There are two ways to solve the glass-formation prognosis problem in the absence of a unified concept of glass-formation that connects its structural-chemical, kinetic, and thermodynamic aspects. Structural-chemical and energetic factors of glass-formation, together with the relaxation conditions of glass- forming ability with increase in atomic numbers of elements have been considered as a starting point for the development of the structural-energetic concept of glass formation.
Main optical, thermal and mechanical properties of new compositions based on alicyclic polyimide and active bright red 6C synthetic dye have been studied. It was shown that the transmission ratio of the new material in the region of 400-900 nm and 2.0 wt.% dye concentration was around 60-70%. Thermal, mechanical and electrical properties of new colored compositions were comparable with the properties of original polyimide.
Paper presents a structure of a micro-mirror element driven by thermal micro-actuators. Micro-mirror dimensions are 100x100 um and it was manufactured by a surface micromachining using microelectronics technologies. Thermal microactuator is a bimorph structure consisting of aluminum and silicon dioxide layers with a polysilicon heater between them. The description of manufacturing process for micro-mirror element is given. The micro-mirror motion is achieved by passing an electric current through the heater. The actuator structure is heated and rotates the mirror. The processes of heating and cooling of thermal micro-actuator structure directly affects the characteristics of manufactured micro-mirror, thus the studying of these processes is essential. The report proposes a method for calculating the heating and cooling time, taking into account the influence of the structure geometry, electrical characteristics of external influence and the environment conditions. Also a method for the experimental determination of the dynamic characteristics is proposed, along with the method of electro-thermal analogy. The results of calculation are in good agreement with the experimental data, which allows one to use it to determine the dynamic characteristics of micro-devices based on thermal microactuators.
In this paper analysis of comb design for the sensing element MEMS accelerometer with longitudinal displacement of the inertial mass under the influence of acceleration to obtain the necessary parameters for the further construction of an electronic circuit for removal and signal processing has been done. Fixed on the stator the inertia mass has the ability to move under the influence of acceleration along the longitudinal structure. As a result the distance between the fixed and movable combs, and hence the capacitance in the capacitors have been changed. Measuring the difference of these capacitances you can estimate the value of the applied acceleration. Furthermore, managing combs that should apply an electrostatic force for artificial deviation of the inertial mass may be used for the initial sensitive elements culling. Also in this case there is a change of capacitances, which can be measured by the comb and make a decision about the spoilage presence or absence.
Research methodology for measuring the natural frequency of the inner and outer frames of micromechanical oscillating system with an electrostatic actuator in filling spaces inside corps with nitrogen, and verification methodology of a micromechanical sensor element (SE) on the basis of rotation angle measurement has been developed. Developed new technical solution was consisted in that for correcting errors in the form of etched shapes compensator topology with special configuration has been used. It was possible to obtain the moving parts of MEMS with etched rectangular shape figures and with a large etching depth about 400 microns. Hydrogenated silicon surface layers were investigated by IR - spectroscopy. It was shown that substrate temperature plays a primary role in the formation of hydrogen-defect layer in silicon. The behavior of the low-frequency band in the region of stretching vibrations of Si-H during annealing has been analyzed. The dependence character of the resonance frequency of the movable (SE) part of MEMS torsion type vs temperature has been investigated. It was found that when the temperature changes from 25 to 80 °C, so natural SE frequency does not change more than 1%. The dependence of the quality factor and the natural frequency of the moving SE part from the inside corps pressure on the various modes of oscillation was investigated.
