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Monoclinic phase in the relaxor-based piezo-/ ferroelectric Pb(Mg$_{1/3}$Nb$_{2/3})O_3$-PbTiO$_3$ system

Z. -G. Ye·B. Noheda·M. Dong·D. Cox·G. Shirane
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Abstract

A ferroelectric monoclinic phase of space group $Cm$ ($M_A$ type) has been discovered in 0.65Pb(Mg$_{1/3}$Nb$_{2/3})O_3$-0.35PbTiO$_3$ by means of high resolution synchrotron X-ray diffraction. It appears at room temperature in a single crystal previously poled under an electric field of 43 kV/cm applied along the pseudocubic [001] direction, in the region of the phase diagram around the morphotropic phase boundary between the rhombohedral (R3m) and the tetragonal (P4mm) phases. The monoclinic phase has lattice parameters a = 5.692 A, b = 5.679 A, c = 4.050 A and $β$ = $90.15^{\circ}$, with the b$_m$-axis oriented along the pseudo-cubic [110] direction . It is similar to the monoclinic phase observed in PbZr$_{1-x}$Ti$_x$O$_3$, but different from that recently found in Pb(Zn$_{1/3}$Nb$_{2/3})O_3$-PbTiO$_3$, which is of space group $Pm$ ($M_C$ type).

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Z. -G. Ye, B. Noheda, M. Dong, D. Cox, G. Shirane. 2001-12-21. Monoclinic phase in the relaxor-based piezo-/ ferroelectric Pb(Mg$_{1/3}$Nb$_{2/3})O_3$-PbTiO$_3$ system. https://doi.org/10.1103/physrevb.64.184114

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