The work is devoted to the study of the dependence of the structure, magnetic properties, and functional properties such as shape memory effect (SME) and magneto caloric effect (MCE) of Heusler alloys of the Ni51 – xMn33.4In15.6Vx family on the degree of vanadium doping x. Studies using scanning electron microscope (SEM), differential scanning calorimetry (DSC) and magnetometry revealed in all studied samples of Heusler Ni51 – xMn33.4In15.6Vx alloys the presence of a Curie point type magnetic phase transition (PT) and a metamagnetostructural phase transition (MMSPT), of the first order which is accompanied by a sharp decrease in magnetization in the low-temperature martensitic phase. The temperature of the magnetic PT is weakly dependent on x, the temperature of the MMSPT decreases with increasing x. The temperature of the MMSPT is very sensitive to the magnetic field. For the Ni50Mn33.4In15.6V1 sample, the sensitivity is—5 K/T. Direct measurements of the MCE in alternating magnetic fields of 0.62 and 1.2 T showed the presence of a direct MCE at the point of magnetic PT and an inverse MCE at the point of MMSPT. There is a strong decrease in the MCE with an increase in the frequency of the alternating magnetic field from 1 to 30 Hz both near the magnetic PT and near the MMSPT. Measurements of the dependence of bending deformation on load and temperature have shown that all studied alloys exhibit SME near MMSPT. It can be concluded that due to the combination of high sensitivity of MMSPT to the field and SME, this family of alloys is promising for the creation of magnetically controlled actuators.

The development of solid-state cooling systems based on the magnetocaloric effect is very attractive for achieving compactness and high efficiency of the refrigerator. The modified surface structure of the heat switch in cryogenic systems may be critical for achieving high heat flow control parameters in solid-state refrigerators. The paper considers a reciprocating type mechanical heat switch for magnetic cooling. The thermal characteristics are determined such as: thermal contact resistance and the inverse value of thermal contact conductance, as well as the time of onset of thermal equilibrium. The surface of the thermal contact was modified using the method of laser interference lithography. As a result of the physical experiment, the values of the studied values were obtained and compared with the literature data in the temperature range of 70–120 K and pressure forces of 160 and 260 kPa.

We investigated the growth conditions of ZnO nanorod arrays using the gas-phase chemical synthesis technology and we fabricated ZnO nanorod arrays. The nanorod arrays were characterized using electron microscopy, Raman spectroscopy, and X-ray diffractometry. We fabricated acoustic resonators based on single ZnO nanorod suspended between electrodes. We used modern electron lithography and FIB methods for the fabricating. The developed technique allows us to form practically significant devices on single ZnO nanorods, such as high-frequency resonators, promising for use in acoustooptics.

The paper reports on the synthesis of up conversion fluoride nanocrystals $\beta-\text{NaYF}_{4}:\text{Yb}^{3+},\text{Er}^{3+}$ and discusses the possibilities of creating linear structures by self-assembly of nanoparticles and nanomanipulation using a piezoelectric nano position system. In both cases, when illuminated with infrared radiation, the arrays exhibited a brighter glow comparing with individual microdisks. The glow that may be interpreted as upconversion laser effect. After infrared laser irradiation, the microdisks begin to glow green. The microdisc structures created in the work are considered as an array of upconversion nanolasers.

