Effect Of Mn Doping Research Articles

Optimizing magnetocaloric and thermoelectric performance of MnCoGe/BiSbTe composites by regulating magnetostructural transition and element diffusion

Composites consisted of MnCoGe magnetocaloric alloy and BiSbTe thermoelectric alloy were prepared to explore their potential use in all-solid-state cooling. It was found that in the composites the phase transition of MnCoGe from orthorhombic to hexagonal phase causes a large drop of magnetostructural transition temperature from room temperature to 270 K. The diffusion of Mn into BiSbTe leads to the formation of interfacial phase Mn(Bi,Sb)2Te4 and doping effect that depresses the thermoelectric performance. By adopting a low-temperature sintering strategy, the phase transition was restricted and the doping effect due to Mn diffusion was alleviated. As a result, the magnetostructural transition temperature around 300 K is maintained and the room-temperature magnetocaloric and thermoelectric properties are simultaneously optimized. The maximum magnetic entropy change of 4.3 × 10−3 J kg−1 K−1 at 2.0 T and maximum ZT value of 0.81 at 384 K have been obtained on the composite incorporated with 1 wt% MnCoGe. This work demonstrates that the control of phase transition and the doping effect of MnCoGe is crucial in optimizing the thermo-electro-magnetic properties of MnCoGe/BiSbTe composites.

Fabrication and Study of the Effect of Mn-Substituted Ba-Zn Nanoferrites on the Enrichment of Structural Properties

In this study, we investigated the effect of Mn doping on the structural properties of barium-zinc ferrites (BZF-NPs) synthesized using the traditional ceramic method. X-ray diffraction (XRD) was used to analyze the structural characteristics of the BZF-NPs, including the structural phases, crystallite size, and lattice parameters. In addition, various physical properties, such as bulk density, X-ray density, porosity, and specific surface area, were investigated. The XRD analysis of the samples revealed that the lattice parameters of the hexagonal M-type structure of the BZF-NPs decreased as the concentration of Mn+2 ions increased. In addition, the average crystallite size of the samples decreased from 52 to 42 nm with increasing Mn+2 concentration. The c/a parameter ratio indicates the formation of a magneto-plumbite structure. Moreover, we found that both the X-ray and bulk densities increased with increasing Mn+2 concentration. This behavior can be attributed to the difference in ionic radii between the donor Mn+2 ions and the host Fe+3 and Zn+2 ions. However, it was observed that the porosity increased with increasing Mn+2 concentration, in contrast to the bulk density behavior. Furthermore, it was observed that as the crystallite size increased, the surface area decreased. This trend can be attributed to the fact that larger crystallites have fewer surface atoms. Finally, it was noted that the bond lengths for both tetrahedral and octahedral structures decreased with increasing Mn2+ ion concentration. Overall, these results provide insights into the impact of Mn+2 ion doping on the structural and physical properties of BZF-NPs and highlight the potential applications of these materials in various fields.

Effect of Mn doping at different sites on the structural and electronic properties of ZnO quantum dots

We constructed ZnO quantum dots (QDs) with a diameter of 1.2[Formula: see text]nm of wurtzite structure, hydrogenated the surface and doped single Mn atoms using Zn-site substitution. We present an investigation of the structural and electronic properties of ZnO QDs of three doping sites: inner, intermediate and outer. Based on the density functional theory and the plane-wave pseudo potential method, the structural characteristics, charge distribution, conductivity and formation energy of doped ZnO QDs are analyzed. We obtained the effect of doping site depth on the properties above with the nearly optimal nanoparticle doping concentration (2.222%). The internal doping (inner and intermedium) configuration results in higher electrical conductivity and stronger bonds than the outer doping configuration. In particular, intermediate doping is highly efficient and valuable for obtaining Mn-doped ZnO nanoparticles with good structural and electronic properties. This study provides a theoretical reference for the survey of zero-dimensional dilute magnetic semiconductors.

