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Thermogravimetric analysis (TGA) is a key material characterization method for studying the thermal stability and thermochemical process. However, the common TGA for bulk samples lacks sufficient spatial information, which blurs the intrinsic thermal decomposition characteristic and limits the understanding of the structure–performance relationship. Here, we report a dark-field microscope (DFM) method for studying thermal desorption process of I2 from I2-loaded zeolitic imidazolate framework-8 (I2@ZIF-8). Because of the high spatial resolution, DFM enables the imaging and tracking of the local mass loss of I2 in single I2@ZIF-8 particles at different reaction temperatures. We obtain from the DFM images the single-particle thermogravimetric and differential thermogravimetric curves to evaluate the inherent thermal stability of single I2@ZIF-8 particles. We also find the heterogeneous thermal decomposition property among different I2@ZIF-8 particles. Furthermore, we demonstrate the capacity of DFM to quantitatively determine thermal kinetics parameters such as the diffusion coefficient and activation energy of I2 in individual and multiple ZIF-8 particles. These useful results are essential for developing high-efficient porous adsorbents for the capture of I2.

We propose a method to extract the properties of the isobaric mass parabola based on the total double β decay energies of isobaric nuclei. Two important parameters of the mass parabola, the location of the most β-stable nuclei Z A and the curvature parameter b A , are obtained for 251 A values based on the total double β decay energies of nuclei compiled in AME2016 database. The advantage of this approach is that we can remove the pairing energies term P A caused by odd-even variation, and the mass excess M (A, Z A ) of the most stable nuclide for mass number A in the performance process, which are used in the mass parabolic fitting method. The Coulomb energy coefficient a c = 0.6910 MeV is determined by the mass difference relation of mirror nuclei, and the symmetry energy coefficient is also studied by the relation a sym (A) = 0.25b A Z A .

The thermochromic properties of hydrated metal halide perovskites (MHPs) are promising for applications in smart windows, solar cells, optical sensors, and information storage. Traditional ensemble characterization methods always study the averaged thermochromic activity, lacking the accurate structure–activity correlation. Here we utilize dark-field microscopy (DFM) to in situ image the thermochromic processes of single isolated hydrated hybrid perovskite (CH3NH3)4PbI6–x Cl x ·2H2O (MA4PbI6–x Cl x ·2H2O) microparticles. The thermal-induced dehydration transition is demonstrated to alter the color of single MA4PbI6–x Cl x ·2H2O particles. Operando single-particle mapping results reveal the significant intra- and interparticle variations of thermochromic behaviors, yielding unexpected single or multistep multicolor thermochromic processes. These phenomena are confirmed to be governed by the crystallinity of single MA4PbI6–x Cl x ·2H2O particles that results in distinct composition-dependent bandgaps and thermal decomposition pathways. The present work highlights the important role of single-particle imaging for resolving the intrinsic thermochromic characteristic of hydrated MHPs, therefore opening a way for rational design of stimuli-responsive materials.

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