Lead zirconate titanatePb(ZrxTi1−x)O3(PZT) thin films have been deposited by rf magnetron sputtering on Si substrates from a metallic target of nominal compositionPb1.1(Zr0.4Ti0.6)in a reactive argon/oxygen gas mixture. During plasma deposition,in situoptical emission spectroscopy measurements show clearly a correlation between the evolution of characteristic atomic emission line intensities Zr—386.4 nm, Ti—399.9 nm, Pb—405.8 nm, and O—777.2 nm and the thin-film composition determined by a simultaneous use of Rutherford backscattering spectroscopy and nuclear reaction analysis. ©1998 American Institute of Physics.