Effects of Mn-doping on the structure and electrical properties of Sm-PMN-PT piezoceramics

Mn[Formula: see text]-modified [Formula: see text] ceramics were prepared via a solid-state reaction approach. Results of detailed characterizations revealed that the addition of Mn[Formula: see text] has influence on the grain size, and all samples exhibit a pure perovskite structure. As the content of manganese increases, the volume of tetragonal phase increases. The ceramics with 1.5 mol.% Mn[Formula: see text] show a high electro-strain of 0.151% at 2 kV/mm. Therefore, this study provides a new insight into the role of Mn[Formula: see text] addition in tailoring the electrical properties of the Sm-PMN-PT ceramics by acceptor doping.

Monolayer black phosphorus: Tunable band gap and optical properties

Black phosphorus, with its tunable optical band gap, has gained significant interest due to its potential applications in optoelectronics. In this study, a first-principles approach based on density functional theory is used to examine the effects of Sc, Mn, and Ni doping on the electronic structure and optical properties of black phosphorus. The results indicate that the addition of impurity atoms with varying radii leads to a shift in the position of atoms surrounding the doping site. The band gaps of the doped systems are all reduced, with the most significant reduction observed in the Ni-doped system. Compared to intrinsic black phosphorus, the doped systems exhibit higher values of the imaginary part of dielectric function, optical absorbance, refractive index, and extinction coefficient in the visible and infrared regions. These findings suggest that Sc, Mn, and Ni-doped black phosphorus are suitable for optoelectronic devices, offering improved performance in the visible and infrared spectrum.

Effect of Mn doping on structural, optical and photocatalytic properties of SnO2 nanoparticles

The bare and Mn-doped SnO2 products were prepared using a simple chemical precipitation process, which was discussed in the preparation aspect. XRD, SEM with EDS, TEM, and HRTEM studies were used to analyse the obtained Mn-doped SnO2. According to the UV-DRS data, SnO2 from Mn doping significantly reduced its band gap. The photoluminescence emissions of doped SnO2 exhibit an intensity reduction caused by the cross-relaxation process when compared to pure SnO2. The photocatalytic degradation of brilliant green (BG) using a bare SnO2 and Mn doped sample was investigated under visible light illumination. The Mn-doped SnO2 sample demonstrated a greater level of degradation (92.84%) due to its increased surface area (32.70 m2/g) and lower band gap (3.57 eV), which prevent the recombination of photogenerated charge carriers.

Effect of Mn doping on structural, optical and magnetic properties of ZnO films fabricated by sol–gel spin coating method

Effect of Mn doping on structural, optical and magnetic properties of ZnO films fabricated by sol–gel spin coating method

Ab-initio study of tuning the electronic and magnetic properties of [formula omitted] Heusler alloy by Co and Mn compound doping

We report the effects of Mn and Co doping on the electronic properties, magnetic exchange interaction, and Curie temperature of intermetallic Ni2MnGa by Green’s function based Korringa–Kohn–Rostoker method with coherent potential approximation(KKR-CPA). The effect of single and compound doping of Mn and Co at different crystallographic positions on these properties are evaluated by computing the electronic and magnetic structures of Ni2MnGa. The study revealed the possibility of tuning magnetic exchange interaction(Jij) and Curie temperature(TC) upon doping. Moreover, it is noted that doping can stabilize the Jahn–Teller distortion. It is also worth noting that TC responds in a different way with concentration as well as the site of the dopant. This study helps in understanding and realizing the cause for magnetic properties in Ni2MnGa, and experimental peers can also use it for further research on doped Ni2MnGa.

