Cd Doping Research Articles

Effectively Improved CH4 Sensing Performance of In2O3 Porous Hollow Nanospheres by Doping with Cd.

Recently, due to the promising application of metal oxide semiconductors in high-performance methane (CH4) sensors, more attention has been paid to the development of feasible strategies for improving CH4 sensing performance. Herein, we present a strategy of cadmium (Cd) doping to improve the CH4 sensing property of In2O3 porous hollow nanospheres (PHNSs). The Cd-doped In2O3 PHNSs were prepared via an impregnation-calcination approach with self-made carbon nanospheres as a hard template. The samples were characterized by various techniques to evaluate their structure, morphology, surface state, composition, and band gap. When applied as a sensitive material in the CH4 sensor, the Cd-doped In2O3 PHNSs, compared with bare In2O3 PHNSs, showed some significant improvements in performance, especially a reduced operating temperature (200 °C vs 300 °C), an enhanced response (9.5 vs 2.5 for 500 ppm of CH4), a faster response speed (16 s vs 276 s), and better selectivity. In addition, the Cd-doped In2O3 sensor can also maintain a commendable long-term stability, and the range of its response amplitude within 30 days is only 6.3%. The sensitization effects of the Cd dopant on the In2O3 PHNSs are discussed.

Effect of Cd-doping on optoelectronic properties of ZnO thin films and their application for MAPbI3 photodetector

Abstract The Sol–gel method was used to synthesize Cd-doped ZnO nanoparticles at different doping concentrations. The nanomaterials crystal structure and microstructure were explained by XRD and SEM analysis of the materials. The absorption and transmission spectra were analyzed to explore the optical properties of Cd-doped ZnO thin films. The band gap of nanomaterials decreases from 3.26 to 3.12 eV with the increase of Cd doping concentration in ZnO. The Cd-doped ZnO shows an increasing trend of electrical conductivity and mobility with the increase of Cd concentration in ZnO. The Cd-doped ZnO-based MAPbI3 photodetectors show substantial responsivity in the wavelength range of 365 to 635 nm. The highest responsivity for devices FTO/ Zn1-xCdxO/MAPbI3/Al, having x = 0.05, 0.10 and 0.15, upon 465 nm wavelength (4 mW cm−2) illumination are ∼0.192, 0.272, and 2.1 μA W−1, respectively. The LDR of the x = 0.15 Cd-doped ZnO photodetector is two times higher than the x = 0.05 concentration of Cd doped ZnO photodetectors. Our studies confirm that the Cd-doped ZnO creates band narrowing and may be used for suitable perovskite photodetector.

Modulating Yeager Adsorption Configuration of O2 Through Cd Doping in Zn3In2S6 for Photosynthesis of H2O2

AbstractThe photocatalytic oxygen reduction reaction (ORR) is a key pathway for producing hydrogen peroxide (H2O2). While most previous studies have focused on the two‐step 2e− ORR process, the one‐step two‐electron ORR route offers thermodynamic and kinetic advantages that can significantly enhance 2e− ORR activity and selectivity. In this study, a photocatalyst design is reported by incorporating cadmium into vacancy‐rich Zn3In2S6 (Cd‐SV/ZIS). This catalyst enables H2O2 production via a one‐step 2e− ORR process without the use of sacrificial agents, achieving a high H2O2 yield of 39.42 µmol g−1 min−1 under UV–vis light irradiation, outperforming most reported ZIS‐based photocatalysts. Theoretical simulations and experimental results demonstrate that Cd doping improves the carrier kinetics of the catalyst, broadens its light absorption range, and promotes the Yeager adsorption configuration of O2, leading to highly active and selective H2O2 generation. This study provides insights into the design of efficient ZIS‐based photocatalysts for H2O2 production.

