Room temperature phosphorescence(RTP)in metal-free organic materials has attracted considerable attention due to its rich excited state properties,high quantum efficiency,long luminescence lifetimes,etc.,showing great...Room temperature phosphorescence(RTP)in metal-free organic materials has attracted considerable attention due to its rich excited state properties,high quantum efficiency,long luminescence lifetimes,etc.,showing great potential in organic optoelectronic devices,bioimaging,information anti-counterfeiting,and so forth.The crystals have excellent rigidity and clear molecular packing patterns,which can effectively avoid non-radiative transitions of excitons for phosphorescence enhancement.In the early stages,researchers paid great attention to the regulation of RTP performance in crystalline states.However,due to the complex preparation and poor processability of crystals,amorphous materials with RTP features have become a new research topic recently.This perspective aims to summarize the recent advances of RTP materials from crystalline to amorphous states,and analyze their molecular design strategies and luminescence mechanisms in detail.Finally,we prospect the future research directions of amorphous RTP materials.This perspective will provide a guideline for the future study of advanced RTP materials.展开更多
The structures of the bulk amorphous Zr41Ti14Cu12.5Nil0.0Be22.5 alloy have been analyzed in solid, supercooled liquid and liquid with X-ray diffraction. The first coordination sphere radii and the first coordination n...The structures of the bulk amorphous Zr41Ti14Cu12.5Nil0.0Be22.5 alloy have been analyzed in solid, supercooled liquid and liquid with X-ray diffraction. The first coordination sphere radii and the first coordination numbers are 0.312 um, 11.2 in solid state.10.932 nm, 10.932 in supercooled liquid region and 0.305 urn, 11.296 in liquid state. The structures are the same in different states. But it shows some tendency to crystallizing that the first coordination sphere radius and the first coordination number drop in supercooled liquid region.展开更多
In this work the statistical mechanical equation of state was developed for volumetric properties of crystalline and amorphous polymer blends.The Ihm-Song-Mason equations of state(ISMEOS) based on temperature and dens...In this work the statistical mechanical equation of state was developed for volumetric properties of crystalline and amorphous polymer blends.The Ihm-Song-Mason equations of state(ISMEOS) based on temperature and density at melting point(T_m and ρ_m) as scaling constants were developed for crystalline polymers such as poly(propylene glycol) + poly(ethylene glycol)-200(PPG + PEG-200),poly(ethylene glycol) methyl ether-300(PEGME-350) + PEG-200 and PEGME-350 + PEG-600.Furthermore,for amorphous polymer blends containing poly(2,6-dimethyl-1,4-phenylene oxide)(PPO) + polystyrene(PS) and PS + poly(vinylmethylether)(PVME),the density and surface tension at glass transition(ρ_g and γ_g) were used for estimation of second Virial coefficient.The calculation of second Virial coefficients(B_2),effective van der Waals co-volume(b) and correction factor(α) was required for judgment about applicability of this model.The obtained results by ISMEOS for crystalline and amorphous polymer blends were in good agreement with the experimental data with absolute average deviations of 0.84%and 1.04%,respectively.展开更多
Curie temperature of amorphous alloys Co_(90-x)Cr_x Zr_(10) decreases linearly with increas- ing x.Average magnetic moment per magnetic atom Co or Cr is 1.51 μB or -3.62 μB respectively.The temperature dependence of...Curie temperature of amorphous alloys Co_(90-x)Cr_x Zr_(10) decreases linearly with increas- ing x.Average magnetic moment per magnetic atom Co or Cr is 1.51 μB or -3.62 μB respectively.The temperature dependence of spontaneous magnetization at low temper- atures is in agreement with Bloch's T^(3/2) law.The spin wave stiffness constant decreases with increasing x from 4 to 20.The range of interaction is 2—3 atoms for x=4 and nearest neighbour atom for x=20.The crystallization temperature increases mono- tonically with increasing x.It may relate to the average number of outer electrons per atom.The crystalline phase components of heat-treated alloys were analyzed by X-ray diffration and thermomagnetic measurement.展开更多
Aim To investigate the multiple melting behavior of polyamide 6(PA 6) in polyamide 6/linear low density polyethylene blends crystallized from the crystal amorphous state. Methods\ The effects of annealing tempera...Aim To investigate the multiple melting behavior of polyamide 6(PA 6) in polyamide 6/linear low density polyethylene blends crystallized from the crystal amorphous state. Methods\ The effects of annealing temperature, annealing time, heating rate, and the step wise annealing were measured by DSC. Results and Conclusion\ There exists a critical heating rate affecting the middle temperature melting peak. When annealed at the temperature close to the melting peak, the main melting peak of PA 6 shifted to a higher temperature. Within a short time, annealing time has much effect on neat PA 6 but little effect on PA 6 in the blends. Addition of PE results in a decreasing in the height of melting peak. These phenomenon show that the melting behavior of PA 6 was affected by PE, compatibilizer, as well as thermal treatment.展开更多
