An analys is of hi gh pressure equati ons of state has been performed to determine th e pressure-vo lume relati onships for NaF. N'ICI. NaBr and Na l crystal s under pressures up to their phase transition pressures. The results have been obtainecl using five dilTeren t phenomenolog ical form s of isothermal equati on of state. It has been found th at the resu lts obtained from th e usu al Tait equa ti on. th e Brennan-Stacey equation. the Vinet uni versal equati on and the Shanker equation arc

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... n good agreement with the ex perimental data for the soli ds under study. Th e M urnaghalfs equati on has heen found to y ield significantly large dev iation s from ex peri ment al data. Modi ficati ons suggested recently to remove the shortcomings of the Murnaghan' s equation have been discussed. Valu es of isothermal hulk modules K T • pressure clerivative of K/. and the Gruneisen parameter have also been calculated for NaClu nder hi gh co mpress ions.