N(CH3)4PbI3 is much more stable than CH3NH3PbI3, both kinetically and thermodynamically, and much less prone to water-induced degradation; the use of quaternary ammonium cations may be effective to produce more stable lead halide perovskites.

We report the results of a multi-technique study on the thermodynamics and kinetics of formamidinium lead iodide (FAPI) thermal decomposition. Thermodynamics was investigated by means of Knudsen effusion techniques. Kinetics was studied either by temperature-controlled powder X-ray diffraction or by two isoconversional treatments of differential scanning calorimetry data. FAPI appears to be much more thermally stable compared to methylammonium lead iodide, as predictable from the lower acidity of the formamidinium cation compared to methylammonium. The chemical processes responsible for its thermal degradation appear to be quite complex as highlighted by the composition of the gaseous phase evolved during the process. The apparent activation energy values of the decomposition obtained from X-ray diffraction (XRD) (112 ± 9 kJ/mol) and differential scanning calorimetry (DSC) measurements (205 ± 20 and 410 ± 20 kJ/mol, respectively, for the first and second decomposition steps identified by the deconvolution procedure) reflect the different steps of the process observed by the two techniques. The thermodynamic properties of the more important decomposition channels and the enthalpy of formation of FAPI were estimated by combining the results of Knudsen effusion measurements.

The Mount Pizzuto earth flow has been periodically active in recent decades. Early in 2006, it surged and created a dam across the Ginestra torrent. Episodic floods induced by the earthflow dam periodically damaged a section of a local road and power and telephone service lines. This paper presents a map showing deformational structures along the flow and a geometric reconstruction of thrust faults at the earth-flow toe from 2006 to 2014. The map, produced on the basis of field observations, shows the spatial distribution of back-tilted surfaces, flank ridges and normal, thrust, and strike-slip faults. Springs, creeks, and ponds are also shown on the map. The map indicates that the earth flow is composed of five kinematic zones. Cartographic data and the spatial-temporal reconstruction of the thrusting evolution offer the basis for interpreting the (mid-term) kinematics of the flow and its controlling factors, and for assessing the influence of earth-flow movement on torrent channel capacity.

No abstract

In the present study, the molar heat capacity of solid formamidinium lead iodide (CH5N2PbI3) was measured over the temperature range from 5 to 357 K using a precise automated adiabatic calorimeter. In the above temperature interval, three distinct phase transitions were found in ranges from 49 to 56 K, from 110 to 178 K, and from 264 to 277 K. The standard thermodynamic functions of the studied perovskite, namely the heat capacity C°p(T), enthalpy [H0(T) − H0(0)], entropy S0(T), and [G°(T) − H°(0)]/T, were calculated for the temperature range from 0 to 345 K based on the experimental data. Herein, the results are discussed and compared with those available in the literature as measured by nonclassical methods.