Effect Of Gd Doping Research Articles

Influence of Gd doping on mechanical properties, thermal conductivity and microstructural evolution of (Yb1-xGdx)2SiO5 ceramics

Yb2SiO5 is one of the most potential candidate materials for thermal/environmental barrier coating (T/EBC). In order to further reduce its thermal conductivity and improve its mechanical properties, a series of Gd doped Yb2SiO5 [(Yb1-xGdx)2SiO5] ceramics were prepared. The effects of Gd doping on the phase composition, mechanical properties, thermal conductivity and microstructural evolution of Gd doped Yb2SiO5 were investigated. The results showed that (Yb1-xGdx)2SiO5 still maintained a single Yb2SiO5 phase. The average fracture toughness of (Yb1-xGdx)2SiO5 ceramics first decreased and then increased in the investigated Gd-doped Yb2SiO5 samples. (Yb0.9Gd0.1)2SiO5 had the highest fracture toughness (2.56 MPa ·m1/2), which was about 30% higher than that of pure Yb2SiO5. Thermal conductivity of (Yb0.9Gd0.1)2SiO5 ceramic (1.47 W∙m-1∙K-1 at 1200 °C) was about 15% lower than that of pure Yb2SiO5. (Yb1-xGdx)2SiO5 (x≤0.4) had good phase stability after sintering at 1550 °C for 100 h. However, a small amount of Gd9.33(SiO4)6O2 and Yb2Si2O7 two new phases were generated besides Yb2SiO5 phase in the sintered (Yb0.5Gd0.5)2SiO5. Taken together, (Yb0.9Gd0.1)2SiO5 ceramic material will be one of potential candidates for T/EBC.

Effect of Gd doping on the microstructure and electrical characteristics of Maghemite (γ-Fe₂O₃) ceramics

AbstractThis paper presents a novel study on the microstructure and electrical properties of gadolinium (Gd) doped maghemite (γ-Fe₂O₃) nanoparticles, emphasizing their significance for advanced applications in efficient materials. X-ray diffraction analysis confirmed that both pure and doped samples crystallized in a cubic structure (P4332 space group) with high purity. Gd doping significantly increased crystallite size and altered particle morphology, as shown by transmission electron microscopy (TEM), which revealed larger nanoparticles with cubic shapes. Thermal analysis (TGA and DTG) indicated that higher Gd concentrations enhanced thermal instability, affecting structural integrity. FTIR spectra showed shifts in Fe-O bond vibrations, suggesting lattice distortions and increased disorder. BET measurements indicated that higher Gd doping led to greater mesoporosity and surface area, countering expectations of densification. Electrical conductivity and impedance studies revealed two distinct regions: a constant conductivity at low frequencies and an exponential increase at high frequencies, attributed to small polaron hopping. Activation energy values below 200 meV support this mechanism. Gd doping decreased overall conductivity due to disrupted atomic arrangements, increased electron scattering, and modifications in the electronic band structure. Complex impedance spectroscopy illustrated higher real impedance values for doped samples, with increased Gd concentration leading to enhanced impedance. These findings elucidate the impact of Gd on the electrical properties of maghemite nanoparticles and highlight their importance in meeting the growing demands for highly efficient technologies in energy storage and electronic devices. Graphical Abstract

Insight into the effect of Gd-doping on conductance and thermal matching of CeO2 for solid oxide fuel cell