Structural modulation of Na4Fe3(PO4)2P2O7 via cation engineering towards high-rate and long-cycling sodium-ion batteries

Mixed iron-based phosphate Na4Fe3(PO4)2P2O7/C (NFPP) has gradually emerged as a promising cathode material for sodium-ion batteries (SIBs) owing to its affordability and convenient preparation. However, poor electrical conductivity and inadequate sodium-ion diffusion limit the exertion of its electrochemical properties. Herein, a structural modulation strategy based on Cd doping is applied to NFPP to address the above limitations. In situ X-ray diffraction analysis reveals that Cd-doped NFPP (NFCPP) undergoes an incomplete solid-solution reaction driven by Fe2+/Fe3+ redox. Cd doping effectively stabilises the crystal structure, resulting in a minimal 1 % change in unit cell volume during cycling. Density of state calculations indicate that Cd doping reduces the band gap, increases the local electron density and significantly improves electron conductivity. Benefitting from the enhanced electrochemical kinetics and intercalation pseudocapacitance, the optimised Na4Fe2.91Cd0.09(PO4)2P2O7/C (NFCPP@3%) exhibits exceptional rate performance (capacity of 62 mAh/g at 20 C) and ultra-long cycling life (82.7 % after 6000 cycles at 20 C). A full SIB prepared using NFCPP@3% and hard carbon, display a 91 % capacity retention rate at a current density of 130 mA g−1 over 200 cycles. This work demonstrates that doping can effectively enhance electrochemical performance and offers insights into future development of SIBs.

Origin of Enhanced Photoelectrochemical Activity of the n-CdS/p-type Semiconductor Interface: Homojunction or Heterojunction?

Surface engineering of photoelectrodes is considered critical for achieving efficient photoelectrochemical (PEC) cells, and various p-type materials have been investigated for use as photoelectrodes. Among these, the p-type semiconductor/n-type CdS heterojunction is the most successful photocathode structure because of its enhanced onset potential and photocurrent. However, it is determined that the main contributor to the enhanced activity is the Cd-doped layer and not the CdS layer. In this study, a Cd-doped n+p-buried homojunction of a CuInS2 photocathode is first demonstrated without a CdS layer. The homojunction exhibited a more active and stable PEC performance than the CdS/CuInS2 heterojunction. Moreover, it is confirmed that Cd doping is effective for other p-type materials. These results strongly suggest that the effects of Cd doping on photocathodes should be carefully investigated when designing CdS/p-semiconductor heterojunction photoelectrodes. They also indicate that the Cd-doped layer has great potential to replace the CdS layer in future photoelectrode designs.

Enhancing n-type PbTe thermoelectric performance through Cd alloying and strategic defects management

The significant performance disparity between n-type and p-type PbTe hinders their commercial viability in thermoelectric (TE) applications. While conventional multi-element alloying has demonstrably improved n-type PbTe thermoelectrics, it introduces stability concerns and cost escalation. Here, we propose a simpler approach utilizing a single isovalent element alloying strategy with Cd and defect management to enhance the TE performance of n-type PbTe. Cd doping widens the bandgap, leading to an increased effective mass and Seebeck coefficient, particularly at higher temperatures due to improved Cd solubility. However, as documented in previous studies on the PbTe-Cd system, Cd introduction can potentially deteriorate TE performance by reducing carrier mobility. To address this, we implemented defect engineering to optimize carrier mobility. A small excess of Pb atoms was introduced to occupy intrinsic Pb vacancies, achieving a remarkable 65.5 % enhancement in carrier mobility. Consequently, the maximum power factor of Cd-alloyed Pb1.01Te samples reaches 31.5 μW cm−1 K−2, marking a significant 69.3 % improvement compared to pristine PbTe. Additionally, the Cd-induced bandgap widening effectively mitigates bipolar diffusion. This, combined with enhanced phonon scattering due to the secondary CdTe phase, results in a 34.3 % decrease in thermal conductivity. By leveraging the multifaceted effects of Cd alloying and defect management, the ZT value of Pb1.01Te-2 %Cd samples reaches 1.35 at 782 K. These findings offer a new perspective on the versatile use of single isovalent element alloying strategy and performance optimization in other TE materials.

