Monoclinic M-B phase and phase instability in 110 field cooled Pb(Zn1/3Nb2/3)O-3-4.5%PbTiO3 single crystals

We report the finding of a monoclinic M-B phase in Pb(Zn1/3Nb2/3)O-3-4.5%PbTiO3 single crystals. High precision x-ray diffraction investigations of [110] field cooled crystals have shown a transformation sequence of cubic(C)-> tetragonal(T)-> orthorhombic(O)-> monoclinic(M-B), which is different from that previously reported [A.-E. Renault , J. Appl. Phys. 97, 044105 (2005)]. Beginning in the zero-field-cooled condition at 383 K, a rhombohedral (R)-> M-B -> O sequence was observed with increasing field. Coexisting M-B and O phases were then found upon removal of field, which fully transformed to M-B on cooling to room temperature.