The crystal structure, texture, martensitic transformation, and magnetic properties of magnetic shape-memory Heusler alloys of Ni51−xMn33.4In15.6Vx (x = 0; 0.1; 0.3; 0.5; 1) were investigated. Experimental studies of the magnetic properties and meta-magnetostructural transition (martensitic transition—MT) confirm the main sensitivity of the martensitic transition temperature to vanadium doping and to an applied magnetic field. This makes this family of shape-memory alloys promising for use in numerous applications, such as magnetocaloric cooling and MEMS technology. Diffuse electron scattering was analyzed, and the structures of the austenite and martensite were determined, including the use of TEM in situ experiments during heating and cooling for an alloy with a 0.3 at.% concentration of V. In the austenitic state, the alloys are characterized by a high-temperature-ordered phase of the L21 type. The images show nanodomain structures in the form of tweed contrast and contrast from antiphase domains and antiphase boundaries. The alloy microstructure in the temperature range from the martensitic finish to 113 K consists of a six-layer modulated martensite, with 10 M and 14 M modulation observed in local zones. The morphology of the double structure of the modulated martensite structure inherits the morphology of the nanodomain structure in the parent phase. This suggests that it is possible to control the structure of the high-temperature austenite phase and the temperature of the martensitic transition by alloying and/or rapidly quenching from the high-temperature phase. In addition, attention is paid to maintaining fine interface structures. High-resolution transmission electron microscopy showed good coherence along the austenite–martensite boundary.

Magnetic field-driven bionanomanipulation continues to be a challenging task because the force applied by current magnetic nanoparticles and nanoactuators is effectively limited to femto and pico Newtons at the proper field and gradient scales. Therefore, of particular interest is search for the new functional materials and new effects that provide a breakthrough opportunity for the influence of a remotely controlled magnetic field on a nano and micro Newton scale on living biological objects, such as bacteria, viruses, individual cells, etc. This work includes deep study of the structure, physical and multifunctional properties of a new family of Heusler Ni-Mn-In-V alloys demonstrating the magnetic shape memory effect responsible for actuation, shape change and the production of mechanical work on objects such as viruses and bacteria in a constant temperature environment. The possibilities of capturing, storing, processing of bionanoobjects are discussed.

Rapidly quenched thin TiNiCu alloy ribbons are precursors in the fabrication of micro- and nanotweezers for the manipulation of micro- and nanoscale objects. The thickness of the ribbons has been reduced by cold rolling in amorphous state. A thickness reduction rate of 1.2-1.5 times has been achieved by rolling with a load of up to 12 tons. We show that shape memory effect has been generated after isothermal crystallization in the rolled ribbons. The characteristic martensitic transformation temperatures have increased, the transformation hysteresis width has decreased and the shape memory effect has decreased slightly. The lateral roughness of the ribbon surfaces has decreased both for the contact and the reverse ribbon surfaces.

Miniaturization of devices based on one-dimensional semiconductor nanocrystals is of high importance for high-frequency applications, photonics, and various sensors. Zinc oxide, one of the materials actively studied for such purposes, can be obtained by several technologies. Among them, chemical vapor deposition is distinguished by a low concentration of defects in the resulting structures. The aim of this work was to fabricate a test device on a single ZnO nanocrystal by means of nanomanipulation and to study its spectral response in the range from near-IR to UV. Since one of the promising applications of ZnO is UV sensors, the task was to test the selectivity of the response to the wavelength range below 400 nm.

The results of the study of the influence of multi-axial isothermal forging on the microstructure and martensitic transformation in a Ni58Mn18Ga24 alloy have been presented. Forging is performed in two stages: the first stage is forging at 700°C by four passes with true strain e ≈ 1.64; the second stage is forging at 500°C by one pass with e ≈ 0.24. The forging deformation results in the transformation of the original equiaxed-grain structure. No new grains are formed after the first stage of treatment. New recrystallized grains in a very negligible extent begin to be observed only after the second stage of deformation. Probably, at the first stage, the mechanism of fragmentation of the grain structure is not started due to an insufficient density of defects upon the deformation at 700°C. The characteristic temperatures of martensitic transformation are shifted after forging to the low temperature region. The anharmonic change in the sample length is observed in the region of martensitic transformation for the both treated states. In general, this indicates a low level of defect density and internal stresses in the sample.

