Introduction Of Mg2 Research Articles

Analysis of the reasons for the enhanced green luminescence of Mg2+-doped Zn2SiO4:Mn2+ phosphor

In the present work, the role of the optically inactive co-dopant magnesium in increasing the emission intensity of Zn2SiO4:Mn2+ has been established. It is shown that the dominant reasons for the increase in green luminescence intensity are the enhancement in the prohibition of the 4T2(4G) → 6A1(6S) transition and the decrease in non-radiative dissipation of absorbed excitation energy upon the introduction of Mg2+ ions.

Electrical conductivity of potassium polyferrite doped with doubly charged cations

To clarify the charge compensation mechanism and the way of alloying additives placement, the authors synthesised samples of potassium βʺ-polyferrites with a wide range of mole fraction of introduced doubly charged cations. For these samples, the authors measured the electronic conductivity, cationic conductivity, and performed X-ray diffraction (XRD) analysis. The authors identified the charge compensation mechanism in potassium β″-polyferrite when doped with divalent ions of calcium, strontium, magnesium, and zinc. The charge compensation mechanisms differ depending on the radius of the introduced doubly charged ion. The results of cationic conductivity measurements of potassium β″-polyferrites show the mobility reduction of large calcium and strontium cations of potassium ions. Such additives are quite promising for improving the mechanical strength and thermal stability of the catalyst granules. They also increase the chemical stability of the contact granules. Corrosion resistance of pellets is a critical parameter. It determines the period of effective functioning of the catalyst. The data on electronic conductivity allow one to conclude that the introduction of Mg2+, Zn2+ cations sharply reduces the electron exchange in the structure of potassium β″-polyferrite. This should inevitably cause deactivation of the catalyst, while Ca2+ and Sr2+ ions do not reduce the electron transfer rate. Moreover, using the proposed approach will intensify the research process.

Structure optimization for AlON system induced novel green light-emitting phosphor of Eu2+-Activated nitroaluminosilicate MgAl3SiO3N3 used for WLEDs

The development of novel nitride-based phosphors is always a significant work, especially for AlON system because of their rigid crystal structure, which is similar to the promising host material of β-SiAlON. In this work, Mg2+ ion was introduced into AlON-related phase Al5O3N3 along with co-doped Si4+ ion used to keep charge neutrality, and thus a novel Mg-based nitroaluminosilicate MgAl3SiO3N3 (MASON) was successfully synthesized under a mild preparation condition due to the high reactivity of MgO. Benefiting from its special crystal structure optimized by the introduction of Mg2+ ion, Eu2+-activated MASON performs significant photoluminescence (PL) and cathodoluminescence (CL) properties. In contrast to most Eu2+-activated AlON related phosphors that commonly emit high-energy blue light, the as-prepared sample emits a high-bright green light along with good thermal stability. Moreover, its broad emission band with the full width at half maximum (FWHM) of 134 nm well compensates the “cyan cavity”, which leads to a full spectrum light-emitting diode. The structure-property relation of Eu2+ in MASON was established in this work, which confirms the significant role of the introduced Mg2+ ion in the structure optimization of AlON system. The result may pave an efficient way to explore more promising AlON-based phosphors.

Enhancing Chronic Wound Healing through Engineering Mg2+-Coordinated Asiatic Acid/Bacterial Cellulose Hybrid Hydrogels.

