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五、过渡族金属和合金的热电性能在常用的热电偶材料组合中,至少有一极是由过渡族金属或合金组成的,这是由于在任何温度下它们的热电势率都比简单金属要大得多(见图1),因而对热电偶材料研究者来说有特别的兴趣。过去大量的理论和实验研究也多集中于此,特别是镍、铁、铂族金属和难熔元素,并创造出一批著名的热电偶材料,如中低温用的镍铬-镍铝(硅)、镍铬-康铜、铁-庚铜,高温用的铂铑-铂、铱铑-铱、钨钼、钨铼等。今后,为了创制新材料,改进传统材料,详细研究这类金属材料显然具十分重要而基本的意义。过渡族金属是指周期表中,以Ni、Pd、Pt结束的三个长周期中的24个元素,分别有3d、4d和5d内壳层的电子未填充满。这些金属的电子结构的共同特点正如莫特(Mott,1936年)指出的:在费米面上
V. Thermoelectric Properties of Transitional Metals and Alloys In commonly used combinations of thermocouple materials, at least one pole is composed of transitional metals or alloys due to their greater thermoelectric power potential than simple metals at any temperature Much more (see Figure 1) and therefore has a special interest for thermocouple materials researchers. In the past a large number of theoretical and experimental research are also concentrated here, especially nickel, iron, platinum group metals and refractory elements, and to create a number of well-known thermocouple materials, such as low temperature nickel-chromium - nickel aluminum ), Nickel-Chromium-Constanton, Iron-Ganthate, platinum rhodium-platinum for high temperature, iridium-rhodium-iridium, tungsten molybdenum, tungsten rhenium, and the like. In the future, in order to create new materials, improve the traditional materials, a detailed study of such metal materials is obviously very important and basic significance. The transition metal is the 24 elements in the three long periods ending in Ni, Pd and Pt in the periodic table, and the electrons in the inner shell are not filled up in 3d, 4d and 5d, respectively. The common characteristics of the electronic structures of these metals are as pointed out by Mott (1936): on the Fermi surface