GDC (Gd-doped CeO2) play a dual role in solid oxide fuel cell (SOFC), effectively blocking the reaction between YSZ (Y2O3-doped ZrO2) electrolyte and high-performance cathode materials such as La0.6Sr0.4Co0.2Fe0.8O3-δ, and improving the low-temperature oxygen ion transport in composite cathodes. It is crucial to systematically investigate the influencing mechanism of Gd-doping on conductance and thermal matching of CeO2 for high-efficiency and stable SOFC. In this paper, the physical phase, morphology and electrochemical performance of Ce1-xGdxO2-δ (x = 0.1, 0.15, 0.2, 0.25) were characterized, and the thermal matching between GDC and other cell components was investigated by finite-element thermal stress calculations and cold-heat-cycling tests. The results indicate that Ce0.8Gd0.2O2-δ obtains the optimum conductivity, whether in the low temperature segment affected by the grain boundary with the space charge layer, or in the activation energy controlled medium temperature segment. Moreover, the finite-element calculation shows that the thermal stresses of the electrolyte facing the barrier layer and the barrier layer facing the cathode decrease gradually with the increase of Gd-doping. Consequently, the cell with Ce0.8Gd0.2O2-δ applied to the composite cathode and the barrier layer presents the optimal output performance of 0.87 W cm−2 at 750 °C, and the cell performance decreased by only 1.15 % after 50 thermal cycles between 25 and 800 °C. This is significant for improving the long-term operational stability of SOFC under thermal cycling conditions.

Influence on the effect of Gd rare earth doped WO3 nanoparticles for enhanced photocatalytic and antibacterial activities: A nanoplate like morphology

Optimizing the photocatalytic antibacterial properties of nanomaterials by defect engineering is becoming a significant tool. The synthesis and characterization of Gd- doped tungsten oxide (Gd:WO3) nanoparticles for potential applications in wastewater treatment and antibacterial activity. Synthesis of the Gd:WO3 nanoparticles were prepared using the co-precipitation method, known for its simplicity and cost-effectiveness in producing nanomaterials. Samples were characterization by XRD confirmed the monoclinic crystal system of all samples and the incorporation of Gd ions into the WO3 lattice. SEM and TEM revealed a nanoplate-shaped morphology of the synthesized nanostructures. EDS confirmed the composition of Gd:WO3. FT-IR verified the presence of functional groups. XPS investigated the effect of Gd doping on the valence states of Gd:WO3, revealing the location of Gd ions within the WO3 lattice. UV-Vis showed increased absorption in the visible region and a decrease in the band gap with increasing Gd concentration up to 5 wt%, indicating potential photocatalytic properties. The nanoparticles demonstrated significant photocatalytic activity, achieving a 98 % degradation of methylene blue (MB) dye under visible light exposure. Among them, the Gd (5 wt%) nanoparticles exhibited the highest photocatalytic performance within 120 min. Additionally, these Gd (5 wt%) nanoparticles showed the greatest antibacterial effectiveness against Staphylococcus aureus, with an inhibition zone of 20 mm. Moreover, the study demonstrates the potential of Gd-doped tungsten oxide nanoparticles as efficient and environmentally friendly materials for wastewater treatment and antibacterial applications.

Structural, magnetic and electrical properties of gadolinium doped cobalt ferrite nanoparticles: Role of Gd doping level

In this communication, effect of Gd doping for CoFe2–xGdxO4 (CFGO) nanoparticles has been investigated for structural, magnetic and electrical properties. X–ray diffraction (XRD) patterns reveal the presence of matrix like CFGO phase fraction with coexisting GdFeO3 (GFO) smaller crystallites and α–Fe2O3 (FO) phase fraction. Variation in crystallite size (D) for all three phases has been explored from the analysis on XRD patterns. Magnetic nature has been understood on the basis of lattice disorder, magnetic linkages between different ions of CFGO lattices that conduces magnetic characteristic of three different phases coexist within the CFGO nanoparticle lattices. Influence of frequency, temperature and Gd doping level on different electrical behaviors has been understood on the bases of various relaxation processes, charge conduction mechanism, correlated barrier hopping (CBH) mechanism, maximum barrier height, activation energy and structure–property correlations.

