Calorimetric study of the glassy state. XIII. Thermodynamic properties of normal and deuterated orthoboric acid crystals.
Calorimetric study of the glassy state. XIII. Thermodynamic properties of normal and deuterated orthoboric acid crystals.
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玻璃态的量热研究。
DOI：
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发表时间：
1977
期刊：
影响因子：
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通讯作者：
S. Seki
中科院分区：
文献类型：
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作者：
M. Oguni;T. Matsuo;H. Suga;S. Seki
利用绝热量热仪和室温以上的差热分析曲线，在13 ~ 370 K的温度范围内测量了正常硼酸和氘化硼酸的热性能。对于这两种晶体，热容异常在290 K左右，取决于试样的热历史；即，在此温度范围内观察到吸热或放热焓弛豫。这种行为是玻璃化转变的特征，被认为是氢键中质子重排运动的冻结现象。用指数律分析了焓松弛曲线，发现焓过剩侧的特征时间常数比焓不足侧的特征时间常数更长。吸热弛豫时间为1ks时的玻璃化转变温度为296.6 K。
Thermal properties of normal and deuterated orthoboric acids were studied through the measurements of heat capacity in the temperature range from 13 to 370 K by using an adiabatic calorimeter and differential thermal analysis curves above room temperature. For both crystals, the heat capacity anomaly was found around 290 K in the heat capacity values dependent upon the thermal history of the specimen; i.e., the endothermic or exothermic enthalpy relaxation was observed in this temperature range. This behavior is of characteristic to the glass transition and is considered to be ascribed to the freezing-in phenomenon of the motion of rearrangement of the protons in hydrogen bondings. The enthalpy relaxation curves were analyzed with the exponential law and the characteristic time constant toward the equilibrium state was longer for enthalpy-excessive side than for enthalpy-deficient side. The glass transition temperature at which the endothermic relaxation time becomes 1 ks is 296.6 K for normal orthoboric ...