The p-type modulation of by Ca and Cd doping

Two-dimensional (2D) Bi2O2Se has been widely used as optoelectronic detector due to its excellent carrier mobility and environmental stability. However, the synthesis of the p-type Bi2O2Se remains challenging which hinders its further applications. In this paper, we have investigated the electronic properties of the native point defects and the Ca/Cd-doping effects on Bi2O2Se using first-principles calculations. The results indicate that Se vacancy (V Se ) and O vacancy (V O ) are shallow donors, which lead to the n-type Bi2O2Se semiconductor. Ca substituting Bi (Ca Bi ) and Cd substituting Bi (Cd Bi ) are acceptors and can compensate the n-type behavior of shallow donors. The compensation effect of Cd Bi is weaker than that of Ca Bi due to its higher formation energies. Additionally, the calculation results of the Fermi level, defect and carrier concentrations indicate that Ca Bi shifts the Fermi level towards the valence band maximum (VBM), however, it is not sufficient to convert Bi2O2Se into the p-type.

Exploring the transformation: High-dosage gamma irradiation's role in tuning structural, optical, and electrical properties of cadmium-doped lead sulfide (PbS) nanoparticles

The effects of gamma irradiation on Cadmium-doped PbS (Cd-PbS) nanoparticles are thoroughly examined in this lattice study. The study sheds light on the changes in structural, morphological, and electrical properties brought about by Cd doping and gamma irradiation by employing a variety of methods such as X-ray diffraction, FESEM imaging, EDAX analysis, Raman spectroscopy, photoluminescence (PL) spectra, and Hall effect measurements. The Cd-doped PbS shows a fluctuating crystallite size as the average size first increases by ∼3 nm and then decreases by ∼3 nm with Cd concentration. This is due to the induced strain by the Cd dopant, which has a smaller ionic radius compared to Pb ions. With Cd substitution, the bandgap of PbS first decreases from 2.29 eV to 2.19 eV and then increases with mild fluctuations. Meanwhile, gamma irradiation causes these changes, decreasing the bandgap from 2.19 eV to 2.03 eV for lower Cd concentrations (x = 0.005) and increasing it to 2.41 eV for higher concentrations (x=0.01). The Hall data shows a wide range shift in electrical characteristics between the cadmium doped gamma-irradiated sample, and the pure sample, PS0. The electrical mobility increases from 6.05 V−1s−1 for PS0 to 4.95×102 V−1s−1 for GPS3 (higher cadmium concentration of x = 0.02), indicating a significant enhancement in which charge carriers can move through the material post-irradiation. Electrical resistivity shows a drastic increase from 4.42×101 Ωcm in PS0 to 9.41×102 Ωcm in GPS3, suggesting a marked increase in electrical conductivity post-irradiation. The findings demonstrate considerable changes in crystal characteristics, morphological transformations, increased crystallinity, and changed electrical properties, showing the promise of gamma-irradiated Cd-doped PbS in advanced optoelectronic device applications.

A comparative investigation into the impact of Cd and Mg on the optoelectronic properties of ZnO thin films by spray pyrolysis for waveguide applications

This study examines the impact of Mg and Cd on ZnO waveguide properties using CdxZn1−xO and CdxZn1−xO thin films (x=0, 0.03, 0.05). X-ray diffraction confirms successful Mg incorporation in the ZnO wurtzite, while CdO segregates, increasing lattice parameters. UV–Vis measurements show opposing trends in band gap energy, increasing for Mg doping and decreasing for Cd doping. Photoluminescence data reveals varying defect characteristics consistent with band gap energy behavior. Through SEM, Mg increased grain size and slightly decreased the surface density. Cd-doped films exhibit no significant morphology change by AFM measurements. Hall measurements show both Cd and Mg doping increase resistivity tenfold. Cd causes a 94.5% decrease in mobility, whereas Mg leads to a substantial 2190 times increase. Charge carrier density decreases by 105 in Mg0.05Zn0.95O and increases threefold in Cd0.05Zn0.95O. M-lines measurements demonstrate birefringent behavior, positive for Mg doping and negative for Cd doping, and a decreasing refractive index.

