A molecular dynamics simulation study was performed to investigate the formation and evolution mechanisms of nano-clusters during the rapid solidification of liquid CaToMg30 alloy. The cluster-type index method （CTIM...A molecular dynamics simulation study was performed to investigate the formation and evolution mechanisms of nano-clusters during the rapid solidification of liquid CaToMg30 alloy. The cluster-type index method （CTIM） was adopted to describe microstructure evolutions of nano-clusters during solidification. Results indicate that amorphous structure is mainly formed with three bond-types of 1551, 1541 and 1431 at the cooling rate of 5~1011 K/S, and glass transition temperature Tg is about 530 K; the icosahedron cluster of （12 0 12 0） plays a key role in formation of amorphous structure, and smaller Mg atoms are much more probable to be central atoms of icosahedron clusters; and nano-clusters are mainly formed by combining medium-size clusters. Interestingly, it was also found that formation and evolution processes of the nano-cluster display a three-stage feature which is analogous to crystallization process of amorphous alloy.展开更多
Ni/Co bimetallic nano-cluters have been prepared from the aqueous solution byreducing their corresponding metal salts under suitable conditions. The experimental conditionsincluding the type and concentration of prote...Ni/Co bimetallic nano-cluters have been prepared from the aqueous solution byreducing their corresponding metal salts under suitable conditions. The experimental conditionsincluding the type and concentration of protective agent, feeding order and the pH of the solutionthat influence the average particle size have been studied in detail. Transmission electronmicroscopy (TEM) indicates that the shape of those bimetallic nano-cluster particles is spheroid.The alloy structure has been shown by X-ray powder diffraction (XRD). The X-ray photoelectronspectroscopic (XPS) data have confirmed that the nickel and cobalt in the bimetallic nano-clustersare in the zero-valence state.展开更多
First-principles energetics analyses were performed to investigate the nucleation of(Y-Si-O)nano-clusters(NCs)in nanostructured ferritic alloys(NFAs).It was predicted that the nucleation of(Y-Si-O)NCs follows the same...First-principles energetics analyses were performed to investigate the nucleation of(Y-Si-O)nano-clusters(NCs)in nanostructured ferritic alloys(NFAs).It was predicted that the nucleation of(Y-Si-O)NCs follows the same general pathway as previously found for(Y-Ti/Al/Zr-O)NCs in NFAs:they all tend to begin with the(O-O)pairs and grow to(O-Y)-cores and further to larger NCs by attracting Y and other solute elements nearby.Nucleation of a hexa-atomic-[2Y-Si-3O]-cluster can reduce the total energy by 4.71 eV.Among various microalloying-induced NCs,the nucleation preference ordering was predicted as(Y-Zr-O)>(Y-Ti-O)>(Y-Al-O)>(Y-Si-O).The number densities and chemical compositions of NCs in multi-microalloyed NFAs would largely depend on the number availability of(O,Y)-cores,as well as the relative abundance and atomic diffusivities of microalloying solute elements nearby.展开更多
A novel Fe-Y composite oxide(Fe:Y-6.5) nanocluster was synthesized by self-assembly approach.The α-Fe_(2)O_(3) and cubic-Y_(2)O_(3) nanocrystalline with diameter around 10 nm are homogeneously assembled to form a clu...A novel Fe-Y composite oxide(Fe:Y-6.5) nanocluster was synthesized by self-assembly approach.The α-Fe_(2)O_(3) and cubic-Y_(2)O_(3) nanocrystalline with diameter around 10 nm are homogeneously assembled to form a cluster architecture which are constituted of Fe6.5Y composite oxide particles.Additional oxygen vacancies are introduced with cubic-Y_(2)O_(3),and the oxygen vacancies as Fe^(3+)-V_(0)-Y^(3+) between α-Fe_(2)O_(3) and cubic-Y_(2)O_(3) nanocrystalline are generated by self-assembly process.Magnetic hysteresis loops recorded by vibrating sample magnetometry at 273 K display a ferromagnetic order,related to the fact that Fe^(3+)-V_(o)-Y^(3+) act as defect centers in the bound magnetic polaron model for Fe-Y composite oxide nanomaterial.The ferromagnetic prope rties are proportional to oxygen vacancy co ntents,and maximum magnetization(M_(m)) value of the nano-cluster reaches 5.14 A·m^(2)/g.展开更多
Understanding the mechanisms of parent-daughter isotopic mobility at the nanoscale is key to rigorous interpretation of Ue The Pb data and associated dating. Until now, all nanoscale geochronological studies on geolog...Understanding the mechanisms of parent-daughter isotopic mobility at the nanoscale is key to rigorous interpretation of Ue The Pb data and associated dating. Until now, all nanoscale geochronological studies on geological samples have relied on either Transmission Electron Microscope(TEM) or Atom Probe Microscopy(APM) characterizations alone, thus suffering from the respective weaknesses of each technique. Here we focus on monazite crystals from a ~1 Ga, ultrahigh temperature granulite from Rogaland(Norway). This sample has recorded concordant UeP b dates(measured by LA-ICP-MS) that range over 100 My, with the three domains yielding distinct isotopic Ue Pb ages of 1034 ± 6 Ma(D1; Srich core), 1005 ± 7 Ma(D2), and 935 ± 7 Ma(D3), respectively. Combined APM and TEM characterization of these monazite crystals reveal phase separation that led to the isolation of two different radiogenic Pb(Pb*) reservoirs at the nanoscale. The S-rich core of these monazite crystals contains Cae Srich clusters, 5 -10 nm in size, homogenously distributed within the monazite matrix with a mean interparticle distance of 40 -60 nm. The clusters acted as a sink for radiogenic Pb(Pb*) produced in the monazite matrix, which was reset at the nanoscale via Pb diffusion while the grain remained closed at the micro-scale. Compared to the concordant ages given by conventional micro-scale dating of the grain,the apparent nano-scale age of the monazite matrix in between clusters is about 100 Myr younger, which compares remarkably well to the duration of the metamorphic event. This study highlights the capabilities of combined APM-TEM nano-structural and nano-isotopic characterizations in dating and timing of geological events, allowing the detection of processes untraceable with conventional dating methods.展开更多
