Increase In Doping Concentration Research Articles

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

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

Atomic-scale carbon framework reconstruction enables nitrogen-doping up to 33.8 at% in graphene nanoribbon

Nitrogen-doping is well-known to be an effective and promising strategy to tune the electronic states and configurations of carbon materials for catalysis, energy conversion and storage. Since 2009, numerous investigations have demonstrated that the catalytic activity of the nitrogen-doped carbon materials can be improved with an increased doping concentration, yet, how to realize a high doping level remains a great challenge, and to what level remains an open and elusive question. Herein, we report an “in situ framework reconstruction of g-C3N4” that can provide a suitable and simple approach for Nitrogen-superdoping, where nitrogen vacancy formed at C-N = C site in the g-C3N4 framework help to activate adjacent C atoms that are endowed with unpaired electrons dwelling, thus, to be more active. Importantly, both density functional theory analyses and experiments reveal that they are energetically favorable to bond with an ethene molecule, reconstructing a π-bonded dual nitrogen-doped hexagonal-C ring that further acts as building block of the as-formed graphene nanoribbons. Finally, the nitrogen-doping level and the configuration can be finely tuned in a wide range, and up to 33.8 at% of nitrogen is homogenously doped. With the Nitrogen-superdoped graphene nanoribbons as counter electrodes in dye-sensitized solar cells, which have attracted wide attention due to their easy fabrication and relative high power conversion efficiency (PCE), a PCE of 8.60% is achieved. This present work represents a breakthrough in high-efficiency nitrogen-doping of carbon materials, and will fastly promote the chemistry, chemical engeering and material industry involved in carbon.

The effect of boron co-doping on thermoluminescence and optically stimulated luminescence properties of LiMgPO4:Tb,Sm

The effect of boron co-doping on optically stimulated luminescence (OSL) and thermoluminescence (TL) properties of LiMgPO4:Tb,Sm,B prepared by solid-state reaction was studied. The structure of the prepared materials was confirmed by X-ray diffraction. The TL glow curves of samples irradiated with different doses of β rays were tested. No matter how much B is doped, the peaks at 190 or 280 °C are for a first-order kinetic glow curve. The activation energy and frequency factor remained almost unchanged with the increase of boron doping concentration, which indicated the trap centers of LiMgPO4:Tb,Sm,B were independent of boron doping concentration. The E at 190 and 280 °C are around 1.16 eV and 1.55 eV. Photo-ionization cross-section showed significant changes and the sensitivity of OSL reached a maximum for a concentration of 4 mol% with increasing of boron doping concentration. B-doping enhanced the OSL-signal with a factor 2.6 when B concentration is 4 mol%. The repeatability of the powders for OSL were also studied and the relative standard deviation was less than 1.5%. The minimal detectable dose (MDD) of LiMgPO4:Tb,Sm,B with a boron doping concentration of 4 mol% was 8.2 μGy. This material has a fast decay time, good repeatability, low MDD and has further research value.

Luminescence properties of Eu2+/3+ co-activated La6Sr4(SiO4)6F2 polychromatic phosphors towards white light-emitting diodes and anti-counterfeiting

To obtain emitting color regulation, series of Eu2+/3+-coactivated La6Sr4(SiO4)6F2 phosphors were synthesized. The crystal structure, morphology, elemental compositions and luminescence performances of the final products were discussed. Excited by 365 nm, all of the studied samples can emit the characteristic emissions of Eu2+ and Eu3+, in which their fluorescence intensities have various responses to doping content. Specially, as the dopant content increases, the emitting color is changed from green to yellow. Moreover, via changing the excitation wavelength, tunable emissions are also realized in the studied samples. On the basis of the temperature dependent emission spectra, it is found that Eu2+/3+-coactivated La6Sr4(SiO4)6F2 phosphors possess good thermal stability. Through selecting the designed phosphors as yellow emitting components, a warm white light-emitting diode (white-LED) was packaged, in which its electroluminescence properties are hardly altered at high injection current. When the working current is 100 mA, the color coordinate, correlated color temperature and color rendering index of the fabricated white-LED are (0.358,0.358), 4580 K and 87.39, respectively. In addition, using the resultant compounds as luminescent labels, different patterns were prepared for the application in information encryption. The results demonstrated that Eu2+/3+-coactivated La6Sr4(SiO4)6F2 phosphors with multicolor emissions and outstanding thermal stability are suitable for white-LED and optical anti-counterfeiting as emitting components.