Infectious chronic wounds have gradually become a major clinical problem due to their high prevalence and poor treatment outcomes. The urgent need for wound dressings with immune modulatory, antibacterial, and angiogenic properties has led to the development of innovative solutions. Asiatic acid (AA), derived from herbs, has demonstrated excellent antibacterial, anti-inflammatory, and angiogenic effects, making it a promising candidate for incorporation into hydrogel carriers for wound healing. However, there is currently no available report on AA-based self-assembled hydrogels. Here, a novel hybrid hydrogel dressing consists of interpenetrating polymer networks composed of self-assembled magnesium ion (Mg2+) coordinated asiatic acid (AA-Mg) and bacterial cellulose (BC) is developed to promote infected chronic wound healing. A natural carrier-free self-assembled AA-Mg hydrogel with good injectable and self-healing properties could maintain the sustained release of AA and Mg2+ over an extended period. Notably, the introduction of Mg2+ boosted some pharmacological effects of self-assembled hydrogels due to its excellent anti-inflammatory and angiogenesis. In vitro studies confirmed the exceptional biocompatibility, antibacterial efficacy, and anti-inflammatory potential of the AA-Mg/BC hybrid hydrogel, which also exhibited a commendable mechanical strength. Furthermore, in vivo biological results displayed that the hybrid hydrogel significantly accelerated the wound healing process by boosting dense and organized collagen deposition and the granulation tissue and benefiting revascularization. The introduced self-assembled AA-Mg-based hydrogel offers a promising solution for the effective management of chronic wounds. This universal strategy for the preparation of self-assembled hydrogels modulated with bioactive divalent metal ions is able to excavate more herbal small molecules to construct new self-assembled biomaterials.

The electrical properties of codoping LaInO<sub>3</sub> perovskite

This paper is devoted to the study of LaInO3 based co-doped materials. Solid solutions in which lanthanum is substituted for strontium have sufficiently high conductivity values, but a low level of oxygen deficiency is realized. Mg2+ and Ca2+ ions were chosen as co-dopants for the B sublattice. Both series of the investigated La0.9Sr0.1In1-xCaxO2.95–0.5x and La0.9Sr0.1In1-yMgyO2.95-0.5y solid solutions crystallize in orthorhombic symmetry with sp. gr. Pnma. The ionic conductivity in a dry atmosphere is determined by the oxygen ions transport. Oxygen-ion transfer in solid solutions is ~30–40% at high temperatures (T 700°C) and increases to 80% as the temperature decreases to 400–300°C. The substitution Ca2+ with In3+ increases the electrical conductivity of the oxygen ions; the highest values are achieved for the compositions La0.9Sr0.1In0.95Ca0.05O2.925 and La0.9Sr0.1In0.9Ca0.1O2.9. The introduction of Mg2+ co-dopant at the In3+ positions leads to a decrease in ionic conductivity compared to La0.9Sr0.1InO2.95. The effects of changing oxygen mobility with changing geometric factors (cell volume, critical radius) are discussed.

Chitosan microcarriers deposited with Mg2+-doped phase-transited lysozyme: osteogenesis, pro-angiogenesis and anti-inflammatory for promoting bone regeneration

Microcarriers, as injectable cell carriers, provide a new strategy for bone defect repair due to their advantages of large specific surface area, flexible and controllable size, and injectability. Magnesium ion (Mg2+) is important trace element and has been demonstrated to improve bone tissue regeneration. The development of bone tissue engineering microcarriers that can sustainably control Mg2+ release could show significant impacts on bone regeneration. Herein, chitosan (CS) microcarriers deposited with Mg2+-doped phase-transited lysozyme (PTL) were fabricated for accelerating bone regeneration. The results prove that Mg2+-doped PTL was successfully self-assembled onto CS microcarriers through hydrogen bonds and electrostatic interactions. The introduction of Mg2+-doped PTL in CS microcarriers increased zeta potential of the materials. The microcarriers exhibited a spherical and interconnected porous structure with sizes of 300–400 μm and pore sizes of 35–40 μm. Due to the PTL deposition, the microcarriers displayed controlled release of Mg2+. Moreover, they showed good degradation ability. In vitro, the composite microcarriers supported cell attachment and improved proliferation and osteogenic differentiation of stem cells, attributed to the combined effects of PTL and Mg2+. Furthermore, they stimulated cell migration and tube formation of HUVECs, and induced LPS-activated macrophages polarized to the anti-inflammatory M2 phenotype. In vivo, the microcarriers accelerated bone regeneration, enhanced angiogenesis, and reduced inflammation in a rat model of right medial femoral malleolus defects. In summary, the results demonstrate that the prepared composite microcarriers have potential to be used as a new type of microcarrier for bone tissue engineering applications.