The construction of nano-hybrid liquid crystals(LCs)has been intensively pursued because the unique traits of nano-objects together with the self-assembly features of LCs allow the development of novel anisotropic mat...The construction of nano-hybrid liquid crystals(LCs)has been intensively pursued because the unique traits of nano-objects together with the self-assembly features of LCs allow the development of novel anisotropic materials.Self-assembly of surfactant-encapsulated polyoxometalate(SEP)complexes,consisting of nano-sized cores and organic shells,provides particularly important contribution in this area.The main motivation for developing those nano-hybrid liquid crystals originates from the added-value combination between anionic polyoxometalates and cationic surfactants.This account describes recent work in our group to develop thermotropic SEP complexes that result from the sophisticated molecular design.Since the polyoxometalates possess well-defined topology,strictly mono-dispersed size,and precise surface charges,it is possible to get more insight into understanding of the influ-ence of nature of components on the thermal property of nano-hybrid LCs.We briefly describe the general impor-tance and advantage of nano-hybrid LCs.We then highlight the synthesis and characterization of thermotropic liquid crystals based on polyoxometalate nano-clusters.The driving forces behind the molecular self-assembly are discussed in depth.The various factors,including chain length,surfactant density and the size-matching effect,affecting the interfacial curvature and the LC properties are summarized.We expect that the structure-property rela-tionships are virtually helpful for the design of new nano-hybrid LC materials.展开更多
基金Project(50831003) supported by the National Natural Science Foundation of ChinaProject(20114BAB215026) supported by Jiangxi Provincial Natural Science Foundation,ChinaProject(ZD201002) supported by Fund for Basic Scientific Research of Gannan Medical University,China
文摘A molecular dynamics simulation study was performed to investigate the formation and evolution mechanisms of nano-clusters during the rapid solidification of liquid CaToMg30 alloy. The cluster-type index method （CTIM） was adopted to describe microstructure evolutions of nano-clusters during solidification. Results indicate that amorphous structure is mainly formed with three bond-types of 1551, 1541 and 1431 at the cooling rate of 5~1011 K/S, and glass transition temperature Tg is about 530 K; the icosahedron cluster of （12 0 12 0） plays a key role in formation of amorphous structure, and smaller Mg atoms are much more probable to be central atoms of icosahedron clusters; and nano-clusters are mainly formed by combining medium-size clusters. Interestingly, it was also found that formation and evolution processes of the nano-cluster display a three-stage feature which is analogous to crystallization process of amorphous alloy.
基金This work was supported in part by the project of KJCXGC-01 of Northwest Normal University the Joint Program between the Educational Committee and the Economic Trade Committee of Gansu Province, China (CX-04).]
文摘Ni/Co bimetallic nano-cluters have been prepared from the aqueous solution byreducing their corresponding metal salts under suitable conditions. The experimental conditionsincluding the type and concentration of protective agent, feeding order and the pH of the solutionthat influence the average particle size have been studied in detail. Transmission electronmicroscopy (TEM) indicates that the shape of those bimetallic nano-cluster particles is spheroid.The alloy structure has been shown by X-ray powder diffraction (XRD). The X-ray photoelectronspectroscopic (XPS) data have confirmed that the nickel and cobalt in the bimetallic nano-clustersare in the zero-valence state.
基金financially suppor ted by the National MCF Energy R&D Program of China(Project No.2018YFE0306100)the National Natural Science Foundation of China(No.51971249)。
文摘First-principles energetics analyses were performed to investigate the nucleation of(Y-Si-O)nano-clusters(NCs)in nanostructured ferritic alloys(NFAs).It was predicted that the nucleation of(Y-Si-O)NCs follows the same general pathway as previously found for(Y-Ti/Al/Zr-O)NCs in NFAs:they all tend to begin with the(O-O)pairs and grow to(O-Y)-cores and further to larger NCs by attracting Y and other solute elements nearby.Nucleation of a hexa-atomic-[2Y-Si-3O]-cluster can reduce the total energy by 4.71 eV.Among various microalloying-induced NCs,the nucleation preference ordering was predicted as(Y-Zr-O)>(Y-Ti-O)>(Y-Al-O)>(Y-Si-O).The number densities and chemical compositions of NCs in multi-microalloyed NFAs would largely depend on the number availability of(O,Y)-cores,as well as the relative abundance and atomic diffusivities of microalloying solute elements nearby.