A series of nominal composition Ti/（ZrO2）x（RuO2）l-x （0.1≤x≤0.9） coatings chan-ged in 10% steps was deposited on titanium substrate from RuCl3·nH2O and ZrCl4 containing ethanol solution by thermal decompos...A series of nominal composition Ti/（ZrO2）x（RuO2）l-x （0.1≤x≤0.9） coatings chan-ged in 10% steps was deposited on titanium substrate from RuCl3·nH2O and ZrCl4 containing ethanol solution by thermal decomposition method. The X-ray diffraction （XRD）, high-resolution transmission electron microscopy （HR-TEM） and electrochemical tests were performed to clarify the effects of ZrO2 content on the structure and capacitive property of Ti/（ZrO2）x（RuO2）l-x. The results show that by adding ZrO2 into the coatings the degree of crystallization of RuO2 decreases. The specific capacitance firstly increases and then deceases with the increase of ZrO2 content in the mixed oxide coatings. The film of Ti/（ZrO2）0.6（RuO2）0.4 consisting of amorphous matrix and fine nano-crystalline RuO2 （about 4 nm） has the maximum specific capacitance of 713.27 F/g（RuO2）.展开更多
Fe/Gd multilayers were prepared by alternate vapor deposition of pure Fe and Gd at a rate of 0.01-0.03 nm/s in an ultra-high-vacuum elec- tron-gun evaporation system. The effects of the constituent metal layer thickne...Fe/Gd multilayers were prepared by alternate vapor deposition of pure Fe and Gd at a rate of 0.01-0.03 nm/s in an ultra-high-vacuum elec- tron-gun evaporation system. The effects of the constituent metal layer thickness on the microstructures and magnetic properties of the films were investigated by low angle X-ray diffraction, transmission electron microscopy, and vibrating sample magnetometer. The experimental results show that a transition from the polycrystalline to amorphous state in the Fe layers occurs with the decrease of Fe layer thickness in the Fe/Gd multilayers. The saturation magnetization of the multilayers reduces significantly with decreasing Fe layer thickness and increasing Gd layer thickness. A superparamagnetic behavior at room temperature is observed for the [Fe（0.6 nm）/Gd（4.0 nm）]15 multilayer due to the formation of discontinuous Fe layers.展开更多
Head-to-tail bonded perylene bisimide(PBI)dyads with different branched alkyl chains substituted at the terminal imide position show various stacking modes,which results in different effects on the excitonic processes...Head-to-tail bonded perylene bisimide(PBI)dyads with different branched alkyl chains substituted at the terminal imide position show various stacking modes,which results in different effects on the excitonic processes and electron transportation.The dyad bearing branched alkyl chains with the branching sites close to the imide positions forms homogeneously amorphous state,while with branching sites being away from the imide positions the PBI core tend to stack with multiple modes.There are fewer energy trapping sites in the homogeneously amorphous state,but in the multiple stacking system the strongπ-πinteractions give more trapping sites.Our study demonstrates that the aggregation state of PBI-based acceptors plays an important role in the performances of organic solar cells(OSCs).Multiple stacking needs to be diminished to avoid the constrained exciton dissociation and retarded charge transport in the active layer.展开更多
1.IntroductionMechanical alloying is one of the effec-tive methods to prepare amorphous alloys[1].This method was first used by Koch etal.to prepare the Ni;Nb;amorphous alloy[2].Since then many other amorphousbinary a...1.IntroductionMechanical alloying is one of the effec-tive methods to prepare amorphous alloys[1].This method was first used by Koch etal.to prepare the Ni;Nb;amorphous alloy[2].Since then many other amorphousbinary alloys have been prepared by the展开更多
CONSPECTUS:The global production of polymer products currently exceeds 400 megatons annually.To ensure effective and environmentally responsible use of this vast resource,optimizing the properties of the products is e...CONSPECTUS:The global production of polymer products currently exceeds 400 megatons annually.To ensure effective and environmentally responsible use of this vast resource,optimizing the properties of the products is essential.Achieving this requires precise control over the internal structure of the polymers.Depending on the materials used,polymers can exist in either amorphous or semicrystalline states.Processing is often performed from the melt state,and the cooling rate plays a critical role in determining whether amorphous or semicrystalline products are formed alongside other process parameters such as the pressure and shear rates.To understand the structure formation during processing,knowledge of the cooling rate dependence is therefore essential.As all of these processes are associated with thermal effects,calorimetry is universally applicable here.Achieving