Low Temperature Chemical Synthesis and Investigation of Cadmium Substituted of Structural Properties of Cobalt Nano Ferrites

This article presents, the systematic and successful preparation of cadmium substituted cobalt ferrite (Co1-xCdxFe2O4) nanoparticles via simple co-precipitation method. X-ray diffraction study confirmed the prepared ferrite nanoparticles were crystallized with a mono phase cubic spinel structure of Fd3m space group. The average crystallite size (Dxrd) was increased with Cd doping content, due to the replacement of Co2+ ions by Cd2+ ions. XRD pattern revealed the high intense peak corresponds to (311) lattice plane and confirmed the formation of cubic structure ferrite nanoparticles. Morphological study was done by using SEM images. The grain size found to be increased with Cd concentration and it reaches the highest of around 0.9μm for Co0.52Cd0.48Fe2O4 composition. Fourier Transform Infrared spectroscopy of prepared samples was recorded in the range of 1000-350 cm-1, confirmed the spinel structure.

Unveiling the synergistic effect of Cd doping on structural, optical, mechanical, and γ-ray shielding characteristics of zinc lead silicate glass

Using the traditional melt quenching process, the glass series of xCdO-(5-x) ZnO-35Pb3O4-60SiO2, where x = 1–5 mol%, were created. The X-ray diffraction method was utilized to investigate the non-crystallinity of the glasses that were created. The densities of the fabricated glasses increased from 5.91 to 6.655 g/cm³. Electronegativity (ΔX), bond density (nb), and field strength (F) were calculated. ΔX decreased while nb and F increased with the supply of Cd ions. The optical characteristics Eg, n, αo, εr, χ(3), n2, M, T and more have been investigated. We found that a change in cadmium concentration in the fabricated system influenced all the optical parameters. The mechanical properties, including elastic moduli, have been investigated alongside ultrasonic velocity measurements. The experimental results demonstrated a strong dependence of calculated parameters on increasing CdO concentration. The observation indicates an increase in the elastic moduli with the increasing CdO concentration. Radiation shielding factors were estimated using EpiXS program. μL, HVL, MFP, Zeff, Neff, EBF and EABF for gamma energy between 15 and 15,000 KeV have been investigated. The results indicate that these parameters are affected by the introduction of CdO content into the glass network. The sample ZPSCd5 exhibits the highest radiation shielding parameters among the studied glass samples.

Cadmium‐Doping Slows Trap Emptying in Ambient‐Air Blade‐Coated Formamidinium Lead Iodide Perovskite Solar Cells

AbstractFormamidinium lead iodide (FAPbI3) in its α‐phase is among the most desirable perovskite compositions for solar cells. However, because of its transition into the yellow δ‐phase at room temperature, it is a challenge to process it in ambient air by scalable fabrication methods. Here the introduction of a trace amount of cadmium (in the form of CdI2) to FAPbI3 is reported and found that it enhances the stability of the perovskite's black α‐phase polymorph, inhibits non‐radiative recombination events, leads to pin‐hole free compact surface morphology, and improves band energy alignment. The 0.6% Cd‐doped FAPbI3 solar cells show a champion efficiency of 22.7% for 0.049 cm2 and 16.4% for cm2‐scale pixels, which, to the best of the knowledge, are among the highest for air‐ambient fully blade‐coated pure FAPbI3 solar cells with an n‐i‐p architecture. Transient absorption microscopy measurements reveal that Cd doping reduces the number of trapped charges and increases their lifetimes, promoting charge accumulation and a higher photovoltage. The study sheds light on the potential of cadmium as a homovalent dopant for the stabilization and performance enhancement of FAPbI3 performance solar cells.

High‐Performance CaMg2Bi2‐Based Thermoelectric Materials Driven by Lattice Softening and Orbital Alignment via Cadmium Doping

AbstractZintl compounds such as n‐type Mg3(Sb,Bi)2 show promising thermoelectric applications benefiting from their high valley degeneracy and low lattice thermal conductivity. However, the heavier p‐type AMg2X2 (A = Ca, and Yb; X = Bi and Sb) Zintl counterparts even exhibit a higher κlat due to strong chemical bonding. Reducing κlat of AMg2X2 is an important route for improving thermoelectric performance. Herein, it is found that Cd doping at the Mg site in CaMg2Bi2 can weaken intralayer covalent bonds and soften acoustic phonons, as well as fill the optical phonon gap. These effects result in large atomic displacement, low phonon group velocity, and strong lattice vibration anharmonicity. Doping 10% Cd leads to a reduction of 56% in the κlat of CaMg2Bi2. Moreover, Cd doping promotes orbital alignment and thus increases the density‐of‐states effective mass and Seebeck coefficient. Eventually, in conjunction with carrier concentration optimization by Na doping and band structure engineering by Ba doping, a high ZT of ≈1.3 at 873 K in (Ca0.85Ba0.15)0.995Na0.005Mg1.85Cd0.15Bi2 sample is realized. This work highlights the significant role of manipulating chemical bonding in suppressing phonon propagation of semiconductors.

