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Thermal properties and remnant state variables of ferroelectric ceramics switched by both electric field and compressive stress at room temperature
摘要： A commercial poled ferroelectric cube specimen is subject to electric ?eld and compressive stress of various magnitudes at the reference temperature 20 °C. After reaching speci?c states of remnant polarization and remnant strains, temperature of the specimen increases under no external load, measuring changes in polarization and strains. Assuming constant values of thermal properties in the temperature range of interest, we estimated pyroelectric and thermal expansion coe?cients for all tested levels of electric and stress ?elds and plotted them versus remnant state variables at 20, 50, 80, and 110 °C. The distributions of thermal properties ?t well into quadratic curves independent of electric and stress ?elds at each of the four temperatures. One could predict successfully the quadratic ?tting curves at high temperatures by using the equations of quadratic ?tting curves at reference temperature. Remnant state variables also seem to have close correlation among themselves, independent of the levels of applied electric ?eld or stress. ? 2018 The Japan Society of Applied Physics
关键词： thermal properties,compressive stress,electric ?eld,ferroelectric ceramics,remnant state variables
更新于2025-09-23 15:21:01
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Recent advances in the chemical strengthening of glass
摘要： Since its development in the early 1960s till recently, applications of the glass chemical strengthening technology were limited mostly to aircraft cockpit windshields, photocopier transparencies, and hard disks. The interest has been renewed by a need to have stronger and lighter glass products, led mostly by display cover in personal mobile electronic devices, such as cell phones, and glass packaging for safe delivery of medicines in pharmaceutical applications. In this paper, I suggest that the science of the compressive stress development is nearly completely understood. The so-called “dilation anomaly” is resolved. Newer technologies are being developed, for example, thin float-produced flat glasses can be strengthened with reduced warp. Molten salt bath maintenance techniques to avoid discarding of degraded salt have been developed to some extent. In addition to more and more pharmaceutical businesses looking to strengthen the glass packaging to avoid costly recalls, interest is also high in break-resistant automobile and locomotive transparencies. Other miscellaneous topics where the use of chemically strengthened glass could bring value-added premium are also mentioned.
关键词： molten salt bath,pharmaceutical packaging,chemical strengthening,compressive stress,glass,automobile transparencies,dilation anomaly
更新于2025-09-09 09:28:46
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Microstructure fabrication process induced modulations in CVD graphene
摘要： The systematic Raman spectroscopic study of a “mimicked” graphene device fabrication is presented. Upon photoresist baking, compressive stress is induced in the graphene which disappears after it is removed. The indirect irradiation from the electron beam (through the photoresist) does not significantly alter graphene characteristic Raman peaks indicating that graphene quality is preserved upon the exposure. The 2D peak shifts and the intensity ratio of 2D and G band, I(2D)/I(G), decreases upon direct metal deposition (Co and Py) suggesting that the electronic modulation occurs due to sp2 C-C bond weakening. In contrast, a thin metal oxide film deposited graphene does not show either the significant 2D and G peaks shift or I(2D)/I(G) decrease upon the metal deposition suggesting the oxide protect the graphene quality in the fabrication process.
关键词： compressive stress,fabrication process,Raman spectroscopy,graphene,metal deposition
更新于2025-09-09 09:28:46