燐酸二水素アムモニウムNH4H2PO4の結晶構造
1948 年 5 巻 1-2 号 p. 21-25
詳細
1948 年 5 巻 1-2 号 p. 21-25
In spite of the fact that the crystal structure of ammonium dihydrogen phosphate is said to be analogous to that of the potassium salt, electrical properties of the two salts are not similar. To develop the theories on the transition of dihydrogen
phosphates, the author revealed the detailed structure of the ammonium salt by the Bragg-Fourier series' method. Lattice' constants are a=7.479±0.000A., c=7.516±0, 005A., space group D122d-I42d. Atomic parameters and interatomic distances compared to those of the potassium salt are given in tables I and II.
Characteristic differences between the two structures are found to be:
i) The axial ratios are reversed.
ii) Hydrogen bonds O-H…O lie almost parallel to the (001) plane in the ammonium salt whereas those of the potassium salt are inclined to the same plane about 4°.
iii) Interatomic distances between nitrogen and oxygen atoms in the ammonium salt are 2.87A which may be comparable to the hydrogen bond distances N—H…O in crystals of urea, glycine and diketopiperazine and the existence of such hydrogen bonds in the ammonium salt is highly, suggested.
