A theory of polarized neutron magnetic form factors based on atomic current densities is presented and applied to Ce3+ ion in CeP. The eigenvectors due to crystal field and induced by the applied magnetic fields are derived and utilized to estimate these form factors. The derived form factors of Γ8 eigenstates are closer to experimental ones than those of Γ7. This finding is in accord with previously published results. The magnetic form factors derived from the pure crystal field Γ8, the induced Γ 8 ( 1 ) and Γ 8 ( 3 ) eigenstates of phase I are almost given the same form factors. Similarly, this is also the case of the form factors of phase III. The similarity of the derived form factors in each phase is attributed to the domination of the crystal field splitting over external and internal applied magnetic fields. Due to other sources of magnetic scattering in phase I some deviations of the estimated form factors from the experimental ones persist. The derived form factors of Γ8 eigenstates of phase III are in good agreement with experimental results.

Theory of polarized neutron form factors of cerium monopnictide CeP

In the present work, we investigate how pressure affects the valence change of cerium in cerium-based compounds CeX (X= O, S, Te, P, As, Sb, and Bi). The valence of cerium at a certain high pressure is estimated by comparing the experimentally observed unit cell volume and the calculated unit cell volume of stable trivalent cerium ion in the compound. The change in unit cell volume with pressure is estimated by employing the Birch equation of state. It is found that the valence of Ce in the CeX is significantly influenced by both the applied pressure as well as the chemical environment around the Ce ion.
J. Bangladesh Acad. Sci. 46(2); 147-154: December 2022   

Pressure-induced valence changes of cerium in some cerium-based compounds

The application of hydrostatic pressure on a solid material has a direct effect on the extra-nuclear electronic states of the constituent atoms in the material. In this work, we have studied the effect of pressure on the various properties of the material, such as structural behavior, crystal lattice behavior, magnetic behaviors of magnetic material and transport behavior like electrical resistivity. We have calculated the Ce valency change in some compounds of cerium monochalcogenides CeX (X=O, S, Se and Te) and cerium monopnictides CeX (X=P, As, Sb and Bi). In doing this task, we have reproduced the reported experimental pressure-volume relationships of the compounds using the Birch equation of state. The corresponding pressure-volume relationships of these compounds for stable trivalent cerium have also been calculated using the same Birch equation. Clear effect of pressure on the cerium valency has been realized for each compound from the present calculation.

Pressure Induced Structural Phase Transition and Valence Change

Application of pressure on a material changes its properties due to the modification of the electronic states of the constituent atoms. Various effects of pressure on the properties of solid material have been identified, and valency change of an element in a compound is one of the effects of pressure. This study was aimed at finding the valency change as a function of pressure of some compounds. The valency changes of cerium in cerium monochalcogenides CeX (X = O and S) and cerium monopnictides CeX (X = P and As) as functions of pressure have been calculated utilising the reported data. For calculating the valency change of Ce, the reported experimental pressure-volume relationships of CeO, CeS, CeP and CeAs have been reproduced using the Birch equation of state. The corresponding pressure-volume relationships of these compounds for stable trivalent cerium have also been calculated using the same Birch equation. The change in valency is calculated by a technique, which considers the difference between the calculated and experimental lattice parameters at each pressure value of the concerned compound. Clear effect of pressure on the cerium valency has been obtained for each compound from the present calculation. J.Natn.Sci.Foundation Sri Lanka 2015 43 (4): 313 - 317

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Md. Tarek Hossain

Papers

Pressure Induced Structural Phase Transition and Valence Change

Effect of pressure on the valency of cerium in cerium monochalcogenides and cerium monopnictides