CsIBr2 at high pressures: An insitu Raman and ADXRD investigation

We report the results of ambient temperature high pressure Raman and synchrotron based ADXRD study of CsIBr2 up to 32 and 25 ​GPa respectively. Raman spectroscopic measurements indicate two phase transitions above 5 and 19 ​GPa respectively. High pressure ADXRD measurements reveal that the ambient orthorhombic (SG:Pnma) phase of CsIBr2 is stable up to a pressure of 5 ​GPa above which a phase transition to a trigonal (SG:P-3c1) phase, coexisting with the ambient phase, is observed. The stability region of the trigonal phase has been found to be up to 19.4 ​GPa above which another phase transition is observed. A third order and second order Birch-Murnaghan equation of state fit to pressure dependence of unit cell volume yielded a bulk modulus of 10.9(8) GPa and 17.8(1) GPa for the orthorhombic and trigonal phase respectively.