Monoclinic M-C vs orthorhombic in 001 and 110 electric-field-cooled Pb(Mg1/3Nb2/3O3)-35%PbTiO3 crystals

Structural phase transformations in Pb(Mg1/3Nb2/3O3)-35%PbTiO3 crystals with an electric field (E) applied along [110] and [001] directions have been performed by x-ray diffraction. In the field-cooling process, a phase transformation sequence of Cubic(C)-> Tetragonal(T)-> Orthorhombic(O) was found for E//[110]; whereas a sequence of C -> T -> monoclinic(M-C) was found for E//[001]. Our results establish that the stability of M-C relative to O (or limiting M-C) is altered by the direction along which E is applied.