近幾十年來，六水金屬過氯酸鹽類包括Mg(ClO■)■‧6H■O、 Ni(ClO■)
■‧6H■O、Co(ClO■)■‧6H■O以及它們的同構物(isom- orphous)等系
列，在室溫、低溫的物理性質已有許多專題研究過，我們則以X-ray繞射
來探討它們在低溫、高溫的結構變化與相變機制。 LiClO■‧3H■O與Mg(
ClO■)■‧6H■O結構蠻相近，我們藉由C.D.We st所提LiClO■‧3H■O室
溫結構圖形，了解其如何推得Mg(ClO■)■‧6H■O的室溫結構為正交晶系
，空間群為Pmn2■。我們再經由X-ray繞射及結構因子的計算，證實C.D.
West的結構模型是正確的。 Ni(ClO■)■‧6H■O、Co(ClO■)■‧6H■O
晶體在室溫的空間群皆為 Pmn2■，由其在低溫時所得繞射圖的反射條件
，我們認為其在低溫發生結構相變，空間群可能轉變為P2■。我們認為水
分子對稱性的改變與運動，以及過氯酸根(ClO■)中相對氧原子位移是Ni(
ClO■)■‧6H■O、Co(ClO■)■‧6H■O晶體低溫結構相變的主因。Ni(
ClO■)■‧ 6H■O晶體在高溫與室溫時之繞射滿足相同的反射條件，因此
其高溫相變後空間群仍可能為Pmn2■。其相變原因可能是氫鍵些許改變所
致。

Perchlorate-hydrates of a series of bivalent metals with
general formula M(ClO■)■‧6H■O,where M=Mg,Mn,Fe,Co,Ni and Zn,
were studied detailedly under room and low temperature for a
few decades lately.X-ray diffraction was used to expl- ore the
change of structure and mechanism of phase transition under low
and high temperature seperately in the thesis. Since the
structure of LiClO■‧3H■O is similar with Mg(ClO■)■‧6H■O.
By the room structure of LiClO■‧3H■O sugges- ted by C.D.
West(1934),we know the room structure of orthorh- ombic and
space group is Pmn2■.By the X-ray diffraction and calculation
of structure factor,we confirm the result of the structure made
by C.D.West. The space group of Ni(ClO■)■‧6H■O and Mg(ClO■)
■‧6H■O are Pmn2■.By the reflection conditions of
diffraction in low temperature,we indicated the space group may
be P2■ since the structure was changed.We think the main
reasons of low-temperature phase transition are the symmetrical
changes and motions of water molecule,and the relative shife of
oxy- gens in the ClO■.In the high and room temperature,the
diff- raction of Ni(ClO■)■‧6H■O have the same reflection
cond- itions,so the space group may still be Pmn2■ in high
tempe- rature phase.The reason of high temperature phase
transition may be produced by appreciable change of hydrogen
bond.
Perchlorate-hydrates of a series of bivalent metals with