CRYSTAL STRUCTURE OF THE FERROELECTRIC PHASE OF (GLYCINE)$sub 3$/CENTER DOT/ H$sub 2$SO$sub 4$

http://feh.scs.uiuc.edu/doc/papers/1201228223_108.pdf

Structure and Cation Effects on Phosphorus-31 NMR Chemical Shifts and Chemical-Shift Anisotropies of Orthophosphates*

Chemical bond analysis of the crystal growth of KDP and ADP

A deuteron magnetic resonance study is made of single crystals of CuSO4·5D2O between 130° and 360°K. The electric quadrupole coupling constant, the asymmetry parameter, and the directions of the principal axes of the field‐gradient tensor are determined for each deuteron at 133.2° and 294.8°K. At low temperatures ten pairs of lines are observed, corresponding to five nonequivalent stationary water molecules. At temperatures above room temperature, five pairs of lines are observed; these are shown to result from fast molecular reorientation about the bisecting axis of each water molecule. An activation energy for the 180° reorientational motion is derived for each water molecule and is discussed in relation to the lonepair coordination of the oxygen atom of the water molecule and the hydrogen‐bond strength. The field‐gradient tensor for each stationary water molecule is discussed in relation to the structure of the hydrogen‐bond system. For relatively weak asymmetric hydrogen bonds of O–H···O, an empirical...

Deuteron Magnetic Resonance Study of Cupric Sulfate Pentahydrate

Growth rates of ammonium- and potassium-dihydrogen phosphate crystal faces have been measured in a simple laboratory apparatus under carefully controlled conditions of temperature, supersaturation and solution velocity. The growth process, which was found to be second-order with respect to the supersaturation, is considered to be controlled by surface reaction.



Growth rates of the ammonium salt (ADP) are much higher than those of the potassium-salt (KDP) under equivalent conditions. It is suggested that this is due to the occurrence of hydrogen bonding between ADP molecules, which give larger integrating units (thicker growth layers) than occur with KDP.

R. Pepinsky

Papers

A neutron structure analysis of tetragonal NH4(H2PO4)