We performed piezoelectric force microscopy (PFM) measurements on arrays of poled nanosize domains in 150 nm thick  preferentially oriented Pb(Zr0.4Ti0.6)O-3 films grown by chemical solution deposition. Each domain of arrays was characterized by dot, egg, and ring structures depending on the pulse width ranging from 1 to 5 ms. The PFM measurements were followed by heat treatments at successively higher temperatures of 100 degreesC, 130 degreesC, and 160 degreesC for 30 min with rapid cooling down to room temperature before each measurement. The retention loss phenomena of the bits were characterized by measuring the number and dimension change of the remaining data bits. It was concluded that the ring-structured bit arrays, which represent fully penetrating domains through the film thickness, were the most stable form in terms of retention loss characteristics. (C) 2002 American Institute of Physics.