Fluctuations of Current in Polycrystalline Ferroelectric Ceramics

Experimental data on fluctuations of leakage currents over time in samples of polycrystalline ferroelectric ceramics (SBPZT-1, ceramics based on sodium bismuth lead zirconate–titanate) upon the application of a constant electric field are considered. Variations in the type of leakage current dependence on time with an increase in electric field strength on samples with different values of the loss-angle tangent are determined. Exponential decay is accompanied by random jumps, i.e., variations in the values of the leakage current.     

Relaxation in polycrystalline ferroelectric ceramics upon the simultaneous impact of mechanical stresses and electric field

The motions of domain walls at low stresses are known to result in the relaxation of structural over-stresses and their balancing, while at high stresses we observe overstress increases and microcrack formation, i.e., the changing of resonance frequencies and emerging of spurious resonances of piezoelectric elements [1, 2]. In view of the above, the influence of electromechanical impacts on ceramics of compositions PZT-19 and PZT-35 are investigated in order to estimate the resonance curve changes.     

Some Transformations of 3-(2,2-Dimethyltetrahydro-2H-pyran-4-yl-2-thioxo-2,3-dihydro-1H-spiro(benzo[h]quinazoline-5,1'-cycloheptan)-4(6H)-one

Russian Journal of Organic Chemistry - Starting from 3-(2,2-dimethyltetrahydro-2H-pyran-4-yl)-2-thioxo-2,3-dihydro-1H-spiro(benzo[h]quinazoline-5,1'-cycloheptan)-4(6H)-one, a series of...     

Experimental study of magnet undulators with pulsed-wire method

Experimental study of magnetic characteristics of planar magnet undulator for terahertz FEL has been carried out with use of pulsed-wire method. Special attention was given to the procedure of measurement of the second integral of undulator magnetic field, which shows variation of the beam position at passing the undulator magnetic system.     

Physical and physicochemical processes accompanying powder synthesis, growth of PbMoO4 crystals, and their annealing in various media: VI. Anomalous biaxiality and thermoplastic stresses in PbMoO4 crystals in the relationship with the growth conditions

The optical anomalies are investigated and the internal stresses are calculated for lead molybdate crystals grown by the Czochralski method. An effect of the growth conditions on the distribution of stresses in the crystals is revealed.     

Undulator with permanent ferrimagnetic magnets

Undulator for terahertz FEL is created of ferrite materials. The length of the undulator period is 9 cm and the number of periods is 27. By means of selection and redistribution of magnetic elements it was succeeded to reduce the spread in amplitudes of the magnetic field down to 7%. Additional windings in magnetic elements were used to compensate for the residual spread. The needed focusing gradient of the magnetic field is obtained by means of relative displacement, along the x-axis, of alternating poles with opposite signs of the magnetic field. The undulator parameters, including the properties of focusing in the horizontal plane, are studied.     

Coplanar monolithic resonator for X-ray and synchrotron radiation

A scheme of a three-block monolithic X-ray resonator with Si \((04\bar 4,40\bar 4)\)-configuration single crystal for NiKα₂ and synchrotron radiation is proposed and realized experimentally. Specialties and advantages of the proposed scheme are given. It is shown that using asymmetric Bragg reflections makes possible to solve one of the basic problems of X-ray resonators, that of the input of radiation into the resonator and creation of the lossless cycle. The technology of fabrication of the resonator is described and the problems of raising the efficiency of its operation are considered.     

FT IR ATR Study of Molecular Interactions in the Urea/Dimethyl Sulfoxide and Urea/Diethyl Sulfoxide Binary Systems

FT IR ATR spectra of urea/dimethyl sulfoxide and urea/diethyl sulfoxide mixtures in the S=O and N—H stretching vibration regions at different molar ratios have been measured. On the basis of the band deconvolution data, various types of intermolecular associated forms, including dimers and hydrogen-bonded urea–sulfoxide complexes, have been revealed. The latter has been confirmed also by ab initio calculations.