Blending of various chemical bonds with different strengths within a framework is expected to induce some anomalous physical properties.Herein,a novel metal squarate framework containing covalent bonds,coordination bo...Blending of various chemical bonds with different strengths within a framework is expected to induce some anomalous physical properties.Herein,a novel metal squarate framework containing covalent bonds,coordination bonds and hydrogen bonds was synthesized and it showed a uniaxial negative thermal expansion(NTE).A combination of in situ powder/single-crystal X-ray diffraction,Raman spectroscopy and density-functional theory(DFT)calculations revealed that this anomalous thermal expansion originates from a hydrogen bond-triggered wine-rack-like distortion.This study can provide a new strategy for the rational design of hybrid NTE compounds.展开更多
Over the past decades,two dimensional(2D)-structured materials have attracted considerable interest due to not only their intrinsic aesthetic appeal but also their intriguing physical properties.Herein,a 2D bilayer si...Over the past decades,two dimensional(2D)-structured materials have attracted considerable interest due to not only their intrinsic aesthetic appeal but also their intriguing physical properties.Herein,a 2D bilayer silver squarate was synthesized,which showed combined colossal positive thermal expansion(PTE)along the packing direction and negative thermal expansion(NTE)within the layer.The combined analyses of high resolution synchrotron X-ray powder diffraction,atomic pair distribution function(PDF)and Raman spectra shed light on the anomalous thermal expansion behaviors being closely related to the interlayer argentophilicity and thermal flipping of the ligand.Furthermore,this compound exhibited an intrinsic moderate proton conductivity(1.2×10^(-4) S cm^(-1) at 80℃ under 98% RH).We believe that this work can not only deepen our understanding of the thermal expansion properties of 2D materials but also provide guidance for the design and synthesis of novel functional materials.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.22005340).
文摘Blending of various chemical bonds with different strengths within a framework is expected to induce some anomalous physical properties.Herein,a novel metal squarate framework containing covalent bonds,coordination bonds and hydrogen bonds was synthesized and it showed a uniaxial negative thermal expansion(NTE).A combination of in situ powder/single-crystal X-ray diffraction,Raman spectroscopy and density-functional theory(DFT)calculations revealed that this anomalous thermal expansion originates from a hydrogen bond-triggered wine-rack-like distortion.This study can provide a new strategy for the rational design of hybrid NTE compounds.
基金supported by the National Natural Science Foundation of China(Grant No.22005340 and 21875285)the Fundamental Research Funds for the Central Universities(20CX06047A)+1 种基金the Taishan Scholar Foundation(ts201511019)the Development Projects of Shandong Province(Grant 2019JZZY010331).
文摘Over the past decades,two dimensional(2D)-structured materials have attracted considerable interest due to not only their intrinsic aesthetic appeal but also their intriguing physical properties.Herein,a 2D bilayer silver squarate was synthesized,which showed combined colossal positive thermal expansion(PTE)along the packing direction and negative thermal expansion(NTE)within the layer.The combined analyses of high resolution synchrotron X-ray powder diffraction,atomic pair distribution function(PDF)and Raman spectra shed light on the anomalous thermal expansion behaviors being closely related to the interlayer argentophilicity and thermal flipping of the ligand.Furthermore,this compound exhibited an intrinsic moderate proton conductivity(1.2×10^(-4) S cm^(-1) at 80℃ under 98% RH).We believe that this work can not only deepen our understanding of the thermal expansion properties of 2D materials but also provide guidance for the design and synthesis of novel functional materials.
