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Acoustic attenuation in ferroelectric Sn2P2S6 crystals

100%

Kohutych A. , Yevych R. , Perechinskii S. , Vysochanskii Y.

Open Physics

2010

tom 8

nr 6

905-914

The temperature and frequency dependencies of sound attenuation for the proper uniaxial ferroelectric Sn2P2S6, which has a strong nonlinear interaction of the polar soft optic and fully symmetrical optic modes that is related to the triple well potential, were studied by Brillouin spectroscopy. It was found that the sound velocity anomaly is described in the Landau-Khalatnikov approximation with one relaxation time. For explanation of the observed temperature and frequency dependencies of the sound attenuation in the ferroelectrric phase, the accounting of several relaxation times is needed and, for quantitative calculations, the mode Gruneisen coefficients are more appropriate as interacting parameters than are the electrostrictive coefficients. Relaxational sound attenuation by domain walls also appears in the ferroelectric phase of Sn2P2S6 crystals.

Jacket effect on strain measurement accuracy for distributed strain sensors based on Brillouin scattering

100%

Ding Y. , Shi B. , Bao X. , Gao J.

2006

tom Vol. 36, nr 1

57-67

Fiber jacket has a function of protecting fibers from harsh environment; it also has an impact on the measured strain accuracy. In this paper, we report on our study of jacket effect to distributed Brillouin sensor system on strain measurement accuracy for constant load stretching and constant length stretching using the 900 m tight-buffered fiber (Type-A) and the 250 m optical fiber (Type-B). We have studied the time-varying performance under the stretching of constant load and length. It was found that, within 48 hours under constant load stretching, the strain value of the Type-A measured by BOTDR (Brillouin optical time-domain reflectometer) increased with time, while the Type-B it kept stable. Within 48 hours under constant length stretching, the strain value of the Type-A decreased with time, while the Type-B it kept stable. After relaxation, the strain value of the Type-B reached zero within 1 hour, while the Type-A declined gradually. We found the creep deformation and stress relaxation of jacket to be the leading cause to this phenomena.

Elastic properties of (PbySn1−y )2P2S6 solid solutions

88%

Bilanych R. , Yevych R. , Kohutych A. , Perechinskii S. , Stoika I. , Vysochanskii Y.

Open Physics

2014

tom 12

nr 9

611-614

Elastic properties of (PbySn1−y )2P2S6 solid solutions were studied using Brillouin scattering technique. Different scattering geometries were used for sound velocities determination that make it possible to find all components of the stiffness tensor. The concentration dependencies of volume compressibility, the Grüneisen parameter and Debye temperature were investigated. The results obtained were used to analyze chemical bonding with substitution of tin by lead at room temperature in the crystals under consideration.

Proces fotopolimeryzacji mieszanin akrylan/nanokrzemionka : badany metodami spektroskopii rozproszeniowej

51%

Nowicka A. , Ziobrowski P. , Szybowicz M. , Sądej-Bajerlein M. , Andrzejewska E. , Drozdowski M.

Przetwórstwo Tworzyw

2012

tom [R.] 18, nr 5

485-488

W niniejszej pracy przedstawiono wyniki badań procesu polimeryzacji inicjowanej promieniowaniem UV mieszaniny akrylanu 2-hydroxyetylu (HEA) zawierającego zdyspergowany nanonapełniacz w postaci hydrofobizowanej krzemionki Aerosil ® R7200. W badaniach wykorzystano metody spektroskopii rozproszeniowej: Brillouina i Ramana. Spektroskopia Brillouiona pozwoliła na określenie zmian właściwości sprężystych w trakcie procesu polimeryzacji dla różnej zawartości krzemionki (nanonapełniacza). Spektroskopia Ramana pozwoliła na monitorowanie procesu fotopolimeryzacji badanych układów. Została ona również wykorzystana do zbadania wpływu tlenu na proces polimeryzacji.

This paper presents the results of the investigation of UV-initiated polymerization of 2-hydroxyetyl acrylate (HEA) containing a nanofiller (modified hydrophilic silica Aerosil ® R7200). The study was performed using scattering spectroscopy methods. Brillouin spectroscopy has been used to estimate changes in elastic properties occurring during the photopolymerization process of formulation containing different nanosilica contents. Raman scattering method was used to follow the photopolymerization process and to study the oxygen effect.