Chemical looping gasification of biomass char for hydrogen-rich syngas production via Mn-doped Fe2O3 oxygen carrier

Because of its low cost, an iron-based oxygen carrier is a promising candidate for hydrogen-rich syngas production from the chemical looping gasification of biomass. However, it needs modification from a reactivity point of view. In this study effect of Mn doping on Fe2O3 has been investigated for hydrogen-rich syngas production from biomass char at different temperatures (700–900 °C) and steam flow rates (60–100 μL/min). Several techniques (XRD, XPS, BET, and TPR-H2) have been utilized to characterize fresh and spent oxygen carriers. The result demonstrated Mn-doing boosted the redox activity and the amount of oxygen vacancies, which increased hydrogen gas generation. Hydrogen production displayed different behavior across temperatures due to detecting Fe2O3 and MnFeO3 phases for spent oxygen carriers. For the Fe2O3 oxygen carrier hydrogen gas yield is 1.67 Nm3/kg which is due to reduction of Fe2O3 phase to Fe3O4. However, the MnFe2O4 spinel phase detected in the spent MnFeO3 oxygen carrier is a reason for improving hydrogen gas yield to 1.84 Nm3/kg. Change reaction temperature from 900 °C to 850 °C reduced hydrogen gas yield from 1.84 Nm3/kg to 1.83 Nm3/kg for with MnFeO3 oxygen carrier. Regarding different steam flows, the proper flow rates that can maintain the formed phases and obtained best hydrogen gas yield are 80 and 90 μL/min, respectively. Meanwhile, the best hydrogen gas yield (2.21Nm3/kg) are obtained with MnFeO3 oxygen carrier at optimum conditions (850 °C and 90 μL/min).

Effect of Mn doping on electrochemically synthesized Mn-La2O3 thin films non-enzymatic glucose sensor

Effect of Mn doping on electrochemically synthesized Mn-La2O3 thin films non-enzymatic glucose sensor

Transforming exciton dynamics in perovskite nanocrystal through Mn doping.

Zn-alloyed CsPb(Cl/Br)3 perovskite nanocrystals (PNCs) have been synthesized and used as a model system for Mn doping in order to understand the effect of Mn doping on exciton dynamics. While keeping the PL emission maximum and PLQY of both PNC samples nearly the same, the radiative decay rate of the host band decreases ∼6.5 times and the non-radiative decay rate increases ∼2.5 times upon Mn doping. Unlike reports in the literature in which the dopant emission decreases to near-zero, in the present case we observe ∼5.5-fold enhancement of the integrated PL intensity of the dopant emission when the temperature decreases from 290 K to 190 K. Interestingly, the FWHM of the host PL emission band increases with a decrease in temperature from 290 K to 190 K. A higher value of phonon energy in PNC2 (58 ± 2 meV) in comparison to CsPbBr3 has been noted. The low magnitude of the Huang-Rhys factor indicates less electron phonon coupling for the Mn-doped PNC system. Temperature-dependent dopant PL decay exhibits biexponential decay behaviour with time constants τ1 = 450-540 μs and τ2 = 1.1-1.2 ms. With a decrease in temperature from 290 K to 190 K, the amplitude of the faster component decreases from 80% to 60%; concomitantly, the amplitude of the slower component increases from 20% to 40%. Ultrasensitive single-particle spectroscopic analyses reveal that, although the probability density distributions (PDDs) of the durations of both ON and OFF events of PNC1 could be fitted with a truncated inverse power law (TIPL), however, for PNC2, both PDDs could be fitted with an inverse power law (IPL). A comparatively lower value of the power law exponent mON indicates a higher probability of longer ON events for PNC1 than for PNC2. Truncation in the PDDs of both ON and OFF events has been observed for PNC1, but not in the PDDs of either ON or OFF events for PNC2. The presence of shallow trap states is responsible for the truncation for PNC1, whereas the presence of deep dopant states does not allow truncation in the host PL emission of PNC2. All these observations clearly demonstrate that Mn doping transforms the host PL exciton dynamics for Zn-alloyed Mn-doped CsPb(Cl/Br)3 PNCs very significantly.

NIR laser-conjugated glutathione-coated Mn-doped CuS nanoprisms as photothermal agent for cancer treatment.