Biochemical Properties of a Promising Milk-Clotting Enzyme, Moose (Alces alces) Recombinant Chymosin.

Moose (Alces alces) recombinant chymosin with a milk-clotting activity of 86 AU/mL was synthesized in the Kluyveromyces lactis expression system. After precipitation with ammonium sulfate and chromatographic purification, a sample of genetically engineered moose chymosin with a specific milk-clotting activity of 15,768 AU/mg was obtained, which was used for extensive biochemical characterization of the enzyme. The threshold of the thermal stability of moose chymosin was 55 °C; its complete inactivation occurred after heating at 60 °C. The total proteolytic activity of moose chymosin was 0.332 A280 units. The ratio of milk-clotting and total proteolytic activities of the enzyme was 0.8. The Km, kcat and kcat/Km values of moose chymosin were 4.7 μM, 98.7 s-1, and 21.1 μM-1 s-1, respectively. The pattern of change in the coagulation activity as a function of pH and Ca2+ concentration was consistent with the requirements for milk coagulants for cheese making. The optimum temperature of the enzyme was 50-55 °C. The introduction of Mg2+, Zn2+, Co2+, Ba2+, Fe2+, Mn2+, Ca2+, and Cu2+ into milk activated the coagulation ability of moose chymosin, while Ni ions on the contrary inhibited its activity. Using previously published data, we compared the biochemical properties of recombinant moose chymosin produced in bacterial (Escherichia coli) and yeast (K. lactis) producers.

Regulation of Anti‐Thermal Quenching and Emission Color in Eu2+‐Activated Na‐Beta‐Alumina Phosphors for Full‐Spectrum Illumination

AbstractBroadband cyan‐emitting phosphors are crucial to close the cyan gap of phosphor‐converted white light‐emitting diodes (pc‐WLEDs) for full‐spectrum illumination. In this work, efficient cyan‐emitting Eu2+‐activated phosphor is achieved through structural modulation, which exhibits anti‐thermal quenching behavior. Redshift from blue (469 nm) to cyan (500 nm) emission and enhancement of emission is achieved by codoping Mg2+ and Ge4+ into Eu2+‐activated Na‐beta‐alumina phosphor. The introduction of Mg2+ ions dominates the redshift, while Ge4+ dominates the enhancement of emission. Furthermore, the introduction of Mg2+ and Ge4+ reduces the content of deep trap levels related to VNa defect, which decreases the degree of anti‐thermal quenching and results in better thermal stability. The prototype pc‐WLED by using the cyan‐emitting phosphor exhibits higher color‐rendering index and potential to close the cyan gap of pc‐WLEDs for full‐spectrum illumination. This work presents a paradigm for exploring phosphors with highly efficient and thermally stable emissions.

Mg-doped LiMn0.8Fe0.2PO4/C nano-plate as a high-performance cathode material for lithium-ion batteries

Lithium-ion battery cathode materials with the high-voltage platform have turned into research highlights. Manganese-based olivine material LiMn0.8Fe0.2PO4 (LMFP), which is synthesized by cheap and environmentally friendly raw materials as precursors, has received high attention due to the higher energy density than commercial lithium iron phosphate products. However, similar to the low conductivity of olivine-structured lithium iron phosphate (LiFePO4), the defect of low conductivity of LMFP has also become the obstacle of LMFP further application. To improve the kinetic properties of LMFP, Mg-doped LMFP/C nano-plate are forearmed by a straightforward and controllable solvothermal approach. The results demonstrate that Mg2+ can be validly doped into the sample, and can partially displace Li+ position in LMFP. It has been found that the Mg-doped LMFP/C material Li0.97Mg0.015Mn0.8Fe0.2PO4 (LMFP-2) presents excellent electrochemical performances and more sustainable application prospect in the fields of electric vehicle and grid energy storage batteries, which can provide a high initial discharge capacity of 156.9 mAh g−1 at 0.1C. In addition, even at high rates of 10 and 20C, the discharge capacity of LMFP-2 can still maintain 120.7 and 104.8 mAh g−1, where the discharge process can be completed in only 255 and 110 s. These results indicate that the introduction of Mg2+ at Li+ site can validly upgradation the electron conductivity and Li+ mobility in the material, thus promoting the electrochemical performances. The rapid discharge ability and cyclic performance of the as-prepared materials make them have great application potential in high-performance lithium-ion batteries.

