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Hybrid halide perovskite-like materials have recently attracted great interest due to their potential applications in optoelectronic devices, energy storage and the semiconductor industry. In this work, two tin(IV) based organic–inorganic hybrid compounds [Cl–(CH2)2–NH3]2SnCl6(1) and [Cl–(CH2)2–NH3]2SnBr5.65Cl0.35(2) were prepared by the reaction of 2-chloroethylamine hydrochloride with SnX2 (X = Cl, Br) in the corresponding concentrated halogen acids. Single-crystal X-ray diffraction analysis reveals that compounds (1) and (2) are isotypic and crystallize in the monoclinic system with space group P21/m. The asymmetric unit of the crystal structure in each compound is composed of an independent [SnX6]2− anion charge balanced by [Cl–(CH2)2–NH3]+ cations, where X is a halogen. Differential scanning calorimetry (DSC) and electric measurements show that no phase transition occurs in the hybrid compounds over the temperature range of 298–453 K. Interestingly, both materials exhibit a semiconducting property with optical bandgaps of 4.7 eV for (1) and 2.94 eV for (2). Photoluminescence (PL) measurements evidenced the presence of green emissive traps activated by excitation below the optical gap for the [Cl–(CH2)2–NH3]2SnCl6(1) compound, resulting in an emissive color change of the crystals, from blue to green. These findings of Sn(IV)-based metal halides with prominent semiconducting behaviors and photoluminescence properties contribute to the exploration of new types of hybrid perovskite-like with adjustable properties. [ABSTRACT FROM AUTHOR]

Herein, NaMnO2 cathode active materials, in both α- and γ-phases, were synthesized via a solid–solid method. Powder X-ray diffraction analysis revealed that these compounds crystallize in a monoclinic system with the C2/m space group and orthorhombic system with the Pnmm space group for the α- and γ-phases, respectively. Raman spectroscopy showed the presence of the MnO6 octahedral group in the α-phase, and the MnO4 tetrahedral group in the γ-phase. The direct band gap (Eg) was calculated to 4.96 eV and 5.14 eV for the α- and γ-phases, respectively, confirming that α-NaMnO2 has better electronic conductivity than γ-NaMnO2. The Urbach energy values, Eu, show that the octahedral α-phase is more disordered than the tetrahedral γ-phase in the NaMnO2 material. The electrical data analysis of the impedance spectra and the imaginary part of the complex modulus showed the presence of two types of relaxations, corresponding to grain and grain boundary effects in both compounds. The thermal evolution of the relaxation time and DC conductivity followed the Arrhenius law with a change in the activation energy at around Tα = 363 K for the α-phase and Tγ = 373 K for the γ-phase. In addition, the frequency behaviour of the AC conductivity, σac, of these two samples was analyzed using the universal Jonscher law. Therefore, the variation in sg for both compounds with temperature showed a change in the conduction mechanism at around Tα and Tγ for the α- and γ-phases, respectively. [ABSTRACT FROM AUTHOR]

In the present study, three chemical compounds, Li2WO4, Li0.5Na1.5WO4, and Li1.5Na0.5WO4, are produced using the solid–solid method. Unlike the compound Li0.5Na1.5WO4, which crystallizes in the orthorhombic system with the space group Pmmm, both compounds Li2WO4 and Li1.5Na0.5WO4 crystallize in the monoclinic system with the space group P2/m. A morphological analysis reveals that all three compounds have a compact structure with some porosity present. An EDX analysis confirms the chemical composition of the three samples. The optical measurements provide information on the optical gaps and Urbach energies of the materials under consideration. Their dielectric characteristics are investigated in a frequency range of 100–106 Hz and at temperatures ranging from 300 to 600 K. Moreover, this research enables us to determine the ferroelectric transition as well as the type of dielectric material. In this study, an investigation of electrical conductivity was conducted for well-defined temperature and frequency values; which provided us with information about the mechanism of conduction and charge carrier transport models. [ABSTRACT FROM AUTHOR]