cooling rates that are comparable to those during processing has therefore long been a challenge for calorimetric measurement methods.With the introduction of MEMS-based chip sensors for calorimetry,significant progress has been made in reproducing conditions,such as those that occur during injection molding.These special calorimetric techniques are often summarized under the terms Fast Scanning Calorimetry(FSC)or Nanocalorimetry,alluding to nanogram samples.Investigations with controlled cooling rates of up to 1×10^(6)K/s are now possible with special chip sensors and allow the study of material properties under extreme conditions.Technological issues such as crystallization and nucleation processes under processrelevant conditions can be investigated in most cases with commercial devices that achieve cooling rates of 10^(4)K/s.The cooling rates to be considered in relation to various manufacturing processes are discussed here,and the functionality of corresponding chip calorimeters is briefly presented.Since calorimetry only provides general information on the processes taking place in the material,but not directly on the resulting structures,combinations of FSC and methods for structure elucidation,e.g.,microscopy,are also presented.The main part of this Account deals with contributions of FSC to the understanding of crystallization processes under conditions as they occur in different manufacturing processes.Not only the influence of the cooling rate during injection molding but also the multistage cooling by chill rolls during film production is considered.Thanks to the high scanning rate of FSC,needed to bypass crystallization in the low-supercooling temperature range where heterogeneous nucleation dominates,an important aspect of polymer structure formation-homogeneous crystal nucleation-has become accessible for direct observation.Homogeneous nucleation can occur not only during cooling but also during storage at temperatures close to or even below the glass transition temperature in the amorphous state.The possibilities of FSC for the generation and investigation of amorphous states are illustrated by an example.Finally,possible further developments of FSC and expected further applications of this fascinating technology are considered.展开更多
The study of temperature-driven phase transitions is significant in phosphate chemistry,as these transitions often lead to unique physical properties for specific applications,such as catalysis,energy storage,ion cond...The study of temperature-driven phase transitions is significant in phosphate chemistry,as these transitions often lead to unique physical properties for specific applications,such as catalysis,energy storage,ion conduction,and nonlinear optics[1–3].The phase transition from room temperature(RT)to high temperature(HT)in phosphates is always from periodic structures to disordered or amorphous states[4–8].At RT,phosphates often maintain a highly ordered crystalline structure,which is stabilized by the lower thermal energy.As the temperature increases,the thermal energy disrupts the periodic arrangement of atoms and leads to a phase transition,where the once ordered structure becomes increasingly disordered or even amorphous.展开更多
基金National Natural Science Foundation of China,Grant/Award Numbers:21975120,62134007,21875104Jiangsu Postdoctoral Research Funding Program,Grant/Award Number:2021K582Cthe fund for Talented of Nanjing Tech University,Grant/Award Number:201983。
文摘Room temperature phosphorescence(RTP)in metal-free organic materials has attracted considerable attention due to its rich excited state properties,high quantum efficiency,long luminescence lifetimes,etc.,showing great potential in organic optoelectronic devices,bioimaging,information anti-counterfeiting,and so forth.The crystals have excellent rigidity and clear molecular packing patterns,which can effectively avoid non-radiative transitions of excitons for phosphorescence enhancement.In the early stages,researchers paid great attention to the regulation of RTP performance in crystalline states.However,due to the complex preparation and poor processability of crystals,amorphous materials with RTP features have become a new research topic recently.This perspective aims to summarize the recent advances of RTP materials from crystalline to amorphous states,and analyze their molecular design strategies and luminescence mechanisms in detail.Finally,we prospect the future research directions of amorphous RTP materials.This perspective will provide a guideline for the future study of advanced RTP materials.
文摘The structures of the bulk amorphous Zr41Ti14Cu12.5Nil0.0Be22.5 alloy have been analyzed in solid, supercooled liquid and liquid with X-ray diffraction. The first coordination sphere radii and the first coordination numbers are 0.312 um, 11.2 in solid state.10.932 nm, 10.932 in supercooled liquid region and 0.305 urn, 11.296 in liquid state. The structures are the same in different states. But it shows some tendency to crystallizing that the first coordination sphere radius and the first coordination number drop in supercooled liquid region.
