Voitech Stankevič

Semiconductor Physics Institute | SPI · Material Science and Electrical Engineering

Introduction Most widely used process for inactivation of microorganisms after fermentation or to avoid contamination of fresh foods is thermal pasteurization. During this treatment, taste and content of vitamins are affected. Novel pasteurization technologies involve pulsed electric fields with long durations compared with the charging time of the...

The results of magnetoresistance (MR) and resistance relaxation of nanostructured La1-xCaxMnO3 films, with different composition x grown by metal-organic chemical vapor deposition technique, are presented and compared with the La0.83Sr0.17MnO3 films. The MR was investigated in pulsed magnetic fields up to 60T in the temperature range 1.5-294K while...

This nanosecond electric pulse generator is designed for the electroporation of biological cells suspended in a liquid media. It is based on a spark-gap switch, which is optically triggered by a 0.45-ns duration and 1-mJ energy laser pulse (wavelength 1062 nm). This system can also be triggered manually by changing the distance between the spark-ga...

The long-term stability of electrical resistance and magnetoresistance in nanostructured La1-xSrxMnO3 (x = 0.17) manganite thin films grown on lucalox (Al2O3 + MgO) substrate by the MOCVD method was investigated. It was found that the storage of up to 3 months of the free surfaces of these films in normal atmosphere (air) conditions increases their...

We report on the use of the colossal magnetoresistance (CMR) effect in manganites for the measurement of pulsed magnetic fields up to the megagauss limit. To increase the application range in a magnetic field, we fabricated nanostructured La-Sr-Mn-O films consisting of nanocrystallites cummulated into clusters separated by highly amorphous inter-cl...

The influence of 50 nm to 100 nm size carbon nanoderivative (CND) on electrodeposition with copper, morphological, electrical and mechanical properties of copper matrix composite coatings were observed. The investigated nanoparticles of carbon nanoderivative stimulatedformation of nanostructured smoother crystallitic coatings than that of pure copp...

A measurement and automation equipment for measuring the manganite resistance dependence on magnetic field is designed and developed in this work. Equipment consists of the electromagnet, the programmable power source, the magnetic field meter and the resistance measurement device. All devices are connected to PC by the GPIB cables and the GPIB-USB...

T. Stankevic, V. Stankevic, D. Pavilonis, N. Zurauskiene, J. Novickij, S. Tolvaisiene. Computer Controlled Thermostat for the Resistivity measurements of the La1-xSrxMnO3 thin films // Electronics and Electrical Engineering. - Kaunas: Technologija, 2012. - No. 3(119). - P. 53-56. The temperature stabilization system for the magnetoresistance measur...

V. Novickij, J. Novickij, V. Stankevic, A. Grainys, S. Tolvaisiene. Analysis of Microelectrode Arrays for Dielectrophoresis using the Finite Element Method // Electronics and Electrical Engineering. - Kaunas: Technologija, 2012. - No. 2(118). - P. 17-20. Dielectrophoresis (DEP) force dependence on microelectrode array size parameters is presented i...

This paper deals with the peculiarities of the behaviour of copper nanocomposite coatings with CNMs inclusions under the free corrosion conditions in the acidic medium. The parameters of corrosion current density (j corr), anodic dissolution current density (i a) and polarization resistance (R p) have been determined. In the acidic medium a stronge...

A new fast high-power fault current limiter made from epitaxial and polycrystalline La_0.83Sr_0.17MnO₃ thin films and operating at 80 K has been demonstrated. An epitaxial film that exhibits a current-induced increase in its resistance is connected in series with a 50--impedance transmission line, while a polycrystall...

The following peculiarities of electron transport in In 0:53Ga0:47As/In0:52Al0:48As quantum wells with δ-Si-doped In0:52Al0:48As barriers at high electric fields are discovered: (1) an enhancement of electron mobility by inserting the InAs phonon wall into the In0:53Ga0:47As/ In0:52Al0:48As quantum well, as well as increasing the InAs content in th...

We present the design and the main character-istics of the CMR-B-scalar sensor based on polycrystalline La 0.83 Sr 0.17 MnO 3 films. The sensor active volume is only 400 μm × 50 μm × 0.4 μm, and it is able to measure a magnetic induction of up to 40 T independently on its direction. The in-vestigations of the influence of film preparation condition...

A sufficient amount of studies worldwide prove an interrelation linking students' learning productivity, emotional and psychological state to physiological parameters. Emotional states and the interest in learning affect learning productivity, while physiological parameters demonstrate such changes. Since the research by the authors of the present...

A brief overview of the high-field facilities at the Vilnius High Magnetic Field Centre (VMC) is presented in this paper. We highlight the main activity of the VMC, which lies in studying the effects of pulsed magnetic and electrical fields on material properties, and give a short description of the pulsed magnets. Anew method for generating nanose...

The electrical conductivity of thin polycrystalline La0.83Sr0.17MnO3 films was investigated. These films were simultaneously affected by a single electrical pulse having a pulse length of several ns and a half-sinus magnetic pulse with a pulse length of 1 ms and amplitude ranging up to 20 T. The influence of the high magnetic field on the electrore...

The design, technology and main characteristics of Ag contacts as well as "loop effect" peculiarities of colossal magnetoresistanee B-scalar high magnetic field sensor based on La1-x (Ca)SrxMnO 3 films used for measuring high magnetic field pulses are presented.

The magnetoresistance of thin polycrystalline La1-xSr xMnO3 films deposited on lucalox substrate using metal organic chemical vapor deposition technique was investigated in pulsed magnetic fields up to 18 T in the temperature range 100-320 K. The influence of film preparation conditions, ambient temperature variation and Sr content is analyzed in o...