The cancer treatment by laser-conjugated nanomaterial has become a new developing trend due of their unique physicochemical performance. The previous few studies reported the preparation of undoped CuS nanoprisms. The current research was concerned with the Mn doping effect on the CuS nanoprisms and its activity in tumor toxicity of M.D. Anderson-Metastatic Breast 231 (MDA-MB-231) cell line with laser treatment. To prepare a novel CuS and Mn-doped CuS nanoprisms with high surface area by two-phase colloidal method, copper nitrate and sulfur powder were used as sources of copper and sulfur respectively. The prepared nanoprisms were investigated as antibacterial and photothermal agents in MDA-MB-231 cancer treatment using near-infrared (NIR) laser. The Mn-CuS nanoprisms were modified with glutathione (GSH) to decrease the cytotoxicity and increase the biocompatibility. The characterization of synthesized nanoprisms involved the structural, compositional, surface charges, optical, and morphological property analyses. X-ray diffraction (XRD) showed the peaks of hexagonal covellite copper sulfide nanoparticles and additional diffraction peaks at Mn-CuS which are assigned to orthorhombic chalcocite CuS. The transmission electron microscopy (TEM) images showed that the CuS and Mn-CuS nanoparticles have nanoprism morphology. The antibacterial activity test revealed that the activity enhances by doping and the prepared Mn-CuS nanostructures were more effective against the Staphylococcus aureus and Escherichia coli bacteria. The results of photothermal treatment indicated that the cancer cells were effectively killed and the GSH@Mn-CuS nanoprisms are able to be used as an efficient theranostic agent for tumor photothermal therapy in the future.

Catalytic and Photocatalytic Degradation Activities of Nanoscale Mn-Doped ZnCr2O4

In the present work, the effect of Mn doping in Zinc Chromite (ZnCr2O4) and particle size reduction on catalytic and photocatalytic degradation performance have been evaluated. The pristine Zn1−xMnxCr2O4 (x = 0 to 0.03) nanoscale samples are synthesized through a hydrothermal approach. The synthesized catalysts are characterized by XRD, HR-SEM, HR-TEM, catalytic, and photocatalytic degradation analyses. X-ray diffraction analysis results confirmed the formation of the ZnCr2O4 structure and its phase purity, crystallite size, and Mn dopant effect. The surface morphology and particle size of Zn1−xMnxCr2O4 samples are evaluated by SEM and TEM measurements. The textural properties of ZnCr2O4 samples are identified by the surface area analysis. The catalytic performance of Mn-doped ZnCr2O4 samples reveals superior catalytic performance compared to pristine ZnCr2O4 in benzaldehyde and carbonyl compound productions. Under UV irradiation, an excellent photocatalytic degradation efficiency of 89.66% for Zn0.97Mn0.03Cr2O4 catalyst with methylene blue has been obtained.

Characterization of ZnO and Mn-doped ZnO nanoparticles and their antimicrobial activity

Zinc oxide nanoparticles (ZnO NPs) are commonly used in optoelectronic device, pharmaceuticals, food, textile, energy, rubber, electrical engineering, and agriculture applications. This study aimed to study the effect of Mn doping on the physical traits and the antimicrobial activity of ZnO NPs. Five Mn-doped ZnO NPs samples were prepared and characterized with a varied Mn content ranging from 0.01 to 0.09. A low-cost and suitable method for synthesizing Mn-doped ZnO NPs with a semispherical shape is presented without using a surfactant. The antimicrobial activity of the given NPs was determined against pathogenic microorganisms, including Gram-positive bacteria (i.e., Staphylococcus aureus and Bacillus subtilis), Gram-negative bacteria (i.e., Escherichia coli), and fungi (i.e., Candida albicans). The antimicrobial activity was evaluated using the well diffusion method, minimum lethal concentrations (MLC) determination, and microbial cell viability assay. X-ray diffraction results confirm that the samples have a single-phase wurtzite structure, where the crystal size decreases with an increasing dopant concentration. This decrease occurs due to the small ionic radius of Mn ions compared to Zn ions. The morphology on the surface shows further that the samples had a spherical shape with an average particle size of 40 nm. The optical bandgap of ZnO NPs decreases with Mn doping, which is attributed to the s–d and p interaction. All tested NPs displayed a higher antimicrobial activity with better efficiency in the case of Mn-doped ZnO NPs compared to standard antibiotics (i.e., cytisoside, fluconazole, and ampicillin). The MLC of ZnO NPs was 160 μg/mL for all tested microorganisms. The best MLC was 40 μg/mL of Zn0.93Mn0.07O, Zn0.95Mn0.05O, and Zn0.91Mn0.09O for E. coli, B. subtilis, and C. albicans, respectively. Compared to ZnO NPs, no better effect on MLC was found against Staphylococcus aureus. It is concluded that Mn doping enhanced the antimicrobial activity of Zn1−xMnxO NPs, which could be used as a more efficient antibacterial and antifungal agent compared to pure ZnO NPs.

