THERMODYNAMIC PROPERTIES OF SYNTHETIC SAPPHIRE (ALPHA-AL2O3), STANDARD REFERENCE MATERIAL 720 AND THE EFFECT OF TEMPERATURE-SCALE DIFFERENCES ON THERMODYNAMIC PROPERTIES
THERMODYNAMIC PROPERTIES OF SYNTHETIC SAPPHIRE (ALPHA-AL2O3), STANDARD REFERENCE MATERIAL 720 AND THE EFFECT OF TEMPERATURE-SCALE DIFFERENCES ON THERMODYNAMIC PROPERTIES
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DOI：
10.1063/1.555931
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发表时间：
1993-11-01
影响因子：
4.3
通讯作者：
ARCHER, DG
中科院分区：
文献类型：
--
作者：
ARCHER, DG
国家标准与技术研究所的标准参考材料720热容量证书值与最近实验测定的值进行了比较，表明证书值可能存在系统误差。为了得到α-Al_2O_3热力学性质的表示式，用标准参考物质(SRM720)对某些类型的量热计进行了拟合，得到了α-Al_2O_3的热容、相对热容和相对热容的拟合方程和计算值。新值比1982年的SRM720证明值更准确，更好地反映了实验值。此外，利用α-Al_2O_3的结果，简要讨论了实际温度标度变化对热力学性质影响的一般问题。IUPAC热力学委员会最近的一份报告给出了一种根据实际温度范围的变化来转换热力学性质的方法。IUPAC方法被证明不是普遍正确的。给出了一种更好的估计这些变化的方法。
Comparison of the National Institute of Standards and Technology's Standard Reference Material 720 certificate values for heat capacity with those obtained from recent experimental determinations indicated the possibility of a systematic error in the certificate values. Selected experimental determinations of enthalpy increments and heat capacities were fitted in order to obtain a representation of the thermodynamic properties of alpha-Al2O3, a sample of which is the standard reference material (SRM720) for calibration of some types of calorimeters, The fitted equation and calculated values of the heat capacity, the relative enthalpy, and the entropy are given. The new values are more accurate and result from a better representation of the experimental values than did the 1982 SRM720 certificate values, Additionally, the general problem of the effect of changes in practical temperature scales on thermodynamic properties is briefly discussed, using the results for alpha-Al2O3. A recent report from the IUPAC Commission on Thermodynamics gave a method for the conversion of thermodynamic properties for changes in practical temperature scale. The IUPAC method is shown to be not generally correct. A better method for estimation of these changes is given.