The vaporization of zinc phosphide
The vaporization of zinc phosphide
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DOI：
10.1021/j100867a043
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发表时间：
1967-07
期刊：
影响因子：
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通讯作者：
R. Schoonmaker;A. Venkitaraman;P. K. Lee
中科院分区：
文献类型：
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作者：
R. Schoonmaker;A. Venkitaraman;P. K. Lee
Shchukarev和他的同事2已经测量了Zn3P2(C)的燃烧热，并报告了298K下的生成热为-98千卡/摩尔。卡维利斯3报告了磷化锌在298K下的生成热，通过测量元素的反应热为-55千卡/摩尔，通过测量水解热的结果为-53.4千卡/摩尔。这些值可以与H[Cd_3P_2(C)]=-27千卡/摩尔进行比较。4在元素周期表中相邻位置的磷化物形成热之间的70千卡/摩尔的差异似乎是反常的，这意味着晶体中的成键发生了显著的变化。Brewer5提出，在核反应堆燃料元件罐中，磷化锌是几种可能具有吸引力的传热液化合物之一。为了评价材料作为传热剂的适宜性，需要了解它们的热稳定性和汽化速率。在最近关于GaN6和GaP蒸发的研究中，7证明了氮化物的蒸发系数很低，某些液态金属可以作为蒸发过程的催化剂。在磷化镓的情况下，总的汽化过程类似于氮化物的汽化过程，类似的实验技术没有产生关于汽化机理的任何详细信息，只能得出结论，GaP的汽化系数远远大于GaN的汽化系数。为了研究金属磷化物的汽化机理，似乎需要研究一些金属磷化物，如锌或镉的汽化，它们可能会通过同组分的分解过程蒸发，在这种过程中，残留液体的催化不能排除从晶体中直接汽化的系数小于1的检测。
Shchukarev and co-workers2 have measured the heat of combustion for Zn3P2 (c) and have reported a heat of formation of—98 kcal/mole at 298 K. Karvelis3 has reported heats of formation for zinc phosphide at 298 K of—55 kcal/mole from measurement of the heat of reaction of the elements and—53.4 kcal/mole from a measurement of the heat of hydrolysis. These values may be compared to AH [Cd3P2 (c)]=—27 kcal/mole. 4 A difference of 70 kcal/mole between heats of formation of phosphides where the metals occupy adjacent places in a group in the periodic table seems anomalous and implies a marked change in bonding in the crystals. Brewer5 has suggested that zinc phosphide is one of several compounds which may be attractive as heat-transfer fluids in nuclear reactor fuel element cans. In orderto evaluate the suitability of materials as heat-transfer agents it is desirable to have information about their thermal stabilities and rates of vaporization. In recent studies of the vaporization of GaN6 and GaP, 7 it was demonstrated that the nitride has a very low vaporization coefficient and that certain liquid metals may act as catalysts for the vaporization process. In the case of gallium phosphide, where the over-all vaporization process is analogous to that for the nitride, similar experimentaltechniques did not yield any detailed information about the mechanism of vaporization and it was only possible to conclude that the coefficient for vaporization of GaP is much larger than the coefficient for GaN. In order to investigate the mechanism of vaporization of metal phosphides, it seemed desirable to study some, like those of zinc or cadmium, which might be expected to vaporize by a congruent decomposition process in which catalysis by a residual liquid phase could not preclude detection of coefficients less than unity for direct vaporization from the crystal.