Exploring the ammonia gas sensing properties of Gd doped CeO2 thin films deposited by spray pyrolysis method

The present study investigates the synthesis and characterization of Gd-doped CeO2 thin films using a simple nebulizer spray pyrolysis method for ammonia sensing application. The films were prepared with varying Gd concentrations from 1 to 5 wt%. The structural, morphological, and optical properties of the samples were analyzed to examine the effect of Gd doping on physical parameters, and the results show that the 4 wt% Gd doped sample exhibits the highest crystallite size, uniform particle size distribution, and a smaller optical band gap. Additionally, the presence of defects and oxygen vacancies in the host lattice is enhanced in this sample. The gas sensing properties of the 4 wt% Gd doped CeO2 exhibits a gas responsivity of 731 %, rise time of 10.4 s, and fall time of 9.2 s indicating that the fabricated thin film sensor was found to be ideal for room temperature gas sensing application. Overall, the study demonstrates that the 4 wt% Gd doped CeO2 thin film is a promising candidate for commercial gas sensor applications.

Enhanced Ethanol Gas Sensor Performance through Adsorption Energy Analysis of Gd-Doped LaFeO3 with rGO Coating: A Density Functional Theory Study

LaFeO3 (LFO) is commonly used as a material for gas sensor applications. However, the LFO material in ethanol gas sensor applications can still improve sensitivity and selectivity parameters. Gadolinium (Gd) doping is widely used in gas sensor applications to increase the sensitivity of gas sensors. In addition, reduced graphene oxide (rGO) materials are commonly used in gas sensor applications to increase gas sensors' selectivity, sensitivity, and working temperature. This study analyzed the effect of Gd doping (LGFO) and the addition of an rGO single layer on LFO material (LGFO@rGO) on sensitivity and selectivity based on the adsorption energy of the system with ethanol gas molecules. Density Functional Theory studies were conducted to yield insight into the LGFO or LGFO@rGO – ethanol gas interactions and the sensitivity and selectivity improvement by changing adsorption energy. Based on the analysis, the presence of Gd doping and single-layer rGO could increase the adsorption energy. The addition of the rGO layer showed an escalation of the adsorption energy of about 9.45%, 2.49 eV in the LGFO to -2.75 eV LGFO@rGO. This improved adsorption capacity translates to a higher sensitivity for detecting lower concentrations of ethanol gas. This result shows the potential of LGFO and LGFO@rGO as ethanol gas sensor materials.

Effect of Gd doping on phase evolution, mechanical and thermal characteristics of 1La-xGd-2Yb-3.5YSZ solid solutions

Thermal barrier coatings (TBCs) are critical for the reliability and lifespan of aircraft engine turbine blades. In this study, a novel quaternary rare-earth oxide (La2O3, Gd2O3, Yb2O3, and Y2O3) co-doped ZrO2 solid solution, referred to as 1La-xGd-2Yb-3.5YSZ, was synthesized by varying the doping amount of Gd2O3 from 0 to 6 mol. %. The impact of co-doping-induced lattice distortion on the phase composition, high-temperature phase stability, sintering resistance, and mechanical and thermal properties of the solid solution has been explored. It is found that the addition of Gd2O3 stabilizer effectively increased the lattice distortion of the solid solution, which led to improved phase stability and sintering resistance, enhanced mechanical properties, and low thermal conductivity. Our findings highlight the promising properties of the 1La-xGd-2Yb-3.5YSZ solid solution, making it an attractive candidate for TBC materials.

Unraveling the effect of Gd doping on the structure, optical, magnetic, dielectric and photocatalytic properties of ZrO2 nanostructures

Nanocrystalline Zr1-xGdxO2 (0≤x ≤ 0.20) samples were synthesized through the sol-gel combustion process and characterized by various characterization techniques.XRDanalysis confirms a highly crystalline tetragonal phase with P42/nmc space group. TEM micrographs exhibitreduction in particle size on Gd doping. Photoluminescence (PL) study shows improved light absorption ability of the Gd-doped ZrO2, signifying an excellent way to control the recombination rate of electron-hole pair. XPS analysis ensures the successful incorporation of Gd in the ZrO2 lattice. Room temperature magnetic measurements revealthe ferromagnetic nature of all the samples. The UV-visible spectroscopy shows increase in band gap from 3.82 eV to 4.45 eV. The dielectric constant varies significantly for the Gd-doped samples. All the prepared catalysts were tested for the photocatalytic activity of the methylene blue (MB) dye under visible light irradiation. After 120 minutes, 20% Gd-doped ZrO2displays∼91% degradation efficiency against the MB dye, which makes it a promising visible light-activated photocatalyst.

