Raman measurements at room temperature reveal a characteristic concentration for a series of aqueous solutions of electrolytes, through which O–H stretching vibration of H2 O or dilute HDO obviously changes their con...Raman measurements at room temperature reveal a characteristic concentration for a series of aqueous solutions of electrolytes, through which O–H stretching vibration of H2 O or dilute HDO obviously changes their concentration dependence. This characteristic concentration is very consistent with another, through which the solutions undergo an abrupt change in their glass-forming ability. Interestingly, the molar ratio of water to solute at these two consistent concentration points is almost solute-type independent and about twice the hydration number of solutes. We suggest that just when the concentration increases above this characteristic concentration, bulk-like free water disappears in aqueous solutions and all water molecules among closely-packed hydrated solutes exhibit the characteristics of confined water.展开更多
In recent years,ionic modulation,particularly hydrogen intercalation,has gained attention as a powerful method for tuning the properties of materials.Although the SrFeO_(x)system is similar to SrCoO_(x),which can be p...In recent years,ionic modulation,particularly hydrogen intercalation,has gained attention as a powerful method for tuning the properties of materials.Although the SrFeO_(x)system is similar to SrCoO_(x),which can be protonated to the HSrCoO_(2.5)phase,it remains a challenge for the hydrogenation of SrFeO_(2.5).In this study,starting from the perovskite SrFeO_(3−δ),we achieved hydrogen intercalation and obtained stable hydrogenated brownmillerite-phase HSrFeO_(2.5)via Pt-catalyzed H-spillover at room temperature.The results indicate that the hydrogenation process is accompanied by the simultaneous oxygen ionic release,that is,perovskite SrFeO_(3−δ)is the prerequisite for the hydrogen-induced phase transition.Subsequently,upon hydrogenation,the entire phase transition cycle among the perovskite SrFeO_(3−δ),brownmillerite SrFeO_(2.5),and the hydrogenated HSrFeO_(2.5)phase,is completed.Furthermore,SrFeO_(3−δ)exhibits a remarkable 9.4%lattice expansion,and its electronic state undergoes a multi-step evolution,transforming from a pristine helical antiferromagnetic insulator to a bad metal,eventually returning to an antiferromagnetic insulator.Based on the obtained results,we fabricated microscale patterns with varied surface morphologies and electrical conductivities that can be used in fabricating electronic devices.This study presents a novel approach for modulating the properties of correlated and functional materials.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11474325,11474335,and 51172272)the Fund from the Chinese Academy of Sciences(Grant No.1731300500030)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB07030100)
文摘Raman measurements at room temperature reveal a characteristic concentration for a series of aqueous solutions of electrolytes, through which O–H stretching vibration of H2 O or dilute HDO obviously changes their concentration dependence. This characteristic concentration is very consistent with another, through which the solutions undergo an abrupt change in their glass-forming ability. Interestingly, the molar ratio of water to solute at these two consistent concentration points is almost solute-type independent and about twice the hydration number of solutes. We suggest that just when the concentration increases above this characteristic concentration, bulk-like free water disappears in aqueous solutions and all water molecules among closely-packed hydrated solutes exhibit the characteristics of confined water.
基金supported by the National Key R&D Program of China(Grant Nos.2022YFA1403000 and 2024YFA1408302)the CAS Project for Young Scientists in Basic Research(Grant No.YSBR-047)the Strategic Priority Research Program of the Chinese Academy of Sciences of China(Grant No.XDB33000000)。
文摘In recent years,ionic modulation,particularly hydrogen intercalation,has gained attention as a powerful method for tuning the properties of materials.Although the SrFeO_(x)system is similar to SrCoO_(x),which can be protonated to the HSrCoO_(2.5)phase,it remains a challenge for the hydrogenation of SrFeO_(2.5).In this study,starting from the perovskite SrFeO_(3−δ),we achieved hydrogen intercalation and obtained stable hydrogenated brownmillerite-phase HSrFeO_(2.5)via Pt-catalyzed H-spillover at room temperature.The results indicate that the hydrogenation process is accompanied by the simultaneous oxygen ionic release,that is,perovskite SrFeO_(3−δ)is the prerequisite for the hydrogen-induced phase transition.Subsequently,upon hydrogenation,the entire phase transition cycle among the perovskite SrFeO_(3−δ),brownmillerite SrFeO_(2.5),and the hydrogenated HSrFeO_(2.5)phase,is completed.Furthermore,SrFeO_(3−δ)exhibits a remarkable 9.4%lattice expansion,and its electronic state undergoes a multi-step evolution,transforming from a pristine helical antiferromagnetic insulator to a bad metal,eventually returning to an antiferromagnetic insulator.Based on the obtained results,we fabricated microscale patterns with varied surface morphologies and electrical conductivities that can be used in fabricating electronic devices.This study presents a novel approach for modulating the properties of correlated and functional materials.
