The Coordination Polymer Cr(en) 2 As 2 VO 7 Consisting of Alternating VO 4 Tetrahedra and As 2 O 5 Handles Decorated by Cr 3+ Centered Complexes

The new coordination polymer Cr(en)2As2VO7 (en=ethylenediamine) was synthesized under solvothermal conditions as deep red crystals. In the crystal structure VO4 tetrahedra and As2O5 handles formed by corner-sharing of two AsO3 pyramidal units are joined by common oxygen atoms into an undulated chain that is directed along the crystallographic b-axis. The chain is decorated by [Cr(en)2]3+ complexes with the Cr3+ cation having bonds to two terminal O2− anions of the As2O5 moiety thus generating a CrN4O2 octahedron, which displays a cis-configuration. The connection mode between Cr3+ and As2O5 leads to formation of a six-membered CrAs2O3 ring. The chains are arranged in a layer-like fashion in the (001) plane and these layers are stacked along [001]. A large number of N−H⋅⋅⋅O and C−H⋅⋅⋅O hydrogen bonds generate a three dimensional network. A Hirshfeld surface analysis was performed for visualizing the extended interchain interactions. The hydrogen bonding interactions are clearly detected in the IR spectrum. The UV-Vis spectrum shows an absorption at 2.3 eV which is in agreement with the red color of the sample

Influence of the Cation on the Reaction Mechanism of Sodium Uptake and Release in Bivalent Transition Metal Thiophosphate Anodes: A Case Study of Fe2_2P2_2S6_6

The layered active material Fe$_2$P$_2$S$_6$ was examined as anode material in sodium-ion batteries (SIBs) and compared to previously investigated Ni$_2$P$_2$S$_6$. A reversible specific capacity of 540 mAh g$^{−1}$ was achieved after 250 cycles, depicting similar electrochemical performance as observed for Ni$_2$P$_2$S$_6$. The rate capability and long-term behavior of these two materials are also very similar. Another objective was to elucidate the reaction mechanism during discharging and charging by applying several techniques such as X-ray diffraction, pair distribution function analysis as well as X-ray absorption and solid state NMR spectroscopy. The results clearly demonstrate that the majority of Fe$^{2+}$ is reduced to elemental Fe during the uptake of 5 Na/f.u., while an amorphous intermediate is generated, which was identified as Na$_4$P$_2$S$_6$ by solid state NMR spectroscopy. Completely discharging against a Na metal counter electrode leads to the formation of nanocrystalline Na$_2$S and indications of the formation of polymeric phosphorus were found. In sum, the Na uptake reaction process observed for Fe$_2$P$_2$S$_6$ coincides with the previously unraveled reaction pathway of Ni$_2$P$_2$S$_6$. We therefore conclude that a universal reaction takes places for bivalent transition metal thiophosphate (M$_2$P$_2$S$_6$) electrodes in SIBs

Directed Dehydration of Na4_4Sn2_2S6_6 ⋅ 5H2_2O Generates the New Compound Na4_4Sn2_2S6_6: Crystal Structure and Selected Properties

The new thiostannate Na$_4$Sn$_2$S$_6$ was prepared by directed crystal water removal from the hydrate Na$_4$Sn$_2$S$_6$ ⋅ 5H$_2$O at moderate temperatures. While the structure of the hydrate comprises isolated [Sn$_2$S$_6$]$^{4−}$ anions, that of the anhydrate contains linear chains composed of corner-sharing SnS4 tetrahedra, a structural motif not known in thiostannate chemistry. This structural rearrangement requires bond-breakage in the [Sn2S6]4− anion, movements of the fragments of the opened [Sn2S6]4− anion and Sn−S−Sn bond formation. Simultaneously, the coordination environment of the Na+ cations is significantly altered and the in situ formed NaS$_5$ polyhedra are joined by corner- and edge-sharing to form a six-membered ring. Time-dependent in situ X-ray powder diffraction evidences very fast rehydration into Na$_4$Sn$_2$S$_6$ ⋅ 5H$_2$O during storage in air atmosphere, but recovery of the initial crystallinity requires several days. Impedance spectroscopy demonstrates a mediocre room-temperature Na$^+$ ion conductivity of 0.31 μS cm$^{−1}$ and an activation energy for ionic transport of E$_a$=0.75 eV

Directed Dehydration of Na 4 Sn 2 S 6 ⋅ 5H 2 O Generates the New Compound Na 4 Sn 2 S 6: Crystal Structure and Selected Properties

The new thiostannate Na4Sn2S6 was prepared by directed crystal water removal from the hydrate Na4Sn2S6 ⋅ 5H2O at moderate temperatures. While the structure of the hydrate comprises isolated [Sn2S6]4− anions, that of the anhydrate contains linear chains composed of corner-sharing SnS4 tetrahedra, a structural motif not known in thiostannate chemistry. This structural rearrangement requires bond-breakage in the [Sn2S6]4− anion, movements of the fragments of the opened [Sn2S6]4− anion and Sn−S−Sn bond formation. Simultaneously, the coordination environment of the Na+ cations is significantly altered and the in situ formed NaS5 polyhedra are joined by corner- and edge-sharing to form a six-membered ring. Time-dependent in situ X-ray powder diffraction evidences very fast rehydration into Na4Sn2S6 ⋅ 5H2O during storage in air atmosphere, but recovery of the initial crystallinity requires several days. Impedance spectroscopy demonstrates a mediocre room-temperature Na+ ion conductivity of 0.31 μS cm−1 and an activation energy for ionic transport of Ea=0.75 eV

