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NaMnF3:Yb,Er and NaMnF3:Yb,Er@NaGdF4:xEu (x = 0, 0.3, 0.6, and 0.9) samples were synthesized by a simple hydrothermal method. The as-obtained NaMnF3:Yb,Er particles show a single red emission under the irradiation of infrared light (980 nm), due to the energy exchange transfer process between Mn2+ ions and Er3+ ions. Notably, further growth of NaGdF4:Eu on the basis of NaMnF3:Yb,Er enhanced the green up-conversion luminescence of Er3+ ions, which gradually shifted from red to green with the increase of the Gd3+ ion doping amount. In addition, NaMnF3:Yb,Er@NaGdF4:Eu exhibits red color under ultraviolet excitation (397 nm). These results provide a possible means for controlling the luminescence properties of the lanthanide doped up-conversion system. The luminescent film synthesized with NaMnF3:Yb,Er@NaGdF4:Eu can show different luminescent colors under different light irradiation (near infrared and ultraviolet), which indicates that they have potential applications in multi-mode anti-counterfeiting.

We present a systematic study on the properties of Na(Y,Gd)F-4-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.

One-micron-sized uniform red-phosphor spheres of an (Y,Gd)BO3 ternary system have been converted from their colloidal moydite precursor spheres facilely synthesized using modified homogenous precipitation. The moydite spheres, possessing the composition (Y0.95−xGdxEu0.05)(B(OH)4)CO3 (0 ≤ x ≤ 0.50), are orthorhombic in structure. Gd3+ is more effective than Y3+ in raising nucleation density, leading to a decreased average size of the precursor particles with a higher addition of Gd3+. The lattice parameters, a and b, increase linearly with increasing Gd incorporation, while the c value shrinks with a higher Gd content. The moydite spheres completely decomposed into hexagonal orthoborate upon heating to 800 °C, while retaining the spherical shape and excellent dispersion of the original particles. However, they lost their spherical shape and underwent significant aggregation at a higher temperature. The lattice constant of (Y0.95−xGdxEu0.05)BO3 calcined at 800 °C follows Vegard's law and increases linearly with an increase in the value of x from 0 to 0.30. Upon excitation with 207 nm wavelength light, (Y0.95−xGdxEu0.05)BO3 spheres show typical Eu3+ emission, with the strongest emission at 610 and 627 nm (5D0 → 7F2 transition of Eu3+) and almost the same CIE chromaticity coordinates of (∼0.632, ∼0.373). The incorporation of Gd3+ resulted in enhanced luminescence intensity and shorter lifetimes (∼5.77–6.56 ms). The optimized doping concentration of Gd3+ is 15 at%. The uniform phosphor spheres obtained in this work are expected to have wide applications for the contemporary interest in high-resolution display technologies.

Rare earth nitrate as the raw material, NaY/GdF4 upconversion luminescent nanoparticles were prepared by hydrothermal method, its diameter is about 200nm. By changing the Gd3+ doping amount achieved NaYF4 transition from the tetragonal to hexagonal phase, and the upconversion emission intensity can be improved by optimizing Gd3+ content. In 980nm excitation light source for the fluorescence test showed that the introduction of Gd3+ can effectively promote size reduction of NaY/GdF4 crystals and decrease luminous intensity. Through mechanism analysis we know that is related to nanosize effect. At the same time, we discussed the upconversion luminescence mechanism of NaY/GdF4 nanocrystals luminous intensity in different wavelength bands and the SEM show the morphology transformation from spherical to double-flower.

We report the influence of glassing solvent deuteration and Gd3+ doping on 13C dynamic nuclear polarization (DNP) nuclear magnetic resonance (NMR) performed on [1-13C] sodium acetate at B0 = 5 T and 1.2 K. Our data reveal that at 5 T, glassing solvent deuteration still results in a 40% improvement of the 13C DNP signal when a large electron spin resonance (ESR) linewidth 4-oxo-TEMPO free radical is used, but results in a 60% decrease of the DNP signal in the case of a sample doped with small ESR linewidth trityl OX063. An addition of a trace amount of the Gd3+ complex Gd–HP–DO3A led to a negligible slight decrease on the 13C polarization TEMPO-doped sample, but is still relatively beneficial for the trityl-doped sample with 30% improvement of the DNP-enhanced 13C polarization. These findings indicate that while these DNP optimization steps are still valid at 5 T, the effects are not as pronounced as observed in 13C DNP at B0 = 3.35 T. These DNP results at 5 T are discussed thermodynamically within the framework of the thermal mixing model of DNP.

