The current study is directed to the rapidly developing field of inorganic material 3D object production at nano-/micro scale.The fabrication method includes laser lithography of hybrid organic-inorganic materials wit...The current study is directed to the rapidly developing field of inorganic material 3D object production at nano-/micro scale.The fabrication method includes laser lithography of hybrid organic-inorganic materials with subsequent heat treatment leading to a variety of crystalline phases in 3D structures.In this work,it was examined a series of organometallic polymer precursors with different silicon(Si)and zirconium(Zr)molar ratios,ranging from 9:1 to 5:5,prepared via sol-gel method.All mixtures were examined for perspective to be used in 3D laser manufacturing by fabricating nano-and micro-feature sized structures.Their spatial downscaling and surface morphology were evaluated depending on chemical composition and crystallographic phase.The appearance of a crystalline phase was proven using single-crystal X-ray diffraction analysis,which revealed a lower crystallization temperature for microstructures compared to bulk materials.Fabricated 3D objects retained a complex geometry without any distortion after heat treatment up to 1400℃.Under the proper conditions,a wide variety of crystalline phases as well as zircon(ZrSiO_(4)-a highly stable material)can be observed.In addition,the highest new record of achieved resolution below 60 nm has been reached.The proposed preparation protocol can be used to manufacture micro/nano-devices with high precision and resistance to high temperature and aggressive environment.展开更多
The shear failure of intact rock under thermo-mechanical(TM)coupling conditions is common,such as in enhanced geothermal mining and deep mine construction.Under the effect of a continuous engineering disturbance,shear...The shear failure of intact rock under thermo-mechanical(TM)coupling conditions is common,such as in enhanced geothermal mining and deep mine construction.Under the effect of a continuous engineering disturbance,shear-formed fractures are prone to secondary instability,posing a severe threat to deep engineering.Although numerous studies regarding three-dimensional(3D)morphologies of fracture surfaces have been conducted,the understanding of shear-formed fractures under TM coupling conditions is limited.In this study,direct shear tests of intact granite under various TM coupling conditions were conducted,followed by 3D laser scanning tests of shear-formed fractures.Test results demonstrated that the peak shear strength of intact granite is positively correlated with the normal stress,whereas it is negatively correlated with the temperature.The internal friction angle and cohesion of intact granite significantly decrease with an increase in the temperature.The anisotropy,roughness value,and height of the asperities on the fracture surfaces are reduced as the normal stress increases,whereas their variation trends are the opposite as the temperature increases.The macroscopic failure mode of intact granite under TM coupling conditions is dominated by mixed tensileeshear and shear failures.As the normal stress increases,intragranular fractures are developed ranging from a local to a global distribution,and the macroscopic failure mode of intact granite changes from mixed tensileeshear to shear failure.Finally,3D morphological characteristics of the asperities on the shear-formed fracture surfaces were analyzed,and a quadrangular pyramid conceptual model representing these asperities was proposed and sufficiently verified.展开更多
We have performed the first-principles calculations onto the structural,electronic and magnetic properties of seven 3d transition-metal(TM=V,Cr,Mn,Fe,Co,Ni and Cu) atom substituting cation Zn in both zigzag(10,0) and ...We have performed the first-principles calculations onto the structural,electronic and magnetic properties of seven 3d transition-metal(TM=V,Cr,Mn,Fe,Co,Ni and Cu) atom substituting cation Zn in both zigzag(10,0) and armchair(6,6) zinc oxide nanotubes(ZnONTs).The results show that there exists a structural distortion around 3d TM impurities with respect to the pristine ZnONTs.The magnetic moment increases for V-,Cr-doped ZnONTs and reaches maximum for Mn-doped ZnONTs,and then decreases for Fe-,Co-,Ni-and Cu-doped ZnONTs successively,which is consistent with the predicted trend of Hund's rule for maximizing the magnetic moments of the doped TM ions.However,the values of the magnetic moments are smaller than the predicted values of Hund's rule due to strong hybridization between p orbitals of the nearest neighbor O atoms of ZnONTs and d orbitals of the TM atoms.Furthermore,the Mn-,Fe-,Co-,Cu-doped(10,0) and(6,6) ZnONTs with half-metal and thus 100% spin polarization characters seem to be good candidates for spintronic applications.展开更多
基金The US AMRDEC grant No.W911NF-16-2-0069“Enhanced Absorption in Stopped-Light Photonic Nanostructures:Applications to Efficient Sensing”EU LASERLAB-EUROPE(grant agreement No.871124Horizon 2020 research and innovation programme)projects are acknowleged for the financial support.D.G.acknowledges the financial support from the European Social Fund(project No 09.3.3-LMT-K712-17-0016)under grant agreement with the Research Council of Lithuania(LMTLT).
