Structure and origin of polar nanoregions in relaxor ferroelectrics · revision history

Revision 2

Accepted · core change · record

Changes against revision 1:

Title
Structure and origin of polar nanoregions in relaxor ferroelectrics
Plain
In relaxors such as lead magnesium niobate, the dipoles never line up into large domains; instead small polar patches, called polar nanoregions, appear and slow down on cooling. What these patches are and why they form is still argued.
Precise · changed · core
Revision 1: In Pb(Mg1/3Nb2/3)O3 (PMN) and $\mathrm{PMN}-x\mathrm{PbTiO3}$, diffuse scattering and frequency-dispersive dielectric response (Vogel-Fulcher freezing near approximately 220 K in PMN) indicate polar correlations below a Burns temperature of approximately 600 K. Determine their structure (size distribution and correlation length versus $T$; discrete nanoregions versus a continuous slush of nanodomains) and their cause (random electric fields from B-site charge disorder, random bonds, or local strain) with a first-principles-based effective Hamiltonian validated against diffuse-scattering line shapes. An answer is a model reproducing the diffuse scattering and dielectric dispersion.
Revision 2: In Pb(Mg1/3Nb2/3)$\mathrm{O_3}$ (PMN) and $\mathrm{PMN}-x\mathrm{PbTiO3}$, diffuse scattering and frequency-dispersive dielectric response (Vogel-Fulcher freezing near approximately 220 K in PMN) indicate polar correlations below a Burns temperature of approximately 600 K. Determine their structure (size distribution and correlation length versus $T$; discrete nanoregions versus a continuous slush of nanodomains) and their cause (random electric fields from B-site charge disorder, random bonds, or local strain) with a first-principles-based effective Hamiltonian validated against diffuse-scattering line shapes. An answer is a model reproducing the diffuse scattering and dielectric dispersion.
Settled by
An atomistic model whose computed diffuse scattering and dielectric spectra match single-crystal data over 100 to 700 K without fitted correlation parameters.
Kind
phenomenon
Answer type
mechanism
References
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Literature status
contested
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Decisions