Defect and doping properties of sliding ferroelectric γ-InSe for photovoltaic applications

Layered van der Waals (vdw) materials have been proposed as light-absorbing materials for photovoltaic applications. InSe is a layered vdw semiconductor with ultra-high carrier mobility, strong charge transfer ability, super deformability, thermoelectricity, and optoelectronic properties. Its γ phase, or γ-InSe, was greatly stabilized by doping recently, which also exhibits sliding ferroelectricity. In this study, we propose that γ-phase InSe (γ-InSe), which was recently synthesized in a high-quality bulk phase, could be an excellent light-absorbing material candidate. Based on the first-principles simulations, bulk γ-InSe is found to possess suitable bandgap, decent absorption, and low effective mass. The investigation of defect properties reveals the major defect types, defect levels, and deep-level defects that could possibly harm the efficiency, and the deep-level defects can be significantly suppressed under Se-rich conditions. In addition, γ-InSe is intrinsically n-type, which can be tuned into weak p-type by Zn and Cd doping. We also identify the defect types of Y and Bi doping, which have been experimentally used to adjust the mechanical property of γ-InSe, and find that Y interstices could play an important role in improving the stiffness of γ-InSe. Our study provides theoretical insights for photovoltaic and other photoelectronic applications based on this interesting ferroelectric layered vdw material.

In-situ construction of cation vacancies in amphoteric-metallic element-doped NiFe-LDH as ultrastable and efficient alkaline hydrogen evolution electrocatalysts at 1000 mA cm−2

Developing efficient and stable electrocatalysts at affordable costs is very important for large-scale production of green hydrogen. In this study, unique amphoteric metallic element-doped NiFe-LDH nanosheet arrays (NiFeCd-LDH, NiFeZn-LDH and NiFeAl-LDH) using as high-performance bifunctional electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) were reported, by tuning electronic structure and vacancy engineering. It was found that NiFeCd-LDH possesses the lowest overpotentials of 85 mV and 240 mV (at 10 mA cm−2) for HER and OER, respectively. Density functional theory (DFT) calculations reveal the synergistic effect of Cd vacancies and Cd doping on improving alkaline HER performance, which promote the achievement of excellent catalytic activity and ultrastable hydrogen production at a large current density of 1000 mA cm−2 within 250 h. Besides, the overall water splitting performance of the as-prepared NiFeCd-LDH requires only 1.580 V to achieve a current density of 10 mA cm−2 in alkaline seawater media, underscoring the importance of modifying the electronic properties of LDH for efficient overall water splitting in both alkaline water/seawater environments.

Nuanced dilute doping strategy enables high-performance GeTe thermoelectrics

In thermoelectrics, doping is essential to augment the figure of merit. Traditional strategy, predominantly heavy doping, aims to optimize carrier concentration and restrain lattice thermal conductivity. However, this tactic can severely hamper carrier transport due to pronounced point defect scattering, particularly in materials with inherently low carrier mean-free-path. Conversely, dilute doping, although minimally affecting carrier mobility, frequently fails to optimize other vital thermoelectric parameters. Herein, we present a more nuanced dilute doping strategy in GeTe, leveraging the multifaceted roles of small-size metal atoms. A mere 4% CuPbSbTe3 introduction into GeTe swiftly suppresses rhombohedral distortion and optimizes carrier concentration through the aid of Cu interstitials. Additionally, the formation of multiscale microstructures, including zero-dimensional Cu interstitials, one-dimensional dislocations, two-dimensional planar defects, and three-dimensional nanoscale amorphous GeO2 and Cu2GeTe3 precipitates, along with the ensuing lattice softening, contributes to an ultralow lattice thermal conductivity. Intriguingly, dilute CuPbSbTe3 doping incurs only a marginal decrease in carrier mobility. Subsequent trace Cd doping, employed to alleviate the bipolar effect and align the valence bands, yields an impressive figure-of-merit of 2.03 at 623 K in (Ge0.97Cd0.03Te)0.96(CuPbSbTe3)0.04. This leads to a high energy-conversion efficiency of 7.9% and a significant power density of 3.44 W cm−2 at a temperature difference of 500 K. These results underscore the invaluable insights gained into the constructive role of nuanced dilute doping in the concurrent tuning of carrier and phonon transport in GeTe and other thermoelectric materials.

