Fanyun Chen,Qingshan Gao,Jing Zhang,Hao Deng,Chen Tian,Zhang Lin
Elemental sulfur is an important non-metallic material that is widely used in various fields including chemical, metallurgical and sulfuric acid industries. Polymetallic sulfur slag (PSS) is an important secondary resource for the recovery of sulfur. However, separation of sulfur from PSS is difficult due to the tight binding of some thiophilic metals to sulfur. Herein, we proposed a recrystallization method for the effective separation of sulfur and metals by using organic solvents to control the particle size of sulfur crystals. It was suggested that the particle size of sulfur recovered in the close to saturation state of toluene is about 2000 μm, while the purity is as high as 99.6%. Moreover, the recovery rate is over 95%, which is more than the current commonly used flotation method. The growth mechanism of sulfur crystals under different saturation conditions lays a foundation for the deepening of the growth theory of large-size sulfur crystals. This method realized the effective separation of sulfur from metal sulfides such as FeS2and ZnS, which provided an important guidance for the recovery of sulfur resources through a novel method of recrystallizing regulation.
Ferroelectric organic field-effect transistor (Fe-OFET) memory devices exhibit low power consumption, low cost and good flexibility, which are indispensable to next generation flexible and wearable memory devices. However, up until the present, the ferroelectric materials used in Fe-OFETs have been limited to ferroelectric polymers, i.e. poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)], and suffer from large surface roughness and high-risk of depolarization. This work integrates a new two-dimensional CuInP 2 S 6 crystal into Fe-OFET, which can introduce excellent ferroelectric property due to its single crystalline smoothness and noncentrosymmetric crystal structure. Meanwhile, the high-mobility rubrene crystal is selected as the channel material to construct rubrene/CuInP 2 S 6 organic/inorganic van der Waals heterojunctions . Associated with synergetic effect of single-crystalline nature of the heterojunction and atomically flat/defect-free interface, the memory devices possess a high programming speed of 0.5 s and long retention time of 10 4 s with a current ratio larger than 10 3 . Furthermore, the performance of flexible devices is also demonstrated, including a programming/erase cycle of 1000 with a current on/off ratio approaching 10 3 , data retention time of 10 4 s with a current on/off ratio of 10 3 and a current on/off ratio maintained at 10 2 even after 100 bending cycles under a bending radius of 25 mm, which are qualified for memory buffer usage or short-term data storage especially when they are integrated with other flexible electronics. The proposed configuration of memory transistors using organic/inorganic heterojunctions provides a rational design of device structure toward flexible Fe-OFET non-volatile memory applications.
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