Effect of Mn doping and charge transfer on LaTi1−x Mn x O3

We report the magnetic and electronic transport properties of Mn-doped LaTi1−x Mn x O3 (x= 0, 0.1, 0.3, 0.5) as a function of temperature and an applied magnetic field. It was found that the Mn-doped samples show a magnetic transition which is not present in the parent LaTiO3. The Mn-doped samples showed fluctuations in magnetization at low fields below their Néel transition temperature indicating electronic phase separation in the material. Increased Mn content in the sample strengthens the ferromagnetic-like moment while maintaining G-type antiferromagnetic phase by charge transfer from Mn to Ti and influencing orbital ordering of the Ti3+ t2g orbitals. The results are discussed in parallel with transport and bulk magnetization measurements detailing the electronic behavior. An additional context for the mechanism is supported by first-principles density-function theory calculations.

Effect of Mn Doping on the Electronic and Magnetic Properties of Full Heusler Alloy Co2FeSi

Heusler compounds are one of the largest families of ternary intermetallics with broad range of applications. In this work, we inspected the electronic and magnetic properties of full Heusler alloy Co2FeSi and the effect induced by doping Mn atom on those properties. We employed plane wave pseudo-potential method based on DFT framework implemented in Quantum ESPRESSO code using PBE type of functional for exchange correlation energy. The calculation demonstrates that Co2FeSi exhibits metallic nature in the majority spin state and semi-conducting nature in minority spin state with indirect energy gap of ≈ 0.132 eV and shows chances of weakened half-metallicity as indicated by the presence of band gap below fermi level. The calculated total magnetic moment is 5.44 μB/cell which is found to be deviated from Slater-Pauling rule M = NV − 24 for full Heusler compounds. The site selection for doping was based on the empirical rule for atomic occupation established for Heusler alloys and the calculation of formation energy. The calculation of formation energy at B and D site showed B site as more favorable for doping for both 25% and 50% concentration. At 25% Mn concentration, calculation shows Co2FeSi has typical metallic behavior for spin-up electrons, but semi-conducting behavior with decreased gap below fermi level for spin-down electrons showing no half-metallicity whereas for 50% Mn concentration the gap gets broadened by 0.089645 eV. The calculated magnetic moment for 25% and 50% Mn doping is 21.93 μB/cell and 21.69 μB/cell respectively. Our calculation depicts that the chances of half-metallicity decreases for 25% concentration of Mn atom and increases for 50% Mn concentration.

Enhancement effect of Mn doping on Co3O4 derived from Co-MOF for toluene catalytic oxidation

The design of Co-Mn composite oxides catalysts derived from MOF is significant for catalytic combustion of toluene. Here, a series of M-CoaMnbOx, with enhanced catalytic properties compared with that of M-Co3O4, were successfully prepared through pyrolysis of Mn-doped Co-MOF. The as-synthesized M-Co1Mn1Ox (Co:Mn = 1:1) exhibits an optimal catalytic activity with 90% toluene conversion reached at 227 °C, which benefits from the increase of Co3+, Oads and the synergistic effect between Mn and Co. According to the analysis of the in situ diffuse reflectance infrared Fourier transform spectroscopy, toluene could be degraded easier on M-Co1Mn1Ox with lower activation energy than M-Co3O4. The main intermediate products are benzaldehyde, benzoic acid, anhydride, and maleate species. Those findings reveal the value of Mn doping for improved activity of toluene oxidation on MOF derived Co3O4, which provide a feasible method for the construction of toluene-oxidation catalysts.