The paper examines the problem of creating an alternative solid-state magnetic cooling technology using the magnetocaloric effect in rare-earth magnetic materials. Known gas cryoculi implement the thermodynamic Stirling (Gifford-McMahon) cycle with a high temperature difference achieved, but low efficiency of the cooling process. The best solid-state materials are, in principle, capable of increasing the efficiency of the thermodynamic process. However, in order to find the ideal efficiency, in a magnetocaloric solid-state refrigerator, it is necessary to turn to the Carnot cycle and study thermal manipulation in a vacuum with high speed and negligible losses. Thus, the problem of creating a thermal switch operating in a vacuum and strong magnetic fields is of primary importance. In this work, the concept of a solid-state magnetic refrigerator with thermal interfaces in the form of a vacuum gap with a surface modified by laser interference lithography (LIL) has been developed. A method for experimental determination of contact thermal conductivity (contact thermal resistance) of unsteady heat flux in a wide temperature range from 7 K to 325 K is described. A review of micro- and nanostructured surfaces for use as thermal interfaces in electronics and cryogenic engineering is provided. The prospect of using LIL modified thermo interfaces in thermal switches is noted.

Heusler compounds are intermetallic alloys that are capable of a wide range of unique properties such as magnetocaloric, thermoelectric, and magnetic-shape-memory effects, antiferromagnetism, superconductivity, and they can even act as topological insulators. These multifunctional behaviors make Heusler alloys prime candidates for numerous smart device applications. However, their specific properties critically depend on their crystalline structures, chemical order, structural phase transformations, and crystallographic texture. Thus, as compositions and processing parameters are varied it becomes essential to be able to accurately characterize the structure of these materials at various scales. This paper provides a brief review of diffraction-based characterization techniques ideally suited for the characterization of Heusler alloys with examples from our previous works including use of synchrotron, neutron, and electron diffraction, especially as a function of temperature and/or magnetic field to explain important phenomena demonstrated by Heusler alloys.

This work study the operating parameters of a cryogenic mechanical thermal switch, a detachable contact pair made of a alloy GdNi2 disk and a copper cylinder. The mechanical thermal switch operates in a vacuum in the temperature range of 8-325 K with a pressure of 250-350 kPa. The time of thermal equilibrium is studied at different contact areas with and without an indium thermal interface at an initial temperature difference of 0.8-10 K in the contact pair in the temperature range from 8 to 122 K. The temperature relaxation value is 33.7...39.9 seconds at a temperature difference of 3±0.14 K in the range of 50...122 K. Reducing the nominal contact area from 177 mm2 to 2.5 mm2 increases the temperature relaxation time at a temperature of 73.3 K from 36.6 to 63.5 seconds. This temperature range corresponds to the maximum magnetocaloric effect near the Curie temperature of the GdNi2 alloy. The values of the heat that must be removed to maintain the required temperature of the cooling object in a cryogenic magnetic refrigerator have been obtained.

In this study, the high-temperature transformation in a thin foil of non-stoichiometric Heusler alloy based on Ni-Mn-In is investigated using in-situ TEM. The highly ordered cubic L21 phase undergoes decomposition upon heating, forming a phase with a composition close to Ni75Mn25, which is identified as disordered FCC-Ni3Mn and secondary phases, mainly manganese oxides and sulfides. All phases formed upon heating to a temperature of 1173 K are preserved during the in-situ cooling experiment to a temperature of 123 K.

We investigate thermal contact resistance of a detachable connection in the copper–copper contact pair with a thermal interface made of graphene layers synthesized by chemical vapor deposition onto the contacting surface. The values of the thermal contact resistance of a detachable copper–graphene–copper contact pair were obtained using the transient heat flow method in the temperature range of 15–150 K under the influence of an external magnetic field of up to 10 T.

Accurate measuring the temperature of materials, especially in high pulsed and alternating magnetic fields, represents a major challenge in magnetic and, in particular, magnetocaloric research. The disadvantages of the used contact temperature sensors (microthermocouples and film thermistors) are: (1) the effect of electromagnetic interference on their indications, which is proportional to the time derivative of the magnetic field, (2) their relatively long response time due to thermal inertia, and (3) the impossibility of accurate measurement temperatures of thin and microstructured samples. The described difficulties can be avoided by using non-contact optical methods for measuring the temperature of magnets in high magnetic fields. In this review, we describe non-contact optical methods for measuring the magnetocaloric effect using known materials as an example, and provide a comparative analysis of the main characteristics of these methods, such as: maximal magnetic field, sampling frequency, time constant and spectral range of the detector, and temperature error and resolution.

