Ferroelectric properties and crystal structure of praseodymium-modified bismuth titanate

Fatigue-free and highly c-axis oriented Bi4−xPrxTi3O12 (BPrT, x=0.85) thin films were grown on Pt/TiO2/SiO2/Si (100) substrates using the method of metalorganic sol decomposition. The BPrT film capacitor with a top Pt electrode showed significantly improved values of the remanent polarization (Pr) and the nonvolatile charge as compared to those of the Bi4−xLaxTi3O12 (x=0.75) film capacitor, recently known as a promising candidate for nonvolatile memories. The 2Pr value of the BPrT capacitor was 40 μC/cm2 at an applied voltage of 10 V while the net nonvolatile charge was as high as 20 μC/cm2 and remained essentially constant up to 4.5×1010 read/write switching cycles at a frequency of 1 MHz. In addition to these, the capacitor showed excellent charge-retention characteristics with its sensing margin of 16 μC/cm2 and a strong resistance against the imprinting failure.