Direct Double Coating of Carbon and Nitrogen on Fluoride-Doped Li4Ti5O12 as an Anode for Lithium-Ion Batteries

Graphite as a commercial anode for lithium-ion batteries has significant safety concerns owing to lithium dendrite growth at low operating voltages. Li4Ti5O12 is a potential candidate to replace graphite as the next-generation anode of lithium-ion batteries. In this work, fluoride-doped Li4Ti5O12 was successfully synthesized with a direct double coating of carbon and nitrogen using a solid-state method followed by the pyrolysis process of polyaniline. X-ray diffraction (XRD) results show that the addition of fluoride is successfully doped to the spinel-type structure of Li4Ti5O12 without any impurities being detected. The carbon and nitrogen coating are distributed on the surface of Li4Ti5O12 particles, as shown in the Scanning Electron Microscopy–Energy Dispersive X-ray Spectroscopy (SEM-EDS) image. The Transmission Electron Microscopy (TEM) image shows a thin layer of carbon coating on the Li4Ti5O12 surface. The fluoride-doped Li4Ti5O12 has the highest specific discharge capacity of 165.38 mAh g−1 at 0.5 C and capacity fading of 93.51% after 150 cycles compared to other samples, indicating improved electrochemical performance. This is attributed to the synergy between the appropriate amount of carbon and nitrogen coating, which induced a high mobility of electrons and larger crystallite size due to the insertion of fluoride to the spinel-type structure of Li4Ti5O12, enhancing lithium-ion transfer during the insertion/extraction process.

Whitlockite-Type Structure as a Matrix for Optical Materials: Synthesis and Characterization of Novel TM-SM Co-Doped Phosphate Ca9Gd(PO4)7, a Single-Phase White Light Phosphors

A series of novel phosphates with the general formulas Ca9Gd0.9−xTm0.1Smx(PO4)7 and Ca9Gd0.9−yTmySm0.1(PO4)7 were synthesized by solid-state method. As-obtained phosphates were characterized by powder X-ray diffraction and second harmonic generation analyses, dielectric measurements, luminescence spectroscopy. All samples were single phase and characterized by the whitlockite-type structure with space group R3c. An influence of admixture concentration of REE3+ ions in the initial host on dielectric properties was studied in details. Synthesized phosphates are characterized by intensive luminescence. The emission in the orange region of the visible spectrum is observed for Ca9Gd0.9Sm0.1(PO4)7 with a maximum intensity band at 602 nm. The line in blue region at 455 nm, which corresponds to 1D2 → 3F4 Tm3+ transition, is registered for Ca9Gd0.9Tm0.1(PO4)7. Emission in the white region of CIE coordinates was registered for Tm-Sm co-doped compounds.

Structural, optical, electric and dielectric characterization of a NaCu0.2Fe0.3Mn0.5O2 compound

The compound NaCu0.2Fe0.3Mn0.5O2 was synthesized using a solid-state method and it crystallized in a hexagonal system with a R3̄m space group in an O3-type phase.

Preparation and investigation of Dy3+/Tm3+ doped NaGd(MoO4)2 with thermal-stable and tunable white light emitting for LED applications

In this work, a series of Dy3+-doped, Tm3+-doped and Dy3+/Tm3+-codoped NaGd(MoO4)2 (NGM) were successfully prepared via high-temperature solid-state method. The crystal structure, band structure, elemental composition, and photoluminescence (PL) properties...

Assessment of Laser Effects on the Structure and Electrical Properties of the Compound Bi2-xAgxSr2Ca2Cu3O10+δ Superconducting

This research contains preparing the superconducting compound Bi2-xAgxSr2Ca2Cu3O10+δ and studying its structural and electrical characteristics. The samples were prepared using the solid-state method in two stages, and different concentrations of x were (x= 0.2,0.4,0.6,0.8) replaced instead of bismuth Bi. Then, using a hydraulic press 9 ton/cm2 and sintering with a temperature of 850°C, the samples were pressed. Next, x-ray diffraction is used to study the structural properties. The study of these samples was presented in different proportions of x values, where x = 0.4 is the best compensation ratio of x. A critical temperature of 1400C and the Tetragonal structure was got. After that, the effect of laser nidinium _ yak (Nd: YAG laser) was used on the compositional. It was found that the temperature value increased, so we got the best critical temperature, which is 142 0C.

Synthesis Method and Thermodynamic Characteristics of Anode Material Li3FeN2 for Application in Lithium-Ion Batteries

Li3FeN2 material was synthesized by the two-step solid-state method from Li3N (adiabatic camera) and FeN2 (tube furnace) powders. Phase investigation of Li3N, FeN2, and Li3FeN2 was carried out. The discharge capacity of Li3FeN2 is 343 mAh g−1, which is about 44.7% of the theoretic capacity. The ternary nitride Li3FeN2 molar heat capacity is calculated using the formula Cp,m = 77.831 + 0.130 × T − 6289 × T−2, (T is absolute temperature, temperature range is 298–900 K, pressure is constant). The thermodynamic characteristics of Li3FeN2 have the following values: entropy S0298 = 116.2 J mol−1 K−1, molar enthalpy of dissolution ΔdHLFN = −206.537 ± 2.8 kJ mol−1, the standard enthalpy of formation ΔfH0 = −291.331 ± 5.7 kJ mol−1, entropy S0298 = 113.2 J mol−1 K−1 (Neumann–Kopp rule) and 116.2 J mol−1 K−1 (W. Herz rule), the standard Gibbs free energy of formation ΔfG0298 = −276.7 kJ mol−1.

Effect of Preparation Method and Ni2+ Substitution on the Structural, Thermal, and Optical Properties of Nanocrystalline Lanthanum Zirconate Pyrochlore

In order to establish the effective application of materials in a particular area, it is important to first investigate the physical and chemical properties, such as the crystallinity, structure, and the optical and surface properties. The objective of the present study is to fabricate thermally stable pyrochlore oxides, namely, lanthanum zirconate (La2Zr2O7, LZ) and Ni-doped lanthanum zirconate (La2Zr1.5Ni0.5O7, LZN) by the solid-state and sol-gel methods. The effects of the preparation and substitution of Zr4+ by Ni2+ for the resulting nanocrystalline samples were characterized in terms of structure, purity, porosity, the thermal and optical properties, and photoluminescence by different techniques: XRD, FT-IR, BET, EDS, TG-DTG, UV-Vis-DRS, and PL. The XRD results confirm that the pyrochlores prepared via the sol-gel method (LZ-sg and LZN-sg) had a cubic unit-cell lattice, whereas the solid-state method (LZ-s and LZN-s) had impurities of the oxides. The XRD patterns, LZ-sg and LZN-sg, were further treated with the Rietveld technique. The textural measurements reveal that LZ-sg had a higher BET surface area compared to LZN-sg. In addition, the substitution of Zr4+ by the Ni2+ ion provides rational evidence for the improvement in the oxygen mobility, as well as the optical and photoluminescence properties through the lowering of the optical band energy and the electron–hole pairs.