Induced p-type semiconductivity in Mg-doped Nd2Zr2O7 pyrochlore system

Heterovalent B-site MgO substitution in the Nd2Zr2O7-system (Nd2Zr2−xMgxO7−x) has been explored. The pyrochlores were synthesized by a polymeric sol-gel method and characterized by X-ray diffraction (XRD), Raman spectroscopy and Scanning Electron Microscopy to determine structure, phase composition and microstructure. Impedance Spectroscopy (IS) was employed to study the electrical behavior of the ceramics over the ranges 200–800 °C and under pure N2 and O2. The XRD showed that the solid solution limit was x > 0.02 and all the materials show a cubic Fd3̅m structure. The Raman results confirm the structural disorder created by the introduction of Mg2+ and the subsequent generation of oxygen vacancies. The IS data shows a dramatical increase of the oxide-ion conductivity when doping and that the conductivity depends strongly on the atmosphere, leading to p-type semiconductivity under pure O2 atmosphere. The present study highlights the use of heterovalent dopants to drastically increase the oxide-ion conductivity of pyrochlore-like materials.

Thermodynamic properties of aluminum titanate‐mullite composite ceramics containing heat stabilizer

AbstractUsing Al2O3 and TiO2 as raw materials, adding MgO as heat stabilizer and mullite as enhancer, aluminum titanate‐mullite multiphase ceramics were successfully prepared by solid phase synthesis. The effects of MgO and mullite were systematically studied on the phase composition, microstructure, thermal stability, sintering properties, and mechanical properties of aluminum titanate ceramics. The results showed that the introduction of Mg2+ can partially replace Al3+ to form MgxAl2(1‐x)Ti(1+x)O5 solid solution, improved the thermal stability of aluminum titanate ceramics, and promoted the formation and growth of grains, which reduced the sintering temperature. The crack deflections caused by mullite particles improved the mechanical properties. The filling effect of mullite particles and the formation of silica in mullite raw materials were conducive to ceramic densification. The statistics of Mg4M10 sample were as follows: the porosity was only 2.9%, the flexural strength was as high as 64.15 MPa, and the thermal expansion coefficient was 1.35 × 10−6 K−1 (RT‐700°C), encouraging the application of ceramics with high thermal mechanical properties.

Enhanced near infrared-to-visible upconversion in the CaTiO3:Yb3+/Er3+ phosphor via the host lattice modification using co-doping of Mg2+ ions.

The CaTiO3:Er3+/Yb3+ upconversion phosphor was synthesized using a simplified co-precipitation method and the effect of Mg2+ ion co-doping was investigated on the structural and optical properties focusing on the near-infrared (NIR)-to-visible upconversion. The introduction of Mg2+ ions into the host lattice produced substantial changes in the crystal structure, grain size, and absorption, thus leading to the enhancement in upconversion emission intensities. X-ray diffraction (XRD) analysis indicated the formation of polycrystalline CaTiO3-Ca4Ti3O10 composite crystals and an increase in the crystallite size was observed upon increasing the Mg2+ ion concentration in the samples. Elemental analysis by energy dispersive spectroscopy (EDS) suggested the substitution of Ca2+ ions by Mg2+ ions in the CaTiO3 host lattice. Moreover, a change in the Yb3+/Er3+ ratio from 0.25 to 1.1 indicated the redistribution of the Er3+ or Yb3+ ions caused by the Mg2+ ions. These lattice deformations further resulted in an improved absorption of Er3+ ions, exhibiting a ∼3-fold enhancement in the upconversion emission intensity (at the excitation intensity of ∼1 W cm-2).

