Ferroelectric Rare-Earth Molybdates

Abstract

The molybdates of Sm, Eu, Tb, and Dy are isotypic with ferroelectric Gd2(MoO4)3. Other compositions of this structure occur in the pseudoternary system Gd–La–Y-molybdate and in the pseudobinary system Gd2(MoO4)3–Gd2(WO4)3. A representative number of these compositions were grown as single crystals and tested for ferroelectricity. Each was found to be ferroelectric as evidenced by a ferroelectric hysteresis loop and by visual observation of domains. The Curie temperatures (TC), spontaneous polarizations (Ps), and coercive fields (Ec) were determined, with values ranging as follows: TC, 148°–190°C; Ps, 0.14–0.23 μC/cm2 at 25°C; Ec, 5.0–14.5 kV/cm at 25°C.

Solid state reaction synthesis and optical spectroscopy of ferroelectric (Gd1−Ln )2(MoO4)3; with Ln = Yb or Tm

“…32), is obtained at room temperature by fast cooling. ␤ phase is ferroelectric, with Curie temperature T c = 432 K [12]. Although, some authors reported the transformation upon heating of ␤ phase into another ␥ phase before melting [10], the presence of the latter phase is not generally found [13].…”

“…These stoichiometric compounds have much higher melting temperatures, namely 1673 K and 1643 K for Yb and Tm compounds, respectively. The ferroelectric Pba2 structure have been shown to be formed to some extend in Gd 2 (Mo 1−x W x O 4 ) 3 compounds [12].…”

Mechanical and thermal properties of Tb2(MoO4)3 crystals

“…and M is a tungstate or molybdate element [1]. These materials undergo a ferroelectric-paraelectric phase transition over the temperature range of about 150-190 • C with the addition of various rare-earth elements Ln [2]. In contrast to some representative ferroelectrics (e.g., LiNbO 3 , BaTiO 3 ), the ferroelectricity of these materials is due to an elastic instability, so they are classified as improper ferroelectrics.…”

X-ray and thermal studies of ferroelectric Dy2(MoO4)3

“…These materials have been found to be promising for many industrial applications, due to some of their special physical properties, such as ferroelectric-ferroelastic, etc. [1][2][3]. Ferroelectric properties have been reported for the orthorhombic modification of gadolinium molybdate [4].…”

“…The ferroelectric, ferroelastic and other related properties for some of the compounds of this family have made them attractive for device applicatiqns [5,6]. Dy2(MoO4)3 (hereafter DMO) is isostructural with gadolinium molybdate, GMO, and of interest by virtue of its ferroelectric properties [1]. Only two rare earth molybdates, GMO and TMO (terbium molybdate Tb2(MoO4)3) , have been thoroughly investigated [7], because of their relatively easy growth of good-quality single-crystals by the Czochralsky method [8].…”