Amorphous PZT Research Articles

PZT phase formation monitored by high-temperature X-ray diffractometry

The crystallisation kinetics of amorphous sol-gel PZT thin films were investigated using high-temperature X-ray diffraction. Crystallisation for different isotherms was monitored as a function of time. Phase transformation data were obtained from integrated X-ray peak intensities which were calibrated based on image analysis of the surface microstructure of the samples at the end of the isothermal treatments. An activation energy of 310 kJ/mol was obtained without assuming a specific kinetic model. From the transformation data, a TTT diagram was constructed for the ranges studied.

Pulsed excimer (KrF) laser induced crystallization of PbZr0.44Ti0.56O3 amorphous films

Amorphous PZT thin films 600 nm thick were rf sputtered from a PbZr0.44Ti0.56O3 ceramic target with excess PbO onto glass substrates maintained at room temperature. After irradiation with a 248 nm KrF pulsed excimer laser with a power density of 2.3×107 W/m2 at a frequency of 50 Hz and a pulsed width of 30 ns for 2 min, the films crystallized into the PZT perovskite structure to a depth of about 120 nm. Comparisons of this work with PZT crystallization obtained from a traditional oven and 488 nm Ar+ laser postdeposition treatments are also given.

Microstructure characterization of sol-gel derived PZT films

The crystallization of sol-gel derived amorphous PZT films deposited on a MgO single-crystal substrate and a SiO2 glass substrate was examined. The pyrochlore crystallites, 5 nm in size, were homogeneously nucleated in the amorphous films at 350 °C. The nucleation temperature of pyrochlore did not depend on the type of substrate. Fine pyrochlore grains were stable even during annealing at high temperatures up to 600 °C. The perovskite formation temperature was dependent on the substrate, and was about 550 °C on the MgO single-crystal substrate and about 750 °C on the SiO2 glass substrate. The perovskite was heterogeneously nucleated preferentially at the substrate-film interface. Perovskite nucleation was more difficult at the SiO2 glass-film interface than at the MgO single crystal-film interface. The ease of nucleation reflected the perovskite formation temperature. Perovskite crystals grew fairly rapidly, once they were nucleated in the films. In the multiple-coated films, the interface between successive layers of PZT films was a favourable nucleation site of perovskite, and the columnar perovskite grains passing through the interface were often developed.

Effect of heating rate on the crystallization behavior of amorphous PZT thin films

The crystallization behavior of amorphous PZT thin films during either conventional furnace annealing (CFA) or rapid thermal annealing (RTA) was studied by both dynamic and static methods. Favorable crystallization behavior was found in the RTA process owing to its very fast heating rates (on the order of 100°C s −1). During RTA, the formation of the metastable phase (pyrochlore) is avoided, and the excess free energy of the amorphous state relative to the stable crystalline phase (perovskite) is instantaneously released to facilitate the perovskite phase formation. While perovskite phase formation during CFA is a slow and sluggish process with a two-stage transition (amorphous phase to pyrochlore phase then to perovskite phase), an easier and faster single-stage transition (amorphous phase directly to perovskite phase) is realized by RTA.

Crystallization Dynamics Of Ferroelectric Pzt (52/48) Thin Film Prepared By Reactive Cosputtering On Pt On Si(100)

ABSTRACTThe crystallization process and microstructural evolution of PZT (52/48) thin films deposited on Pt thin film electrode on Si (100) by reactive multitarget cosputtering technique have been studied as a function of post-annealing temperature and holding time. As annealing temperature increases, the Amorphous PZT films as-deposited at low substrate temperature of 200 °C crystallize into pyrochlore at 450 °C and ferroelectric perovskite phase with pseudo-cubic structure at 550 °C in sequence. X-ray diffraction data show crystallization into perovskite phase to be complete in 30 Minutes at 550 °C. Furthermore, the change of PZT/Pt/Ti/SiO2/Si interfacial TEM Morphology during heat-treatment has been closely scrutinized.

Raman Spectra from Laser-Processed Lead Zirconate Titanate (PbZr0.3Ti0.7O3) Prepared by a Sol-Gel Process

We report on investigations of laser-induced crystallization of PbZr0.3Ti0.7O3 (PZT) gel-powder. By means of micro-Raman spectroscopy, and of optical and scanning electron micrography (SEM), we show that, upon laser irradiation, amorphous PZT material is transformed into microcrystals of the perovskite structure. It was found that the laser-induced crystallization is much faster than crystallization through calcination in a conventional oven.

Electrical Properties of Crystalline and Amorphous Pb(ZrxTi1−x)O3 Thin Films Prepared by the Sol-Gel Technique

ABSTRACTPb(ZrxTi1−x)O3 (PZT) solutions were prepared by reacting lead 2-ethylhexanoate with titanium n-propoxide and zirconium n-propoxide. Films were deposited on several kinds of metal substrate by dip-coating. Crystalline PZT films and amorphous PZT films were heat-treated for 1 hour at 650°C and at 400°C, respectively. Electrical properties including dielectric, pyroelectric and ferroelectric properties of both crystalline and amorphous PZT films were measured and compared. The amorphous PZT thin films exhibited ferroelectric-like behaviors.

Microstructural Rearrangement in PZT(52/48) Thin Film Prepared By Reactive Cosputtering on Pt on Si(100)

ABSTRACTThe experimental conditions which render the exact stoichiometry of PZT(52/48) thin films deposited on Pt thin film on Si(100) by reactive cosputtering have been investigated. As-deposited PZT is amorphous containing α-PbO2microcrystallites. As annealing temperature increases, the amorphous PZT films crystallize into pyrochlore and perovskite with pseudo-cubic structure in sequence. The perovskite PZT annealed above 750 °C evolves into a phase of morphotropic phase boundary. In the perovskite PZT thin films, the leakage current increases with annealing time. Also, the dielectric constant increases with film thickness and annealing temperature, which is discussed in conjunction with PZT/Pt interfacial morphology.

Crystallization Kinetics Of Metallo-Organics Derived Pzt Thin Film

ABSTRACTPZT films on fused silica substrates were prepared by a multiple dipping-firing process from a stable solution of titanium isopropoxide, zirconium n-propoxide and lead 2- ethylhexanoate. The crystallization kinetics of the amorphous PZT films was studied by quantitative X-ray analysis. The crystallization of the amorphous film to perovskite phase involved a transitional pyrochlore structure phase. The entire crystallization was described by a consecutive phase transformation process in which nucleation dominated.