NMR Observation of Static Low-Temperature Clusters above the Phase Transition in the H-Bonded Antiferroelectric Squaric Acid (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi mathvariant="normal">C</mi></mrow><mrow><mn>4</mn></mrow></msub></mrow></math><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi mathvariant="normal">O</mi></mrow><mrow><mn>4</mn></mrow></msub></mrow></math><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi mathvariant="normal">H</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></math>)

Michael Mehring; Dirk Suwelack

doi:10.1103/PhysRevLett.42.317

NMR Observation of Static Low-Temperature Clusters above the Phase Transition in the H-Bonded Antiferroelectric Squaric Acid ( $C_{4}$ $O_{4}$ $H_{2}$ )

Michael Mehring and Dirk Suwelack

Phys. Rev. Lett. 42, 317 – Published 29 January 1979

Abstract

Static low-temperature clusters above the phase transition in the H-bonded antiferroelectric squaric acid are observed by high-resolution ${}^{13}C$ NMR spectroscopy. Cluster formation and decay at different temperatures is observed to depend strongly on the type of impurity center inducing the cluster. Connection with the appearance of a "central peak" in light and neutron scattering is drawn.