文摘The current study is directed to the rapidly developing field of inorganic material 3D object production at nano-/micro scale.The fabrication method includes laser lithography of hybrid organic-inorganic materials with subsequent heat treatment leading to a variety of crystalline phases in 3D structures.In this work,it was examined a series of organometallic polymer precursors with different silicon(Si)and zirconium(Zr)molar ratios,ranging from 9:1 to 5:5,prepared via sol-gel method.All mixtures were examined for perspective to be used in 3D laser manufacturing by fabricating nano-and micro-feature sized structures.Their spatial downscaling and surface morphology were evaluated depending on chemical composition and crystallographic phase.The appearance of a crystalline phase was proven using single-crystal X-ray diffraction analysis,which revealed a lower crystallization temperature for microstructures compared to bulk materials.Fabricated 3D objects retained a complex geometry without any distortion after heat treatment up to 1400℃.Under the proper conditions,a wide variety of crystalline phases as well as zircon(ZrSiO_(4)-a highly stable material)can be observed.In addition,the highest new record of achieved resolution below 60 nm has been reached.The proposed preparation protocol can be used to manufacture micro/nano-devices with high precision and resistance to high temperature and aggressive environment.
基金supported by the National Natural Science Foundation of China(Grant No.51974173)the Natural Science Foundation of Shandong Province,China(Grant No.ZR2020QD122).
文摘The shear failure of intact rock under thermo-mechanical(TM)coupling conditions is common,such as in enhanced geothermal mining and deep mine construction.Under the effect of a continuous engineering disturbance,shear-formed fractures are prone to secondary instability,posing a severe threat to deep engineering.Although numerous studies regarding three-dimensional(3D)morphologies of fracture surfaces have been conducted,the understanding of shear-formed fractures under TM coupling conditions is limited.In this study,direct shear tests of intact granite under various TM coupling conditions were conducted,followed by 3D laser scanning tests of shear-formed fractures.Test results demonstrated that the peak shear strength of intact granite is positively correlated with the normal stress,whereas it is negatively correlated with the temperature.The internal friction angle and cohesion of intact granite significantly decrease with an increase in the temperature.The anisotropy,roughness value,and height of the asperities on the fracture surfaces are reduced as the normal stress increases,whereas their variation trends are the opposite as the temperature increases.The macroscopic failure mode of intact granite under TM coupling conditions is dominated by mixed tensileeshear and shear failures.As the normal stress increases,intragranular fractures are developed ranging from a local to a global distribution,and the macroscopic failure mode of intact granite changes from mixed tensileeshear to shear failure.Finally,3D morphological characteristics of the asperities on the shear-formed fracture surfaces were analyzed,and a quadrangular pyramid conceptual model representing these asperities was proposed and sufficiently verified.
基金supported by the National Natural Science Foundation of China (Grant No. 51071098)the State Key Development for Basic Research of China (Grant No. 2010CB631002)
文摘We have performed the first-principles calculations onto the structural,electronic and magnetic properties of seven 3d transition-metal(TM=V,Cr,Mn,Fe,Co,Ni and Cu) atom substituting cation Zn in both zigzag(10,0) and armchair(6,6) zinc oxide nanotubes(ZnONTs).The results show that there exists a structural distortion around 3d TM impurities with respect to the pristine ZnONTs.The magnetic moment increases for V-,Cr-doped ZnONTs and reaches maximum for Mn-doped ZnONTs,and then decreases for Fe-,Co-,Ni-and Cu-doped ZnONTs successively,which is consistent with the predicted trend of Hund's rule for maximizing the magnetic moments of the doped TM ions.However,the values of the magnetic moments are smaller than the predicted values of Hund's rule due to strong hybridization between p orbitals of the nearest neighbor O atoms of ZnONTs and d orbitals of the TM atoms.Furthermore,the Mn-,Fe-,Co-,Cu-doped(10,0) and(6,6) ZnONTs with half-metal and thus 100% spin polarization characters seem to be good candidates for spintronic applications.
基金Project(S-MIP-20-17) supported by the Research Council of LithuaniaProject(871124) supported by the EU Horizon 2020, Research and Innovation program LASERLAB-EUROPE JRA。
文摘本文研究了有机-无机混合预聚物SZ2080^(TM)在不借助任何光引发剂的情况下,使用~100 fs振荡器在517 nm波长和76 MHz重复频率下的飞秒激光直写(一种精密3D打印技术,也称为双光子聚合光刻技术)。实验证明了该技术的可行性,并成功地生产出了三维柴堆形纳米结构、微支架、自由形式的微型物体“Benchy”和微立方体。本文创新点为:非放大激光系统仅提供40~500 p J的单个脉冲就能够在横截面数百纳米内诱导局域交联反应。证明了放大激光器的高脉冲能量和低重复率不是构造非光敏化聚合物的必需条件。本文对于理解激光驱动的纳米三维增材制造具有重要意义,拓宽了不使用光引发剂条件下的应用领域,如微光学、纳米光子学和生物医学。
