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

Abstract

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.