文摘In this work the statistical mechanical equation of state was developed for volumetric properties of crystalline and amorphous polymer blends.The Ihm-Song-Mason equations of state(ISMEOS) based on temperature and density at melting point(T_m and ρ_m) as scaling constants were developed for crystalline polymers such as poly(propylene glycol) + poly(ethylene glycol)-200(PPG + PEG-200),poly(ethylene glycol) methyl ether-300(PEGME-350) + PEG-200 and PEGME-350 + PEG-600.Furthermore,for amorphous polymer blends containing poly(2,6-dimethyl-1,4-phenylene oxide)(PPO) + polystyrene(PS) and PS + poly(vinylmethylether)(PVME),the density and surface tension at glass transition(ρ_g and γ_g) were used for estimation of second Virial coefficient.The calculation of second Virial coefficients(B_2),effective van der Waals co-volume(b) and correction factor(α) was required for judgment about applicability of this model.The obtained results by ISMEOS for crystalline and amorphous polymer blends were in good agreement with the experimental data with absolute average deviations of 0.84%and 1.04%,respectively.
文摘Curie temperature of amorphous alloys Co_(90-x)Cr_x Zr_(10) decreases linearly with increas- ing x.Average magnetic moment per magnetic atom Co or Cr is 1.51 μB or -3.62 μB respectively.The temperature dependence of spontaneous magnetization at low temper- atures is in agreement with Bloch's T^(3/2) law.The spin wave stiffness constant decreases with increasing x from 4 to 20.The range of interaction is 2—3 atoms for x=4 and nearest neighbour atom for x=20.The crystallization temperature increases mono- tonically with increasing x.It may relate to the average number of outer electrons per atom.The crystalline phase components of heat-treated alloys were analyzed by X-ray diffration and thermomagnetic measurement.
文摘Aim To investigate the multiple melting behavior of polyamide 6(PA 6) in polyamide 6/linear low density polyethylene blends crystallized from the crystal amorphous state. Methods\ The effects of annealing temperature, annealing time, heating rate, and the step wise annealing were measured by DSC. Results and Conclusion\ There exists a critical heating rate affecting the middle temperature melting peak. When annealed at the temperature close to the melting peak, the main melting peak of PA 6 shifted to a higher temperature. Within a short time, annealing time has much effect on neat PA 6 but little effect on PA 6 in the blends. Addition of PE results in a decreasing in the height of melting peak. These phenomenon show that the melting behavior of PA 6 was affected by PE, compatibilizer, as well as thermal treatment.
基金Supported by the National High Technology Research and Development Projects (863) of China (2007AA03Z325)the Natural Science Foundation of China (50472002)+1 种基金Provincial Science Foundation of Fujian (2009J05116)the program for Innovative Research Team in Fuzhou University
文摘A series of nominal composition Ti/（ZrO2）x（RuO2）l-x （0.1≤x≤0.9） coatings chan-ged in 10% steps was deposited on titanium substrate from RuCl3·nH2O and ZrCl4 containing ethanol solution by thermal decomposition method. The X-ray diffraction （XRD）, high-resolution transmission electron microscopy （HR-TEM） and electrochemical tests were performed to clarify the effects of ZrO2 content on the structure and capacitive property of Ti/（ZrO2）x（RuO2）l-x. The results show that by adding ZrO2 into the coatings the degree of crystallization of RuO2 decreases. The specific capacitance firstly increases and then deceases with the increase of ZrO2 content in the mixed oxide coatings. The film of Ti/（ZrO2）0.6（RuO2）0.4 consisting of amorphous matrix and fine nano-crystalline RuO2 （about 4 nm） has the maximum specific capacitance of 713.27 F/g（RuO2）.
基金the National Natural Science Foundation of China (No. 50871060)
文摘Fe/Gd multilayers were prepared by alternate vapor deposition of pure Fe and Gd at a rate of 0.01-0.03 nm/s in an ultra-high-vacuum elec- tron-gun evaporation system. The effects of the constituent metal layer thickness on the microstructures and magnetic properties of the films were investigated by low angle X-ray diffraction, transmission electron microscopy, and vibrating sample magnetometer. The experimental results show that a transition from the polycrystalline to amorphous state in the Fe layers occurs with the decrease of Fe layer thickness in the Fe/Gd multilayers. The saturation magnetization of the multilayers reduces significantly with decreasing Fe layer thickness and increasing Gd layer thickness. A superparamagnetic behavior at room temperature is observed for the [Fe（0.6 nm）/Gd（4.0 nm）]15 multilayer due to the formation of discontinuous Fe layers.
