3＋ doped NaYF4 and NaGdF4

The phosphors that are able to convert vacuum ultraviolet（VUV） light into visible light are demanded for the development of novel displaying and lighting devices.NaYF4：Pr3＋,Dy3＋,NaGdF4：Pr3＋,NaGdF4：Dy3＋and NaGdF4：Pr3＋,Dy3＋were prepared by hydrothermal synthesis method and their luminescent properties in VUV-vis spectral region were investigated at room temperature.For NaYF4：Pr3＋,Dy3＋,no energy transfer process from Pr3＋to Dy3＋was observed.However,the introduction of Gd3＋into the fluoride lattice led to intense Dy3＋emissions upon Pr3＋4f5d state excitation.Gd3＋acted as an intermediate,resulting in efficient energy transfer from Pr3＋to Dy3＋in NaGdF4.Pr3＋transferred most of its energy to Gd3＋,and then the energy was transferred from Gd3＋to Dy3＋.So NaGdF4：Pr3＋,Dy3＋not only took full advantage of the intense Pr3＋4f5d absorption,but converted the VUV excitation light into the near-white emission of Dy3＋.     

Photoluminescence emissions of Ca1−xWO4:xEu3+: Bridging between experiment and DFT calculations

In this work, the impact of the doping process on the photoluminescence emission of CaWO₄ as a function of the concentration of Eu³⁺ cation (0.01 mol%, 0.02 mol%, 0.04 mol%, 0.06 mol%, 0.08 mol%, and 0.10 mol%) is discussed in detail. Ca_1?xWO₄:xEu³⁺ samples were successfully synthesized by a simple co-precipitation method followed by microwave irradiation. The blue shift in the absorption edge confirms the quantum confinement effect and the band gap energy covers the range from 3.91 to 4.18 eV, as the amount of Eu³⁺ cations increases. The experimental results are sustained by first-principles calculations, at the density functional theory level, to decipher the geometry and electronic properties, thereby enabling a more accurate and direct comparison between theory and experiment for the Ca_1?xWO₄:xEu³⁺ structure.     

A novel blue-light excitable Pr3+ doped(Sr,Ba)LaMgTaO6 phosphor for plant growth lighting

In this work,a series of Pr³⁺ ions doped(Sr,Ba)LaMgTaO₆ phosphors were prepared and applied for plant growth lighting.Under 450 nm excitation,(Sr,Ba)LaMgTaO₆:Pr³⁺ exhibits intense reddish emission at around 650 nm which is assigned to the ³p₀→³F₂ transition of Pr³⁺ ions.The luminescence intensity reaches to the maximum at 2.5 mol% Pr³⁺ doping content both in SrLaMgTaO₆:Pr^...     

Effect of doped strontium on catalytic properties of La1‒xSrxMnO3 for rhodamine B degradation

A series of La_1‒xSr_xMnO₃ samples were prepared by sol–gel method and used to degrade rhodamine B (RhB) in water. All samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N₂ adsorption–desorption, temperature-programmed reduction of H₂ (H₂-TPR) and temperature-programmed desorption of O₂ (O₂-TPD). The results show that the degradation of RhB is highly dependent on the initial pH value of solution. Sr doping enhances the degradation ability of LaMnO₃ for RhB in the time range of 0–40 min under a strong acidic environment, but all samples exhibit similar degradation rate from 40 to 60 min. In La_0.7Sr_0.3MnO₃–RhB reaction system, there are two different degradation pathways, including N-de-ethylation, chromophore cleavage, ring-opening and mineralization. La_1‒xSr_xMnO₃ (x ≤ 0.3) has the perovskite structure of La–Mn oxides, while La_0.6Sr_0.4MnO₃ exhibits a Sr_0.4MnLa_0.6O_2.98 perovskite phase. Sr doping leads to distortion of rhombohedral crystal structure and increases the relative content of Mn⁴⁺. The perovskite structure is stable in strong acidic environment during RhB degradation, but the relative content of Mn⁴⁺ and Mn³⁺ on the material surface changes. Sr doped LaMnO₃ achieves specific surface area of 58.8 m²/g and total pore volume of 0.152 cm³/g. Furthermore, Sr²⁺ doping improves redox properties of La–Mn oxides, and the presence of defects makes oxygen diffusion easier compared with the undoped samples.     

