X-ray Photoelectron Spectroscopy of the Surface of Solid Electrolyte La0.88Sr0.12Ga0.82Mg0.18O3 – α

The composition and chemical state of elements on the surface of solid oxygen-conducting electrolyte La_0.88Sr_0.12Ga_0.82Mg_0.18O_{3 –} is studied by x-ray photoelectron spectroscopy before and after annealing it at 973 K in a CO₂ atmosphere. Products of interaction between doped lanthanum gallate and CO₂ are localized in a surface layer 8–10 nm thick. The annealing does not lead to the formation of chemical carbon compounds with metals on the electrolyte surface. Surface layers of the electrolyte both in the initial state and after the annealing are rich in strontium oxide and contain some lanthanum hydroxide.     

Review of Nontopological Solitons in Theories with U (1)-Symmetry

We provide a review of nontopological solitonic solutions arising in theories with a complex scalar field and global or gauge U(1)-symmetry. It covers Q-balls, homogeneous charged scalar condensates, and nonlinear localized holes and bulges in a classically stable condensate. A historical overview is followed by the discussion of properties of solutions, including their stability, from different perspectives. Solitons in models with additional massive degrees of freedom are also revisited, and their relation to one-field Q-balls is showed. We also discuss theories with a gauge field giving rise to gauged Q-balls and theories with dynamical gravity giving rise to boson stars.     

Preparation of a single-phase solid electrolyte La1 ? xSrxGa1 ? yMgyO3 ? (x + y)/2 by self-propagating high-temperature synthesis

Highly dispersed single-phase powders described as La_0.88Sr_0.12Ga_0.82Mg_0.18O_2.85 were prepared using a method based on the principles of self-propagating high-temperature synthesis (SHS). Lanthanum, strontium, gallium, and magnesium nitrates were used in the SHS as “oxidants”, and ethylene glycol was used as the reducing agent. The initial reaction mixture was liquid. According to X-ray diffraction and scanning electron microscopy data, the sample becomes a single phase after annealing of the primary SHS product at 1200°C, which is substantially lower than in other synthetic methods. Using so active powders (grain size of about 100–130 nm), it is possible to reduce the temperature of the final annealing of the ceramics to 1275°C, which gives rise to single-phase finely dispersed ceramics having specific properties.     

Effect of ethylene carbonate concentration on the conductivity of carbonate-based electrolytes with LiPF6 for Li-ion batteries

A four-probe pouch-type cell was used to study the influence of carbonate-based electrolyte composition on the total conductivity of polyolefin separator impregnated with electrolyte through the electrochemical impedance spectroscopy. A frequency dispersion of separator with electrolyte is found to be dependent on the volume ratio of ethylene carbonate and ethyl methyl carbonate in an electrolyte solution. The origin of high- and low-frequency relaxation processes obtained from the impedance spectra is discussed. A correlation between the direct current resistance of separator with electrolyte and dissociation degree of electrolyte salt is found.     

Electroconduction of Solid Electrolyte La0.88Sr0.12Ga0.82Mg0.18O2.85: Effect of a Prolonged Exposure

The overall resistance and resistances of the bulk and grain boundaries of solid electrolyte La_0.8Sr_0.12Ga_0.82Mg_0.18O_2.85 kept for a long time in air at 773-1073 K are studied by impedance spectroscopy. The increase in the electrolyte resistance with time is shown to be connected with that in the resistance of grain boundaries.     

Studies of a Model Mesh Electrode O2,Pt/O2- under Galvanostatic Polarization

The impedance of model platinum mesh electrode in contact with a doped zirconium-dioxide-based single-crystal electrolyte is studied by impedance spectroscopy under constant-current polarization. The electrode is distinguished for its readily determinable geometrical characteristics of the metal/electrolyte interface, in particular, the length of the triple-phase boundary and the electrode contact area. Three different orientations of the electrolyte face are studied. The impedance dispersion is discussed in terms of the electrode prehistory, orientation, and potential.     

Paramagnetic properties of triple molybdates CsNa<Subscript>5</Subscript>M<Subscript>3</Subscript>(MoO<Subscript>4</Subscript>)<Subscript>6</Subscript> (M = Ni,Co, Mn)

The static magnetization of CsNa₅M₃(MoO₄)₆ single phase molybdates, where M = Co, Ni, and Mn, is measured at 4–300 K in magnetic fields of up to 20 kOe. It is shown that the materials are paramagnetic. Magnetization as a function of temperature is described using the Curie–Weiss law. The intrinsic magnetic moments of the phases are found to be 9.759 (Co), 6.958 (Ni), and 12.203 Bohr magnetons for manganese molybdates. It is concluded that the charge state of Co, Ni, and Mn cations in the compounds is +2.     

Phase transition in mayenite Ca12Al14O33

A phase transition in Ca₁₂Al₁₄O₃₃ has been discovered and investigated by thermogravimetric analysis, differential scanning calorimetry, dilatometry, and high-temperature X-ray diffraction. The phase transition occurs at 922 ± 45 K (??H = ?406 ± 13 kJ/mol, ??S = ?440 ± 14 J/(mol K)) and is presumably a first-order one. It does not change the symmetry of the cationic subsystem. The phase transition is difficult to reveal because the material changes its mass, probably by releasing water bound in several different ways.     

Ceramics with mayenite structure: Molecular sieve for helium gas

It was found that mayenite {ie536-1} has selective transmission of helium gas, which is associated with its unique structural features. The permeability of helium through mayenite is (16.5–17.0) × 10^?8 cm² s^?1 Pa^?1.