A study of capacitance-voltage characteristics of lead zirconate titanate ferroelectric thin films and their usage to investigate polarization and coercive field.

Capacitance-voltage (C-V) characteristics of lead zirconate titanate (PZT) thin films with a thickness of 130 nm were measured between 300 and 533 K. The transition between ferroelectric and paraelectric phases was revealed to be of second order in our case, with a Curie temperature at around 450 K. A linear relationship was found between the measured capacitance and the inverse square root of the applied voltage. It was shown that such a relationship could be fitted well by a universal expression of C/A = k(V+V(0))(-1/2) and that this expression could be derived by expanding the Landau-Devonshire free energy at an effective equilibrium position of the Ti/Zr ion in a PZT unit cell. By using the derived equations in this work, the free energy parameters for an individual material can be obtained solely from the corresponding C-V data, and the temperature dependences of both remnant polarization and coercive voltage are shown to be in quantitative agreement with the experimental data.

Which diagrams and when? Health workers' choice and usage of different diagram types for service improvement

Diagrammatic representations, such as process mapping and care pathways, have been often used for service evaluation and improvement in healthcare. While a broad range of diagrammatic representations exist, their application in healthcare has been very limited. There is a lack of understanding about how and which diagrams could be usable and useful to health workers. In this study, ten mental health workers were asked to discuss positive and negative issues around their service delivery using one or two diagrams of their choice out of seven different diagrams representing their service: care pathway diagram; organisation diagram; communication diagram; service blueprint; patient state transition diagram; free form diagram; geographic map. Their interactions with diagrams were video-taped for analysis. The patient state transition diagram was the most popular choice in spite of relatively low previous familiarity. The overall findings provided insight into a better use of diagrams in healthcare. © 2012 Springer-Verlag.