Polysulfides crystals

Sodium thiosulfate is a by-product of the manufacture of Sulfur Black and other sulfur dyes (qv), where organic nitro compounds are treated with a solution of sodium polysulfide to give thiosulfate. The dyes ate insoluble and ate recovered by fUtration. The fUtrate is treated with activated carbon and filteted to obtain a sodium thiosulfate solution. After concentration and crystallization, the final product assays ca 96% Na2S202 5H20 (34) (see Dyes AND... 

C2h isomer (8) is less well characterized but is said to result from the reaction of hexachlorobutadiene, CCI2 =CC1—CCl=CCl2, with polysulfide anions. The treatment of S2CI2 with [NBu4]2[Zn(o -C3S5)2] yields a mixture of C3Sg and C6S12 which can be separated by fractional crystallization from CS2 ... 

Reactions with sulfides, polysulfides, sulfur oxides and the oxoacids of sulfur are complex and the products depend markedly on reaction conditions (see also p. 745 for blue crystals in chamber acid). Some examples are ... 

Many of the polysulfides described above have been investigated by X-ray diffraction on either powders or single crystals. In all cases the more sulfur-rich anions (n>3) form unbranched chains the symmetry of which varies between Ci, C2, and Cs. According to Fig. 1 the symmetry C2 results if all torsion angles have the same sign (right-handed helix + + +... left-handed helix ----...). If the different torsion angles of the anion vary between + and... 

Some compounds with network structures are synthesized by high-temperature reactions of metals with elemental sulfur [2, 8]. Rauchfuss et al. exploited the low-temperature synthesis of metal polysulfides by the reaction of metals with elemental sulfur in strong donor solvents. The reaction of copper powder with Ss in pyridine gives a copper polysulfide cluster Cu4(S5)2(-py)4 as orange crystals (Scheme 10) [45]. Furthermore, zinc powder reacts... 

The monosulfides of the alkaline earth metals crystallize in the rock salt (MgS, CaS, SrS, BaS) and zinc blende (BeS) structures. BaS is insoluble in water, while the other monosulfides are sparingly soluble but hydrolyzed on warming (except MgS that is completely hydrolyzed). The monoselenides are isomorphous to the sulfides. The monotellurides CaTe, SrTe, BaTe adopt the rock salt stmcture, while BeTe has the zinc blende and MgTe the wurtzite structure. Alkaline earth polysulfides may be prepared by boiling a solution or suspension of the metal hydroxide with sulfur, e.g.,... 

After demonsfrafing fhe sfabilizafion of CdS- and CdSe-based PEC, using sulfide- or polysulfide-confaining elecfrolytes, Ellis el al. [51] proceeded lo show dial fhe photoanodic dissolution of single-crystal n-type CdTe, which was found to be unstable in a polysulfide electrolyte, could be completely quenched by adding Na2Te in the alkaline solution of NaOH. The photoelectrochemistry in their cell was considered to be consisting of the reactions... 

The importance of controlling the operating temperatures of single-crystal and polycrystalline n-CdSe/polysulfide/CoS liquid junction cells to obtain the maximum possible photoconversion has been emphasized [55], In fact, a dramatic effect of temperature was established on the power output of the cells, particularly those based on thin film electrodes. 

It has been illustrated that polycrystalline materials can be operated in regenerative electrolytic solar cells yielding substantial fractions of the respectable energy conversion efficiency obtained by using single crystals. Pressure-sintered electrodes of CdSe subsequently doped with Cd vapor have presented solar conversion efficiencies approaching 3/4 of those exhibited by single-crystal CdSe electrodes in alkaline polysulfide PEC [84]. 

Differences in behavior between polycrystalline and single-crystal CdSe electrodes in polysulfide PEC involving the short- and long-term changes in photovoltage and photocurrents have been discussed by Cahen et al. [88], on the basis of XPS studies, which verified the occurrence of S/Se substitution in these electrodes when immersed in polysulfide solution, especially under illumination. The presence of a thin (several nanometers) layer of CdS on top of the CdSe was shown to influence... 

Fig. 5.4 Power characteristics of CdS/sodium polysulfide solar cells. Solution composition is 0.1 M NaiS + 0.01 M S+ 0.01 M NaOH. (i) Single-crystal photoanode ...

An early discovery about n-CuInSe2 and n-CuInS2 semiconductor crystals was that they are extremely stable when used as photoanodes in aqueous polysulfide... 

Colorless crystals or white crystalline mass rapidly deliquesces converts to a yellow rhomhohedral crystalline mass upon exposure to air, forming polysulfides and H2S density 1.68g/cm3 the hemdiydrate loses water at about 175°C melts at 455°C to a dark red hquid decomposes in water soluble in alcohol. 

It is supposed to originate from the dissociation of 84 . This dissociation is perhaps significant at high temperatures, like those of the synthesis of ultramarine pigments or those of doping of alkali halide crystals. 83 and 82 radicals have also been observed in the alkali halides doped with sulfur [30, 31]. Another radical anion polysulfide, 84 , has been identified, by EPR experiments, in solution in DMF, originating from the dissociation of 8g , which is the least reduced polysulfide in this solvent [32]. 

H.15 Sodium thiosulfate, which as the pentahydrate, Na2S203-5H20, forms the large white crystals used as photographer s hypo, can be prepared by bubbling oxygen through a solution of sodium polysulfide,... 

Figure 3. Impedance response curves for n-CdSe single crystal in polysulfide (CdSe in NaOH/S=/S/1 1 1 potential +0.5 V, area = 0.15 cm2)...

We have measured the EER spectra of single crystal CdSe in a polysulfide electrolyte using the same configuration for which the relaxation spectrum analysis was applied. Preliminary results are shown in Fig. 6. 

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