Macroscopic quadrupole moment of a crystal in the region of a structural phase transition
Gladkii V.V., Kirkikov V.A.
An electric method is proposed for the investigation of the structural changes occuring in phase transitions in nonpolar crystals. The method is based on recording the changes of the potential φ of the electrostatic field produced by the macroscopic quadrupole moment. The possibilities of the method and its effectiveness are illustrated by an example consisting of a measurement of the nonlinear dependences of φ on the temperature and on the mechanical stress in an NH4Br crystal in the region of the transition from the cubic to the tetragonal phase.