Oguama, F. A. and Shields, H. and De, Dilip Kumar (1997) EPR studies of phase transitions in cadmium calcium acetate hexahydrate as a function of different paramagnetic impurity-ion concentrations. PHYSlCAL REVIEW B, 56 (5).
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Abstract
The phase tt':lnsition in cadmium calcium acetate hexahydrate (CCDAH) has been studied in detail with electron paramagnetic resonance (J;PR) as a function of two different paramagnetic ion concentrations. namely. Cu:• and Mn:• ions. The change in transition temperature (1:!2-143 Kl with Cuz• ion concentrations is explained in terms of mean-field theory and a soft vibrational mode of the -Ca-Cd1 _ ,Cu,-Ca- chain along the c axis of the crystal. While the same theory can also explain our observed transition temperature ( 118-128 K) as a function of the Mn2• ion concentration in this crystal. it does not explain why the limiting value of the transition temperature (i.e .• 145 K) of CaCd1 -.,CuzCCH3C00)4 ·6H~O as x tends to zero, is strikingly different from the limiting value of ( -128..+ K) of CaCd1_.,Mn,(CH3C00)4·6H:O as x tends to zero. The same theory also successfully c:xplains the absence of any phase transition in isomorphous CaCu(CH 3C00)~·6H 20. The value of -dT~Id.t is significantly higher with Mn:• than with Cu!• in CCDAH. [50163-1829(97)01329-5]
| Item Type: | Article |
|---|---|
| Subjects: | Q Science > Q Science (General) Q Science > QC Physics |
| Divisions: | Faculty of Engineering, Science and Mathematics > School of Physics |
| Depositing User: | Mrs Hannah Akinwumi |
| Date Deposited: | 22 Apr 2015 14:48 |
| Last Modified: | 22 Apr 2015 14:48 |
| URI: | http://eprints.covenantuniversity.edu.ng/id/eprint/5087 |
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