High-pressure behavior of some binary 1:1 actinide-arsenide compounds

Structural phase transition and elastic properties of thorium pnictides at high pressure

“…2 then the volume of the unit cell should increase at transition since r 1 > r. However, it has been noted in the high pressure X-ray diffraction studies [7][8][9][10][11][12][13][14][15] that for B1 to B2 transition the unit cell volume always collapses at transition. This is possible only if the unit cell volume of the B2 phase is (8/3 √ 3)(r 1 ) 3 [16] instead of (8/3)(r 1 ) 3 [1]. In view of the facts indicated from (i) to (iii), it may be emphasized, here, that the work reported by Aynyas et al needs a complete revision.…”

“…For B1 phase hardness (p 1 ) and range (b 1 ) parameters are calculated from eqs (9) and (10). For B2 phase the value of range parameter may be given as [2,16] [18] 92.00 Ref. [1] 208.510 33.150 32.600 91.00…”

“…To calculate the second-order elastic constants we have divided them into the contributions from Coulombic and short-range forces. The Coulombic contributions are calculated following the method given by Cowley [19] and the short-range contributions are calculated as the combination of the first-and secondorder derivatives of the short-range potential [16]. Further, the bulk modulus is calculated from the relation…”

Pressure-induced phase transition phenomena in NpSe and NpTe

“…But due to the problem of handling these radioactive materials, less attention has been drawn about their structural, phonon and thermo-physical properties. Theoretical investigations [6][7][8] are made which reveal that 5f unfilled electrons are mainly responsible for the structural and elastic properties of these compounds. These 5f electrons have lower binding energies and less effective shielding by the outer electrons as compared to the 4f electrons in case of lanthanides.…”

“…Jha and Sanyal [7] have successfully investigated the high-pressure behavior of NpSe and NpTe using same set [ , b, f(r)] of model parameters in both B1 and B2 phases. More recently Kholiya and Gupta [8] employed the potential model taking different set of [ , b, f(r)] and shown the realistic approach to analyze the high-pressure phase transition and elastic properties of actinide-arsenides. They reported some weaknesses in the potential model developed by Jha and Sanyal [7] viz (a) They have used the same ionic radii in both phases and (b) They have used same model parameters for both the phases etc.…”