Optical studies of the incommensurate phase of quartz

Behaviour of the Optical Birefringence in Conditions of the "Viscous" Interaction

“…Their shape vIew has been discussed in different works [3,4]. Moreover, the magnitude of δ(Δn) anomalies is considerably changed depending from the investigated crystal [5][6][7] and the sample of the same crystal [8].…”

“…In accordance with Refs. [3,4] the "viscous" interaction is affected by the interaction of the movable defects with the soliton structure that causes the appearance of the region of the interaction of two commensurate phases. Such anomalous behaviour of the physical parameters in a transition region relates with the interaction of the space-modulated oscillations causing an appearance of the resulting oscillation.…”

Behaviour of the optical indicatrix and small‐angle light scattering in the case of “Devil's Staircase”

“…1, at d v d t = 36 mK/h the anomaly has an "S"-like form. The analogous change of intensity, connected with depolarization peaks was observed in [15]. According to (1) the deformation of the optical indicatrix is followed by an intensity change according to the law sin2 (27rd(n, -nl)/i).…”

Novel features of the α–β phase transition in quartz-type FePO4as evidenced by x-ray diffraction and lattice dynamics

“…This structural phase transition (SPT) has attracted a great deal of attention because of related anomalies in the thermal expansion, elastic and optical properties [6]. Recent renewal of interest in the αβ SPT was inspired by the discovery of an incommensurate phase in quartz [7,8] that has to be taken into account to understand the old problem of small-angle light-scattering anomalies [9][10][11][12][13][14].…”