Na2Co1−xFexSiO4 (NCFS)-based ceramics are some of the most promising alternatives to sodium-ion rechargeable batteries (SIBs). It was believed that the intrinsic qualities would be improved by the defect chemistry and the doping impact of iron in Na2CoSiO4 (NCS). In this study, Na2Co1−xFexSiO4 with x = 0.1 and 0.2 sample structural characteristics, optical properties, ionic conductivities, and Na migration are examined. Contrary to the space group Pna21 undoped compound, the Rietveld refinement of the XRD patterns of NCFSs reveals an orthorhombic phase with the space group Pca21. It is discovered that the temperature dependence relaxation obeys the Arrhenius law, and the identical relaxation times for the charge transport mechanism are suggested by the weak separation of the activation energies for the two relaxation processes (R(A) and R(B)). The transportation behavior of Na+ in many chemical environments is made more favorable by Fe doping, and this has a significant impact on the electrical characteristics. As the Fe content increases, the conductivity increases as well. As the frequency increases, the frequency dependence of ac conductivity is examined to identify the conduction mechanisms such as OLPT, CBH, and inverse OLPT models. [ABSTRACT FROM AUTHOR]

Na2Co1−xFexSiO4 (NCFS)-based ceramics are some of the most promising alternatives to sodium-ion rechargeable batteries (SIBs). It was believed that the intrinsic qualities would be improved by the defect chemistry and the doping impact of iron in Na2CoSiO4 (NCS). In this study, Na2Co1−xFexSiO4 with x = 0.1 and 0.2 sample structural characteristics, optical properties, ionic conductivities, and Na migration are examined. Contrary to the space group Pna21 undoped compound, the Rietveld refinement of the XRD patterns of NCFSs reveals an orthorhombic phase with the space group Pca21. It is discovered that the temperature dependence relaxation obeys the Arrhenius law, and the identical relaxation times for the charge transport mechanism are suggested by the weak separation of the activation energies for the two relaxation processes (R(A) and R(B)). The transportation behavior of Na+ in many chemical environments is made more favorable by Fe doping, and this has a significant impact on the electrical characteristics. As the Fe content increases, the conductivity increases as well. As the frequency increases, the frequency dependence of ac conductivity is examined to identify the conduction mechanisms such as OLPT, CBH, and inverse OLPT models. [ABSTRACT FROM AUTHOR]

Hybrid organic–inorganic lead-free halide materials have attracted widespread attention due to their applications in the field of optoelectronics. Herein, we synthesized a new binuclear Pd(II) complex templated by 3-bromopropyltrimethylammonium, which undergoes a high-temperature phase transition at about 428 K. Differential scanning calorimetry confirmed this reversible transformation with a large heat hysteresis of 65 K, which depicts a typical first-order phase transition in the compound. The X-ray crystal structure reveals that this material is composed of anionic dimers and organic cations. The complex, [(CH3)3N(CH2)3Br]2Pd2Cl6, crystallizes in the monoclinic system, space group P21/c. The inorganic layer, built up by two crystallographically independent [Pd2Cl6]2− dimer units, is connected to the [(CH3)3N(CH2)3Br]+ organic cations through C–H···Cl hydrogen bonds, which lead to a 3D supramolecular architecture. Each Pd atom is coordinated to two bridging Cl atoms in a slightly distorted square planar geometry. Furthermore, experimental results confirm the semiconducting behavior of [(CH3)3N(CH2)3Br]2Pd2Cl6 with an optical bandgap of ∼2.2 eV. The electric properties were investigated in detail with the study of impedance and AC conductivity. Based on the Elliot theory, the conduction mechanism was deduced with two models: the overlapping polaron model (OLPT) is the right model describing the conduction in phase I, and the correlated barrier hopping model (CBH) describes the conduction in phase II. [ABSTRACT FROM AUTHOR]

LiCoO2 was synthesized by the conventional solid-state reaction. The X-ray diffraction indicates that the LiCoO2 sample crystallizes in a hexagonal system with an R-3 m space group. The optical properties were studied. The band gap energy was established and seems to be equal to 2.15 eV which confirms the semiconductor character of this compound. The study of the refractive index and the extinction coefficient proved the connection between the sample transparency and a low optical absorption loss. Furthermore, thermal analysis shows an exothermic peak at 335 K which was proven by studying the temperature dependence of the electrical properties. The equivalent circuit was chosen and the electrical conductivity was analyzed. The AC conductivity values (10−4 Ω−1 cm−1) confirm the semiconductor character and the ionic conduction type. The conduction mechanism was attributed to CBH for the first phase and NSPT for the second one. Additionally, electrical modulus investigation reveals the existence of grain boundary and grain effects. [ABSTRACT FROM AUTHOR]