Enhanced optical third-harmonic generation in phase-engineered nanostructured Zn1−x Cd x S thin films for optoelectronic device applications

A polycrystalline nanostructured thin film of zinc cadmium sulfide was meticulously fabricated on a glass substrate using the thermal evaporation method physical vapor deposition within a vacuum chamber. Different doping concentrations were introduced by varying the cadmium (Cd) content, resulting in Zn1-x Cd x S films with Cd concentrations ranging from x = 0.00–0.20 wt %. The impact of Cd doping on the third-order nonlinear optical (TONLO) properties of these films was thoroughly studied using the Z-scan method, employing a diode-pumped solid-state continuous-wave laser. To gain insight into the structural characteristics, the Zn1-x Cd x S thin films underwent analysis through x-ray diffraction. Optical studies confirmed the tunability of the optical band gap (Eg) in the Zn1-x Cd x S films, ranging from 3.88 eV for undoped ZnS to 2.80 eV for the film fabricated with 20 wt. % of Cd-content. This significant reduction in ‘Eg’ renders the films highly suitable for use as absorbing layers in applications such as solar cells and optoelectronics. Surface morphology analysis, performed via field emission scanning electron microscopy, revealed noticeable alterations with increased Cd doping. Significantly, the doped films exhibited a substantial redshift in the band edge and an increase in transmittance within the visible and near-infrared regions. The investigation of TONLO properties, including the nonlinear absorption coefficient (β), nonlinear refractive index (n 2) and susceptibility χ(3), yielded values ranging from 3.15 × 10−3 to 8.16 × 10−3 (cm W−1), 1.65 × 10−8 to 7.45 x 10–8 (cm2 W−1), and 3.12 × 10−5 to 7.86 × 10−5 (esu), respectively. These results indicate the presence of self-defocusing nonlinearity in the films. Overall, the outcomes underscore the potential of Cd-doped ZnS nanostructures in modifying surface morphology and enhancing NLO characteristics. Zn1-x Cd x S thin films exhibit promise for applications in nonlinear optical devices, as evidenced by these encouraging findings.

Synthesis of pure and Cd-doped hydroxyapatite for the photo-catalytic degradation of Amoxicillin and Ciprofloxacin: Crystallographic characterization using XRD

Nanosized hydroxyapatite (HAp) is considered an elementary material for artificial bone tissue engineering and the applications are expanding and one of them is the photocatalytic degradation of environmentally hazardous pollutants. In this research, HAp nanoparticles, in pure form and doped with cadmium (Cd), were synthesized using a conventional wet-chemical precipitation method. Additionally, the synthesized samples such as pure and Cd-doped HAp were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV–Vis spectroscopy. Moreover, the XRD analysis allowed for a detailed estimation of the crystallite size, assisting in their tailoring of increased photocatalytic activity. The crystallite sizes of the nano-crystallite Hap were evaluated using the Scherrer Method (SM), Williamson-Hall Method (WHM), Size-Strain Plot (SSP), Halder-Wagner Method (HWM), and Sahadat-Scherrer Method (SSM). The models confirmed the formation of nano crystallite hydroxyapatite in pure and doped form. Cadmium doping in HAp showed great photocatalytic activity for example at 150 min, 31 % amoxicillin and 52 % ciprofloxacin were degraded upon 1.5 wt % Cd doping in HAp crystal. The research demonstrated that doping Cd in HAp crystal improved photocatalytic activity towards antibiotic solution (ciprofloxacin and amoxicillin) under all test circumstances.

