The present paper deals with motion of carbon nanotubes in a temperature gradient field. A determined-static theory of nanosized particles’ thermophores is developed. Analytical expressions for thermophoretic velocit...The present paper deals with motion of carbon nanotubes in a temperature gradient field. A determined-static theory of nanosized particles’ thermophores is developed. Analytical expressions for thermophoretic velocity and force of ultramicroheterogeneous particles in a gaseous atmosphere under near-normal conditions are provided. The calculations performed according to the suggested theory, as applied to closed carbon nanotubes, found the value of dimensionless velocity of thermophoresis. In accordance with the proposed hypothesis, Waldman’s limit is achieved, which is expressed in constancy of thermophoretic velocity within the interval of the Knudsen parameter change from 10 to 100. In addition, it is found out that under conditions defined below, velocity of thermophoresis is independent of the length of a carboxylic nanotube. A good agreement with experiments is reached, which makes it possible to assume correspondence of the theory to the physical truth.展开更多
In this review,we introduce the current state of the art of the growth technology of pure,lightly doped,and heavily doped(solid solution)nonlinear gallium selenide(GaSe)crystals that are able to generate broadband emi...In this review,we introduce the current state of the art of the growth technology of pure,lightly doped,and heavily doped(solid solution)nonlinear gallium selenide(GaSe)crystals that are able to generate broadband emission from the near infrared(IR)(0.8 mm)through the mid-and far-IR(terahertz(THz))ranges and further into the millimeter wave(5.64 mm)range.For the first time,we show that appropriate doping is an efficient method controlling a range of the physical properties of GaSe crystals that are responsible for frequency conversion efficiency and exploitation parameters.After appropriate doping,uniform crystals grown by a modified technology with heat field rotation possess up to 3 times lower absorption coefficient in the main transparency window and THz range.Moreover,doping provides the following benefits:raises by up to 5 times the optical damage threshold;almost eliminates two-photon absorption;allows for dispersion control in the THz range independent of the mid-IR dispersion;and enables crystal processing in arbitrary directions due to the strengthened lattice.Finally,doped GaSe demonstrated better usefulness for processing compared with GaSe grown by the conventional technology and up to 15 times higher frequency conversion efficiency.展开更多
The shape memory behavior of [111]-oriented Ni_（51）Ti_（49） （at.%） single crystals was investigated after stressassisted aging at 500 °C for 1.5 h under a compressive stress of-150 MPa.It was found that a si...The shape memory behavior of [111]-oriented Ni_（51）Ti_（49） （at.%） single crystals was investigated after stressassisted aging at 500 °C for 1.5 h under a compressive stress of-150 MPa.It was found that a single family of Ni_4Ti_3 precipitates with two crystallographically equivalent variants was formed after aging under compressive stress.Stressassisted aging resulted in tensile two-way shape memory effect strain of 1.56% under-5 MPa.Thermal cycling under-600 MPa resulted in a transformation strain of-2.15%,while the subsequent thermal cycling under-5 MPa resulted in a tensile two-way shape memory effect strain of 2.2%.展开更多
文摘The present paper deals with motion of carbon nanotubes in a temperature gradient field. A determined-static theory of nanosized particles’ thermophores is developed. Analytical expressions for thermophoretic velocity and force of ultramicroheterogeneous particles in a gaseous atmosphere under near-normal conditions are provided. The calculations performed according to the suggested theory, as applied to closed carbon nanotubes, found the value of dimensionless velocity of thermophoresis. In accordance with the proposed hypothesis, Waldman’s limit is achieved, which is expressed in constancy of thermophoretic velocity within the interval of the Knudsen parameter change from 10 to 100. In addition, it is found out that under conditions defined below, velocity of thermophoresis is independent of the length of a carboxylic nanotube. A good agreement with experiments is reached, which makes it possible to assume correspondence of the theory to the physical truth.
基金This work is supported in part by the Visiting Professor Program of State Key Laboratory of Laser Interaction with Matter of Changchun Institute of Optics,Fine Mechanics and Physics CAS,Changchun,China,the Open Fund by State Key Laboratory of Laser Interaction with Matter(No.SKLLIM1012)the RNF(Project No.15-19-10021,physical properties study),the Tomsk State University(8.1.51.2015)+1 种基金Tomsk Regional Common Use Center,with the support of the Russian Ministry of Education and Science(Agreement No.14.594.21.0001,code RFMEFI59414X0001,spectroscopic study)the Presidium SB RAS,Project VIII.80.2.4(optical properties study in THz range).
文摘In this review,we introduce the current state of the art of the growth technology of pure,lightly doped,and heavily doped(solid solution)nonlinear gallium selenide(GaSe)crystals that are able to generate broadband emission from the near infrared(IR)(0.8 mm)through the mid-and far-IR(terahertz(THz))ranges and further into the millimeter wave(5.64 mm)range.For the first time,we show that appropriate doping is an efficient method controlling a range of the physical properties of GaSe crystals that are responsible for frequency conversion efficiency and exploitation parameters.After appropriate doping,uniform crystals grown by a modified technology with heat field rotation possess up to 3 times lower absorption coefficient in the main transparency window and THz range.Moreover,doping provides the following benefits:raises by up to 5 times the optical damage threshold;almost eliminates two-photon absorption;allows for dispersion control in the THz range independent of the mid-IR dispersion;and enables crystal processing in arbitrary directions due to the strengthened lattice.Finally,doped GaSe demonstrated better usefulness for processing compared with GaSe grown by the conventional technology and up to 15 times higher frequency conversion efficiency.
基金supported in part by the NASA Fundamental Aeronautics ProgramSupersonics Project and the NASA EPSCOR program(Grant No.NNX11AQ31A)RFBR Project(Grant No.10-03-0154-a)
文摘The shape memory behavior of [111]-oriented Ni_（51）Ti_（49） （at.%） single crystals was investigated after stressassisted aging at 500 °C for 1.5 h under a compressive stress of-150 MPa.It was found that a single family of Ni_4Ti_3 precipitates with two crystallographically equivalent variants was formed after aging under compressive stress.Stressassisted aging resulted in tensile two-way shape memory effect strain of 1.56% under-5 MPa.Thermal cycling under-600 MPa resulted in a transformation strain of-2.15%,while the subsequent thermal cycling under-5 MPa resulted in a tensile two-way shape memory effect strain of 2.2%.
