ORCID Profile
0000-0002-9225-0095
Current Organisation
Wuhan University
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Publisher: AIP Publishing
Date: 28-07-2014
DOI: 10.1063/1.4891827
Abstract: Fresnoite crystals with the nominal composition Ba2TiSi2O8 (BTS) were grown using the Czochralski technique. The full matrix material constants were determined based on the IEEE standards, with d31, d33, and d15 coefficients being on the order of 2.7, 4.0, and 17.5 pC/N, respectively. A positive sign of d31 was confirmed using strain measurements and rotated crystal cuts, where a maximum d33* value of 9.1 pC/N was achieved for ZXl50° crystal cut. The dielectric, piezoelectric, and related thermal properties were investigated as a function of temperature, showing strong anisotropic behavior, inherently associated with its layered crystal structure. The temperature dependence of d15 and d33* revealed a variations of & % over the temperature range of 20–700 °C. The good thermal stability, together with the high piezoelectric properties and electrical resistivity (& Ω·cm at 600 °C), makes fresnoite BTS crystals promising candidates for high temperature sensing applications.
Publisher: AIP Publishing
Date: 11-02-2015
DOI: 10.1063/1.4908113
Abstract: Melilite-type crystals, including Ca2Ga2SiO7, Ca2MgSi2O7, and CaNdGa3O7, were successfully grown by the Czochralski technique. Thermal properties were investigated and full matrices of electromechanical constants of these melilite crystals were evaluated by impedance method, with d14 being on the order of 5.3–9.3 pC/N. The relationship between microstructure and electromechanical properties of the three kinds of crystals was established, in order to explore the piezoelectric origin and further optimize the piezoelectric properties. The distortion of eight-fold antiprisms and the distortion/rotation of tetrahedrons were thought to contribute to the piezoelectric d14 and d36, respectively. In addition, the layered structure leads to strong anisotropic behavior, accounts for the high resistivity along Z direction in Ca2MgSi2O7, while the disordered structure accounts for the degraded resistivity in CaNdGa3O7. The properties at elevated temperature were investigated, where the elastic constants show high thermal stability over the range of 25–500 °C, with minimal variation of 6%.
Publisher: American Chemical Society (ACS)
Date: 11-05-2018
Publisher: Springer Science and Business Media LLC
Date: 02-12-2022
DOI: 10.1038/S41467-022-35218-0
Abstract: Formamidinium lead iodide (FAPbI 3 ) perovskites are promising emitters for near-infrared light-emitting diodes. However, their performance is still limited by defect-assisted nonradiative recombination and band offset-induced carrier aggregation at the interface. Herein, we introduce a couple of cadmium salts with acetate or halide anion into the FAPbI 3 perovskite precursors to synergistically passivate the material defects and optimize the device band structure. Particularly, the perovskite analogs, containing zero-dimensional formamidinium cadmium iodide, one-dimensional δ-FAPbI 3 , two-dimensional FA 2 FA n-1 Pb n I 3n+1 , and three-dimensional α-FAPbI 3 , can be obtained in one pot and play a pivotal and positive role in energy transfer in the formamidinium iodide-rich lead-based perovskite films. As a result, the near-infrared FAPbI 3 -based devices deliver a maximum external quantum efficiency of 24.1% together with substantially improved operational stability. Combining our findings on defect passivation and energy transfer, we also achieve near-infrared light communication with device twins of light emitting and unprecedented self-driven detection.
No related grants have been discovered for Hengjiang Cong.