Preparation, characterization and electrochromic properties of amorphous Gd-doped TiO2 films

Titanium oxide has been widely studied in the field of electrochromism due to its unique color-changing behavior induced by ion insertion. In this paper, amorphous Gd-doped TiO2 films were synthesized via the RF magnetron reactive sputtering. The effects of Gd doping on the electrochromic performance of TiO2 films were explored in detail. The improved coloration efficiency of ∼60% at 540 nm for low Gd-doped TiO2 film (0.61%) is due to the formation of monoclinic Gd2O3 island nanostructure on the surface of TiO2, which enhances the reaction kinetics and charge capacity of the film. The wide optical modulation (73% at 650 nm), large coloration efficiency (59.7 cm2 C−1 at 650 nm) and short response time (coloring time is 16.9 s, bleaching time is 9.1 s) were obtained for the moderately Gd-doped TiO2 film (0.83%). However, for the high Gd-doped TiO2 films (≥1.0%), the coloration efficiency reduced, which is due to the excessive Gd2O3 hindered the electrolyte penetration into the TiO2 active material. By studying the effects of Gd doping on the electrochemical performance of TiO2, it can provide a valuable reference for determining the appropriate doping element and content for electrochromic materials.

Effects of Gd doping on the structural, optical and magnetic properties of [formula omitted] nanoparticles and the impact of the oxygen vacancy

In this study, we report on the structural, optical and magnetic properties of Ce1−xGdxO2−δ nanoparticles (NPs) (0.00 ≤x≤ 0.20) synthesized by the polymeric precursor method. The synthesis protocol successfully fabricated single-phase NPs in the whole range of x-values investigated. The samples were studied by using x-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), UV-Vis absorption, Raman spectroscopy, and vibrating sample magnetometry (VSM). TEM images and XRD analyses revealed the formation of fully crystalline single-phase cubic fluorite NPs having a mean crystallite size in the range of 6 – 4 nm. XRD data analysis showed a linear increase of the lattice constant with Gd-content (x), evidencing an effective incorporation of Gd3+-ions substituting Ce4+-ions in the cerium oxide matrix. The quantitative analysis of the Raman spectra revealed a gradual increase of defects concentration as the Gd-content increased. In order to maintain charge neutrality, it was observed that the formation of intrinsic oxygen vacancy follows different behavior depending on the Gd-content. This result is in agreement with the Gd-content dependence of optical band gap determined from UV visible absorption spectra. The analysis of magnetic measurements revealed the coexistence of ferromagnetic and paramagnetic contributions. At room temperature, the ferromagnetic contribution show a maximum saturation magnetization (Ms) for the sample with x = 0.02 and a decreasing trend for higher x values. 5 K magnetic measurements data analysis corroborates with the Raman spectroscopy data analysis. The paramagnetic contribution follows a typical paramagnetic Curie-Weiss behavior with antiferromagnetic/ferromagnetic correlations, which depend on the Ce3+- and Gd3+-contents.

