|
|||||
|
|
Renormalization phenomena in Ba-diluted ferroelastic lead phosphate, (Pb1-x Ba x )3(PO4)2 |
||
| Authors: | U Bismayer J Hensler E Salje B Güttler | |
| Institution: | 1. Institut fur Mineralogie und SFB 173, Universitat Hannover , Welfengarten 1, 30060 , Hannover 1 , Germany;2. Department of Earth Sciences , University of Cambridge , Downing Street, Cambridge , CB2 3EQ, UK;3. Physikalisch Technische Bundesanstalt , Abt 3.3, Bundesallee 100, 38116 , Braunschweig | |
| Abstract: | Abstract In the improper ferroelastic palmierite-type lead phosphate order parameter coupling with a defect induced conjugate field leads to the renormalization of the two different critical temperatures of three order parameter components {Q 3} and {Q 1 Q 2}. The influence of the lead dilution by barium on the ferroelastic domain pattern, the critical temperature of the ferroelastic transformation R ![/></span> <i>m</i>–<i>C</i>2/<i>c</i> and the development of the intermediate regime in (Pb<sub>1–<i>x</i> </sub>Ba<sub> <i>x</i> </sub>)<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub> is studied using optical birefringence measurements, Raman and infrared spectroscopy. At the ferroelastic transition temperature T<sub> <i>c</i> </sub> the orientational contribution of the three-states Potts model becomes critical. <i>T</i> <sub> <i>c</i> </sub> is reduced from 453 K (<i>x</i> = 0) to zero <i>K</i> at <i>x</i>? 0.12. Modifications of the shape of zigzag needle domains as well as the angle between the monoclinic binary axis and the W walls along 031] with temperature and increasing Ba-content are reported. Above the ferroelastic transition point the component <i>Q</i> <sub>3</sub>, which corresponds to the displacive part in the Gibbs free energy, leads to dynamic short-range monoclinic deformation in the trigonal matrix. The temperature where <i>Q</i> <sub>3</sub> shows critical behaviour is renormalized to 720 K (<i>x</i> = 0.12) as compared with 563 K in pure lead phosphate. For <i>x</i>>0.13 no monoclinic precursor clusters were found.</td>
</tr>
<tr>
<td align=](/na101/home/literatum/publisher/tandf/journals/content/gpht20/1994/gpht20.v048.i01-03/01411599408200358/20180821/images/medium/gpht_a_8200358_ilm0001.gif){kind=small} | |
| Keywords: | Improper ferroelastic zigzag domains lead dilution conjugate field T c -renormalization | |