文摘Head-to-tail bonded perylene bisimide(PBI)dyads with different branched alkyl chains substituted at the terminal imide position show various stacking modes,which results in different effects on the excitonic processes and electron transportation.The dyad bearing branched alkyl chains with the branching sites close to the imide positions forms homogeneously amorphous state,while with branching sites being away from the imide positions the PBI core tend to stack with multiple modes.There are fewer energy trapping sites in the homogeneously amorphous state,but in the multiple stacking system the strongπ-πinteractions give more trapping sites.Our study demonstrates that the aggregation state of PBI-based acceptors plays an important role in the performances of organic solar cells(OSCs).Multiple stacking needs to be diminished to avoid the constrained exciton dissociation and retarded charge transport in the active layer.
文摘1.IntroductionMechanical alloying is one of the effec-tive methods to prepare amorphous alloys[1].This method was first used by Koch etal.to prepare the Ni;Nb;amorphous alloy[2].Since then many other amorphousbinary alloys have been prepared by the
基金support by Wenzhou City’s key R&D project,“Unveiling the List and Assigning the Leader”(ZG2023044)Anhui Provence key R&D project(202304a05020081)the DFG SPP2122 project ZH 662/3−2 and Open Research Fund of the State Key Laboratory of Polymer Physics and Chemistry,Changchun Institute of Applied Chemistry,Chinese Academy of Sciences.
文摘CONSPECTUS:The global production of polymer products currently exceeds 400 megatons annually.To ensure effective and environmentally responsible use of this vast resource,optimizing the properties of the products is essential.Achieving this requires precise control over the internal structure of the polymers.Depending on the materials used,polymers can exist in either amorphous or semicrystalline states.Processing is often performed from the melt state,and the cooling rate plays a critical role in determining whether amorphous or semicrystalline products are formed alongside other process parameters such as the pressure and shear rates.To understand the structure formation during processing,knowledge of the cooling rate dependence is therefore essential.As all of these processes are associated with thermal effects,calorimetry is universally applicable here.Achieving cooling rates that are comparable to those during processing has therefore long been a challenge for calorimetric measurement methods.With the introduction of MEMS-based chip sensors for calorimetry,significant progress has been made in reproducing conditions,such as those that occur during injection molding.These special calorimetric techniques are often summarized under the terms Fast Scanning Calorimetry(FSC)or Nanocalorimetry,alluding to nanogram samples.Investigations with controlled cooling rates of up to 1×10^(6)K/s are now possible with special chip sensors and allow the study of material properties under extreme conditions.Technological issues such as crystallization and nucleation processes under processrelevant conditions can be investigated in most cases with commercial devices that achieve cooling rates of 10^(4)K/s.The cooling rates to be considered in relation to various manufacturing processes are discussed here,and the functionality of corresponding chip calorimeters is briefly presented.Since calorimetry only provides general information on the processes taking place in the material,but not directly on the resulting structures,combinations of FSC and methods for structure elucidation,e.g.,microscopy,are also presented.The main part of this Account deals with contributions of FSC to the understanding of crystallization processes under conditions as they occur in different manufacturing processes.Not only the influence of the cooling rate during injection molding but also the multistage cooling by chill rolls during film production is considered.Thanks to the high scanning rate of FSC,needed to bypass crystallization in the low-supercooling temperature range where heterogeneous nucleation dominates,an important aspect of polymer structure formation-homogeneous crystal nucleation-has become accessible for direct observation.Homogeneous nucleation can occur not only during cooling but also during storage at temperatures close to or even below the glass transition temperature in the amorphous state.The possibilities of FSC for the generation and investigation of amorphous states are illustrated by an example.Finally,possible further developments of FSC and expected further applications of this fascinating technology are considered.
基金supported by the National Natural Science Foundation of China(22105218)Science and Technology Project of Jiangxi Provincial Education Department(GJJ2201525).
文摘The study of temperature-driven phase transitions is significant in phosphate chemistry,as these transitions often lead to unique physical properties for specific applications,such as catalysis,energy storage,ion conduction,and nonlinear optics[1–3].The phase transition from room temperature(RT)to high temperature(HT)in phosphates is always from periodic structures to disordered or amorphous states[4–8].At RT,phosphates often maintain a highly ordered crystalline structure,which is stabilized by the lower thermal energy.As the temperature increases,the thermal energy disrupts the periodic arrangement of atoms and leads to a phase transition,where the once ordered structure becomes increasingly disordered or even amorphous.
