Publications by authors named "Dmitry Roshchupkin"

8 Publications

  • Page 1 of 1

Single crystals of ferroelectric lithium niobate-tantalate LiNbTaO solid solutions for high-temperature sensor and actuator applications.

Acta Crystallogr B Struct Sci Cryst Eng Mater 2020 Dec 16;76(Pt 6):1071-1076. Epub 2020 Nov 16.

Universität Potsdam, Institut für Physik, Karl Liebknecht Str. 24-25, Potsdam, 14471, Germany.

Ferroelectric LiNbTaO solid solutions with various Nb/Ta ratio were grown from the melt by the Czochralski method. The exact composition of the grown crystals was determined by inductively coupled plasma atomic mass spectrometry. The dependence of the crystal composition on the composition of the initial melt was obtained and explained by a wide separation between the phase boundaries of the liquid and solid phases on the LiNbO-LiTaO phase diagram. Using high-resolution X-ray diffraction, the parameters a and c of a crystal unit cell were determined (LiNbTaO: a = 5.1574 Å and c = 13.8498 Å). Further, the Curie temperature T of the crystals was measured using the differential scanning calorimetry technique. T was found to depend on the composition of the crystals that allowed conditions for the monodomainization of the grown crystals to be defined (LiNbTaO: T = 1102°C; LiNbTaO: T = 794°C). Finally, the velocity of surface acoustic waves was determined by scanning electron microscopy and X-ray diffraction techniques (YZ-cut of a LiNbTaO crystal: V = 3440 m s).
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http://dx.doi.org/10.1107/S2052520620014390DOI Listing
December 2020

Pulse picker for synchrotron radiation driven by a surface acoustic wave: erratum.

Opt Lett 2018 06;43(11):2490

An erratum is presented to correct the typographical errors concerning the composition of the multilayer used in the experiment in Opt. Lett. 42, 1915.
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http://dx.doi.org/10.1364/OL.43.002490DOI Listing
June 2018

Influence of the Quantum Well Structure and Growth Temperature on a Five-Layer InGaMnAs Quantum Well with an InGaAs Buffer Layer.

J Nanosci Nanotechnol 2018 Jun;18(6):4355-4359

Institute of Microelectronics Technology and High-Purity Materials, Russian Academy of Sciences, Chernogolovka 142432, Russian Federation.

The influence of quantum well structure and growth temperature on a synthesized multilayer system composed of a five-layer InMnGaAs quantum well with an InGaAs buffer layer grown on semi-insulating (100)-oriented substrates prepared by low temperature molecular beam epitaxy was studied. The magnetization measurements using a superconducting quantum interference device indicated the existence of ferromagnetism with a Curie temperature above room temperature in the five-layer InGaMnAs quantum well structure with an InGaAs buffer layer in a GaAs matrix. X-ray diffraction and secondary ion mass spectroscopy measurements confirmed the second phase formation of ferromagnetic GaMn clusters. The ferromagnetism that exists in the five-layer of the InMnGaAs quantum well with the InGaAs buffer layer results from a superposition of the ferromagnetism of the low temperature region from the substitutional Mn ions into Ga sites or interstitial Mn ions as well as the presence of manganese ions dopant clusters such as GaMn clusters.
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http://dx.doi.org/10.1166/jnn.2018.15008DOI Listing
June 2018

Study of middle infrared difference frequency generation using a femtosecond laser source in LGT.

Opt Lett 2017 Sep;42(18):3698-3701

We demonstrate phase-matched difference frequency generation in the emerging nonlinear crystal LaGaTaO. Tunable wavelengths between 1.4 and 4.7 μm are generated by using femtosecond sources. We also report on the measurements of the optical damage threshold in the femtosecond regime and on the nonlinear refractive index n.
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http://dx.doi.org/10.1364/OL.42.003698DOI Listing
September 2017

Pulse picker for synchrotron radiation driven by a surface acoustic wave.

Opt Lett 2017 May;42(10):1915-1918

A functional test for a pulse picker for synchrotron radiation was performed at Diamond Light Source. The purpose of a pulse picker is to select which pulse from the synchrotron hybrid-mode bunch pattern reaches the experiment. In the present work, the Bragg reflection on a Si/B4C multilayer was modified using surface acoustic wave (SAW) trains. Diffraction on the SAW alters the direction of the x rays and it can be used to modulate the intensity of the x rays that reach the experimental chamber. Using electronic modulation of the SAW amplitude, it is possible to obtain different scattering conditions for different x-ray pulses. To isolate the single bunch, the state of the SAW must be changed in the short time gap between the pulses. To achieve the necessary time resolution, the measurements have been performed in conical diffraction geometry. The achieved time resolution was 120 ns.
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http://dx.doi.org/10.1364/OL.42.001915DOI Listing
May 2017

Observation of sagittal X-ray diffraction by surface acoustic waves in Bragg geometry.

J Appl Crystallogr 2017 Apr 14;50(Pt 2):525-530. Epub 2017 Mar 14.

Helmholtz Zentrum Berlin für Materialien und Energie, Germany; Freie Universität Berlin, Germany.

X-ray Bragg diffraction in sagittal geometry on a Y-cut langasite crystal (LaGaSiO) modulated by Λ = 3 µm Rayleigh surface acoustic waves was studied at the BESSY II synchrotron radiation facility. Owing to the crystal lattice modulation by the surface acoustic wave diffraction, satellites appear. Their intensity and angular separation depend on the amplitude and wavelength of the ultrasonic superlattice. Experimental results are compared with the corresponding theoretical model that exploits the kinematical diffraction theory. This experiment shows that the propagation of the surface acoustic waves creates a dynamical diffraction grating on the crystal surface, and this can be used for space-time modulation of an X-ray beam.
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http://dx.doi.org/10.1107/S1600576717002977DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5377346PMC
April 2017

Phase-matching directions, refined Sellmeier equations, and second-order nonlinear coefficient of the infrared Langatate crystal La₃Ga(5.5)Ta(0.5)O₁₄.

Opt Lett 2014 Jul;39(13):4033-6

We directly measured phase-matching directions of second harmonic, sum, and difference frequency generations in the Langatate La₃Ga(5.5)Ta(0.5)O₁₄ (LGT) uniaxial crystal. The simultaneous fit of the data enabled us to refine the Sellmeier equations of the ordinary and extraordinary principal refractive indices over the entire transparency range of the crystal, and to calculate the phase-matching curves and efficiencies of LGT for infrared optical parametric generation.
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http://dx.doi.org/10.1364/OL.39.004033DOI Listing
July 2014

X-ray topography analysis of acoustic wave fields in the SAW-resonator structures.

IEEE Trans Ultrason Ferroelectr Freq Control 2005 Nov;52(11):2081-7

Institute of Microelectronics Technology and High Purity Materials, Russian Academy of Sciences, Laboratory of X-ray Acoustooptics, Chernogolovka, Russian Federation.

The formation of fields of standing surface acoustic waves (SAW) in LiNbO3 and La3Ga5SiO14 (LGS) crystals was studied by high-resolution topography method on a laboratory X-ray source. The fields of standing SAW were formed using SAW-resonator structures consisting of interdigital transducer (IDT) and reflecting gratings. The SAW amplitudes and power flow angles were measured by X-ray topography, diffraction in acoustic beam was visualized, and the SAW interaction with the crystal structure defects was studied.
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http://dx.doi.org/10.1109/tuffc.2005.1561678DOI Listing
November 2005