S. V. von Gratowski

Shape Memory Effect in Microsized Samples of Rapidly Quenched Ferromagnetic Alloy Ni-Mn-Ga

The melt spun ribbons of ferromagnetic shape-memory alloy (FSMA) Ni53Mn24Ga23 have been prepared by rapid quenching. Thermomechanical properties have been studied by multi-point technique and perfect shape memory effect (SME) observed. The magnetic field effect on thermomechanical behavior was studied by placing multi-point press into Bitter magnet. A giant (1.2%) bending strain, due to magnetic field-induced martensitic transformation (magnetic-field-induced SME), has been observed at a constant temperature T= 56 °C in a field of 6 T. At least 80% of martensitic transformation reversibly induced by the external field was observed experimentally. Submicron sized samples of the alloy with thicknesses down to 300 nm have been milled by focused ion beam (FIB) technique. The deformation behavior of these samples was studied by Omniprobe micromanipulator in the vacuum chamber of FIB device. The SME response was tested in situ by heating the samples with a semiconductor laser. Strong two-way SME was observed due to bending strains of the samples under study.

Shape memory effect in nanosized Ti2NiCu alloy-based composites

The shape memory effect (SME) in alloys with a thermoelastic martensite transition opens unique opportunities for the creation of miniature mechanical devices. The SME has been studied in layered composite microstructures consisting of a Ti2NiCu alloy and platinum. It occurs upon a decrease in the active layer thickness at least to 80 nm. Some physical and technological restrictions on the minimum size of a material with SME are discussed.

Practical system for nanomanipulation

the paper reported about new practical system for 3D three dimensional (3D) nano-manipulation. The system consists of advanced high precision nano-manipulators based on piezoelectric resonance motors and end-effectors. The end-effector is the bimetallic composite nanotweezers based on Ti2NiCu alloy with shape memory effect. This nano-tweezer is easy in use micron-size nano-tool controlled by semiconductor laser radiation or electric current in vacuum chamber or other (i.e. liquid) environment in different types of microscopes. The new system for the first time gives the real possibility for 3D high accurate, cheap and easy in use, controllable, reproducible, quick manipulation and fabrication of large-scale nanostructures. The system can manipulate real nano-objects, such as nanotubes, bio-nanoparticles etc. The motion range - 15 mm, minimal step - 0, 4-10 nm, thermal drift <;5 nm/h at 20°C; speed of linear motion: 20 nm/s - 20 mm/s, nano-tweezers dimensions: 20*2.3*1.6 μm3, the size of the objects to be manipulated: 30 - 1000 nm.

Ion beam nanofabrication for mass production of nanotweezers based on new composite functional material with shape memory

Miniaturization is the central theme in modern fabrication technology. Many of the components used in modern products are becoming smaller and smaller. The applicability of the standard lithographic technologies to processing the new functional materials is crucial for their successful wide implementation in practice. Recently we have reported experimental design and test of the new generation for nano-mecanical devices like nano-tweezers based on original bilayer Ti2NiCu/Pt composite structures. In the present paper it is demonstrated that standard ion beam nano-fabrication technology is quit suitable for full cycle of production operational stages of practical nano-tweezers production. The technological experiments were done on realizing by usage of a novel focused ion beam instrument Raith ionLiNE™ device. This device is a novel focused ion beam instrument for low dose nanolithography and nano-fabrication. ionLiNE™ Raith was applied for experimental composite nano-tweezers production on the base of Ti2NiCu/W with length - 30 μm, gap width 0.9 μ. The tests showed high quality of reproduction and long term operation under thermal control at temperature change only 14 K.

Structure and Morphology of Zinc Oxide Nanorods

The properties of nanorods made of high-energy-gap ZnxMg1 – xO semiconductors are experimentally investigated using the new system of 3D manipulation of individual nanospecimens. The technology used to prepare ZnxMg1 – xO nanorods via gas-phase deposition on a substrate, the process whereby individual nanorods are selected by means of nanocomposite tweezers with the shape-memory effect in the vacuum chamber of a two-beam scanning microscope, and the results obtained when their structure and morphology are experimentally studied using transmission electron spectroscopy are described. The prospects that nanophotonic, nanosensorial, and nanoelectronic devices can be fabricated from ZnxMg1 – xO nanorods via the new nanomanipulation technique are discussed.

Thermally controlled nanoobjects manipulation system based on composite Ti 2 NiCU/Pt nanotweezers

We report the new system for manipulation of nanoobjects based on composite Ti2NiCu/Pt nanotweezers with shape memory effect. The design consists of the bimetallic Ti2NiCu/Pt shape memory nanotweezers placed on the tip of electrochemically etched tungsten needle. The semiconductor diode placed on the tip of the needle plays both role of resistive element of the heater and temperature sensor for feedback control loop closing. The device is compatible with existing positioning systems like OmniProbe®, Kleindiek®, etc. and may find numerous practical applications in various tasks of nanotechnology connected with 3D manipulation.

The shape memory effect in nanoscale composites based on Ti2NiCU alloy

The shape memory effect (SME) in alloys with thermoelastic martensitic transformation provides a unique possibility to create the tiny mechanical devices for NEMS / MEMS technology. SME observed in layered composite microstructors produced by FIB CVD technology, consisting of Ti2NiCu alloy layer with SME and platinum elastic layer at reducing the thickness of the active layer for at least 80 nm. In this paper the physical and technological restrictions were experimentally examined on the minimum thickness of the active layer of the composites for SME manifestation.

Millimeter waves as a tool for determination of the composition of biodiesel fuel

Dielectric properties of biodiesel fuel, as well as its blends with conventional mineral diesel fuel are investigated experimentally. It is shown that millimeter weaves allow one to carry out real-time nondestructive control of the composition of biodiesel blends with conventional mineral fuel. The highest sensitivity to the composition of blends is exhibited by the measurement of absorption of waves in the short millimeter wave band.

Structural phase stability, magnetism and microwave properties of Co2FeO4 spinel oxide

Correlation between crystal structure and physical properties for Co2FeO4 spinel oxide are studied. There are two coexisting phases, Fe rich and Co rich spinels, for S80, S86, S100 samples. The S90 and S95 samples showed single phase nature. A small signature of second phase is noted for S95 sample from the temperature dependence of magnetization measurement. The single phase with single Curie temperature at about 453 K is confirmed for S90 sample. Interestingly, S95 sample showed minimum magnetic energy loss. The complex magnetic permittivity and dielectric permeability at 4.6 GHz and 7.2 GHz has been measured for all samples. There is a correlation between annealing temperature for the samples and measured electromagnetic properties.

Dynamic phase transitions in moving vortex structures in type II superconductors

A theoretical explanation for the I–V characteristic of type II superconductors in the vortex state is provided. The run of the experimental I–V curves is associated with discontinuities and depends on the experimental prehistory. It is conjectured that dynamic phase transitions occur in the network of mobile and immobile channels along which the vortices travel when a transport current is applied. This work has been done on the author’s own initiative.