Structure, phase transition and vibrational spectra of the NaH5(PO4)2 and NaD5(PO4)2 crystals
作者:J Baran、T Lis、M Drozd、H Ratajczak
DOI:10.1016/s0022-2860(99)00141-6
日期:2000.1
respectively. Two corresponding moieties are joined into dimers by two equivalent hydrogen bonds. The structures of title crystals differ from that of KH5 (PO4)2. The powder IR and Raman spectra were measured at room temperature. The IR spectra of the NaH5 (PO4)2 crystal were also measured at low temperatures. It is suggested that the phase transition is related to the changes in the motions of the protons in
摘要 首次获得了五氢二磷酸钠NaH5(PO4)2[NaH2PO4·H3PO4]及其氘代类似物NaD5(PO4)2[NaD2PO4·D3PO4]晶体。它们在约 2 处表现出二阶相变。根据 DSC 实验确定,200 K 对氘化(约 6-8 K)略微敏感。它们的结构通过 X 射线方法在 150 K(对于 NaH5(PO4)2)和 240 K(对于氘化)晶体下解析。这两种晶体都属于单斜晶系的 P21/c 空间群 (a=8.464(4), b=7.817(5), c=10.337(5) A, β=90.58(4)° NaH5(PO4) 2 和 a=8.495(3), b=7.854(3), c=10.352(3) A, β=90.67(3)° 为氘代) 并且它们的结构相似,尽管在不同的阶段确定。晶体由正磷酸分子层和磷酸二氢阴离子层构成。这些层分别由正磷酸分子和磷酸二氢阴离子的中心对称二聚体构成。两个