Effects of Gd doping on microwave absorption properties and mechanism for CaMnO3 perovskites

ABO3 type perovskite oxides have been widely studied due to their unique structure and special electromagnetic properties. CaMnO3 is well known for its excellent thermoelectric performance and temperature stability. In this paper, Ca1-xGdxMnO3 (x = 0, 0.1, 0.2, 0.3, 0.4) perovskites were comprehensively studied by first-principles calculations and experimental characterizations on their crystal structure and electromagnetic properties to finally elaborate the microwave absorption mechanism. It is found that Gd doping significantly enhances the dielectric polarization effects, resulting in better electromagnetic wave absorption performance than undoped CaMnO3. Especially for CG2MO perovskite, its reflection loss and bandwidth below −10 dB at 2–18 GHz reaches −31.9 dB and 3.3 GHz approximately, exhibiting excellent microwave absorption property. Moreover, the microwave absorption mechanism of CGMO perovskites involves various modes of conductive loss, resonance loss, multiple reflection and scattering as well as the polarization phenomenon including interfacial polarization, dipole polarization and defect polarization. Among them, polarization effects and conductive loss contributes the most to the microwave absorption performance.

Competition effect of light and heavy rare earth in Pr1-xGdxCo3 compounds with large coercivity and exchange bias

The effect of Gd doping on the structure and magnetic properties of PrCo3 compound was systematically studied, and a large zero-field cooling exchange bias effect at room temperature was observed. The results show that Pr1-xGdxCo3 (x = 0.0–1.0) series ribbons samples retains the rhombohedral structure of PuNi3 type. The addition of Gd element linearly reduce the lattice constant. Large coercivity strengthening and zero-field cooling exchange bias effect were stable below Curie temperature. At 10 K, the abnormal minimum saturation magnetization MS occurs at the critical point xc = 0.6, which corresponds to the maximum critical field, and the pinning effect is the strongest. At the same time, the maximum critical field is accompanied by the strongest exchange bias field, up to 14.92 kOe, showing a large unidirectional anisotropy. The coercivity HC is also improved by pinning effect, reaching a maximum of 23.17 kOe at the critical point xh = 0.5. Due to the influence of HEB, the actual coercivity HC1 was as high as 36.23 kOe. The mechanism of these phenomena was explained specifically in this paper. This work provides a novel idea for the development of permanent magnet materials and exchange bias materials.

In-situ synthesis and densification of Ce1-xGdxB6 ceramics by spark plasma sintering

The study aims to investigate the effect of Gd doping on phase evolution, microstructural development, sintering behavior, mechanical and electrical properties of polycrystalline bulk Ce1-xGdxB6 ceramics (x = 0, 0.2, 0.4, 0.6). For this purpose, in-situ synthesis and densification of Ce1-xGdxB6 ceramics were carried out via spark plasma sintering by applying a two-step-heating schedule (1000°C-10min & 1950°C-30min) under 50 MPa using CeO2, Gd2O3, and B starting powders. XRD, SEM, and image analysis results showed that all ceramics mainly composed of Ce1-xGdxB6 (>97 vol%); however, the total volume of secondary phases (B2O3 and B4C) slightly increased from 1 to 2.7% with Gd content, which reduced relative density from 98 to 93%. Temperature-displacement curves obtained through SPS referred to the condensation of B2O3 gases and the reduction of densification rate because of the heavier Gd cations. Vickers hardness values were in the range of 16.3–19.9 GPa. Ce0.8Gd0.2B6 exhibited the highest fracture toughness (4.5 MPa.m1/2) through toughening mechanisms. The electrical resistivity values, found between 100 - 10−2 ohm.m, enhanced with Gd content by reason of imperfections. Briefly, 20% Gd doped CeB6, having 95% relative density, 98.3% matrix volume, 16 GPa Vickers hardness, 4.5 MPa.m1/2 fracture toughness, and 9.3 × 10−2 ohm.m electrical resistivity, carries a potential to be used as an electron-emitter.

