Crucial Role of Water in the Mechanosynthesis of CsPbI3 and Other ABX3 Halides

Mechanochemical synthesis of CsPbI₃, as a model system for ABX₃ halides, was studied. Water was shown to strongly promote the kinetics of formation of CsPbI₃ from the CsI+PbI₂ mixture through increased mobility of the constituting ionic species. Since many binary and ternary halides are hygroscopic, it was concluded that the presence of small, uncontrollable and unintentional additions of water should often occur in both precursor mixtures and synthesized complex halides boosting the kinetics of formation of many, if not all, ternary organic–inorganic hybrid halides such as, for example, MAPbX₃ (X=Cl, Br, I). In addition, trace amounts of water should influence the transport characteristics of complex halides. Thus, the presence of water explains, at least partially, the huge scatter in both the reported mechanochemical reaction times necessary for obtaining single-phase APbX₃ perovskite halides and the activation energies of ionic diffusion in APbX₃.     

Statistical models in sounding problems

Scientific-Research Institute of Mechanics, Gor'kii University. Translated from Izvestiya Vysshikh Uchenykh Zavedenii, Radiofizika, Vol. 32, No. 12, pp. 1502–1505, December, 1989.     

Specific feature of synthesis and technological scheme for manufacture of nonstoichiometric hydroxo chromium(III) formates

Specific features of the hydrothermal interaction between chromium(VI) oxide and formic acid to give water-soluble nonstoichiometric hydroxo chromium(III) formates with compositions from the range Cr(OH)_0.66(HCOO)_2.34-Cr(OH)_1.55(HCOO)_1.45 were studied. These compounds can be used in formulations for chromium-plating electrolytes and tanning agents.     

Unexpected behaviour of tosylated and acetylated imidazolinium salts

Tosylated and acetylated imidazolinium salts revealed an unexpected reactivity when treated with methyl iodide or benzyl bromide. Moreover an unprecedented acid-catalysed rearrangement for an acetylated imidazolinium salt was observed during an anion metathesis.     

Crystal structure of lanthanum potassium octacyanomolybdate(IV) nonahydrate

The crystal structure of KLaMo(CN)₈ · 9H₂O was determined from X-ray diffraction data. The crystals are monoclinic, space group P2₁/c, a = 8.7451(4), b = 25.2761(13), c = 10.6744(5) Å, β = 117.059(3)°, V = 2101.22(17) ų, Z = 4, ρ(calcd) = 2.037 g/cm³, R = 0.0242, wR ₂ = 0.0500 for 5656 independent reflections. The coordination polyhedra of the Mo, La, and K atoms are the tetragonal antiprism [Mo(CN)₈], the monocapped tetragonal antiprism [La(NC)₄(OH₂)₅], and the strongly distorted monocapped trigonal prism [K(NC)₃(OH₂)₄], respectively. The La and K atoms are N-linked by seven bridging cyano groups to form double layers with two sandwiched uncoordinated water molecules and the sandwiched terminal CN group. The complex can be formulated as “[K(H₂O)₂][La(H₂O)₅][Mo(CN)₈]” _n · 2nH₂O.     

Water-soluble ionic liquids as novel stabilizers in suspension polymerization reactions: engineering polymer beads

Aqueous solutions of ionic liquids have been used as novel and environmentally friendly reaction media to synthesize and "control" the size of different cross-linked polymer beads by suspension polymerization reactions. It was found that the investigated ionic liquids can act as novel stabilizing agents of the suspensions as a result of their surface-active properties. The results have demonstrated that the average size of polymer beads can be varied from the macro- to the nanoscale and their surface area can also be "adjusted" by this synthetic approach. Furthermore, the use of a combination of ionic liquids and water for the synthesis of polymers, the simple isolation of the products formed in this polymerization procedure, as well as the recycling of the continuous medium for further reactions open up possibilities for the development of "new and green" polymerization processes.     

Effect of nuclear quadrupole interactions on the dynamics of two-level systems in glasses

The standard tunneling model describes quite satisfactorily the properties of amorphous solids at temperatures T < 1K in terms of an ensemble of two-level systems including the logarithmic temperature dependence of the dielectric constant. Yet, experiments have shown that at ultralow temperatures T< 5 mK such a temperature behavior breaks down and the dielectric constant becomes temperature independent (plateau effect). In this Letter we suggest an explanation of this behavior exploiting the effect of the nuclear quadrupole interaction on tunneling. We also predict that the application of a sufficiently large magnetic field B> 10T should restore the logarithmic dependence because of the suppression of the nuclear quadrupole interaction.