Effect of pressure on atomic volume and crystal structure of indium to 67 GPa

The crystal structure of indium is studied by energy-dispersive x-ray diffraction with diamond anvil cells at ambient temperature under pressures up to 67 GPa. The present results are compared with previous volumetric data for the lower-pressure region as well as with data from shock-wave measurements extending to higher pressures. A comparison of these data with different forms representing equations of state for solids under strong compression shows that indium can be classified as a ``simple'' solid. No structural phase transitions are observed in the present experimental range up to 67 GPa.