Magnesium Niobate-lead Titanate Research Articles

Influence of Buffer Layers on Lead Magnesium Niobate Titanate Thin Films Prepared by Pulsed Laser Ablation

Lead magnesium niobate titanate ( Pb[(Mg1/3Nb2/3)0.9Ti0.1]O3; PMN-PT) thin films were prepared on Pt/Ti/SiO2/Si substrates with buffer layers by pulsed laser ablation (PLA). Lead titanate (PT), barium titanate (BT) and barium strontium titanate (BST) were chosen as the materials of the buffer layer. The crystalline structure of the PMN-PT thin films on the buffer layers was a mixture of perovskite and pyrochlore phases. Among these samples, the PMN-PT thin films on the BST buffer layer have the highest perovskite fraction of over 95%. Average dielectric constant of the PMN-PT thin film on the BST buffer layer was about 1200. No serious interdiffusions between the bottom electrode, the buffer layer and the PMN-PT layers were observed.

Particle Engineering and Intelligent Processing of Piezo Ceramics

The sequence of reactions and morphological changes during the calcination of lead magnesium niobate titanate solid solution (PMNT) from a variety of reactant mixtures were studied. As predicted, the formation of the perovskite phase occurs with an expansion of the compact of the mixture and is accompanied by drastic changes in the microstructure. Reactive calcining of the mix to the point of maximum expansion (750°-800°C) results in ultrafine sinteractive powder and this facilitates the fabrication of dense, high performance PMNT ceramics at temperatures as low as 1150°C.

Preparation of Lead Magnesium Niobate Titanate Thin Films by Chemical Vapor Deposition

Lead magnesium niobate titanate (PMN-PT) thin films were prepared on Pt-coated magnesium oxide single-crystal substrate (Pt(100)/MgO(100)) and Pt- and Ti-coated oxidized Si wafer (Pt(111)/Ti/SiO2/Si(100)) at 680-780° C by metalorganic chemical vapor deposition (MOCVD). The PMN-PT thin films comprising perovskite structure as a main phase were obtained in the composition of Ti/(Mg+Nb+Ti)≥25 mol%. Their room-temperature dielectric constant was 1000-1500 measured at 100 mV and 1 kHz.

Polarization reversal and high dielectric permittivity in lead magnesium niobate titanate thin films

Ferroelectric thin films of the morphotropic phase boundary composition in the lead magnesium niobate-lead titanate solid solution system were fabricated through the sol-gel spin-on technique. The rapid thermally annealed films showed a very high dielectric constant of 2900, with a concomitant low dissipation factor of 0.02; the films were hysteretic with a saturation remanence of 11 μC/cm2 and a coercive voltage of 0.5 V. The storage charge density observed at 5 V was 210 fC/μm2. These films merit consideration for potential application in ferroelectric nonvolatile random access memories (NVRAMs), and in high bit density metal-oxide-semiconductor (MOS) dynamic random access memories (DRAMs).

Chemical reactions of lead magnesium niobate titanate in the presence of a glass

A relaxor ferroelectric of composition 0.93Pb(Mg1/3Nb2/3)O3-0.07PbTiO3 was sintered with 3 wt.% commercial sealing glass at 750 °C for 30 min to achieve ≥95% of theoretical density and a nearly pure perovskite phase. At higher glass additions (up to 20 wt.%), higher sintering temperatures (up to 800 °C), and longer sintering times (up to 4 h), the amount of perovskite (PMN type) decreases and that of pyrochlore (6PbO · MgO · 3Nb2O5 or 3PbO · 2Nb2O5) increases. On sintering at 800 °C for 4 h no perovskite phase is present in compositions with even 1% glass addition. The reaction of glass with the PMN phase was found to lead to the disappearance of the perovskite. Addition of 0.1 to 0.6 wt.% MgO to compositions containing 1 and 3 wt.% glass (and balance PMN-PT) results in essentially pure PMN perovskite phase on sintering at 700–800 °C for 30–240 min, confirming that the reaction of glass with PMN and depletion of MgO from PMN can be arrested. The sintered ceramics exhibit relaxor behavior and possess dielectric properties essentially commensurate with the phase composition.