High energy x-ray diffraction measurements have been performed on CaO-Al 2 O 3 liquids suspended in a flow of pure argon for six compositions containing 50-67 mol% CaO. The results indicate that AlO 4 tetrahedra dominate the liquid structure. The radial distribution functions show a significant broadening of the Ca-O peak occurs in the liquid compared to the corresponding glass and, on average, each Ca is surrounded by approximately five oxygen atoms in the melt at a distance of 2.3Å. It is also found that the structure for the eutectic (64% CaO) liquid does not change measurably with temperature between 1600 and 1970 • C.

We studied the crystallization of sol-gel derived Pb(Zr0.4Ti0.6)O3 [PZT(40/60)] thin films at 400 down to 390°C on Pt/SiO2/Si substrates by combination of diol-based solutions and modified film preparation processes. It was found that PZT films could be crystallized at 390°C and that PZT films crystallized at 400°C had microstructures with perovskite-single-phase columnar grains and good ferroelectric characteristics such as switched polarization (2 Pr) of 20 μC/cm2 and relative permittivity (εr) of 740. Next, we evaluated annealing temperature dependence of PZT(40/60) thin films crystallized at 390 to 435°C. The results indicated that (111)-orientation of perovskite phases became weaker, (100)-orientation of those became stronger, and the perovskite grain size increased with decreasing in annealing temperature.

2001) Low-temperature sintering of ferroelectric Pb(Zr, Ti)O 3 thick films derived from stable sol-gel solutions,We have studied sintering and densification of PbZro 52Ti04803 (PZT) films derived from diol-based sol-gel solutions. We found that densification by sintering began at below 750°C and completed at 850°C in 5 min. Initially, 0.83-pm-thick PZT single-coated films were prepared on F't/Ti/SiOz/Si substrates from stable propylene-glycol (1 ,2-propanedio1)-based solutions by crystallization at 700°C. The crystallized films consisted of fine perovskite grains and voids. We studied the firing temperature dependence of various properties such as microstructure, crystallinity, and ferroelectric properties for the single-coated films. Finally, 0.54-pm-thick PZT single-coated dense films were prepared by tiring at 850°Cfor 5 min. In order to prepare thicker PZT dense films, we studied low-temperature sintering of PZT rnulticoated thick films. Using this approach, 1.7-pm-thick PZT dense films were prepared by firing at 850°C for 5 min.

No abstract

2001) Preparation and evaluation of sub-100 nm Pb(Zr,Ti)O 3 films derived from modified sol-gel solutions for low-voltage operation of feram, Sub-100 nm PbZr0.3Tb.703 (PZT) films were prepared on WSi02/Si substrates ftom modified sol-gel solutions without using any seeding layers. Firstly, we studied Pb content [Pb/(Z#Ti)] dependence of 90-nm-thick films. In the wide Pb content region of 108 -125%, the films had perovskite-single-phase fine columnar grains with (1 1 l)-orientation and no voids. Electric properties were dependent on Pb content. The film with good microstructure, rectangular hysteresis, high remanent polarization (PJ, and low leakage current was gained for Pb content of 1 16%. Secondly, we studied film thickness dependence of PZT( 1 16/30/70) films. Films from 90 down to 61 nm in thickness were prepared. We found that the sub-100 nm films with good microstructures could be prepared h o r n the modified solutions. The sub-100 nm films had saturation voltage of 1.25 V and high P, even at 1 V or less. In particular, a 61-nm-thick film had high P, of 17 pC/cmZ at 0.75 V.