Two compaction equations (isothermal equations of state) for powders w
ere developed, and experimemts on the compaction of various ceramic po
wders were designed to examine these equations. A nonlinear least-squa
res technique was utilized to evaluate these and other published compa
ction equations for press compaction of submicrometer and nanosize pow
ders. A modified linear least-squares method was developed for fitting
experimental data to one of the present equations. The root-mean-squa
re deviation per degree of freedom (rms) for fitting compaction data o
f powders using the present equations was reduced by almost one order
of magnitude by comparison with fitting to that of Cooper and Eaton's
equation. Data analysis indicates that our equations yield better fitt
ing of data than the previous equations, and these equations can be ap
plied to chemically different powders, powders with different size dis
tribution of particles.