Facile synthesis of Cu-doped BiVO4 using domestic microwave-assisted chemical precipitation method with fleeting time of microwave irradiation for the photocatalytic application

Semiconductor-based visible light active photo-catalyst has been synthesized through microwave-assisted chemical precipitation method under acidic pH with minimal time of reaction using microwave irradiation. The monoclinic crystal phase of the material with no impurity is confirmed with XRD data. We can observe slight left shift after doping with copper (Cu) in 2Θ peak of XRD data. SEM analysis exhibits a gradual change in morphology with the increase in doping concentration. UV–Vis data confirms an improvement in absorption with the increase in dopant concentration. PL analysis further clarifies the change in recombination rate of photo-induced charge carriers. Photocatalysis has been tested with methylene blue (MB) synthetic dye. The maximum percentage of degradation was determined to be 61.08% and it is obtained for 0.25% Cu-doped BiVO4. It is also observed that 0.25% Cu-doped BiVO4 has lower energy band gap value, i.e., 2.03 eV and lesser PL intensity than pure un-doped BiVO4. The HRTEM analysis proves that 0.25% Cu-BiVO4 is well crystalline in nature with the d spacing corresponding to (121) plane of BiVO4.

Exploring the effect of V doping on the tribological mechanism of MoS2 coatings in atomic oxygen environment

MoS2 coatings are subject to severe oxidation and erosion under atomic oxygen (AO) irradiation due to its loose microstructure. This concern can be alleviated by means of metal doping. In this work, MoS2 coatings with different V doping content are deposited by magnetron sputtering. The morphology, chemical stability and tribological properties are investigated by scanning electron microscopy, energy dispersive spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, film stress tester and ball-on-disk tribometer, respectively. As the V doping content increases, the MoS2-V coating changes from a loose columnar crystal structure to a more dense structure. Friction and wear results show that the MoS2-V coating deposited at V target current of 0.5 A owns the best tribological properties with a friction coefficient of 0.04 and wear rate of 1.29 × 10−6 mm3/N·m under simulated AO environment. The objective is to develop MoS2-V composite coatings to AO irradiation resistance in order to select suitable lubricant for reliable space applications.

High energy devices and display technology applications of silver doped zirconium titanate nanoparticles

For the first of its kind, Silver activated (1–9 mol%) Zirconium Titanate nanoparticles (NPs) have been synthesized by green solution combustion method using AloeV era gel extract as a reducing agent followed by calcination at 720 °C for 3 h. All the synthesized samples crystallizes in orthorhombic crystal structure with the space group of Pbcn. Initially a less intense peak corresponding to monoclinic ZrO2 phase is observed up to 7 mol% and thereafter it diminishes at 9 mol%. The surface and bulk morphology were analyzed. The crystallite size increases whereas the direct energy band gap was found to decrease with increase in dopant concentration. Further, the effect of dopant concentration on photoluminescence and electrochemical properties were studied. The PL spectra show a single broad emission peak at 440 nm along with a satellite peak at 466 nm. These peaks appearing in the case of Ag-doped ZTO corresponds to the radiative transition of the excited electrons from occupied d bands to higher states of the Fermi level. The CIE and CCT coordinates imply that the present nanophosphor can be employed as a blue emitting phosphor material in display technology. The cyclic voltammetry analysis is performed for oxidation and redox peaks. EIS revealed the ion transport kinetics and Super capacitance values were obtained from GCD analysis. Specific capacitance values were found to be in the range 279 to 329 F/g for ZTO:Ag (1 to 9 mol%) NPs respectively. Thus, the present synthesized material might find applications in the field of display technology as well as in energy storage materials.