[N (CH3)4][N(C2H5)4]CoCl4 new hybrid compound was synthesized by slow evaporation at room temperature. The X‐ray powder diffraction indicates that this material has an orthorhombic structure with P212121 space group. Two endothermic peaks at T1 = 293 K and T2 = 387 K are observed by differential scanning calorimetric. The real and imaginary parts of the permittivity as function of temperature shows the ferroelectric phase below T = 288 K. The Nyquist diagrams are simulated based on the equivalent circuit chosen by the Z‐View‐software and show the contribution of the grain and electrodes effect. Raman spectroscopy study at room temperature confirms the composition of the synthesized compound. Furthermore, the ferroelectric–paraelectric phase transition T1 is demonstrated by temperature‐dependent Raman spectroscopic studies. [ABSTRACT FROM AUTHOR]

Lead free organic‐inorganic hybrid perovskites have attracted increasing attention because of their variety of applications such as photovoltaics or lighting. Here, we reported a new iodobismuthate organic‐inorganic perovskite (PyrCO2H)2BiI5 where PyrCO2H+ is the 4‐carboxy‐1‐methylpyridinium. In the room temperature orthorhombic phase, the one‐dimensional (1D) inorganic framework which consists of cis‐connected corner‐sharing BiI6 octahedra, exhibits a sinusoidal deformation along the chain axis, while a regular chain leading to a sub‐cell is found in the high temperature phase (T>390 K). An original structural feature is the relative position of consecutive 1D chains in planes leading to a layered character of this organic‐inorganic compound. The electrical properties as function frequencies and temperatures have been studied in particular allowing the extraction of Rg and further the calculation of σg=f(T). Interestingly, a change of activation energy is detected at the phase transition temperature (390 K). The higher value of activation energy above 390 K can be attributed to change of the conduction mechanism involving ionic conduction. [ABSTRACT FROM AUTHOR]

The β-NaCoPO 4 and γ-NaCoPO 4 materials were prepared using the mechanical milling technique followed by heat treatment. The investigated samples were characterized by combining X-ray powder diffraction, scanning electron microscopy (SEM), thermal analysis and electrical impedance spectroscopy techniques. The Rietveld refinement of X-ray diffraction (XRD) pattern revealed that these β-NaCoPO 4 and γ-NaCoPO 4 phases are indexed in the hexagonal and monoclinic system with P6 1 and P2 1 /n space group, respectively. The grain shapes illustrate homogeneous particle size distribution. Differential scanning calorimetric (DSC) for the β-NaCoPO 4 and γ-NaCoPO 4 disclosed a single-phase transition at 506 K and 560 K respectively. Furthermore, the electrical and dielectric properties of these materials have been investigated using complex impedance spectroscopy between 1000 Hz and 2 MHz at various temperatures (400–600 K). The temperature dependence of the exponent S suggests that the conduction of β-NaCoPO 4 compound is interpreted in the first phase (I) by the OLPT model and the second by the NSPT model, while γ-NaCoPO 4 can be attributed to the CBH model. • Differential scanning calorimetric for the β-NaCoPO 4 and γ-NaCoPO 4 disclosed a single-phase transition at 506 K and 560 K respectively. • The conduction of β-NaCoPO4 is interpreted in the first phase by the OLPT model and the second by the NSPT model, while for γ-NaCoPO4 can be explained to the CBH model. • The conduction of β-NaCoPO4 is interpreted by the tunnel model, while for γ-NaCoPO4 can be explained to the CBH model. [ABSTRACT FROM AUTHOR]

• The electricity market in Europe is based on a zonal system. • A minimum of 70% of the cross-zonal capacity will have to be available for trade. • Such a minimum threshold could decrease the socio-economic welfare. • A smart redispatch is needed to avoid a decrease of the socio-economic welfare. The current organization of the internal electricity market in Europe relies on a zonal market system: the European power system is divided in bidding zones, electricity trades within a bidding zone can occur in an unconstrained manner, while electricity trades between bidding zones are limited by cross-zonal capacities. Two approaches can be used to calculate and allocate cross-zonal capacity: the coordinated Net Transmission Capacity (NTC) approach or the flow-based approach. In Central Western Europe, the flow-based approach is implemented for the day-ahead market since 2015. To avoid undue discrimination between internal and cross-border power exchanges, a minimum threshold of 70% on the cross-zonal capacity available for trade will be enforced in a near future. Such a threshold could significantly impact the socio-economic welfare and its distribution between the various actors. However, no assessment of the impacts of such a threshold has been performed so far, in particular because no convincing approach exists to perform such an assessment (e.g. security constraints and redispatch neglected). This paper develops such an approach and demonstrates its applicability on a case study, in order to assess the impact of a minimum threshold on cross-zonal capacity in a flow-based market. [ABSTRACT FROM AUTHOR]