Low-temperature sintering of 0.5Pb(Zn1∕3Nb2∕3)O3–0.5Pb(Zr0.47Ti0.53)O3 ceramics (0.5PZN–0.5PZT) was investigated using Li2CO3 as sintering aids. The addition of Li2CO3 significantly improved the sinterability of 0.5PZN–0.5PZT ceramics, resulting in a reduction of sintering temperature from 1100to950°C. Moreover, the effect of Li2CO3 addition on the dielectric and piezoelectric responses in 0.5PZN–0.5PZT systems was systematically studied in this work. The analysis of x-ray diffraction patterns and scanning electron microscopy indicated that the solubility limit of Li ions in perovskite structures was near 0.5wt% in Li2CO3 form. Below the solubility limit, Li+ ions entered the six-fold coordinated B sites of oxygenic octahedral center and enhanced the compositional fluctuation in nanoscale, resulting in the increase of the degree of diffuseness γ. While at high doping level above the solubility limit, γ decreased subsequently, which was attributed to the formation of pyrochlore phase. Raman analysis on the B-site cation order correlates well with the dielectric measurement results. The large improvements in the piezoelectric properties such as the coupling factor and piezoelectric constant were also observed for doped specimens. Optimized parameters, such as d33=278pC∕N, kp=0.50, and εmax=8800, were achieved by doping 0.5wt% Li2CO3 in low-temperature sintered 0.5PZN–0.5PZT systems, which shows great promise as practical materials for multilayered piezoelectric device applications. The observed improvement in the electric properties can be attributed to the grain size effect. After doping, the clamping effect caused by oxygen vacancies and grain boundary phases on domain wall motion was largely reduced due to the increase of grain size; therefore, a significant reduced coercive field and an increased remanent polarization were observed in doped 0.5PZN–0.5PZT systems.
Graphene resting on a silicon-on-insulator platform offers great potential for optoelectronic devices. In the paper, we demonstrate all-optical modulation on the graphene–silicon hybrid waveguides (GSHWs) with tens of micrometers in length. Owing to strong interaction between graphene and silicon strip waveguides with compact light confinement, the modulation depth reaches 22.7% with a saturation threshold down to 1.38 pJ per pulse and a 30-μm-long graphene pad. A response time of 1.65 ps is verified by a pump–probe measurement with an energy consumption of 2.1 pJ. The complementary metal-oxide semiconductor compatible GSHWs with the strip configuration exhibit great potential for ultrafast and broadband all-optical modulation, indicating that employing two-dimensional materials has become a complementary technology to promote the silicon photonic platform.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.