Search

Synchrotron x-ray diffraction (SR-XRD) and X-ray absorption fine structure spectroscopy (XAFS) were used to investigate the crystal and electronic properties of boron-substituted CuFeO2 material at room temperature. Without boron substitution, the polycrystalline structures of the trigonal (rhombohedral) ' $R\bar{3}m$ R 3 ¯ m ' CuFeO2 (87.7%) and hexagonal 'P63/mmc' (12.3%), which were also present in each sample but in different proportions, were utilised to identify the base material. XRD patterns revealed that, beyond 10% boron substitution, the metal–oxygen bonds (Fe-O and Cu-O) weakened, resulting in the formation of new tetragonal 'I41/amd' CuFe2O4 crystals. Although the CuFeO2 structure was preserved, it is conceivable that the presence of other crystal structures could lead to the formation of new features. This state arose as a result of CuFe2O4 crystallization and the impact of boron activity on the surrounding oxygen structures. By measuring magnetisation at both swept temperatures (10–300 K) and applied magnetic fields (±30 kOe), the magnetic properties of the samples were investigated. In the 10–300 K temperature range, the polycrystalline samples exhibit a ferromagnetic property without a magnetic phase transition. This suggests that replacing B with Fe in CuFe1−xBxO2 does not influence the primary magnetic property of CuFeO2. The samples' saturation magnetisation (Ms) values gradually fall as the B substitution content increases with Fe. This is because there's a chance that the non-transition metal B in CuFe1−xBxO2 will boost antiferromagnetic superexchange Cu-O interactions while lowering the p-d exchange interaction. [ABSTRACT FROM AUTHOR]

The influence of Mn substitution on the iron lattice sites in LiFeO2 material was investigated with respect to the electronic, crystalline, and electrochemical properties of the material, using the LiFe1−xMnxO2 (x = 0.0, 0.05, and 0.10) series. The electronic structure study was conducted with the acquisition of x-ray absorption fine structure spectroscopy data, while the crystal structure properties of the studied materials were investigated using x-ray diffraction patterns. The data collected for the ionic conductivity properties of the samples by electrochemical impedance spectroscopy under increasing temperature conditions around and above room temperature aided the crystal and electronic structure studies on cathode materials. Furthermore, studies were conducted with the addition of CrFe2O4 material in varying molar concentrations into LiFeO2 material, as CrFe2O4 is known to have thermoelectric properties well above the room temperature of 400 K (127°C). Encouraging results for next-generation battery cathodes were obtained. [ABSTRACT FROM AUTHOR]

An investigation of temperature-dependent ionic activity of a representative sodium oxide material was carried out in the current research work due to the known importance of heat challenges in the battery development process. To assess the heat effects on the ionic conductivity capabilities, the electrochemical, electronic, and crystal structure properties of β-NaFeO2 and β-NaFeO2:Bi2Te3 composite materials were examined. The ionic conductivity of samples was slightly decreased by increasing the temperature, especially above 50–70°C. In contrast, better results were achieved for the β-NaFeO2:Bi2Te3 composite material than the parent β-NaFeO2 material as an indicator of the impacts of thermoelectric properties. At comparable temperatures, x-ray absorption (XAS) and x-ray absorption fine structure (XAFS) spectroscopic data were collected and processed to demonstrate the physical background influence of the increase in temperature on the atoms of the materials. It was found that the sodium atoms were the greatest contributors to the ionic conductivity loss at an increasing temperature among the materials. By separating from the spinel structure Fe–O ligand, sodium atoms increased the ionic capacitance by raising the temperature with a worse ionic conductivity. However, studies on the β-NaFeO2:Bi2Te3 composite material revealed a better ionic conductivity change than the β-NaFeO2 material with increasing temperature. This achievement was very clearly highlighted, particularly at the best working temperatures of Bi2Te3 material with a mechanism of absorbing waste heat and emitting free electrons. Additionally, the inactivity of β-NaFeO2 material could be determined by the instability of Na sites, which worsens with the increase in heat. [ABSTRACT FROM AUTHOR]

A series of Zn doped copper materials were investigated upon their crystal and electronic structure with the general formula Cu1-xZnx. CuZn alloys were produced via electrodeposition method. Galvanostatic deposition was preferred for the deposition. Crystal properties of the samples were studied via X-ray diffraction (XRD) patterns and supported by the X-ray absorption fine structure spectroscopy (XAFS) data. According to the crystal structure analysis, crystal geometries of the substituted samples were mainly determined in bcc cubic. The study has revealed that, low amount of Zn substitution (0.1M) are inactive in the molecular interplays and treated as an impurity in fcc copper environment. However, higher Zn concentrations (> 0.1 M) have built bcc structure under the influence of the highly overlapped 4p levels wavefunctions of the neighbouring Cu and Zn atoms. Thus, 0.1 M zinc substitution has been determined as a threshold of the phase transition from fcc to the bcc structure. [ABSTRACT FROM AUTHOR]