Synthesis,characterization, pyrolysis kinetics and conductivity studies of chloro substituted cobalt phthalocyanines

Cobalt(II) phthalocyanine (CoPc), cobalt(II) tetrachloro phthalocyanine (CoPcCl₄), cobalt(II) octachloro phthalocyanine (CoPcCl₈) and cobalt(II) hexadecachloro phthalocyanine (CoPcCl₁₆) are synthesized pure and characterized using elemental analysis, UV-visible, IR-spectroscopy, magnetic susceptibility, X-ray crystallography, and thermogravimetry. All four complexes have monoclinic structure with different crystal lattice constants. Broido's, Coats-Redfern and Horowitz-Metzger relations were employed to calculate the kinetic and activation parameters associated with thermal decomposition of the above complexes. The compounds are analyzed for kinetic parameters, activation energies for decomposition and the Arrhenious pre-exponential factors, in their pyrolysis. Using these factors and standard equations, thermodynamic parameters such as enthalpy, entropy and free energies are calculated. The activation energies are evaluated based on their electrical conductivity conducted over the temperature range 30–200°C. The electrical conductivities observed at 30°C are in the order CoPcCl₁₆?>?CoPcCl₄?>?CoPcCl₈?>?CoPc. The relevant electrical conductivity data are reported.     

Determination of deep trapping center parameters in as-grown Tl2Ga2S3Se layered crystals

Thermally stimulated current measurements were carried out on as-grown Tl₂Ga₂S₃Se layered single crystals. The investigations were performed in temperatures ranging from 10 to 320 K with heating rates of 0.6–1.2 K s⁻¹. The analysis of the data revealed the hole trap level located at 498 meV. The activation energies of the traps have been determined using various methods of analysis, and they agree with each other. The calculation for these traps yielded 2.1 × 10⁻¹⁸ cm² for capture cross-section and 2.3 × 10⁹ cm⁻³ for the concentration. It was concluded that in this center retrapping was negligible, as confirmed by the good agreement between the experimental results and the theoretical predictions of the model that assumes slow retrapping.     

Transport, magnetic, internal friction, and Young's modulus in the Y-doped manganites La0.9−xYxTe0.1MnO3

The resistivity, magnetization, internal friction, and Young's modulus for the polycrystalline samples La_0.9−xY_xTe_0.1MnO₃ (x=0, 0.05, 0.10 and 0.15) have been investigated. All samples have rhombohedral crystallographic structure with the space group . The Curie temperature T_C of the studied samples decreases with increasing Y-doping level. For the samples with x=0,0.05 and 0.10, the temperature dependence of the resistivity ρ(T) exhibits two metal-insulator transitions (MIT) at T_p1 (which is close to its Curie temperature T_C) and T_p2 (which is below T_p1). When the doping level to 0.15, these two MIT temperatures are suppressed and an upturn at low temperatures below T* is observed from the ρ(T) curve. A change of Young's modulus E is observed in the vicinity of T_C accompanied by a broad peak of the internal friction Q⁻¹ for all studied samples. The values of the relative Young's modulus ΔE increase with increasing Y-doping level at the low temperatures. These results are discussed in terms of the local Jahn-Teller (JT) distortion by the substitution of smaller Y³⁺ ions for larger La³⁺ ions and the increased bending of the Mn-O-Mn bond with decreasing the average ionic radius of the A-site element 〈r_A〉 and the tolerance factor t, resulting in the narrowing of the bandwidth, the decrease of the mobility of e_g electrons and the weakening of double-exchange (DE) interaction.     

Enhanced electrical properties of lead-free Bi4−xSbxTi3O12 ceramics with high Tc

Bi_4?xSb_xTi₃O₁₂ (BST) ceramics were prepared and studied in this work in terms of Sb³⁺-modified microstructure and phase development as well as electrical response. By increasing Sb content, the phase structure of the ceramics changed from orthorhombic (Bi₄Ti₃O₁₂-like) to pyrochlore (Bi₂Ti₂O₇-like) phase. Raman spectroscopy showed that the intensities of the lattice vibration modes at frequencies decrease, whereas all bands and bandwidths in all frequency numbers also demonstrate changes. According to the results processed from SEM, Sb³⁺ into the Bi₄Ti₃O₁₂ (BIT) matrix had the effect of increasing the material grain size. ε_r, ε_m, P_r, d₃₃ and T_c of Bi_3.90Sb_0.10Ti₃O₁₂ ceramics are found to be 307, 3492, 8.09 μC cm^?2, 18 pC/N and 660 °C, respectively. And Bi_4?xSb_xTi₃O₁₂ ceramics have good temperature stability, which is very suitable for the practical high-temperature applications.     

Progress on predicting the electrochemical stability window of electrolytes

The advancement of novel electrical energy storage systems with high energy density encourages the development of electrolytes with wide electrochemical stability windows (ESWs). For the design of electrolytes, atomistic simulations have been used to investigate their electrochemical stability, providing a fast and economical approach for electrolytes screening, in which the simulation models are the key to predicting the electrolyte ESWs. Herein, the completing progress of the simulation models on predicting electrolyte ESWs is overviewed, which ranges in complexity from an isolated molecule/ion model to a solvation model and finally to a complex model of the electrode–electrolyte interface. We highlight the limitation and applicability of these models in detail and advocate a perspective of possible future research on the prediction of the electrolyte ESWs.     

Determination of electrolytic conductivity of a 0.01D aqueous potassium chloride solution at various temperatures by an absolute method

A critical study of the conductance calibration standard, 0.01D aqueous potassium chloride solution, at 0°C, 18°C, and 25°C has been made using a highly precise thermostat and temperature program, a conductance measuring assembly of comparable precision, and a new type of absolute conductance cell. In spite of the high precision with which cell constants can be determined at any one temperature, the values at differents temperatures are only compatible with a linear temperature dependence within much larger limits.