The main aim of this work is to study heat transfer in mechanical thermal switch under conditions close to a real magnetic refrigeration. This study examines the thermal behavior of a mechanical thermal switch which comprise a detachable pair of copper - copper contact bulks, incorporating an indium foil thermal interface with a 100 mu m thickness. We investigated the time it took to reach thermal equilibrium from initial temperature span of 3 K, 5 K, and 10 K and explored the influence of the indium foil thermal interface within a temperature range of 15 to 300 K. The experimental data provided the heat dissipation values required to maintain the specified temperature of the object being cooled. As the results showed, the use an indium thermal interface significantly reduces the time until thermal equilibrium occurs.

The relationship between antiphase boundaries (APBs), antiphase domains (APDs) and the functional properties of alloys of the Ni-Mn-In system has been studied. The density of APBs was controlled using various thermal treatments. The fine domain structure was observed by transmission electron microscopy (TEM), high-angle dark-field scanning transmission electron microscopy (HAADF-STEM), and electron backscatter diffraction (EBSD). The results obtained are discussed in the context of the possibility of modeling and designing materials with specified characteristics and properties.

The paper reports the creation of a nano-soldering method in a circuit with tungsten microneedles separated by an air gap. An external voltage was applied to the microneedles separated by air gap. During the experiments, a plasma discharge, and the formation of metallic-organic composite "nano-fluff" on tungsten microneedles was observed. At the same time, the current-voltage characteristic (CVC) was studied. The CVC revealed the regions of negative differential resistance that arose at the moment of formation of the plasma discharge. In the three-needle design, the reliable electrical and mechanical contact was achieved between two microneedle due to nano-fluff formation, featuring a new approach to the creation of the nano-soldering technology for 3D mechanical bottom-up nano-assembling of individual nano-devices.

Many modern advances in the field of nano- and microrobotics are used in the creation of a new generation of bionanosensors. Individual semiconductor nanowires (NWs) are considered in biomedical technologies as highly sensitive elements for tracking important biological agents. For this sake the single nanowires are biologically functionalized, and on their basis the active elements are integrated in the configuration of field-effect transistors (FET). This paper reports on experiments on the development of a technology for the designing of nanobiosensor prototypes based on single semiconductor zinc oxide nanowires using a new microrobotic system for nanomanipulation with shape memory actuator elements. The NW nanopositioning was carried out with an accuracy of about 10 nm using a Kleindick nanomanipulator in the vacuum chamber of a cross-beam SEM/FIB microscope. Specially designed thermally controlled shape memory nanotweezers were used to capture a suitable individual NWs from the forest. The corresponding angular arrangement of the NWs and nanotweezers was achieved by a new torsion actuator with shape memory effect, which is combined with the control element of the nanotweezers. The integration of the prototypes of FETs based on zinc oxide NWs was achieved by 3D nanomanipulation of single nanowires 300–15 nm thick and 50-µm long.

A physical model of a mechanical thermal switch at cryogenic temperatures is studied. In the model, heat is transferred due to contact heat conduction in a detachable contact pair of two copper cylinders. A mechanical thermal switch is developed using a cryomagnetic system with a 10-T superconducting solenoid, and the values of thermal contact conductance are determined in a temperature interval of 10–160 K, including values at a magnetic field of 5 T. In an experimental temperature interval of 60–80 K, close to the phase transition of the DyAl 2 and GdNi 2 compounds, the thermal contact conductance is 2300–3300 W/(m 2 K). The effect of magnetic field of up to 5 T on thermal contact resistance is experimentally determined under vacuum conditions.