本實驗採用偏光顯微鏡觀察X■H(SO■)■（X=Na，NH■）晶體之外形與光
學性質，及以X–ray繞射進動方法探討X■H(SO■)■( X=Na，NH■) 單晶
的室溫結構與高溫相變情形。Na■H(SO■)■在室溫下發現有兩種單晶樣
品，其中一種為不規則長柱狀，bm軸橫躺於晶面（001）上，am軸則與長
柱方向平行，另一晶體為平形四邊形，bm軸垂直於晶面（如圖一）。兩種
晶體由偏光顯微鏡沿bm軸看其conoscopic image為雙光軸，室溫晶體結構
屬單斜晶，空間群為P2■/c，當溫度升高時，晶體發生結構相變，在溫度
為241℃時，可能空間群為P3 。(NH■)■H(SO■)■在室溫下是單晶形式
，晶體外觀呈菱形，cm■軸垂直於晶面上，單晶室溫結構為單斜晶，空間
群為A2/a，當溫度逐漸升至140℃時，晶體發生結構相變，可能空間群為R
■m。

We observe the shape and optic nature of X■H(SO■)■ (X=Na，NH
■) by polarizing microscope．We also study X■H(SO■)■(X=Na，
NH■) single crystal both room and high temperature structures
by x-ray precession meth- od ．At room temperature Na■H(SO■)■
grows two kinds of single crystal．The one is irregular long
shape，the other is swallow twin ．The irregular long sh- ape
crystal’s bm axis is lying on (001) surface．We can cut
swallow twin by knife into single crystal(as figure 1)．Its
shape is parallelogram． Its bm axi- s is perpendicular to
crysatl surface．Two kinds of crystal are both optic biaxials．
The single crystals’ room temperature structure are monoclinic
． Their space group are P2■/c．When temperature are added．
Crystal occurs structural phase transition ．Their space group
may turn into P3．(NH■)■H(SO■)■is also single crystal．The
shape of (NH■)■H(SO■)■is para- llelogram ． Its cm■axis is
perpendicular to (001) surface ．The room temperature structure
is monocl- inic with the space group A2/a．When temperature is
added to 140℃．It occurs structural phase transition．The
space group may turn into R■m．
We observe the shape and optic nature of X■H(SO■)■ (X=Na，NH