&beta, NaYF4 microcrystals co-doped with Yb3+, Er3+/Tm3+, and Gd3+ ions were synthesized via a hydrothermal method using rare-earth chlorides as the precursors. The SEM and XRD data show that the doped &beta, NaYF4 form uniform hexagonal prisms with an approximate size of 600&ndash, 800 nm. The partial substitution of Y by Gd results in size reduction of microcrystals. Upconversion luminescence spectra of microcrystals upon 980 nm excitation contain characteristic intra-configurational ff bands of Er3+/Tm3+ ions. An addition of Gd3+ ions leads to a significant enhancement of upconversion luminescence intensity with maxima at 5 mol % of dopant.

Well crystallized layered rare-earth hydroxide (LRH) crystals of [(Y1−xGdx)0.95Eu0.05]2(OH)5NO3·nH2O (0 ≤ x ≤ 0.50), with a tens of micron-sized lateral, have been hydrothermally synthesized in the presence of the mineralizer NH4NO3. Smaller LRH particles, expanding in the ab plane, and a shrinked interlayer distance (c/2) were observed for a higher Gd content. The interaction between the adjacent hydroxide main layers of the LRH has been weakened by inserting water insoluble oleate anions into the interlayer via hydrothermal treatment. Unilamellar and single-crystalline nanosheets with lateral sizes close to those of the parent crystals and a thickness of ∼1.76 nm were delaminated by dispersing the oleate-containing LRH in toluene. Through a quasi-topotactic phase transformation, highly [111] oriented [(Y1−xGdx)0.95Eu0.05]2O3 (0 ≤ x ≤ 0.50) films with a transmittance of up to 81% and a thickness of ∼55 nm have been constructed through spin-coating colloidal suspension of the exfoliated nanosheets on quartz, followed by calcination at 800 °C. Gd3+ doping leads to greatly enhanced red emission of Eu3+ at 615 nm and obvious red shifting of the charge transfer excitation band (CTB) owing to the smaller electronegativity of Gd3+. The asymmetry factor of luminescence, I(5D0 → 7F2)/I(5D0 → 7F1), remains nearly constant at ∼4.9 up to x = 0.05, followed by a steady increase to ∼8.2 at x = 0.50, which has been ascribed to the splitting of the C1 symmetry from distorted S6 lattice sites at x > 0.05. Gd3+ doping has little influence on the fluorescence lifetime of the 615 nm emission, which was determined to be ∼1.6 ± 0.1 ms.

CaZrO3:Sm and CaZrO3:Sm, Gd nanophosphors were synthesized by a facile and efficient sol-gel combustion method. Their structure and optical properties were studied. The photoluminesce (PL) results showed that the phosphor could be efficiently excited by irradiation at wavelengths in the visible light region (350-430 nm). The CaZrO3:Sm nanophosphor exhibited strong yellow-green, orange and red emissions with peak wavelength centered at 565 nm (4G5/2→6H5/2), 601 nm (4G5/2→6H7/2) and 645 nm (4G5/2→6H9/2), respectively. The incorporation of Gd3+ ions could greatly improve the luminescence intensity. The highest emission intensity was observed with 2 mol.% Gd3+ doped CaZrO3:3 mol.% Sm powder. The material had potential application in the development of materials for LED's and other optical devices in the visible region.

