Possible observation of a glassy ferroelectric:Bi1.8Pb0.3Sr2

Abstract

A glass sample of composition Bi 1.8 Pb 0.3 Sr 2 Ca 2 Cu 2.8 K 0.2 O z was prepared by the conventional quenched-melt technique. The as-quenched sample has been confirmed to be amorphous by x-ray diffraction measurements. The scanning electron microscopy shows no sign of crystalline grain precipitation. Differential thermal analysis indicates a prominent endotherm at 530 K in addition to the glass transition at 607 K and crystallization at 717 K and melting at 1043 K. This extra endothermic peak could possibly be identified as due to a ferroelectric to paraelectric phase transition. This possibility was explored by performing electrical measurements, which include dielectric constant trace, polarization, and hysteresis loops measurements as a function of temperature. It was also found that the transition is irreversible if the glass-transition temperature was reached.

Ferroelectricity in the glassy material of the composition Bi2O3–Pb3O4–CuO–K2O

“…It can be seen that there are only the broad diffraction peak characteristic of glassy structure. Similar patterns were obtained for glasses of comparable constituents [12,22,38]. On the other hand, a TEM micrograph is shown in Fig.…”

“…In these publications we put forward another hypothesis [12][13][14]. According to our original assumptions a ferroelectric state in the investigated glassy materials arises during the manufacture of the bulk glassy samples by ultrarapid melt quenching.…”

“…On the other hand, the hypothesis put forward by us [12][13][14] concerning the effect of the residual microstresses as due thermal quashing on the local dipolar ordering was examined and explicitly confirmed on thin Quasi-amorphous films of BaTiO 3 [23,24]. Nevertheless, the generation of electric polarization in an insulating crystalline solid by an elastic strain gradient is referred to as the flexoelectric effect [25].…”

“…Recently in our series of publications [12][13][14] it was possible for the first time to demonstrate ferroelectricity in a single phase metastable glassy material namely Bi 1.8 Pb 0.3 Sr 2 Ca 2 Cu 3−x K x O z (x = 0.1-0.4) having spontaneous polarized state. In these publications we put forward another hypothesis [12][13][14].…”

“…This stress induced poling process ought to strain which aligns the internal dipoles within the glass network in a long-range interacting manner and causes it to act very similar as in a crystal, even so the atomic arrangement in the glass structure remains random. This stress-strain induced poling cease completely if the glass sample was annealed at or above the glass transition temperature [12][13][14] where the glass network is completely relaxed and all microstresses are released. As a result of the ultrarapid quenching a displacement of alkaline cations due to induced strain, e.g., K + and probably Ca 2+ , to off center positions within the glassy network would takes place.…”