The important piezoelectric material, lead zirconate titanate perovskite PbZr0.52Ti0.48O3 (PZT) was investigated as a function of pressure and temperature by Raman spectroscopy. At ambient pressure, the transition between the low-temperature and high-temperature ferroelectric monoclinic phases occurs near 210 K and is followed by transformation to the tetragonal phase at close to 305 K. The critical pressure for the transition to the disordered polar cubic phase increases with decreasing temperature from 5 GPa at 298 K to 9 GPa at 44 K. The ferroelectric monoclinic phases thus have an extended stability range at low temperatures and high pressure. A strong Raman spectrum is obtained for the cubic phase at high pressure over the temperature range between 44 and 298 K indicating the presence of polar nanodomains. A P–T phase diagram of this material is proposed based on the present results.