Paper presents the study results and modeling of functional characteristics of the linear acceleration transducers, enabling sensors creation with the specified parameters. Sensing element made for linear acceleration transducer with torsion cruciform section has been proposed on the based design and technological principles. It allows minimizing the impact of cross-acceleration and gives the maximum of center mass displacement for high sensors sensitivity in the given dimensions. The range of measured acceleration from ± 0.2g to ± 50g was provided by changing the torsion bar thickness n = 34 ÷ 56 microns. The transducers frequency range of linear acceleration 100-150 Hz depends on the gas pressure P = 700-800Pa in which the sensor element was located. Methods converting displacement of sensing element in the sensor output have been provided. On their basis the linear acceleration transducers with analog output signal having a predetermined frequency range and high linearity of the transformation (nonlinearity 0.2-1.5%) was developed. Also the linear acceleration transducers with digital signal consuming little (no more than 850 μA), low noisy (standard deviation to 0.1mg/rt-Hz) and high sensitivity (up to 0.1mg) to the accelerations was made. Errors in manufacturing process of sensitive elements and operating environment temperature affect the changes in the characteristics of the linear acceleration transducers. It has been established that different plate thickness up to 3.6% leads to the scale factor error to 4.7%. Irreproducibility of depth anisotropic etching of silicon up to 6.6% introduces an error in the output signal of 2.9 ... 13.8mg.
Optical, dielectric, thermal, physico-mechanical properties of new fluoro-containing alicyclic polyimides were investigated. High optical transparency in visible and UV ranges of the films with thickness 10-25 μm, which lower boundary was registered at 125-260 nm; as well as reflectivity index being 1.492-1.515 were recorded. Dielectric permeability was characterized with low rates and stability up to 300 °С depending on chemical structure. Polyimides were stable with heating in air up to 320-380 °С. Prepared films show break tensile at 145 MPa with elongation up to 50% due to the excellent film-forming properties. Films based on polyimides with polyaniline composition demonstrates reflectivity index 1.60.
Although, several reviews have appeared on various physical properties and applications of
chalcogenide glasses, there is no thorough study of local atomic structure and its modification for eutectic Ge-Sb-Te
alloys doped with Bi. Ge2Sb2Te5 pure and Bi-doped films were deposited by ion-plasma sputtering method of
synthesized GTS material on Si (100) and glass substrates coated with a conductive Al layer which was used as a
bottom electrode. Current–voltage characteristics of different points of the same samples have been measured.
Random distribution of inclusions within the sample made it possible to investigate the dependence of switching and
memory effects on the phase composition at a constant value of other parameters. Measurements in the current
controlled mode clearly showed that the memory state formation voltage does not depend on current in a wide range.
Results indicate that the development of imaging technologies phase memory cells need to pay special attention to
the conditions of Ge-Sb-Te film preparation. To increase the number of cycles “write – erase” should be additional
prolonged annealing of the synthesized films.
Design studies method of star sensor thermal stability with liquid cooling using modern CAD
has been described. Optimal operation of two circuits for liquid cooling structure of star sensor has been
chosen using a mathematical model for calculating the convective heat transfer coefficient. Study defined
the angular displacement of the star sensor with liquid cooling (~ 0.3 arc seconds), which is acceptable for
star sensors with 1 arc seconds accuracy. At this level of scientific investigation the developed 3D model
of the star sensor assembly comprising a thermally stabilizing ground test equipment allows to determine
the angular error due to the temperature loads and optimal parameters liquid of cooling system (for
example, the flow rate of fluid , geometrical parameters of cooling circuits , etc.). In the future, this model
should be improved, which will consider the impact of other factors (e.g. gravity, vibration, etc.) on the
performance of the star sensor.
Lead-zirconate-titanate (PZT) is a typical piezoelectric material with outstanding properties. The preparation behavior of Lead Zirconate Titanate (PZT) composite films comprised of Si, SiO2, Pt, PZT and Pt for MEMS applications was investigated. The choice of precursors can affect the microstructures and properties of the product, so in this paper we compared the crystallization behavior of PZT films derived from different precursors, stressing the influence of experiment conditions. Dense PZT films were prepared by electrophoretic deposition method (EPD), using commercial powder PZT precursor and metal alkoxide components for the same composition. Some specific comments were underlined about structure of PZT films.