Effect of Gd doping on spray pyrolyzed NiO thin films for optoelectronic applications

In the present work, we systematically investigated the effect of Gd (1, 3, and 5%) doping on the structural, morphological, electrical, and optical properties of NiO thin films deposited on glass substrate using the spray pyrolysis method. X-ray diffraction study revealed that the deposited Gd:NiO(0–5%) films exhibit cubic structure with preferred orientation along (111) direction. The average crystallite size decreases from 15 nm to 12 nm with increasing Gd doping concentration. The atomic force microscope (AFM) topography study revealed that there is a decrease in grain size and variation of roughness with increasing Gd content into NiO lattice . The energy-dispersive X-ray spectroscopy (EDX)/ scanning electron microscope (SEM) mapping studies show the presence and uniform distribution of Gd in the Gd:NiO films. The average optical transparency (70%) and the optical band gap energy values decrease in Gd doped NiO films. The refractive index values are found to be in the range of 1.5–2.6. The higher values of linear and nonlinear optical parameters like χ1, χ3 and n2 are found to be 0.98 esu, 3.31 × 10−10 esu and 2.92 × 10−9 esu, respectively in Gd doped NiO films. The current study indicates that the Gd doping concentration has a strong influence on linear and non-linear optical properties of NiO films and makes them useful in several optoelectronic device applications.

Effect of Gd-doping in Ni/NiO core/shell magnetic nanoparticles (MNPs) on structural, magnetic, and hydrogen evolution reaction.

In this study, Gdx-doped Ni/NiO MNPs (x: 0.0%, 2.5%, 5.0%, and 10.0%) with a protective polyvinylpyrrolidone (PVP) layer have been synthesized via a polyol reduction process. The x-ray diffraction patterns revealed that samples have a cubic structure with Fm3̄m space group and no change in the crystallite structure was observed with doping Gd3+ ions. The crystallite size (Dc) decreases from 2.70 to 1.27nm when Gd is doped into Ni/NiO MNPs. Transmission electron microscopy analysis revealed that the Ni/NiO MNPs with Gd(5%) concentration are formed as spherical multicore-like shape core/shell MNPs with a protective PVP layer. The magnetic hysteresis measurements taken at 10 and 300K show that the saturation magnetization (Ms) decreases with increasing Gd3+ ions in the structure. The highest effective magnetic moment (μeff) was obtained as 10.34μB in the NG-2 sample. We ascribe that the high μeff value in this sample is due to the increase in d-f exchange interaction between Ni(3d7) and Gd(4f7) and the contribution of the dipole moment of PVP molecules. The electrochemical measurements showed that the current density values were 0.294 and 0.319 mA/cm2 at-1.3V in the absence of Gd (NG-0) and Gd(5%) doped (NG-2) samples, respectively. βc was 159 and 132 mV/dec for NG-0 and NG-2 samples, respectively. The diminishing of βc and the charge resistance (Rct) proved that the Gd doped catalyst enhanced the hydrogen evolution activity and the Gd(5%) doped sample exhibited the highest catalyst performance.

Structural characterization, Gd3+ → Eu3+ energy transfer and radiative properties of Gd/Eu in codoped Li2O–ZnO–SrO–B2O3–P2O5 glass

A series of Gd doped Li2O–ZnO–SrO–B2O3–P2O5 glasses and co-doped samples with different Eu3+ concentrations was synthesized through the conventional melt quenching route. The structural, morphological, and elemental distributions were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and energy dispersive X-ray analysis. The effect of Gd doping on the thermal properties of prepared glasses was studied by differential thermal analysis. Characteristics photoluminescence (PL) emissions of Gd3+ (6P7/2→8SJ/2) and Eu3+ (5D0→7FJ) were observed in the doped glass matrix. Strong PL emissions at 312 nm (6P7/2 → 8S7/2) shown by the Gd-doped glasses upon excitation at 274 nm suggests its prospect in phototherapy applications. Phonon energy of the glass matrix calculated from the phonon sidebands of Eu3+ spectra was obtained as 970 cm−1. The values of branching ratios and stimulated emission cross-sections obtained from Judd-Ofelt analysis indicate the suitability of the prepared Gd–Eu co-doped glasses for optical display devices. The Observed Ω2 > Ω4 suggests Eu3+ occupancy preferably at less centrosymmetric sites in the studied glass hosts. The change in the local symmetry environment of the dopant ions with Gd incorporation was further analyzed by determining the asymmetry ratio of Eu3+ emission in the co-doped glass. The emission spectra and luminescence lifetimes suggested the efficient energy transfer from Gd3+ to Eu3+. Co-doping of Gd led to better chromaticity values and improved color purity of Eu3+ red emission.

