Science 24 March 2006:
Vol. 311. no. 5768, pp. 1758 - 1761
The Preparation and Structures of Hydrogen Ordered Phases of Ice
Christoph G. Salzmann,1,2* Paolo G. Radaelli,3,4 Andreas Hallbrucker,1 Erwin Mayer,1 John L. Finney4
Two hydrogen ordered phases of ice were prepared by cooling the hydrogen
disordered ices V and XII under pressure. By doping ices V and XII with
hydrochloric acid(塩酸), we have prepared ice XIII and ice XIV, and we
analyzed their structures by powder neutron diffraction.
Introduction
Water molecules in all of the 12 known crystalline phases are tetrahedrally hydrogen bonded to four
neighbors. A consequence of this connectivity is that individual water molecules may adopt six
different orientations. In ice structures, the Bernal Fowler rules require that one hydrogen atom
participates in each hydrogen bond. Therefore, the orientation of a given molecule is restricted by
its local environment and cannot rotate to another hydrogen-bonded orientation without its
neighbors also reorienting. 氷：12 の相，水分子：4 配位，氷の規則
H が２個の O 原子の
中間にいる
Proton disorder
対応関係
Proton order
?
Ice II は対応する disorder 相なし
Glass transition T ?
Ice V, VI, XII ?
D defect
H
L defect
O
At high temperatures, water ices can explore their configurational manifold thanks to the presence
of mobile point defects. The two types of thermally induced point defects(点欠陥) uniquely found
in ices are rotational defects, in which either two (D defect) or no hydrogen atoms (L defect) are
found between neighboring oxygen atoms, and ionic defects (H3O+ and OH–) . These defects can
migrate along chains of molecules through the crystal structure leaving reoriented molecules behind
them, thus providing the mechanism for collective reorientation in ice.
Liquidus phases of ice (Ih, III, IV, V, VI, VII, and XII) are hydrogen disordered(無秩序相). As the
temperature is lowered, the tendency to occupy the energetically most favored orientations increases.
However, for most phases, this ordering process is hampered by the decreasing number density and
mobility of the point defects. 低温では点欠陥の密度や移動度の減少により，秩序化が困難に
Point defects can also be introduced by doping ices with impurities. Ordering of ice Ih to ice XI has
been partially achieved through KOH (potassium hydroxide) doping . This is thought to create
extrinsic L and OH– defects. 氷IhにKOHをドープすると一部が秩序相である氷XIに転移
Experimental method (ice XIII)
We explored the effect of HCl (hydrochloric acid) doping, which is thought to produce L and H3O+
defects. Doped ice V samples were prepared by freezing 0.01 mol L–1 solutions of HCl or KOH in
H2O, or DCl or KOD in D2O, in a piston-cylinder apparatus precooled to 77 K and then by heating
the frozen ice isobarically at 0.5 GPa to 250 K (Fig. 1). Thereafter, the samples were cooled from
250 K at 0.8 K min–1 to 77 K, decompressed, and recovered under liquid nitrogen. 塩酸ドープ
上向き矢印：出発物質
の作製法
(ただし，ice XII では，
横向き矢印の次に縦の
上向き矢印で)
下向き矢印：秩
序相の作製法
Ih
Metastable extension of
liquidus line of ice Ih
Method?
Fig. 1. The phase diagram of ice, including liquidus lines of metastable ices IV and XII (long dashed lines)
and extrapolated equilibria lines at low temperatures (short dashed lines). The pathways of preparation of
DCl-doped ices V and XII are indicated by arrows. Ice V was produced by isobarically heating ice Ih to 250
K at 0.5 GPa. Pure ice XII was crystallized from high-density amorphous ice by isobaric heating at 1.2 GPa
at 11 K min–1 to 190 K.
Results and discussion (ice XIII)
Raman spectroscopy (O-D stretching). ラマン散乱
(5%D2O+H2O)+dopant
+KOH
HKOH
typical broad features of disordered ice V
+HCl
秩序 XIII
+DCl
無秩序 V
+KOD
six distinct peaks, indicating considerable
hydrogen ordering (ice XIII)
Fig. 2. (A) Raman spectra of the decoupled O-D
stretching transitions of KOH- (1) and HCl- (2) doped
ice V samples recorded at 80 K in vacuum. (B) Change
of lattice constant a from powder neutron diffraction
during heating and cooling of a KOD-doped ice V
sample (triangles), and heating (circles) and cooling
(diamonds) of a DCl-doped ice V sample. The sequence
of heating and cooling (0.2 K min–1) is indicated by
numbered arrows. Solid lines are guides to the eye.
