利用非线性参量B／A研究SDS水溶液液——固相变  

THE STUDY OF LIQUID SOLID PHASE TRANSITION IN SDSAQUEOUS SOLUTION BY NONLINEARITY PARAMETER B/A

作　　者：鲁志劬[1,2] 龚秀芬[1,2] 刘杰惠[1,2] 

机构地区：[1]南京大学国家重点实验室近代声学实验室 [2]南京大学声学研究所

出　　处：《南京大学学报（自然科学版）》1996年第1期30-35,共6页Journal of Nanjing University（Natural Science）

摘　　要：报导了利用非线性参量Ｂ／Ａ研究ＳＤＳ水溶液随温度变化时发生液—固相变的情况，首次发现ＳＤＳ水溶液在发生液——固相变时Ｂ／Ａ随温度变化规律反常，这说明Ｂ／Ａ不仅能反映物质结构的变化。Nonlinearity parameter B/A is a basic parameter in nonlinear acoustics. It is defined as the dependency of sound velocity of pressure. The paper reports the study of Liquid solid phase transition in SDS aqueous solution by using nonlinearity parameter B/A. It is found that when the inner temperature of SDS solutions decreases to a specific point, the liquid-solid phase transition of SDS solutions takes place. During this procedure, nonlinearity parameter B/A is measured by the improved thermodynamic method for nonlinearity parameter B/A measurement system for four SDS solutions with concentrations 1%, 2%, 3% and 4% as a function of temperature. Generally speaking, the B/A values decrease linearly with temperature decreasing and increase with concentration increasing. However, the results show that in both cooling process and heating process, the relationship between B/A and temperature is abnormal when liquid solid phase transition happens, i.e. the turning points of the B/A-T curves of SDS solutions just appear at the phase transition point. This means that the B/A can perfectly indicate the liquid solid phase transition of SDS solutions. According to the definition of B/A, the B/A values are related to thermodynamic quantities such as β, ρ o, c o, α, C P, T,cP T, and cT P. Among them, the values of ρ o, c o, T and cT P given by experimental data, do not show sudden changes when liquid-solid phase transition occurs. However, with the knowledge of physicalchemistry, it is commonplace to see that the values of α, C P, β and (c/P) T are of some discontinuities when first or second order phase transition happens. It is the sudden changes of these physical quantities at phase transition point that lead to the variation of B/A values with temperature. Moreover, B/A represents the dependency of elastic parameter of stress and displays the dynamic properties of materials. The alternation of matter structure, which causes the change of dynamic properties, leads to the appearance

关 键 词：非线性参量B/A SDS水溶液 相变 温度 

分 类 号：O646.16[理学—物理化学] O424[理学—化学]