Gd3+ ion induced UV upconversion emission and temperature sensing in Tm3+/Yb3+:Y2O3 phosphor

Cubic phase Tm³⁺/Yb³⁺:Y₂O₃ and Tm³⁺/Yb³⁺/Gd³⁺:Y₂O₃ phosphors were prepared by low temperature combustion technique for upconversion emission in UV-visible range.The 980 nm excitation has generated UV emission at 314 nm in tridoped phosphor due to the energy transfer from Tm³⁺ to Gd³⁺ion.Characteristic emission bands from Tm³⁺ are also observed in both the phosphors....     

Effect of erbium doping on phase composition,mechanical and thermal properties of ZrO2-based ceramics

Er_xTi_0.1Zr_0.9–xO_2–1.5x (x = 0.04, 0.05, 0.06, 0.07, 0.08) ceramics were synthesized by a solid-state reaction method. The influence of the Er³⁺ addition on the phase composition, Vickers hardness, fracture toughness, and thermal conductivity of this ceramic material was investigated. The X-ray diffraction results reveal that the c-ZrO₂ content increases from 1.85 vol% to 33.89 vol%, and the percentage of t-ZrO₂ decreases from 98.15 vol% to 66.11 vol% with the increase in Er³⁺ content from 4 mol% to 8 mol%. Moreover, the addition of Er³⁺ is beneficial to the volume expansion of the unit cell. At the same time, the incorporation of Er³⁺ weakens the coordination of oxygen ions around the metal cations, resulting in a corresponding decrease in the tetragonality of the t-ZrO₂. The Vickers hardness and fracture toughness of the Er_xTi_0.1Zr_0.9–xO_2–1.5x ceramics show increasing and decreasing trends, respectively. The thermal conductivity has a significant decline due to point defects caused by the Er³⁺ doping. The 8ETZ ceramic exhibits the highest Vickers hardness (12.7 GPa), the lowest fracture toughness (7.6 MPa?m^1/2), and the lowest average thermal conductivity (1.85 W/(m·K)) in the temperature range of 200–1000 °C. All of the above properties are higher than those of the Y₂O₃-stabilized ZrO₂ ceramic.     

Synthesis and optical properties of novel Gd3+-doped BaZn2(PO4)2 glass-ceramics for radiation detection applications

45P₂O₅–15BaO–25ZnO–15B₂O₃ glasses doped with different concentrations (0 mol%, 0.1 mol%, 0.25 mol%, 0.5 mol%, and 0.75 mol%) of Gd³⁺ were prepared by a melt-quenching method and treated to fabricate glass-ceramics containing BaZn₂(PO₄)₂ crystals by controllable crystallization. The structural, optical, and dosimetric properties were investigated. FTIR spectra indicate that the glasses are composed of [PO₄], [BO₃], and [BO₄] basic structural units. The XRD pattern analysis indicates that the samples contain BaZn₂(PO₄)₂ crystals. In the photoluminescence (PL) spectra, two emission bands are observed at 307 and 313 nm due to the ⁶P_5/2→⁸S_7/2 and ⁶P_7/2→⁸S_7/2 transitions of Gd³⁺, respectively. The OSL dosimetric properties of glass-ceramics were studied further under beta radiation of ⁹⁰Sr. The optimal Gd³⁺ doping concentration of 0.5 mol% was determined. The fading of the OSL signal shows that the CW-OSL signal of Gd³⁺-doped BaZn₂(PO₄)₂ glass-ceramics decays by about 58.95% within 120 h, and the intensity remains stable thereafter. The thermoluminescence (TL) curve has three peaks at 164, 240, and 344 °C. Minimum detectable dose (MDD) of the 0.5 mol% Gd³⁺-doped BaZn₂(PO₄)₂ glass-ceramics was calculated as 0.675 mGy. The samples also exhibit good signal reusability and a broad linear dose-response range (0.3–500 Gy). Results show the excellent dosimetric properties of Gd³⁺-doped BaZn₂(PO₄)₂ glass-ceramics and their potential application in radiation dosimetry.     

Promotional mechanism of activity of CeEuMnOx ternary oxide for low temperature SCR of NOx

Due to strong synergistic effect of the elements,a series of XEuMnO_x ternary oxides(X=Ce,Ni,Co,Sb,Sn,Mo) were synthesized by one-pot co-precipitation method,and composite components were identified and optimized to maintain high activity and superior SO₂ and H₂O endurance in selective catalytic reduction of NO_x with NH₃(NH₃-SCR).NO_x conversion of CeEuMnO_x ternary oxide catalysts attains more than 90% at 100-2...