Analysis of variance (anova) of the influence of molybdenum and cobalt additives on piezoelectric, dielectric and ferroelectric properties of Pb(Zr0.52Ti0.48)O3

This study aims to determine how molybdenum and cobalt additives affect the structural and electrical characteristics of Pb(Zr0.52Ti0.48)O3. by substituting zirconate and titanate with molybdenum and cobalt, individually or in combination, in the range of 0–2%. The powders were initially made in order to achieve this via a wet chemical process. They were then calcined at 800 °C for 4 h. The calcined powders' XRD examination indicates that the tetragonal phase rapidly diminishes with dopant concentration and concurrently gives way to rhombohedral phase. With an increase in dopant concentration, a SEM analysis of sintered discs showed a considerable change in grain size initially at the Zr site. Detailed investigations of the PZT's piezoelectric properties Significant changes in the piezoelectric charge coefficient, electromechanical coupling coefficient, resonant frequency, and mechanical quality factor can be seen in the samples that were created and examined. Analysis of Variance was used to evaluate the impact of additives on resonance frequency, and the results revealed that the addition of molybdenum and cobalt has a significant impact on resonance frequency.

Synthesis and structural characterization of PVDF-based lead-free ceramic composites

PVDF-based compounds are one of the most promising materials for technological application. In this work, structural and optical techniques have been used to study PVDF-based lead-free ceramic composites, considering the inclusion of the ferroelectric BaTiO3 (BT) and magnetic BaFe12O19 (BHF) and SrFe12O19 (SHF) phases. Results obtained from X-Ray diffraction measurements revealed the formation of the PVDF/ceramic composites with the respective ferroelectric and magnetic phases related to the BT and BHF and SHF ceramics. On the other hand, from the analyses of the Raman and FT-IR spectroscopies, it was possible to confirm the incorporation of the ceramics into the PVDF matrix. It was observed that the β-phase % decreased with the increase of doping content, except for the PVDF/BHF composite, which showed to remains almost constant. The results reveal that the studied hybrid PVDF/ceramic samples could be considered potential candidates for electronic applications.

Investigation of IR Reflective Coating for Plexiglas Canopy

Purpose: Solar energy is necessary for our global ecosystem. In certain times and parts of the world, the heat generated from the energy of the Sun becomes uncomfortable for us and we need to use additional energy to cool down the generated heat from the Sun. This additional energy usage is detrimental to our environment due to generation of air pollution and use of our natural energy resources. The purpose of this paper is to investigate prevention of undesired generation of heat by the Sun using reflective coating materials.
 Methodology: In this study, using literature review, Ga doped Zinc Oxide (GZO) is theoretically investigated as a visible light transparent and infrared reflective coating material for the Plexiglas canopy of a solar car. The effect of doping concentration and film thickness is reviewed and discussed. Indium Tin Oxide (ITO) is also studied, using various literature reviews, as an infrared reflective coating material that is transparent in the visible light region. Finally, a spectrophotometer was used to examine the optical properties of a Plexiglas, slide glass, and ITO coated glass, and the results of UV and visible light transmittance measurement of the three materials is presented and discussed.
 Findings: GZO and ITO films both have high transparency in the visible region of the solar spectrum and high reflectivity to IR radiation starting from 1500 nm to higher wavelengths. None of these films completely reflect the IR radiation with wavelengths in the range of 700 nm to 1500 nm which contribute to generation of heat most. Many factors such as doping concentration and thickness of the films affect reflectivity of the films due to their effect on shifting the plasma frequency. Increasing doping concentration and thickness of the GZO films until a certain threshold improves IR reflectivity of GZO films, but it was not possible to precisely formulate these factors within this study. Reducing the particle size in nanoparticle ITO film improves transmittance of the film in the visible light region and its reflectance in the IR region. The measurement results showed that Plexiglas and glass have a high transparency to visible and near IR radiation.
 Recommendations: Further investigation and experimentation is recommended to fully understand and formulate doping concentration and film thickness of GZO and ITO to achieve optimal IR reflectivity within the 700 to 1500 nm wavelength region while maintaining visible light transparency. In regards to ITO coating, reduced nanoparticle size is recommended to improve the desired visible and IR transparency and reflectivity of the film. Although GZO and ITO coatings’ doping concentration and thickness to achieve IR reflectivity within the 700 to 1500 nm wavelengths is not well understood in this study, to reduce heat generation they are still recommended as a coating material due to their reflectivity to IR with wavelengths of above 1500 nm which also play a role in generation of heat.

