Skip to main content

NOTICE: Due to a lapse in annual appropriations, most of this website is not being updated. Learn more.

Form submissions will still be accepted but will not receive responses at this time. Sections of this site for programs using non-appropriated funds (such as NVLAP) or those that are excepted from the shutdown (such as CHIPS and NVD) will continue to be updated.

U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Understanding Ferroelectricity in Perovksite-like Metal-Organic Frameworks through EPR, NMR, and AC Dielectric Permittivity Measurements

Nandita Abhyankar

Florida State University

Perovskite-like metal-organic frameworks (MOFs) of the ABX3 type have received extensive research interest because of their ease of synthesis, compositional tunability, and multiferroicity. They are also of interest as potential lead-free alternatives to the technologically important class of PZT piezoelectrics. Dimethylammonium metal formates, with the general formula [(CH3)2NH2]M(HCOO)3; where M = Mn, Fe, Co, Ni, Zn, comprise the model system for these multiferroic MOFs. This talk will discuss the mechanism of the ferroelectric transition in [(CH3)2NH2]Mn(HCOO)3 (DMMnF) and [(CH3)2NH2]Zn(HCOO)3 (DMZnF). The size-dependence of dielectric properties of DMMnF shows the emergence of relaxor-like properties in ensembles of particles in the size range of ~1-10 um. A single-crystal X-band EPR study is used to provide an explanation for the apparent magnetoelectric effect in DMMnF. A comparison of the dielectric properties of DMMnF and DMZnF shows that DMZnF exhibits relaxor-like behavior while DMMnF does not. A high-resolution 13C CP-MAS study of DMZnF, combined with AC dielectric permittivity measurements and DFT calculations, is used: (i) to demonstrate the combined order-disorder and displacive nature of the phase transition in DMZnF, and (ii) to elucidate the relaxor-like behavior of DMZnF.

Created December 16, 2016, Updated October 2, 2018
Was this page helpful?