Experimental and theoretical investigation of FeCrVAl and related compounds

We have carried out a combined theoretical and experimental investigation of FeCrVAl, and the effect of Mn and Co doping on its structural, magnetic, and electronic band properties. Our first principles calculations indicate that FeCrVAl, FeCr0.5Mn0.5VAl, and FeCr0.5Co0.5VAl exhibit nearly perfect spin polarization, which may be further enhanced by mechanical strain. At the same time, FeCrV0.5Mn0.5Al and FeCrV0.5Co0.5Al exhibit a relatively small value of spin polarization, making them less attractive for practical applications. Using arc melting and high vacuum annealing, we synthesized three compounds FeCrVAl, FeCr0.5Mn0.5VAl, and FeCr0.5Co0.5VAl, which are predicted to exhibit high spin polarization. The room temperature x-ray diffraction patterns of all samples are fitted with full B2 type disorder with a small amount of FeO2 secondary phase. All samples show very small saturation magnetizations at room temperature. The thermomagnetic curves M(T) of FeCrVAl and FeCr0.5Co0.5VAl are similar to that of a paramagnetic material, whereas that of FeCr0.5Mn0.5VAl indicates ferrimagnetic behavior with the Curie temperature of 135 K. Our findings may be of interest for researchers working on Heusler compounds for spin-based electronic applications.

Effect of Mn Doping on the Microstructure and Electrical Properties of Potassium Niobate Ceramics Using Plasma Spraying

KNN piezoelectric ceramics are of great importance in the field of scientific research due to their high Curie temperature, good electrical properties, etc. The application of potassium sodium niobate K0.5Na0.5NbO3 (KNN) is strictly limited due to the volatility of Na+ and K+ in KNN and its leakage current. In order to investigate the effect of Mn doping on KNN-based piezoelectric ceramic coatings, KNN and KNN-0.02Mn (KNMN) coatings were successfully prepared using a plasma spraying technique. The phase structure, microscopic morphology, and electrical properties of the coatings were studied in the research. The results showed that both the KNN and KNMN coatings had chalcogenide structures. The KNN coating had an orthogonal phase structure, whereas the KNMN coating had a tetragonal phase structure. Compared with the KNN coating, the microhardness of the KNMN coating was improved through doping with Mn ions. The doping of Mn ions could replace both the A and B sites in the KNN piezoelectric ceramics, further reducing the oxygen vacancies and leakage currents in the coating, and its dielectric properties were improved.

Stable lithium storage behavior observed in Mn-doped MgCo2O4 anode materials

Cation substitution strategy is considered to be an effective way to create defect structure in the spinel structure for improving the performance of Li-ion batteries. In this work, a series of MgMnxCo2-xO4 (x = 0, 0.5, 1, 1.5, 2) materials with Mn ions replacing Co ions were synthesized by a facile hydrothermal method. The collected X-ray diffraction and scanning electron microscope results show that the lattice parameters and particle size of the materials increase with the increase of Mn doping concentration. The O 1s X-ray photoelectron spectra results show that there are more oxygen vacancies and interstitial hydroxyl groups in MgMn0.5Co1.5O4 samples, which is conducive to the improvement of conductivity of the material. Analyses of XPS spectra of Mg 1s, Mn 2p and Co 2p reveal that magnesium exists as Mg2+ ions, manganese and cobalt exist in multivalent states (Mn2+/3+/4+ and Co2+/3+), and these ions are mixed and distributed in the spinel structure. The effect of Mn doping on the inversion degree of spinel and electrochemical performance of materials is discussed. Compared with pure MgCo2O4 material, Mn-doped MgCo2O4 anode materials exhibit good cycle stability. When x = 0.5, MgMn0.5Co1.5O4 anode material has the highest cycle capacity with an initial discharge capacity of 1165.2 mAh g−1, and a capacity of 427.6 mAh g−1 after 100 cycles. Mn-doped MgCo2O4 can significantly improve the cycle stability of the material while maintaining a high specific capacity.