Mechanochemical Synthesis and Magnetic Characterization of Nanosized Cubic Spinel FeCr₂S₄ Particles

Nanosized samples of the cubic thiospinel FeCr2S4 were synthesized by ball milling of FeS and Cr2S3 precursors followed by a distinct temperature treatment between 500 and 800 °C. Depending on the applied temperature, volume weighted mean (Lvol) particle sizes of 56 nm (500 °C), 86 nm (600 °C), and 123 nm (800 °C) were obtained. All samples show a transition into the ferrimagnetic state at a Curie temperature TC of ∼ 167 K only slightly depending on the annealing temperature. Above TC, ferromagnetic spin clusters survive and Curie–Weiss behavior is observed only at T ≫ TC, with T depending on the heat treatments and the external magnetic field applied. Zero-field-cooled and field-cooled magnetic susceptibilities diverge significantly below TC in contrast to what is observed for conventionally solid-state-prepared polycrystalline samples. In the low-temperature region, all samples show a transition into the orbital ordered state at about 9 K, which is more pronounced for the samples heated to higher temperatures. This observation is a clear indication that the cation disorder is very low because a pronounced disorder would suppress this magnetic transition. The unusual magnetic properties of the samples at low temperatures and different external magnetic fields can be clearly related to different factors like structural microstrain and magnetocrystalline anisotropy

Preparation, Structure and Spectroscopic Properties of NH 4 [Ln(S 2 CNH 2 ) 4 ] ⋅ H 2 O (Ln=La, Eu)

The title compounds were prepared under mild ambient conditions by a facile co-precipitation route. NH4[Eu(S2CNH2)4] ⋅ H2O (a) and NH4[La(S2CNH2)4] ⋅ H2O (b) crystallize isotypically in the monoclinic space group P21/c with a=8.4461(3), b=13.6367(3), c=16.2945(5) Å, β=103.759(2)° (for (a)), and a=8.50484(9), b=13.84476(16), c=16.20816(17) Å, β=103.7644(11)° for (b), respectively. The spectroscopic data reveal the presence of a ligand-to-metal charge transfer (LMCT) process of low energy in a and in the solid solutions NH4[La1−xEux(S2CNH2)4] ⋅ H2O (x=0.016 and 0.05). Despite of the consequent efficient luminescent quenching, it was possible to recorded excitation and emission spectra at room temperature. These spectra are characterized by narrow bands due to intraconfigurational-4f transitions of the Eu3+ ion. However, broad bands associated to the LMCT state were also observed, mainly for the solid solutions NH4[La1−xEux(S2CNH2)4] ⋅ H2O (x=0.016 and 0.05). Consequently, an intramolecular energy transfer mechanism is proposed, taking into account the role of the LMCT on the spectroscopic properties of dithiocarbamate complexes

Bis(methyl­ammonium) tetra­sulfido­tungstate(VI)

The title compound, (CH6N)2[WS4], was synthesized by the reaction of ammonium tetra­sulfidotungstate(VI) with aqueous methyl­amine. The title compound is isotypic with the corresponding Mo analogue (CH6N)2[MoS4], and its structure consists of a slightly distorted tetra­hedral [WS4]2− dianion and two crystallographically independent methyl­ammonium (MeNH3) cations, all of which are located on crystallographic mirror planes. The tetra­sulfidotungstate anions are linked to the organic cations via hydrogen-bonding inter­actions

Ветро-дизельная система электроснабжения поселка

Работа направлена на решение проблемы электроснабжения отдаленных районов. Объектом исследования является гибридная ветро-дизельная система электроснабжения, находящаяся на юге Кемеровской области на высоте 1260 метров. В процессе исследования проводились анализ материалов в открытом доступе, запросы производителям, технико-экономическое сравнение. В результате исследования определен наиболее выгодный вариант. Область применения: энергодефицитные отдаленные районы, наиболее перспективные с точки зрения малой энергетики и обладающие потенциалом ВИЭ, в частности ветропотенциалом. Экономическая эффективность проекта заключается в снижении стоимости электроэнергии в шесть раз.Die Arbeit zielt auf die Losung der Energieversorgung von entlegenen Gebieten. Gegenstand der Studie ist ein Hybrid wind-Diesel-System der Elektrizitatsversorgung, das sich im Suden vom Gebiet Kemerowo auf einer Hohe von 1260 Meter. In der Studie wurden fur die Analyse von Materialien in der offentlichkeit, Anfragen von Herstellern, die technisch-wirtschaftlichen Vergleich. Die Studie ermittelt die Gunstigste Variante. Einsatzbereich: energiedefizite Randgebiete, die vielversprechendsten in Bezug auf niedrige Energie und mit dem Potential der erneuerbaren Energien, insbesondere Energiepotenzial. Die Wirtschaftseffektivitat des Projektes besteht in der Reduzierung der Kosten der Stromerzeugung in sechs mal