Pressure induced phase transition behaviour in f-electron based dialuminides

Abstract

The rare-earth and actinide based compounds are endowed with several exotic physical and chemical properties due to the presence of -electrons. These properties exhibit interesting changes under the action of various thermodynamic fields and hence continues to be a subject of extensive research. For instance, under pressure, the nature of -electrons can be changed from localized to itinerant, leading to a variety of changes in their structural, physical and chemical properties. The present review on the high pressure phase transition behaviour of dialuminides of rare earths and actinides is an outcome of research in our laboratory during the last five years using a unique combination of a Guinier diffractometer and a diamond anvil cell built in-house. To bring out the correlations between the compressibility and structural behaviour with the electronic structure, we have also carried out electronic structure calculation. Further, the usefulness of Villars' three parameter structure maps in predicting pressure induced structural transitions has been explored and this has been illustrated with the available phase transition data.

Pressure-induced structural transition in UGa2

“…Introduction Systematic investigations of pressure-induced structural stability and possible structural sequences observed along homologues of various compounds lay the foundation for the construction of detailed high-pressure structural stability maps (Pettifor 1998, Sahu andChandra Shekar 2000). These maps have proved their usefulness by offering the means of finding correlations between various crystal structures and of predicting new structures, at both atmospheric and high pressures.…”

The structural, elastic and thermodynamic properties of intermetallic compound CeGa2

“…The rare-earth intermetallic compound cerium di-gallide crystallizes in the AlB 2 -type structure at ambient conditions with the space group symmetry P6/mmm [1][2][3][4][5]. * E-mail: yasemin@gazi.edu.tr Several similar systems exhibiting the AlB 2 -type structure was investigated by Chandra Shekar et al [1][2][3].…”

“…* E-mail: yasemin@gazi.edu.tr Several similar systems exhibiting the AlB 2 -type structure was investigated by Chandra Shekar et al [1][2][3]. They found that these systems have a tendency to follow a sepecific structural sequence under pressure, namely AlB 2 (P6/mmm) to ZrSi 2 (Cmcm) to ThSi 2 (I4 1 /amd) to Cu 2 Sb (P4/nmm) type, by using X-ray diffraction techniques.…”

Structural stability and electronic structure of actinide and rare-earth based intermetallics under high pressure

“…Pressure plays a significant role in studying the nature of f-electron based rare-earth (4f) and actinide (5f) systems [1][2][3]. In the rare-earth elements, the 4f states are localized and magnetic, whereas in the actinides, the 5f states exhibit dual nature [4,5].…”

“…This influences the physical properties of the felectron based systems and studies on pressure effects in these systems are quite exciting [7]. Further, a systematic study of the pressure induced structural sequences has become very important in probing their electronic structure, in understanding the transition mechanisms and in predicting phase transitions [1][2][3][4]. Electronic structure calculations as function of reduced volume or pressure, on the other hand, bring out the correlations between the structural stability and phase transition behaviour in these systems with their electronic structure.…”