Effect of Gd Doping on the Microstructure and Magnetocaloric Properties of Lafe11.5si1.5 Alloy

Effect of Gd Doping on the Microstructure and Magnetocaloric Properties of Lafe11.5si1.5 Alloy

Effect of Gd doping on magnetic and MCE properties of M-type barium hexaferrite

Gd doped barium hexaferrite (BaFe12−xGdxO19, x = 0.0–0.7) has been synthesized by the sol-gel method to explore its magnetic and MCE (magnetocaloric effect) properties. The materials crystallize to hexagonal magnetoplumbite phase. Average particle size decreases with the increase in Gd concentration in barium hexaferrite (BHF). The coercive field increases from 3.2 to 4.8 kOe, and saturation magnetization decreases from 68.21 to 54.23 emu/g with the increase in Gd concentration from x = 0.0 to x = 0.7. These large changes in magnetic parameters reveal the effect of Gd concentration in BHF. The saturation magnetization monotonously reduces with an increase in Gd concentration in BHF due to a decrease in average particle sizes. The saturation magnetization is found to be higher at a lower temperature (60 K) compared to that of room temperature (300 K). It is due to a reduction in thermal energy at low temperature which is smaller compared to the magnetic Gibbs free energy at low temperature. Hence, the magnetic spins are freezing along the applied magnetic field direction at the low temperature. Also, the magnetocrystalline anisotropy constant (obtained by the "Law of Approach to Saturation method") is found to be more at low temperature compared to that of room temperature due to an increase in the strength of spin-orbit coupling with the decrease in temperature (i.e. thermal energy). The M-T curves and M-H hysteresis loops reveal paramagnetic to ferromagnetic transition at the Curie temperature. The maximum entropy change was found to be in the range of 0.12–0.72 J/kgK in a window of the applied magnetic field of 0.5–3 T, and the corresponding RCPmax was found to be 2.5–27.5 J/kg. The present study opens a window to explore the MCE on BHF based material.

Atomically precise multi-domain GdxFe3−xO4 nanoclusters with modulated contrast properties for T2-weighted magnetic resonance imaging of early orthotopic cancer

The use of multi-domain magnetic iron oxide nanoclusters (MMIONs) as Magnetic resonance imaging (MRI) contrast agent is facing problems of strong ferromagnetism and thus weak T2 contrast ability. The doping of Gd ions holds potential to solve these problems by reducing ferromagnetism and enhancing transverse relaxivity (r2), but the exact role of doping in modulating the contrast properties remain unknown. Herein, we prepared a series of atomically precise GdxFe3−xO4 nanoclusters and systematically explored the effect of Gd doping on tuning their morphology, magnetic property, and r2 value. After the doping of Gd ions, the specific surface area of GdxFe3−xO4 nanoclusters significantly increased, and meanwhile, the magnetic property of GdxFe3-xO4 nanoclusters transformed from ferromagnetism to superparamagnetism, which led to stronger T2 contrast. Specifically, the highest r2 value was obtained at 488 mM−1s−1 (7.0 T) for Gd0.072Fe2.928O4 nanocluster, four times higher than that for pristine Fe3O4 (110 mM−1s−1). For potential applications, we validated the outstanding contrast of Gd0.018Fe2.982O4 nanocluster (r2 = 481 mM−1s−1 at 7.0 T) to diagnose early orthotopic cancer in mice. This work opens up a new avenue for the development of atomically precise Gd-doped MMIONs as efficient T2-weighted MRI contrast agents.