Regulation of magnetic moment and magnetic anisotropy of magnetite by doping transition metal elements

Magnetic Fe<sub>3</sub>O<sub>4</sub> nanoparticles show promising applications in nanomedicine. The saturation magnetization (<i>M</i><sub>S</sub>) and magnetic anisotropy are critical for the applications of Fe<sub>3</sub>O<sub>4</sub> nanoparticles in drug delivery and magnetic hyperthermia. Here, by density functional computation, the doping effects of 3d and 4d transition metal elements (including Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag and Cd) on the magnetic properties of Fe<sub>3</sub>O<sub>4</sub> are investigated in-depth. A conventional cell of Fe<sub>3</sub>O<sub>4</sub>, containing 24 Fe atoms and 32 O atoms, has been used to investigate the doping of group III elements. One 3d or 4d atom is doped in one conventional cell of Fe<sub>3</sub>O<sub>4</sub>, resulting in the formation of X<sub>0.125</sub>Fe<sub>2.875</sub>O<sub>4</sub> where X represents the dopant. The results show that the doping of most 3d and 4d transition metal elements will reduce the total magnetic moment, while the doping of Ag, Zn and Cd in Fe<sub>3</sub>O<sub>4</sub> will increase the total magnetic moment by 19%–22%. However, it is hard to dope Ag into Fe<sub>3</sub>O<sub>4</sub> according to the positive formation energy. Therefore, Zn and Cd are good candidates to improve the <i>M</i><sub>S</sub> of Fe<sub>3</sub>O<sub>4</sub>. The doping of Zn and Cd has also an influence on the magnetic anisotropy of Fe<sub>3</sub>O<sub>4</sub>. For Zn<sub>0.125</sub>Fe<sub>2.875</sub>O<sub>4</sub>, the magnetic anisotropy energy is about 0.25 meV per cell, which is slightly larger than that of intrinsic Fe<sub>3</sub>O<sub>4</sub> (0.2 meV per cell). Interestingly, the doping of Cd (Cd<sub>0.125</sub>Fe<sub>2.875</sub>O<sub>4</sub>) will greatly increase the magnetic anisotropy energy to 0.8 meV per cell, which is significant for the specific absorption rate in the magnetic hyperthermia application. In addition, the doping of Zn and Cd will not induce any defect states in the band gap according to the density of states. Zn<sub>0.125</sub>Fe<sub>2.875</sub>O<sub>4</sub> and Cd<sub>0.125</sub>Fe<sub>2.875</sub>O<sub>4</sub> are both semiconducting and both the top of valence band and the bottom of conduction band originate from octahedral Fe. This is because the impurity states are very deep in energy. Our research results show that doping Cd is a feasible way to improve the performance of Fe<sub>3</sub>O<sub>4</sub> as a material for drug delivery and magnetic hyperthermia.

Understanding role of cadmium substitution on thestructural, microstructural, transport properties of ferrites synthesized by different methods

The structural studies (XRD and SEM), the dielectric constant (??), dielectric loss (tan ? or ??), AC conductivity studies (?ac), and Cole-Cole plot studies are carried out for Co0.5Zn0.5Cd1.5xFe2-xO4 (Cd doped Co-Zn ferrites) with x=0.0, 0.1, 0.2, 0.3, 0.4, 0.5 series synthesized by co-precipitation (CPP) method and solid state reaction (SSR) method, and for Co0.5Ni0.5Cd1.5xFe2-xO4 (Cd doped Co-Ni ferrites) with x=0.0, 0.1, 0.2, 0.3, 0.4, 0.5 series synthesized by co-precipitation (CPP) method. The XRD confirms the cubic spinel structure of all the samples. The SEM images show the agglomeration of particles observed to be increasing with increase in Cd doping. The dielectric constant increased with Cd concentration. The dielectric constant is observed to be higher for samples prepared CPP method compared to SSR. Dielectric loss graphs have shown the resonance for certain frequencies. The AC conductivity increased with Cd doping. The samples prepared by CPP method shown lower AC conductivity compared to samples synthesized by SSR method. The Cole-Cole plots show the dual contribution of grain and grain boundaries in conductivity.