基金Project supported by National Key R&D Program of China(2017YFB0305801)the Joint Funds of NSFC-Liaoning(U1508213)。
文摘A novel Fe-Y composite oxide(Fe:Y-6.5) nanocluster was synthesized by self-assembly approach.The α-Fe_(2)O_(3) and cubic-Y_(2)O_(3) nanocrystalline with diameter around 10 nm are homogeneously assembled to form a cluster architecture which are constituted of Fe6.5Y composite oxide particles.Additional oxygen vacancies are introduced with cubic-Y_(2)O_(3),and the oxygen vacancies as Fe^(3+)-V_(0)-Y^(3+) between α-Fe_(2)O_(3) and cubic-Y_(2)O_(3) nanocrystalline are generated by self-assembly process.Magnetic hysteresis loops recorded by vibrating sample magnetometry at 273 K display a ferromagnetic order,related to the fact that Fe^(3+)-V_(o)-Y^(3+) act as defect centers in the bound magnetic polaron model for Fe-Y composite oxide nanomaterial.The ferromagnetic prope rties are proportional to oxygen vacancy co ntents,and maximum magnetization(M_(m)) value of the nano-cluster reaches 5.14 A·m^(2)/g.
基金Both UJM and CNRS (INSU TelluS-SYSTER) are thanked for financial support for AMSG and ATL. The Australian Resource Characterisation Facility (ARCF), under the auspices of the National Resource Sciences Precinct (NRSP) - a collaboration between CSIRO, Curtin University and The University of Western Australia e is supported by the Science and Industry Endowment Fund (SIEF RI13-01)
文摘Understanding the mechanisms of parent-daughter isotopic mobility at the nanoscale is key to rigorous interpretation of Ue The Pb data and associated dating. Until now, all nanoscale geochronological studies on geological samples have relied on either Transmission Electron Microscope(TEM) or Atom Probe Microscopy(APM) characterizations alone, thus suffering from the respective weaknesses of each technique. Here we focus on monazite crystals from a ~1 Ga, ultrahigh temperature granulite from Rogaland(Norway). This sample has recorded concordant UeP b dates(measured by LA-ICP-MS) that range over 100 My, with the three domains yielding distinct isotopic Ue Pb ages of 1034 ± 6 Ma(D1; Srich core), 1005 ± 7 Ma(D2), and 935 ± 7 Ma(D3), respectively. Combined APM and TEM characterization of these monazite crystals reveal phase separation that led to the isolation of two different radiogenic Pb(Pb*) reservoirs at the nanoscale. The S-rich core of these monazite crystals contains Cae Srich clusters, 5 -10 nm in size, homogenously distributed within the monazite matrix with a mean interparticle distance of 40 -60 nm. The clusters acted as a sink for radiogenic Pb(Pb*) produced in the monazite matrix, which was reset at the nanoscale via Pb diffusion while the grain remained closed at the micro-scale. Compared to the concordant ages given by conventional micro-scale dating of the grain,the apparent nano-scale age of the monazite matrix in between clusters is about 100 Myr younger, which compares remarkably well to the duration of the metamorphic event. This study highlights the capabilities of combined APM-TEM nano-structural and nano-isotopic characterizations in dating and timing of geological events, allowing the detection of processes untraceable with conventional dating methods.
基金supported by National Basic Re-search Program (2013CB834503)National Natural Science Foundation of China (91227110,21221063,20703019)+2 种基金Sci-Tech development project of Jilin Province (20130522133JH)111 Project (B06009)Open Project of State Key Laboratory of Polymer Physics and Chemistry of CAS.
文摘The construction of nano-hybrid liquid crystals(LCs)has been intensively pursued because the unique traits of nano-objects together with the self-assembly features of LCs allow the development of novel anisotropic materials.Self-assembly of surfactant-encapsulated polyoxometalate(SEP)complexes,consisting of nano-sized cores and organic shells,provides particularly important contribution in this area.The main motivation for developing those nano-hybrid liquid crystals originates from the added-value combination between anionic polyoxometalates and cationic surfactants.This account describes recent work in our group to develop thermotropic SEP complexes that result from the sophisticated molecular design.Since the polyoxometalates possess well-defined topology,strictly mono-dispersed size,and precise surface charges,it is possible to get more insight into understanding of the influ-ence of nature of components on the thermal property of nano-hybrid LCs.We briefly describe the general impor-tance and advantage of nano-hybrid LCs.We then highlight the synthesis and characterization of thermotropic liquid crystals based on polyoxometalate nano-clusters.The driving forces behind the molecular self-assembly are discussed in depth.The various factors,including chain length,surfactant density and the size-matching effect,affecting the interfacial curvature and the LC properties are summarized.We expect that the structure-property rela-tionships are virtually helpful for the design of new nano-hybrid LC materials.