Co2Z type planar hexaferrite doping of Gd3+ 2CoO·3BaO ·xGd2O3·(10.8-x) Fe2O3 is made with common production process of cermet. The paper studies the influence of Gd2O3 doping quantity on microstructure and magnetic performance of Co2Z type planar hexaferrite. The result indicates that Gd3+ doped Co2Z type ferrite still keeps structure of Z type planar hexagonal, when the doping quantity x=0.025, the magnetic performance in ultrahigh frequency will get improved, the initial permeability can grow to 16, and the cut-off frequency will also relatively reduce to the lowest value 1.965GHz.

The upconversion luminescences of YAlO3:Er3+ phosphor co-doping with different Gd3+ concentrations are investigated under the excitation of 980- and 532-nm diode lasers. A near ultraviolet upconversion emission at 410 nm is observed in YAlO3 under 532-nm excitation. Moreover, the inactive Gd3+ ions can improve the upconversion intensity efficiently in a certain range of concentration. Under 980-nm excitation, the visible upconversion emissions at 546 and 646 nm are enhanced by about 10 and 8 times at the Gd3+ concentration of 40%, respectively. The upconversion emission at 410 nm under 532-nm excitation is also enhanced by 7 times. The substitution of Gd3+ ions for Y3+ sites changes the local symmetry of Er3+, leading to the improvement of upconversion efficiency.

MgGd x Fe 2− x O 4 ( x = 0.0, 0.05, 0.1 and 0.15) ferrites, with improved dc resistivity, initial permeability, saturation magnetization, and extremely low relative loss factor, have been synthesized by solid state reaction technique. The microstructures, electric, dielectric and magnetic properties have been investigated by means of X-ray diffraction, Keithley 2611 system, impedance analyzer and VSM respectively. The addition of Gadolinium in Mg ferrite has been shown to play a crucial role in enhancing the electric, dielectric and magnetic properties. The dc resistivity is increased by two orders of magnitude as compared to Mg ferrite. Saturation magnetization has been increased by two times and remnant magnetization has been increased by more than three times due to the doping of Gd 3+ ions in Mg ferrite. The relative loss factor was found to have very low values and is of the order of 10 −4 –10 −5 in the frequency range 0.1–30 MHz. The variations of electric, dielectric and magnetic properties of the samples have been studied as a function of frequency and Gd 3+ ions concentration measured at room temperature. High resistivity and improved magnetic properties can be correlated with better compositional stoichiometry and the replacement of Fe 3+ ions by Gd 3+ ions. The mechanisms responsible to these results have been discussed in this paper.

Gd3+ doped TiO2 nanopowders were successfully synthesised by sol–gel method using gadolinium nitrate and tetra-n-butyl titanate as the precursors. The as prepared nanopowders were characterised by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results indicated that Gd3+ doping effectively inhibits the phase transformation from anatase to rutile until 700°C, which was propitious to promote the catalytic activity of the catalysts. The fine and uniform Gd3+ doped TiO2 nanopowders with the size of 10–15 nm were obtained using the 0·75 g L−1 hydroxypropyl cellulose (HPC) as dispersant for the excellent steric stabilisation. Compared with the nanocrystalline TiO2, the Gd3+ doped TiO2 nanopowders exhibited higher photocatalytic activity to methylene blue degradation.

Uniform red-phosphor spheres (∼60−300 nm in diameter) of Y2O3:Eu3+ binary and (Y,Gd)2O3:Eu3+ ternary systems exhibiting excellent emission at 610 nm have been converted from their colloidal precursor spheres synthesized via homogeneous precipitation. The precursor spheres (approximate composition: [(Y1-xGdx)1-yEuy](OH)CO3·1.3H2O, x = 0−0.5 and y = 0−0.11) are directly solid solutions, but arising from sequential nucleation each of the spheres has more Gd and especially Eu while having less Y going from the particle surface to the core. Eu3+ is more effective than Gd3+ in raising nucleation density, leading to rapidly decreased average size of the precursor particles at a higher Eu3+ addition. Diminishing the concentration gradients through adequate annealing is identified to be crucial to high luminous intensity of the oxide particles. At the optimal annealing temperature of 1000 °C, cation homogenization is achieved and the oxide particles largely retain their precursor morphologies, yielding dispersed u...