The unique morphology and structure significantly enhance the performance of photoelectric detection. Herein, titanyl phthalocyanine (TiOPc) coarse crystal and microspheres are obtained by a simple physical vapor deposition (PVD) method designed to produce TiOPc structures that undergo significant changes in the crystal structure. The photoelectric experimental results show that the photocurrent of TiOPc coarse crystal and microspheres increases with the increase of voltage and exhibits better stability compared to the raw materials. Under a bias voltage of 10 V, the photoresponsivity of microspheres reaches the maximum, which is 77 times that of raw materials. Under different monochromatic lights, the raw materials are most sensitive to red light (850 nm), with a photocurrent of 1.3556 × 10 −6 mA, but the coarse crystal/microspheres are most sensitive to blue light (455 nm) with photocurrents of 1.281 × 10 −5 mA/2.609 × 10 −5 mA, respectively. It is worth mentioning that although the photocurrent and responsivity of coarse crystal are slightly lower than those of microspheres, the response speed is faster, with a rise/fall time is 271 and 194 ms, respectively. The good photoelectric properties indicate the potential research value of TiOPc coarse crystal and microspheres in the field of photoelectric detection.
Jiyuan Chen,Feng Luo,Yuanshui Liu,Denghui Jiang,Linzhuang Xing,Zhimin Li
The lead-free BiFeO 3 -BaTiO 3 (BF-BT) based ceramics with large piezoelectric coefficient ( d 33 ) have been desired for promising applications in high-temperature fields. Herein, the 0.7Bi(Fe 0.9985 Mn 0.0015 )O 3 -0.3BaTiO 3 ceramics with different grain sizes are intentionally prepared by solid-state method, and a large d 33 (232 pC/N) and high Curie temperature T c (501 °C) are simultaneously achieved in the case of large grain size (>9 µm). X-ray diffraction and Rietveld refinement analyses indicate that these coarse-grained samples possess stronger rhombohedral distortion and enlarged lattice parameter compared to fine-grained samples, which make domain switching easier and give rise to the increase in strain. As a result, the piezoelectric and ferroelectric properties of such samples are significantly improved with increasing grain size from 3.05 µm to 9.07 µm. In addition, electric domain configuration and field-induced strain further prove that the strong piezoelectric response in coarse-grained samples is attributed mainly to enhanced non-180° domain mobility. This study reveals the origin of large piezoelectric response in coarse-grained BF-BT ceramics, and proposes an effective approach to improve the piezoelectric properties of BF-BT ceramics.
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