某些氟化物的升华提纯　Ⅱ．ZrF_4和HfF_4的升华提纯

Purification of Some Fluorides by Sublimation Ⅱ. Purification of ZrF_4 and HfF_4 by Sublimation

尽管升华方法在除去氧化物方面很有成效，但也必须注意ＺｒＦ４和ＨｆＦ４的水解温度和脱水温度．由于升华方法不能有效地除去象ＦｅＦ３等氟化物杂质．作者根据ＦｅＦ６３－，ＣｏＦ６３－是属于外轨道络合物，它们是不稳定的和容易离解出Ｆｅ３＋和ＣＯ３＋，同时ＦｅＺｒＦ６·６Ｈ２Ｏ也易于离解出Ｆｅ２＋，以致使（ＮＨ４）３ＺｒＦ７和（ＮＨ４）３ＨｆＦ７可以用ＤＤＴＣ－ＣＨＣｌ３，在ｐＨ３～３．５的有效萃取成为可能．在ＺｒＦ４－ＨｆＦ４的二元组分系统中，它们的升华、凝华过程是遵循图２的相平衡规律进行的．用ＸＲＤ检测升华产品，为无水单斜态的ＺｒＦ４或ＨｆＦ４晶体，用ＧＦＡＡＳ检测，升华前后Ｆｅ含量各自为０．８ｐｐｍ和０．５ｐｐｍ，批生产量２５０ｇ．

Even if sublimation method is very effective for removing oxides, one still must take note of dehydrating and hydrolyzing temperatures of ZrF4 and HfF4, and FeF3 etc. inclusions of fluorides cannot effectively be separated out. On the ground of that FeF63-, CoF63- are outer orbital complexes, and instable and easily dissociate into Fe3+ and Co3+, while FeZrF6-6H2O also easily dissociates into Fe2+, so that the extraction of (NH4)3ZrF7 and (NH4)3HfF7 becomes posible by DDTC-CHCl3 with pH 3～3.5. In two-component system of ZrF4 and HfF4, sublimating and solidifying processes will follow the law of the phase equilibrium shown in Fig.2. Sublimated products were examined by XRD to be β-monoclinic anhydrous ZrF4 or HfF4 crystals; By GFAAS, before and after sublimation, Fe contents were 0.8ppm and 0.5ppm respectively. The batch was 250g.