Photocatalytic and antibacterial properties of NaTaO3 nanofilms doping with Mg2+, Ca2+ and Sr2+

In this research, we prepared pure and alkaline earth metal elements (Mg2+, Ca2+ and Sr2+) doped NaTaO3 nanofilms by a simple hydrothermal method. Compared with traditional powder photocatalysts, they possess better stability and recycling performance, which makes them more practical in wastewater treatment. The as-prepared NaTaO3 crystals show nanoscale grain size that increases its redox ability owing to the small size effect and surface effect. After further introduction of Mg2+, Ca2+ and Sr2+, the band gaps were reduced to 2.83, 3.01 and 2.96 eV, respectively. Meanwhile, elemental doping induces a phase transition in the crystal structure of NaTaO3, creating an additional energy level that improves its responsiveness to visible light. According to the results, Mg-NaTaO3 catalyst possessed a higher photodegradation efficiency of 80.1 % for methylene blue solution under visible light irradiation. Furthermore, the photocatalytic bactericidal performance of different samples was investigated with Gram-positive and negative bacteria. In particular, the ROS (⋅O2–, ⋅OH, 1O2) induced by Mg-NaTaO3 could effectively destroy cell membranes, and the inhibition effect on E. coli and S. aureus reached 99.99 % within 50 min. Lastly, the results of cyclic photocatalytic experiments showed that Mg-NaTaO3 still had a high photodegradation capacity (75.2 %) and sterilization performance (98.8 %) after three cycles.

Shape-selective catalysts of Mg2+ ion exchange modified SAPO-11 molecular sieves for alkylation of 2-methylnaphthalene

The conversion of 2-methylnaphthalene (2-MN) and methanol by molecular zeolites to 2,6-dimethylnaphthalene (2,6-DMN) is significant for the preparation of polyethylene naphthalate. However, there is still a challenge to develop catalysts with efficient selectivity and activity. In this work, the hydrothermally synthesized SAPO-11 samples were modified by ion-exchange of Mg2+ for the catalytic alkylation of 2-MN, and thus the selectivity of 2,6-DMN was greatly improved. The results show that the Mg2+ ion-exchanged SAPO-11 molecular sieves could maintain the original main structure and morphology. However, the introduction of Mg2+ regulated the pore structure, acid content, acid strength and the distribution ratio of Brönsted acid and Lewis acid sites in the molecular sieves, and thus the Mg/SAPO-11 catalyst presented better catalytic performance than the pure SAPO-11. After 6 h of reaction, the selectivity of 2,6-DMN could still maintain 41.3% and the ratio of 2,6-/2,7-DMN was 1.87 over 0.06M-Mg/SAPO-11 sample. The deep isomerization of methylnaphthalene was reduced due to the Mg2+ ion exchange resulting in a shape-selective effect from passivation of the outer surface of the catalyst and adjustment of the open pore size. Therefore, this work presents a shape-selective catalysis in zeolites using Mg2+ ion exchange strategy for the alkylation of 2-MN.

Significant study of BaTiO3 as a cathode for magnesium battery applications

The attempts to tailor the physical properties of barium titanate (BTO) to qualify it as a promising cathode for metal-ion batteries are interesting strategies. Herein, the paper attempts to modify the structure of BTO via electrochemical insertion of Mg ion within the framework of BTO. Introduction of Mg2+ ions within the framework of BTO drives the characteristic ferroelectric transition from 388K to 393K; furthermore, heat treatment of BTO beyond ferroelectric transition temperature Tc redistributes Mg ions within the framework of BTO, which results in downshifting of the Tc near the room temperature. XRD results confirm magnesiation and heat treatment of the magnesized BTO stimulates structure transformation from tetragonal to a cubic phase. The synthesized liquid Mg-electrolyte has exhibited an excellent LSV and Mg-platting/stripping. The assembled Mg/BTO cells with magnesized BTO cathode has relatively high initial specific capacity of 179.7 mAhg−1, compared with the pristine BTO of 72.5 mAhg−1.

