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La-doped 0.75Pb(MgNb)O-0.25PbTiO (PMN-PT) transparent ceramics were fabricated by uniaxial hot-pressing sintering, oxygen atmosphere sintering and two-stage sintering technology, respectively. PMN-PT ceramics fabricated by two-stage sintering method show the best densification and highest transparency. Its optical transmittance reaches to 70% at 900 nm which is very close to its theoretical transmittance 71%. The temperature dependent dielectric properties and P- E hysteresis loops of these three ceramics show that they all exhibit relaxor characteristics. Effects of sintering methods on the dielectric and ferroelectric properties, diffusivity coefficient, and polarization current density were investigated. [ABSTRACT FROM AUTHOR]

The machining accuracy of workpiece is influenced by its orientation deviation, which is caused by the fixture-workpiece error. Based on the spatial coordinate theory, the orientation deviation of workpiece is measured by using an on-machine verification system, which can take into account the errors resulting from fixture manufacturing, installation and adjustment, location and clamping of workpiece. According to the least square method, the model of orientation deviation is built to determine the relationship between the theoretical and actual coordinate systems. The influence of orientation deviation on machining accuracy is quantified, and it is shown that the orientation deviation only affects the dimensional precision and position precision, rather than shape precision. In the experiment, the compensation processing of realtime errors was conducted, and the perpendicularity and inclination errors of the tetragonal part were reduced by 38.46% and 47.06%, respectively. [ABSTRACT FROM AUTHOR]