High-pressure behavior and equations of state of the cobaltates YBaCo4O7, YBaCo4O7+δ, YBaCoZn3O7 and BaCoO3−x

► Compressibilities were investigated by in situ DAC powder X-ray diffraction experiments. ► Pressure-induced phase transitions were observed in all the samples. ► High-pressure phases were very sensitive to small amounts of stresses and strains. ► Due to the metastability of the compounds, laser annealing leads to decomposition. ► Oxygen-content has a very large effect on the high pressure behavior in these materials.