転移温度(110〜120 K)
Neutron powder diffraction
可逆的
中性子粉末回折
The lattice constant(格子定数) a as a function of temperature was found to be a very sensitive
indicator of changes in hydrogen order. Upon heating the DCl-doped sample, a stepwise contraction
of the lattice parameter a was observed between 110 and 120 K. The reversibility of this transition
was observed by cooling back to 80 K at 0.2 K min–1 and by an additional heating/cooling cycle.
Space group(空間群) symmetry reduction and thus formation of a different phase upon cooling is
indicated by the appearance of the (31-2) (Fig. 3, inset) and (110) reflections in the neutron powder
pattern. [注：(110)は d=5.669Åにでるはず] Space group is monoclinic P21/a. The refinement(精
密構造解析) of the ordered structure revealed the formation of highly ordered molecules as the
refined occupation probabilities of the deuterium (Table 1).
Table 1. 省略 ice XIII の D-site での占有率≃1 （ほぼ order）
a=9.2417Å
b=7.4724Å
c=10.2970Å
β=109.6873°
青：秩序相
赤：無秩序相
Bragg 反射
a=8.3499Å
b=8.1391Å
c=4.0825Å
ice IV impurity
Fig. 3. Observed, calculated, and difference profiles for the observed phases of ice at 80 K and ambient
pressure. Data for hydrogen ordered ice V (ice XIII) are shown in the upper plot, and data for hydrogen
ordered ice XII (ice XIV) are shown in the lower plot. Tick marks indicate the positions of the Bragg peaks.
For ice XIV, the lower tick marks represent a small ice IV impurity. Both plots show magnifications of
regions where new reflections (ice XIII) or peak splitting (ice XIV) were observed for the ordered phases
(blue). The diffractograms of the corresponding disordered phases, which were obtained on heating to 130 K
(ice V) or 118 K (ice XII), are shown in red. Unit cell(単位格子) projections of the refined structures are
shown in both plots. Oxygen and deuterium atoms are drawn in red and gray, respectively. Deuterium
positions in ice XIV still containing some disorder are depicted in blue. Covalent and hydrogen bonds are
indicated by solid and dashed lines, respectively.
In contrast with the DCl-doped sample, neither cooling under pressure from 250 to 80 K nor cooling
at ambient pressure from 130 to 80 K at 0.2 K min–1 of the KOD-doped ice V sample led to new
reflections. Furthermore, heating and cooling at ambient pressure induced no substantial changes in
the lattice constant (Fig. 2B), and all collected data could be refined using the disordered structural
model of ice V. KOH doping was thus confirmed to be ineffective in promoting hydrogen ordering
in ice V.
KODをドープした氷Vでは秩序化は起きなかった．
Experimental method (ice XIV)
DCl-doped D2O ice XII samples were prepared by following a procedure described in (25). First,
high-density amorphous ice (HDA) was prepared by compression of ice Ih doped with 0.01 mol L–1
DCl at 77 K. HDA was then heated isobarically starting from 77 K at 1.2 GPa at 11 K min–1 to
crystallize pure ice XII (Fig. 1). After cooling from 180 to 77 K at 0.8 K min–1, the sample was
decompressed, recovered in liquid nitrogen, and characterized at 80 K by powder neutron
diffraction.
Results and discussion (ice XIV)
Again, hydrogen ordering was indicated by changes in the lattice constants: A transition from
tetragonal ice XII (a = b) to an orthorhombic phase (a≠b) could be observed and is visualized most
clearly by the splitting of the tetragonal (310) reflection to (130) and (310) orthorhombic reflections
(Fig. 3, inset). Space group is P212121. Hydrogen positions still containing some residual disorder
are drawn in blue.
Table 2. 省略 ice XIV の D-site での占有率≃1, 0.5（一部 disorder）
おまけ：命名法
The generally accepted view for the naming of phases of ice is that Roman numeral labels should
only be given for experimentally established crystalline phases, with crystallographic or at least
spectroscopic evidence (6, 10). Consequently, we label the reported ordered phases ice XIII for
ordered ice V and ice XIV for ordered ice XII, in chronological accordance with their dates of
discovery. 実験的（結晶学的orスペクトル）に確認された順にローマ数字をあてる理論的な予言
はだめ（以前，理論的に予言された超高圧相を「氷XI」と呼んだ例あり．あとで撤回され，「氷XI」
は氷Ihの秩序相に割り当てられる）．