The structural phase transformations in various phases (monoclinic, ortho I, ortho II, and tetragonal) of zirconia (ZrO2) have been investigated using an effective interionic interaction potential. The cohesive energy, the equation of state, and the elastic properties of these phases have also been studied and found to reproduce well the experimentally observed data for almost all the phases of zirconia ceramics.

The pressure induced phase transition and associated volume collapse have been investigated in CuI using an interionic interaction potential. This interaction potential has been found to yield good agreement with of the experimentally observed phase (B3–BT–B1–BO) transitions and associated volume collapse. Furthermore, the results on elastic properties are discussed in detail.

We have investigated the pressure induced phase transition of Cesium Iodide using Effective Interionic Potential, The cubic phase (B-2) of the compound Cesium Iodide (CsI) was found to undergo a phase transformation to an Orthorhombic (B-0) through intermediate tetragonal phase under high pressure. The calculated values of die structural properties, the phase transition pressure (P-t) and relative volume collapse [V(P-t)/V(O)] obtained by us are in good agreement with the available experimental data.

The structural changes within copper halides induced by pressure from zinc-blend to rock-salt passing through an intermediate tetragonal structure have been investigated using an effective interionic interaction potential. The values of the phase transition pressures obtained by us for the copper halides are in good agreement with their available experimental data. We have also investigated the equation of state, which shows an appreciable volume collapses at the phase transition pressures.

The effect of high pressure over the structural stability of silver iodide (AgI) has been investigated. The structural properties of silver iodide have been calculated using Two Body Potential Model, comprising of Long-Range (L-R) Coulomb and van der Waals interactions and Short-Range (S-R) Hafemeister Flygare (HF) type overlap repulsive interactions. The phase transition pressure (P-t) and relative volume collapse Delta[V(P-t)/V(O)] as a function of pressure calculated by us for zinc-blende (B-3) and tetragonal (B-T) structure are found to be in good agreement with the available experimental data.

In the present investigation the Zinc-Blende (ZnS)-Tetragonal (Intermediate Phase)-Rock-Salt (NaCl) phase transition pressure of Copper Iodide (CuI) has been predicted using an interionic potential theory. The calculated compression curves and values of different high-pressure properties for Cut are reported and compared with the available experimental values. The calculated values for the phase-transition pressures (P-t) and the associated volume collapses [V(P-t)/V(0)] are generally in good agreement with their measured data.

The structural changes within the Silver iodide (AgI) and Copper iodide (CuI) induced by pressure have been investigated using an effective interaction potential. CuI and AgI in their parent zinc blende (ZnS) to rock salt (NaCl) through an intermediate structure have been reported. The calculated values for the phase transition pressures and associate volume collapses are generally in good agreement with measured data.