Co-substitution of Mg2+ and Ti4+ in Na3V2(PO4)3 nanoparticles coated with highly conductive carbon nanotubes for superior sodium storage

Benefiting from the stable structure, high theoretical specific capacities and long voltage plateau, Na3V2(PO4)3 has been considered as a promising cathode material for sodium-ion batteries (SIBs). Nevertheless, the poor intrinsic conductivity has seriously impeded its deeper development. Herein, unlike previous researchers who doped Mg2+ and Ti4+ separately, a simultaneously modified strategy combining Mg2+/Ti4+ co-substitution and coating carbon nano-tube is proposed. The replacement of V3+ by Mg2+ and Ti4+ can generate the beneficial p- and n-type doping effect. The introduction of Mg2+ produces the extra acceptor level, obtaining another hole carrier to increase the electronic conduction. Ti4+ is utilized to meet the charge compensation. Meanwhile, it can bring excess electrons due to the n-type substitution when Ti4+ replaces V3+. Moreover, carbon nano-tube (CNT) can construct a conductive network between the particles to facilitate the transport of electrons. Consequently, the optimized Na3V1.93Mg0.07Ti0.07(PO4)3 @CNT (MgTi0.07 @CNT) has superior electrochemical performance. Therefore, MgTi0.07 @CNT sample can be a promising cathode with excellent sodium storage properties and accelerated kinetic characteristics.

Effect of Mg2+-, Sr2+-, and Fe3+-substitution on 85Sr and 60Co adsorption on amorphous calcium phosphates: Adsorption performance, selectivity, and mechanism

Hydroxyapatite Ca10(OH)2(PO4)6 is a well-known efficient adsorbent of dyes, heavy metal ions, and radionuclides. Its adsorption efficacy strongly depends on crystalline/amorphous structure, defectiveness, texture characteristics, and morphology. Herein, we synthesized Mg2+-, Sr2+-, and Fe3+-substituted (5 mol%) amorphous calcium phosphates as an effective 85Sr and 60Co radionuclides adsorbents. The introduction of Mg2+-, Sr2+-, and Fe3+ ions led to the formation of amorphous calcium phosphates with particles size in the nanoscale range of approximately 10–50 nm. The features of the adsorption behavior of amorphous calcium phosphates were determined depending on the variation of the pH of aqueous, NaCl and CaCl2 solutions. Fe3+-substituted samples demonstrated the superior adsorption efficiency to 85Sr (Kd 7.77 ×103 cm3/g) and 60Co (Kd 6.84 ×104 cm3/g) radionuclides at pH of 10.0 and 4.0, respectively. The adsorption performance of obtained adsorbents slowly decreased at 0.1 M NaCl backgrounds and Kd85Sr and 60Co reached 1.67 × 103 and 2.78 × 104 cm3/g for non-substituted calcium phosphate. The dramatic decrease of calcium phosphates adsorbents efficiency to 85Sr (Kd <150 cm3/g) and 60Co (Kd <1.34 ×103 cm3/g) for 0.05 M CaCl2 model solution was established. The adsorption mechanism of dissolution-precipitation (for 85Sr) and chemisorption (for 60Co) was proposed. Fe3+-substituted calcium phosphate showed the competitive affinity and selectivity to 85Sr and 60Co comparing with described inorganic adsorbents and to be considered as prospective adsorbent for wastewater treatment in nuclear industry.

Synergetic stability enhancement with magnesium and calcium ion substitution for Ni/Mn-based P2-type sodium-ion battery cathodes.

