Час релаксацiї флуктуацiй концентрацiй поблизу критичної точки розшарування бiнарного розчину н-пентанол-нiтрометан

• Main Authors: Bulavin, L. A., Bilous, O. I., Svechnikova, O. S.
• Format: Article
• Language: English; Ukrainian
• Published: Publishing house "Academperiodika" 2019
• Subjects: швидкiсть; поглинання ультразвуку; критична точка розшарування; бiнарний розчин; час релаксацiї флуктуацiй концентрацiй; ultrasound velocity; ultrasound absorption; critical stratification point; binary solution; concentration fluctuations; relaxation time; -
• Online Access: https://ujp.bitp.kiev.ua/index.php/ujp/article/view/2019024

The propagation velocity and the absorption coefficient of ultrasound in a frequency range of 5–2800 MHz in a n-pentanol–nitromethane solution in a vicinity of its critical stratification point from the homogeneous state side have been studied. The research make it possible to reveal the influence of concentration fluctuations on the sound propagation velocity. Three regions of dynamical parameters are analyzed: the mean-field (wтFL ≪ 1), fluctuation (wтFL ≫ 1), and transition (crossover, wтFL = 1) ones. On the basis of experimental data, the temperature dependence of the concentration fluctuation relaxation time т(T) is studied, and its magnitude т0 is determined. The contribution to the fluctuation part of the sound absorption coefficient at high frequencies (w > 300 MHz), which is connected with the sound scattering by concentration fluctuations near the critical stratification point is estimated.