Exploring the optical and biological aspects of sodium- doped CuO nanoparticles

In this article, we present a novel coprecipitation technique for synthesizing pure and sodium-doped CuO (Cu1-xNaxO) nano powders with different sodium concentrations (x = 0, 0.01, 0.02, 0.04, 0.06, 0.08, and 0.10). The structural properties of the samples were analysed using powder X-ray diffraction (PXRD), which revealed an average crystallite size of 12.48–10.50 nm. The bonding nature of the Cu1-xNaxO samples was described by Fourier transform infrared (FTIR) spectroscopy. The UV–Visible spectroscopic analysis showed a band gap energy of 1.240–1.456 eV and a refractive index that decreased with an increase in Na doping concentration. Field emission scanning electron microscopy images revealed the spherical, flower-shaped, and flake-like morphologies of the nanoparticles, which had sizes ranging from 42.45 ± 5.49–33.98 ± 4.32 nm. Energy-dispersive X-ray spectroscopy and elemental mapping were used to confirm the purity of the samples and the presence of Cu, O, and Na elements in the Cu1-xNaxO samples. High-resolution transmission electron microscopy photomicrographs confirmed that the samples were polycrystalline and the nanoparticles exhibited nucleation with lattice spacing, as shown by selected-area electron diffraction patterns. Furthermore, the Cu1-xNaxO nano powders exhibited efficient antibacterial and antifungal activities. The antibacterial activity was tested against major bacterial strains, and the highest inhibition zones were observed to be 13.67 ± 1.11 mm (x = 0.06), 10.67 ± 0.94 mm (x = 0.10), 15 ± 1.11 mm (x = 0.10), and 9.25 ± 0.25 mm (x = 0.06) for P. aeruginosa, B. subtilis, S. aureus, and K. pneumonia, respectively. In addition, the antifungal activity of the Na-doped CuO nano powders was found to be enhanced against polymorphic fungus C. albicans and filamentous fungus A. niger with dopant concentration. These results suggest that Na-doped CuO NPs have potential applications in formulating new antifungal drugs and treating various life-threatening bacterial infections.

Structural, optical and dielectric properties of nanostructured La1−xSrxMnO3 perovskites

In this study, a series of nanocrystalline perovskites, La1−xSrxMnO3 (x = 0, 0.3, 0.5, 0.7), were synthesized via the combustion method, utilizing citric acid as fuel, which is an inexpensive synthesis method compared to the vacuum methods for growth. The powder X-ray diffraction study confirms the formation of the desired compositions. The XRD pattern shows that as the Sr doping concentration increases, crystallite size decreases from 30 nm to 14 nm. SEM micrographs reveal the spongy, porous structure of the prepared samples. A good optical absorbance is present in the UV and higher wavelength regions. The optical bandgap energy was increased from 1.4 eV to 2.5 eV. The concentration of Sr2+ ions can be correlated with the differences in refractive index, high frequency dielectric constant, and static dielectric constant. The BDS scrutiny of the specimens discloses that La0.3Sr0.7MnO3 harbours a prodigious dielectric constant at ambient temperature and subsonic frequencies. The dissemination of dielectric constants within the realm of low-frequency regions is elucidated in the context of the Maxwell-Wagner model. According to the results of the dielectric analysis, the dielectric constant exhibits a decrease as frequency increases, while it shows an increase with an increase in Sr doping concentration. The conductivity scrutiny lucidly expounds Johnscher's universal power law in the realm of the high-frequency region, and from the log σ – log f plot, the discernible effects of electrode polarization become manifest. Moreover, the presence of Sr ions enhances the ac conductivity.

Aloe vera mediated synthesis of silver doped cerium oxide nanoparticles for display and supercapacitor applications

In the current study, Ag+ (1-11 %) doped CeO2 NPs are synthesized by versatile solution combustion synthesis using Aloe vera extract as reducing agent. To validate the effective synthesis, the synthesized samples are characterized by different techniques. PXRD analysis confirmed the formation of cubic fluorite structure with Fm-3m space group. The average crystallite size and direct energy band gap was found to decrease with increase in dopant concentration. SEM analysis confirmed the surface morphology and EDAX analysis affirmed the presence of Ce, O, and Ag elements in the synthesized samples. Photoluminescence studies confirmed that the obtained NPs exhibit characteristic emission peaks, highlighting their promising importance in display applications. Further, Electrochemical analysis confirms the highest specific capacitance of synthesized NPs at the lowest scan rates. CV, GCD and EIS suggest that Ag-doped CeO2 NPs find potential applications in energy storage devices such as supercapacitors.

