Crystallization of calcium sulfate dihydrate (CaSO4·2H2O, gypsum) in sodium chloride solutions has been studied in the presence of magnesium ion. It was shown that Mg2+ has an inhibiting effect on the two stages of precipitation: nucleation and growth. Kinetic results were explained on the basis of the strong effect of magnesium ions on gypsum solubility. In the studied range of the ionic strength (IS), it was found that in the presence of NaCl the solubility increase stops beyond IS = 0.31 mol·L–1 whereas it continues to rise in the presence of MgCl2. X-ray diffraction analyses showed that magnesium ions act by substituting the calcium ones or by insertion in the defects of the gypsum crystal lattice.

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Here we have done SCAPS simulation for optimizing the performance of CsPbBr3-based PSC. We first optimized the BMC with HTL connected mode and then optimized the CsPbBr3, TiO2, & CFTS layers' various parameters in both with-HTL and without-HTL modes.

Incommensurately modulated ammonium tetrafluoroberyllate (AFB) occurs in a narrow temperature interval between the paraelectric room-temperature phase with space group Pnma (Ti = 178 K) and the ferroelectric low-temperature phase with space group Pna2(1) (Tc = 173 K). The structure is determined from accurate single-crystal X-ray diffraction data collected with synchrotron radiation at 175 K. The superspace group of the structure is Pnma(alpha00)0ss with alpha = 0.4796 (4). Both structure refinements and the maximum entropy method lead to the same structure model, which involves only single harmonic modulations. The building units of the structure are BeF4(2-) and NH4+ complex ions with approximately tetrahedral point symmetry. They are relatively rigid and the modulations consist mainly of translations of the tetrahedra and their rotations around a fixed axis. The modulation is related to changes in the network of the hydrogen bonds. The low-temperature superstructure can be described as a commensurately modulated structure with the same superspace symmetry. The first harmonic modulations of the low-temperature and incommensurate phases are related by a scale factor with a value of approximately two. In addition, the low-temperature phase exhibits a second harmonic modulation that is responsible for shifts along c and the ferroelectricity in this phase. The experimental data of the incommensurate phase do not contain any evidence for the presence of a second harmonic in the modulation functions. This suggests that the development of the second harmonic, i.e. the development of the spontaneous polarization, is responsible for the lock-in transition.