Reversibility of Temperature-Induced Liquid Transition in Pb26Sn42Bi32 Melt: Experimental Evidence with Electrical Property

Exploring nature of liquid structures and properties is becoming more interesting in various fundamental and applied fields. With different resorts including the resistivity method, temperature-induced liquid-liquid structure transitions （TI-LLST） have been suggested and verified to occur in some liquid alloys, while the reversibility of TI- LLST has rarely been examined as yet. Unlike some other investigated liquid alloys, here we show that electrical resistivity of Pb26Sn42Bi32 melt exhibit an anomalous change in the first heating run and a reversible change in the following cooling and heating cycles. Taking account of the structural sensitivity of electrical resistivity, the abnormal patterns suggest two sorts of TI-LLST that are irreversible and reversible in the liquid ternary alloy, respectively. This interesting phenomenon together with other growing evidence imply that liquid structures and their change characteristics are multiform and complex.     

中学化学教学中生活性知识要求异变的研究

随着“教育回归生活”的呼声渐高,生活性知识逐渐成为化学课程中不可或缺的部分,但是在教学实践中,生活性知识逾越预设的功能和要求而异变的现象却屡见不鲜。本文就“碳酸钠溶液显碱性”知识点围绕文本、教学及评价3个层面展开分析比较,提炼其异变特征,探讨异变的原因及对化学课程实践产生的影响,进而思考改进生活性知识应用的途径与方法。