The magnetoresistance (MR) of polycrystalline La0.83Sr0.17MnO3 thin films have been studied in high pulsed magnetic fields up to 38 T in the temperature range 100–300 K. The lucalox substrates were used to obtain polycrystalline structures with naturally formed grain boundaries (GBs) and crystallites whose dimensions were determined by film deposit...

In order to increase the efficiency of employees' activities, a Web-based Biometric Mouse Decision Support System for User's Emotional and Labour Productivity Analysis (MDSS-UELPA) was developed by the authors. MDSS-UELPA con-sists of seven subsystems: Data Capture and Collection Subsystem, Feature Extraction Subsystem, Database Management Subsyste...

The authors report on fast reversible switching of epitaxial and polycrystalline La0.83Sr0.17MnO3 films from the ferromagnetic to the paramagnetic state induced by high power nanosecond electrical pulses. It was demonstrated that for the epitaxial films adiabatic and uniform Joule heating is the reason of the switching. For polycrystalline films, e...

The structural, electrical and magnetic properties of ultra-thin La0.83Sr0.17MnO3 (LSMO) films, deposited on NdGaO3 substrate by using the MOCVD technique, were studied. The film thickness d varied in the range from 4 to 140 nm. X-ray and RHEED measurements demonstrated that the films had a two-phase structure. One phase had an orthorhombic face ce...

Magnetic field sensors based on polycrystalline La0.83Sr 0.17MnO3 films were used to measure the magnetic field distribution and disturbances during the operation of an electromagnetic launcher. Hollow cylinders made from dural aluminum and iron were used as propelled objects inside the solenoidal coil. The obtained results revealed the ability of...

Copper coatings modified with chromium and sulfur inclusions were electrodeposited in acidic copper sulfate electrolytes containing a metallic powder of chromium. It was found that a metallic powder of chromium is not suitable to obtain Cu–Cr composites in contrast to chemical inert particles of other non-metallic powders. Due to electrochemical re...

Influence of strong electric field in wide frequency range (from DC to 35 GHz) on electrical resistance of thin La0.67Ca0.33MnO3 polycrystalline manganite films was investigated in the range of (78/300) K. Different behavior of resistance change vs. temperature was observed when pulsed DC electric field and microwaves were applied to the films. Whe...

Epitaxial, textured, and polycrystalline La0.7Ca0.3MnO3 films, having about 150 nm thickness, were prepared by pulsed laser deposition techniques onto (110) NdGaO3, MgO and lucalox substrates and investigated using 10 ns duration, 0.5 ns rise time electrical pulses having amplitude up to 500 V. Electroresistance of the films [R(E) - R(0)]/R(0) was...

The matrix durability properties were improved when micrometer-sized artificial diamond particles were incorporated into an electroplated copper matrix. Those diamond particles have a hardening effect on the metal matrix and its microhardness is increased fourfold. Copper composite coatings are distinguished for their low electrical resistivity in...

The effects of strong pulsed magnetic field and shock waves on the electrical properties of La0.67Ca0.33MnO3 and La0.7Sr0.3MnO3 thin films were investigated. It was demonstrated that these films could be used to measure the magnetic fields produced by magnetocumulative generators. Possible ways to design fast magnetic field sensors operating at roo...

Thin films of La(0.7)Sr(0.)3MnO(3) grown on (001) NdGaO3 substrate using vertical hot wall Injection CVD reactor were investigated by means of standard fish-bellied beam inducing uniaxial compressive (or tensile) strain of the films. The measurements were carried out in current direction both parallel (longitudinal resistance R-l) and perpendicular...

The responses of piezoresistive, micromachined, absolute and gauge pressure sensors to step waveforms were investigated experimentally in a wide range of diaphragm thickness. The dynamic behavior of these sensors is described using the main mode of second-order system. The distinguishing feature of the sensors is their low damping ratio, a critical...

Media-separating housings for pressure sensors are perspective constructions which enable pressure-sensitive elements to be protected from aggressive mediums. They also improve pressure sensor stability with regard to thermal shock. The systematic thermal errors which result from the placement of a pressure-sensitive chip in a media-separating hous...

Aluminum thin film resistors are proposed for use as temperature sensors for the compensation of the thermal sensitivity and offset shift of pressure sensor output. An experimental investigation of Al films with different thicknesses and heat treatment was carried out in order to optimize the electric parameters of such temperature resistors. It wa...

The use of a semiconductor pressure sensor based on AlGaAs thin films to measure shock-wave pressures in lithotripters is described. The selection of an optimal thickness of encapsulant on the face of the pressure-sensitive chip enables a satisfactory durability and dynamic accuracy of the sensors to be obtained. Pressure sensors with a diameter of...

The use of graded-composition epitaxial films of mixed compound semiconductor AlxGa1-x As as high-pressure sensors has been studied. It is shown that sensors made of Alx Ga1-x As films have a high sensitivity to uniform pressure (5–10%/100 MPa), a nearly linear dependence of resistance on pressure (non-linearity in the range 0–1 GPa is less than 2%...

An array consisting of four magnetic field sensors made from thin polycrystalline La 0.83 Sr 0.17 MnO 3 film was used for measurement of magnetic field distribution inside the bore of multi-layer coil during electromagnetic launching of Cu hollow cylinder. The magnetic field distribution along the axis of the bore at different time points during mo...

The dependences of the fraction of electroporated mouse hepatoma MH-22A cells on the pulse intensity were obtained for the cells exposed to a single square-wave electric pulse with the duration from 95 ns to 20 μs. The amplitude of an electric pulse was varied from 0.4 to 12 kV/cm. Increasing the intensity of the electric field pulse increased the...