Abstract
Precursor effects were observed inKMnF3 using infrared hard-mode spectroscopy. The intensity of the infrared-active mode near265 cm−1 follows the thermodynamic order parameter,Q, in thetetragonal phase (I4/mcm). An additional weak signal is found in the cubic phase (). The order parameter step at To = 185.95 K (L = 0.129 J g−1) is smeared with excess intensity due to the tetragonal short range order extending toT>215 K. The intensity follows the predictions of Landau theory with a defect fieldGdefect = −hQ,h = 6 J mol−1. The observed excess intensities are compared with the appearance of precursor elasticsoftening. It is concluded that the precursor softening and the local tetragonal short rangeorder are likely to be related to an extended defect structure, such as a tweed pattern,which may be stabilized by extrinsic defects.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
