Orientation control of sol-gel-derived lead zirconate titanate film by addition of polyvinylpyrrolidone

Abstract

Highly (100)- and (111)-oriented lead zirconate titanate (PZT) films with a thickness of 350 nm were deposited on platinized Si substrates through a single spinning of a PZT sol containing polyvinylpyrrolidone (PVP) as an additive. The crystallographic orientation of the film was strongly influenced by pyrolysis conditions after spin coating. When the spin-coated sol was pyrolyzed at temperatures above 320 °C for relatively long periods of time (>5 min), (111)-oriented film was formed after annealing at 700 °C for 10 min. On the other hand, when the same sol was pyrolyzed at 320 °C for short periods of time (<5 min), the film was strongly oriented to the (100) direction after annealing. Organic residues derived from PVP decomposition acted as nucleation sites for the (100) oriented grains during annealing after the pyrolysis. The effective d33 of the (100)-oriented PZT film (100 pC/N) was much higher than that of the (111)-oriented film (62 pC/N) with the same thickness.

Effect of excess PbO on microstructure and orientation of PZT(60/40) films

“…As a result, the (100) oriented film has higher dielectric properties than the (111) oriented film. It is well known that (100) oriented films have higher dielectric and piezoelectric properties [7,8,13,14]. (100) and (111) films measured using the pneumatic load method (PLM), [15] as a function of the poling field.…”

“…The electrical properties of the films strongly depend on their crystallographic orientations [7,8,13,14]. Moreover, the residual stress derived from the decrease in the grain size can also affect their dielectric and piezoelectric properties [18,19].…”

“…The orientation of a film deposited using the sol-gel method with organics is influenced more strongly by the pyrolysis process than by the amount of excess Pb; therefore, the combustion characteristics (thermal stability and organic contents) determine the behavior of Pb during pyrolysis [6,[9][10][11]13]. On the other hand, the films deposited by sputtering do not require a pyrolysis step.…”

Effects of Thickness on Piezoelectric Properties of Highly Oriented Lead Zirconate Titanate Films

“…The sol was prepared using a modified sol–gel‐containing PVP. The sol synthesis processes involved are described elsewhere in the literature 16,17 . The molar composition of the starting solutions was Pb(NO 3 ) 2 :Zr(O n Pr) 4 :Ti(O i Pr) 4 :PVP:H 2 O:CH 3 COCH 2 COCH 3 :CH 3 OCH 2 CH 2 OH=1.2:0.6:0.4:1:8:0.5:15, where the molar ratio of PVP was defined for the monomer.…”

“…Recently, a novel method of controlling the texture of polycrystalline PZT films on conventional Pt(111)/Ti/SiO 2 /Si substrates deposited by the sol–gel technique was developed. Using this method, the texture of the PZT films was able to be reproducibly controlled using a Pb(NO 3 ) 2 –Zr(O n Pr) 4 –Ti(O i Pr) 4 –CH 3 COCH 2 COCH 3 –CH 3 OCH 2 CH 2 OH solution containing polyvinylpyrrolidone (PVP) 16 . It was possible to change the orientation of the PZT films from (100) to (111) by varying the pyrolysis temperature and time.…”