The conventional P2-type cathode material Na0.67Ni0.33Mn0.67O2 suffers from an irreversible P2–O2 phase transition and serious capacity fading during cycling. Here, we successfully carry out magnesium and calcium ion doping into the transition-metal layers (TM layers) and the alkali-metal layers (AM layers), respectively, of Na0.67Ni0.33Mn0.67O2. Both Mg and Ca doping can reduce O-type stacking in the high-voltage region, leading to enhanced cycling endurance, however, this is associated with a decrease in capacity. The results of density functional theory (DFT) studies reveal that the introduction of Mg2+ and Ca2+ make high-voltage reactions (oxygen redox and Ni4+/Ni3+ redox reactions) less accessible. Thanks to the synergetic effect of co-doping with Mg2+ and Ca2+ ions, the adverse effects on high-voltage reactions involving Ni–O bonding are limited, and the structural stability is further enhanced. The finally obtained P2-type Na0.62Ca0.025Ni0.28Mg0.05Mn0.67O2 exhibits a satisfactory initial energy density of 468.2 W h kg−1 and good capacity retention of 83% after 100 cycles at 50 mA g−1 within the voltage range of 2.2–4.35 V. This work deepens our understanding of the specific effects of Mg2+ and Ca2+ dopants and provides a stability-enhancing strategy utilizing abundant alkaline earth elements.

Insights into the Fast Sodium Conductor NASICON and the Effects of Mg2+ Doping on Na+ Conductivity

Na super ionic CONductor (NASICON), Na1+xZr2SixP3–xO12, is an excellent solid-state electrolyte on account of its high sodium-ion conductivity, which can be further enhanced through chemical doping. However, the underlying sodium diffusion mechanism and how it is affected by chemical doping are not fully understood. This, in part, stems from the ambiguity between reported average structure models, where there is variation in the number and location of the sodium crystallographic sites. In this work, we present a neutron scattering study on monoclinic NASICON and Mg2+-doped NASICON, with a focus on the characterization of the sodium sites. Our difference Fourier maps show that the sodium sites have limited long-range order at temperatures as low as 3 K. In addition, our characterization of Mg2+-doped NASICON suggests that although Mg2+ preferentially dopes the secondary Na3PO4 phase rather than the bulk NASICON phase, its NASICON sodium sites are comparatively more diffuse. Furthermore, quasi-elastic neutron scattering data show broader spectra for the Mg-doped NASICON compared to NASICON at 300 K, supporting a more dynamic environment. We propose that the more diffuse character of the sodium sites arising from the introduction of Mg2+ contributes to the improvement of ionic conductivity in Mg-doped NASICON near room temperature.

Ultrahigh energy storage capacity with superfast discharge rate achieved in Mg-modified Ca0.5Sr0.5TiO3-based lead-free linear ceramics for dielectric capacitor applications

For the urgent demand of environmental protection and energy conservation, it is of great significance to develop environmentally-friendly dielectric ceramics with outstanding characteristic of energy storage and quick charge discharge capacity. For this study, we applied a strategy to achieve the enhancement of energy storage performance in (Ca0.5Sr0.5)1-xMgxTiO3 (abbreviate as CSMTx, x = 0.005, 0.010, 0.020, 0.040) linear ceramics based on the introduction of Mg2+ ion. Scanning electron microscopy and complex impedance measurement reveal that Mg2+ ion doping can refine grain size and increase grain boundary density, which results in grain boundary barrier strengthening owing to high-resistance grain boundaries. As a result, the marvellous energy storage properties, including an ultrahigh recoverable energy density of 2.88 J/cm3 combined with a giant energy efficiency of 90% are concurrently obtained in (Ca0.5Sr0.5)0.99Mg0.01TiO3 ceramic at an enhanced breakdown field (460 kV/cm). Meanwhile, this composition ceramic also exhibits the superior stability of frequency (1–1000 Hz) and temperature (20–100 °C) with minimal variation. In addition, the actual performance of ceramic capacitors in operation can be evaluated via the pulsed charge-discharge process. Delightedly, the superfast discharge speed (t0.9 = 20.4 ns), large current density (CD) of 421.23 A/cm2 and ultrahigh power density (PD) of 25.27 MW/cm3, as well as prominent thermal stability (20–100 °C) are synchronously produced in the CSMT2 ceramic. These merits qualify the unleaded linear ceramic as a competitive candidate for high-power capacitor applications, which offers a practicable approach for exploration on high-performance dielectric materials.