Ti-O coordination at a Pb(Zr,Ti)O3/Pt interface annealed in a hydrogen-containing ambient analyzed using spatially resolved electron energy-loss spectroscopy

We have investigated how annealing in a hydrogen-containing ambient changes the Ti-O coordination structure in a Pb(Zr, Ti)O-3 (PZT) film fabricated on a Pt electrode by using spatially resolved electron energy-loss spectroscopy (EELS). Experimental results show that the Ti-O coordination structure was changed by the annealing at the PZT/Pt interface. However, there were no clear changes in the coordination number of O atoms to a Ti atom at the interface. Our EELS spectrum analysis using DV-X alpha molecular orbital calculations indicates that the orbital overlaps between the 3d orbitals of a Ti atom and the 2p orbitals of the neighboring O atoms differ at the interface from those in the bulk PZT crystal. Therefore, our results indicate that the H-2 annealing deformed the PZT crystal structure at the PZT/Pt interface, changing the Ti-O orbital overlaps. This structural change in the PZT film should be attributed to the marked decrease in Pb concentration at the H-2-annealed PZT/Pt interface [N. Ikarashi, Appl. Phys. Lett. 73, 1955 (1998)]. (C) 1999 American Institute of Physics. [S0021-8979(99)03611-7].