Room temperature structure of Pb(ZrxTi1−xO3) around the morphotropic phase boundary region: A Rietveld study

Abstract

We have carried out a detailed Rietveld analysis of x-ray powder diffraction data of Pb(ZrxTi1−x)O3 (PZT) compositions across the morphotropic phase boundary (MPB) region (x=0.515, 0.520, 0.525, 0.530). It is shown that the structure of PZT is pure tetragonal for x⩽0.515 with space group P4mm. In the MPB region, 0.515<x<0.530, the tetragonal and monoclinic (space group: Cm) phases are found to coexist as a result of a first order phase transition between the low temperature monoclinic and high temperature tetragonal phases. Further, arguments are advanced to show that the hitherto believed rhombohedral structure (FRHT) of PZT for 0.530⩽x⩽0.62 is more likely to be monoclinic.

Antiferrodistortive phase transition in pseudorhombohedral (Pb0.94Sr0.06)(Zr0.550Solanki1, Mishra2, Senyshyn3 et al. 2012Phys. Rev. BSelf Cite82130View full textAdd to dashboardCite

“…The characteristic feature of this phase is anomalously large broadening of (h00) pc and (hh0) pc reflections as was first pointed out by Ragini et al work, other workers have also accepted the assignment of Cm space group to such 'pseudorhombohedral' compositions [20][21][22][23][24] . The anomalous broadening of the (h00) pc and (hh0) pc reflections of the pseudorhombohedral monoclinic phase disappears in the tetragonal phase stable at x<0.520 19 . This phase has been traditionally assigned the R3m space group and is stable in the composition range 0.530≤x≤0.620 in chemically homogeneous samples 14,15,19 .…”

“…The anomalous broadening of the (h00) pc and (hh0) pc reflections of the pseudorhombohedral monoclinic phase disappears in the tetragonal phase stable at x<0.520 19 . This phase has been traditionally assigned the R3m space group and is stable in the composition range 0.530≤x≤0.620 in chemically homogeneous samples 14,15,19 . (iii)Thirdly, there is a rhombohedral phase 1 or a pseudorhombohedral monoclinic phase 14,15 for 0.620 x 0.940 which also exhibits anomalous broadening of the (h00) pc reflections but to a lesser extent as compared to the case for 0.530≤x≤0.620.…”

High-resolution synchrotron x-ray diffraction study of Zr-rich compositions of Pb(ZrxTi1−x)O3 (0.525⩽x⩽0.60): Evidence for the absence of the rhombohedral phase

“…We present here the results of Rietveld analysis of the powder synchrotron XRD data which reveals that the structure of PZT for x=0.525 is monoclinic of M A type, and not a mixture of (a) T and R [1][2], (b) coexistence of M A and T [4,16] and (c) coexistence of R and M A [17], proposed by the pervious workers. More significantly, our results suggest the absence of any rhombohedral phase on the Zr-rich side (x≥0.525) of the MPB raising doubts about the applicability of the widely believed notion of M A structure as the bridging phase between T and R phases.…”

Three intrinsic relationships of lattice parameters between intermediate monoclinicMCand tetragonal phases in ferroelectricPb[(Wang1 2006Phys. Rev. B771200View full textAdd to dashboardCite

“…Recent extensive experimental investigations have discovered new intermediate phases and revealed fascinating while puzzling phase behaviors around the MPBs. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] Since the recent discovery of an intermediate monoclinic M A phase in PZT near its MPB, [23][24][25][26][27][28] new intermediate phases have also been discovered in PZN-xPT and PMN-xPT near their respective MPBs, namely, monoclinic M A , [8][9][10] monoclinic M C , [8][9][10][11][12] orthorhombic ͑Refs. 8 and 13-15͒ phases in PZN-xPT, and orthorhombic, 16,17 monoclinic M C , 12,[18][19][20][21] monoclinic M A , 21,22 as well as a third monoclinic M B phase ͑Refs.…”