Experimental Observation of the High Pressure Induced Substitutional Solid Solution and Phase Transformation in Sb2S3

Potential Roles of Metals in the Pathogenesis of Pulmonary and Systemic Hypertension

Pulmonary and systemic hypertension (PH, SH) are characterized by vasoconstriction and vascular remodeling resulting in increased vascular resistance and pulmonary/aortic artery pressures. The chronic stress leads to inflammation, oxidative stress, and infiltration by immune cells. Roles of metals in these diseases, particularly PH are largely unknown. This review first discusses the pathophysiology of PH including vascular oxidative stress, inflammation, and remodeling in PH; mitochondrial dysfunction and metabolic changes in PH; ion channel and its alterations in the pathogenesis of PH as well as PH-associated right ventricular (RV) remodeling and dysfunctions. This review then summarizes metal general features and essentiality for the cardiovascular system and effects of metals on systemic blood pressure. Lastly, this review explores non-essential and essential metals and potential roles of their dyshomeostasis in PH and RV dysfunction. Although it remains early to conclude the role of metals in the pathogenesis of PH, emerging direct and indirect evidence implicates the possible contributions of metal-mediated toxicities in the development of PH. Future research should focus on comprehensive clinical metallomics study in PH patients; mechanistic evaluations to elucidate roles of various metals in PH animal models; and novel therapy clinical trials targeting metals. These important discoveries will significantly advance our understandings of this rare yet fatal disease, PH.

Pressure-induced phase transitions, amorphization and alloying in Sb2S3

Despite the extensive and systematic studies of pressure-induced phase transitions in sesqui-chalcogenides, several puzzles still remain to be solved. Here, the complicated phase transitions, amorphization, and alloying behaviors of the binary semiconductor antimony trisulfide (Sb₂S₃) were observed by performing in situ high-pressure angle-dispersive x-ray diffraction, Raman spectroscopy and resistance measurements. Upon compression, two phase transitions are observed in Sb₂S₃ before it transforms into a high-density amorphous state (HDA). Notably, it is found that the pressure transmitting medium has a great effect on these changes. Then, Sb₂S₃ shows an irreversible process after full decompression and a low-density amorphous state (LDA) can be obtained. Unexpectedly, a site-disordered Sb-S alloy can be formed via recompressing LDA. These results indicate that the Sb³⁺ lone electron pair activity will be destroyed at high pressures, which may make Sb₂S₃ a promising thermoelectric material at high pressures.

Phase transition mechanism and bandgap engineering of Sb2S3 at gigapascal pressures

Earth-abundant antimony trisulfide (Sb2S3), or simply antimonite, is a promising material for capturing natural energies like solar power and heat flux. The layered structure, held up by weak van-der Waals forces, induces anisotropic behaviors in carrier transportation and thermal expansion. Here, we used stress as mechanical stimuli to destabilize the layered structure and observed the structural phase transition to a three-dimensional (3D) structure. We combined in situ x-ray diffraction (XRD), Raman spectroscopy, ultraviolet-visible spectroscopy, and first-principles calculations to study the evolution of structure and bandgap width up to 20.1 GPa. The optical band gap energy of Sb2S3 followed a two-step hierarchical sequence at approximately 4 and 11 GPa. We also revealed that the first step of change is mainly caused by the redistribution of band states near the conduction band maximum. The second transition is controlled by an isostructural phase transition, with collapsed layers and the formation of a higher coordinated bulky structure. The band gap reduced from 1.73 eV at ambient to 0.68 eV at 15 GPa, making it a promising thermoelectric material under high pressure.