Dielectric and photoelectric properties of Sm2O3 regulated by ZnO

With the trend of electronic information technology towards miniaturization, integration and intelligence, higher requirements are put forward for the performance of dielectric ceramic materials. In this paper, a series of doped samples Sm2O3-xZnO (x = 0, 0.1, 0.2, 0.4, 0.6, 0.8) were successfully prepared by the traditional solid state reaction method, and the complex dielectric properties of the ceramic samples were investigated as a function of temperature (100 K–400 K) and frequency (102–106 Hz) separately. A new phase Zn6.76Sm2.58O10.6 was found in all samples, and all samples were complex. At a higher temperature, 350 K, with the increase of ZnO doping content, the maximum dielectric constant is 434.7, the dielectric loss is as low as 0.0098, and the dielectric performance is significantly increased compared with room temperature. UV–Vis DRS test showed that the absorbance of the sample increased with the increase of ZnO content, and the side reaction showed that the dielectric constant and dielectric loss of the sample were improved under the action of UV light. These provide an experimental basis for the application of samarium based dielectric ceramics.

Exploring the Photoluminescence Property, Photocatalytic Efficiency, and Antibacterial Activity of Eu-Doped ZnO/SnO2 Heterostructure

In this study, nanocomposites of ZnO–SnO2 doped with Eu ions were synthesized by sol-gel method. The samples show the co-existence of hexagonal ZnO and tetragonal SnO2 crystallographic phases as observed from X-ray diffractometry studies. Eu doping facilitates the grain growth as the average grain size is found to increase with the increase in Eu dopant concentration. Surface morphology of the samples also gets altered with Eu doping with EDAX measurement giving the confirmation of existence of elements like Zn/Sn/Eu. FTIR measurement specifies the appearance of peaks linked with functional groups like Zn–O, Sn–O and O–H. Photoluminescence study shows the evolution of characteristic emissions of Eu ions (5D0→ 7F1, 5D0→ 7F2 and 5D0→ 7F3). Photodegradation of toxic environmental dyes like Congo red and methylene blue was executed and the efficiency of degradation was estimated under visible light illumination. The presence of Eu3+ ions in ZnO/SnO2 helps to enhance the degradation efficiency by facilitating to form Z- scheme heterojunctions between ZnO and SnO2. This allows the delay in recombination rate of the photoinduced electron/hole pairs. The antibacterial behavior of the prepared nanocomposites against E. coli and S. aureus has also been studied in detail which demonstrates improved antibacterial efficiency of the samples.

Less is better: Insight into the concentration dependency of the photoreduction of Eu3+ in Ba2SiO4

Photoinduced electron transfer processes in luminescent materials drive numerous applications like medical imaging, ionizing radiation dosimetry and safety signage. However, the concentration dependency of the photoreduction of the dopants during this process is still poorly understood. Here, optical spectroscopy and electron paramagnetic resonance (EPR) experiments are systematically performed to reveal the doping concentration-dependent photoreduction behavior in Ba2-xEuxSiO4 where a fraction of the Eu3+ dopants can be reduced to Eu2+ upon irradiation with X-rays. EPR measurements show that the conversion ratio of Eu3+→Eu2+ decreases with increasing concentration at the same irradiation dose, resulting in the concentration dependency of the photoreduction behavior in Ba2-xEuxSiO4. Optical spectroscopy measurements show that although the incorporated Eu3+ ions occupy at least three crystallographic sites, Eu3+ can only be photoreduced on one of these sites. Meanwhile, the relative occupancy of this photoreducible site decreases as the doping concentration increases. The combination of these two factors might be responsible for the decreased conversion ratio of Eu3+→Eu2+ as the doping concentration increases. These findings provide insights into the photoreduction of dopants in luminescent materials and can facilitate the exploration of this functional behavior for advanced devices.

