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Dilute magnetic semiconductors (DMSs) are crucial for various spintronic and magneto-optical applications, typically created by doping d- or f-orbital-based metal ions into wide bandgap nonmagnetic semiconductors. In this study, we synthesized Pb1–xCoxI2 (x = 0.05–0.14) alloys by doping PbI2 with Co2+ ions using a simple mechanochemical method and characterized their morphology, structure, thermal stability, and magnetic properties. The Co2+ ions in the alloys formed CoI2 clusters with dimensions less than 10 nm, homogeneously distributed within the PbI2 lattice. These alloys exhibited a paramagnetic phase transition with a thermal hysteresis loop at high temperatures (>370 K) and Co2+-content-dependent magnetic short-range ordering behaviors (spin glass, cluster glass, or superparamagnetism) at low temperatures (<15 K). The strong interactions between itinerant electrons and the localized 3d electrons of Co2+ ions indicate Pb1–xCoxI2 alloys, with characteristic behaviors observed in DMSs. This study demonstrates that mechanochemical synthesis is a facile and efficient method for preparing alloys of van der Waals crystals, offering precise control over alloy composition, particularly when dealing with reaction systems involving components with different soft–hard acid–base properties. [ABSTRACT FROM AUTHOR]

Demonstrating the mechanism of a structural phase transition (SPT) is significantly important for guiding the precise design of new phase transition materials. Herein, an ion-pair compound [DPIm][Ni(mnt)2] (1, DPIm+ = 1,3-dipropylimidazolium and mnt2− = maleonitriledithiolate) has been obtained and thoroughly characterized through microanalysis, spectral, and thermal analysis techniques. The [Ni(mnt)2]− anions form columnar stacks, featuring one-dimensional (1D) S = ½ spin chains. 1 undergoes an SPT, associated with thermal, magnetic, and dielectric anomalies. The SPT results from the competition between antiferromagnetic (AFM) coupling interactions within anion stacks and elastic deformation of the lattice. The magnetic anomaly arises from changes in the magnetic coupling constant within an anion stack between two phases, while the dielectric anomaly is due to the volume-conserving motion of the imidazolyl ring in the cation. 1 exhibits high-κ characteristics, attributed to the electron polarization of both anions and cations, ion displacement, and dipole orientation polarization of cations. It is also demonstrated that a longer dialkyl chain inhibits the rotational freedom of the imidazolyl ring, resulting in the absence of a plastic crystal state in 1 compared to others containing [Ni(mnt)2]− and dialkylimidazolium. [ABSTRACT FROM AUTHOR]

A new haloargentate hybrid, [Et‐dabco]₂Ag₂Br₄ (1) (Et‐dabco+=1‐Ethyl‐1,4‐diazabicyclo[2.2.2]octan‐1‐ium), has been successfully synthesized by a solution diffusion method and characterized using microanalysis, single crystal X‐ray diffraction, variable‐temperature powder X‐ray diffraction (PXRD), differential scanning calorimetry (DSC), and dielectric spectra. The crystal structure of 1 at 273 K contains one‐dimensional (1D) anionic [Ag₂Br₄]2− chains, with the [Et‐dabco]+ cations embedded in the gaps between the inorganic chains. Hybrid 1 underwent a reversible structural phase transition (SPT) at around 464.5 K on heating, and the Pawley refinement revealed similar crystal structures in the low‐ and high‐temperature phases. The SPT endows 1 with switchable and bistable dielectric properties. Combined with previous studies, it was revealed that the self‐assembly of silver halide (AgX) with the lower rotational energy barrier of 1‐alkyl‐1,4‐diazabicyclo[2.2.2]octan‐1‐ium in solution probably achieves new phase transition materials. [ABSTRACT FROM AUTHOR]

In this study, three supramolecular compounds, namely [Na(18-crown-6)]ReO4 (1), [K(18-crown-6)]ReO4 (2) and [NH4(15-crown-5)2]ReO4 (3) were synthesized and characterized using microanalysis, thermogravimetric, differential scanning calorimetric and powder X-ray diffraction techniques, among others. Herein, 15-crown-5 and 18-crown-6 represent 1,4,7,10,13-pentaoxacyclopentadecane and 1,4,7,10,13,16-hexaoxacyclooctadecane, respectively. Both 1 and 2 experienced one-step reversible phase transition at ∼436 K and ∼360 K, respectively, while 3 underwent three steps of reversible phase transitions at ∼289 K, ∼352 K and ∼380 K. A dielectric anomaly occurred at ∼433 K (∼363 K) for 1 (2), consistent with the temperature obtained from DSC measurement. In the dielectric spectra of 3, anomalies were observed at ∼386 K and ∼433 K, corresponding to two thermal anomalies observed at higher temperatures in the DSC plot. However, there was an absence of dielectric response around 289 K where a thermal anomaly appeared in the DSC plot. The distinct crystal structures, phase transitions and dielectric properties in 1–3 stem from the degree of compatibility between the radii of M+ (Na+, K+ and NH4+) and the ring sizes of crown ethers (18-crown-6 and 15-crown-5). [ABSTRACT FROM AUTHOR]