Studies of multiferroic palladium perovskites
Date
08/02/2019Author
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Abstract
We have studied the atomic force microscopy (AFM), X-ray Bragg reflections, X-ray absorption spectra (XAS) of the Pd L-edge, Scanning electron microscopey (SEM) and Raman spectra, and direct magnetoelectric tensor of Pd-substituted lead titanate and lead zirconate-titanate. A primary aim is to determine the percentage of Pd+4 and Pd+2 substitutional at the Ti-sites (we find that it is almost fully substitutional). The atomic force microscopy data uniquely reveal a surprise: both threefold vertical (polarized out-of-plane) and fourfold in-plane domain vertices. This is discussed in terms of the general rules for Voronoi patterns (Dirichlet tessellations) in two and three dimensions. At high pressures Raman soft modes are observed, as in pure lead titanate, and X-ray diffraction (XRD) indicates a nearly second-order displacive phase transition. However, two or three transitions are involved: First, there are anomalies in c/a ratio and Raman spectra at low pressures (P = 1 − 2 GPa); and second, the c/a ratio reaches unity at ca. P = 10 GPa, where a monoclinic (Mc) but metrically cubic transition occurs from the ambient tetragonal P4 mm structure in pure PbTiO3; whereas the Raman lines (forbidden in the cubic phase) remain until ca. 17 GPa, where a monoclinic-cubic transition is known in lead titanate.
Citation
Pradhan , D K , Mishra , A K , Kumari , S , Basu , A , Somayazulu , M , Gradauskaite , E , Smith , R M , Gardner , J , Turner , P W , N’Diaye , A T , Holcomb , M B , Katiyar , R S , Zhou , P , Srinivasan , G , Gregg , J M & Scott , J F 2019 , ' Studies of multiferroic palladium perovskites ' , Scientific Reports , vol. 9 , 1685 . https://doi.org/10.1038/s41598-018-38411-8
Publication
Scientific Reports
Status
Peer reviewed
ISSN
2045-2322Type
Journal article
Rights
Copyright © The Author(s) 2019. Open Access. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
Description
Work at St. Andrews supported by EPSRC grant EP/P024637/1; at Queens University Belfast by EPSRC Grant No. EP/J017191/1 and EP/N018389/1, at Univ. Puerto Rico by DoD AFOSR Grant FA9550-16-1-0295 and at West Virginia University by DOE (DE-SC0016176).Collections
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