Point defects substitution mechanism in indium-doped LiNbO3 single crystals revealed by UV–Visible and Micro-Raman analysis

This work reveals relevant information about the mechanism of substitution of point defects by In ions in lithium niobate single crystals doped with In in moderate concentrations ranging from 0.5 to 4 mol % in the melt. It was found that the In ions, first replace Nb ions at Li sites, and then Li ions. However, it does not occur continuously because while the doping concentration approaches a given critical value (0.65 mol % into the crystal), the Li concentration reaches a maximum, and the Li vacancies and niobium antisites remain practically constant. At this critical doping concentration point, the crystal stops the introduction of indium into its structure. After this critical value, as the doping concentration increases, the In replaces the Li but also the Li vacancies and niobium antisites. The niobium antisite is not the most stable point defect due to as the In-doping increases it takes values between five and fourteen times lower than the Li vacancies. From a compressive strain in the lattice of LN crystals induced by the In ion, the phonon modes with a Raman shift in the range from 300 to 500 cm−1 were appreciably attenuated. Close to the peaks centered at 151 cm−1 and 878 cm−1 appeared one extra vibration mode for crystals doped with 2.0 mol % and 1.3% mol of In in the melt, which reveals important structural changes induced by the In ion.

Assessment of Cr doping on TiO2 thin films deposited by a wet chemical method

Undoped and Cr-doped TiO2 thin films were synthesized by the dip-coating sol-gel process with titanium isopropoxide and chromium (III) chloride hexahydrate being used as the precursors. The chromium concentrations changed for different molar ratios, namely, 2, 4, and 8 wt.%. The samples, coated on glass substrates, were later annealed in air at 450 °C for 60 min. The influence of Cr doping on the structural, surface chemical, and optical properties of the samples was studied by several techniques, including EDS, Raman, UV–Vis, RT-PL, and XPS spectroscopies, as well as SEM and XRD. The diffraction patterns indicated that all the films displayed the anatase structure with the crystallite size decreasing with chromium doping. The same structure was confirmed by Raman spectroscopy measurements. UV–Vis absorption spectra of the samples showed a red shift of the fundamental absorption edge in the visible range following the increase of Cr doping concentration. In addition, the RT-PL study revealed that the dopant incorporation causes a decrease in the PL intensity. The EDS analysis revealed the presence of Ti, O, and Cr in the materials. Moreover, from high-resolution XPS Ti 2p spectra, titanium was found to be in the Ti4+ oxidation state evidencing the formation of TiO2, while the Cr 2p fitting analysis showed that chromium is present in the Cr (III) and Cr-metal states.

Tuning of the optical and magnetic properties of Nd2Ni1-xCoxMnO6−δ (0.2 ≤ x ≤ 0.5) perovskite by cobalt doping

The citric-nitrate technique was used to synthesize polycrystalline Nd2Ni1-xCoxMnO6−δ (0.2 ≤ x ≤ 0.5) perovskite oxide. Phase formation was studied by X-ray powder diffraction (XRPD). The unit cell parameters and unit cell volume were refined by the Rietveld analysis, increase with the increasing doping concentration of cobalt. The optical study was performed for the samples in the range of 200–800 nm using UV–vis spectroscopy an absorption peak has been observed in around 330 nm. The energy bandgap (Eg) of the studied samples is slightly influenced by the increasing concentration of cobalt due to the interaction of electronic states between doped Co and other 3d metals. Partial substitution of nickel by cobalt at B-site decreases the Curie temperature (TC) and increased the irreversibility between the zero-field cooled (ZFC) and field-cooled (FC) below TC. The decreasing tendency of TC for the studied samples with the increasing concentration of cobalt in Nd2Ni1-xCoxMnO6−δ might be associated with the decreasing Ni/Co–O–Mn bond angle.

Magnetic, DC Electrical, and Impedance Properties of Zn Doped Yttrium Iron Garnet Nanoparticles

Y3Fe5-xZnxO12 with x = 0; 0.02; 0.04; 0.06; 0.08; 0.1 (YIG) particle materials were fabricated by sol-gel method combined with heat treatment at 900 °C and 1,000 °C with different annealing times (2 h and 5 h) and heating rates (5 °C/min and 2 °C/min). X-ray diffraction patterns show that the obtained samples are single crystalline phases at the condition of an annealing temperature of 900 °C for 5 h and a heating rate of 2 degrees/min. FESEM images of the samples show particle sizes from the submicron to the micrometer. The magnetization of the samples decreases as the doping concentration increases. I-V characteristics and complex impedance spectra at room temperature of samples were measured. The results show that the resistivity value of the doped samples decreases in the range of 5-6 orders in magnitude compared with that of the pure YIG sample. The contribution of the grain boundaries to the impedance was analyzed. The conducting process is explained due to the tunneling of charge carriers across the grain boundary.