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Full-Text Articles in Nanoscience and Nanotechnology
Peridynamic Model For Dynamic Fracture In Unidirectional Fiber-Reinforced Composites, Wenke Hu, Youn Doh Ha, Florin Bobaru
Peridynamic Model For Dynamic Fracture In Unidirectional Fiber-Reinforced Composites, Wenke Hu, Youn Doh Ha, Florin Bobaru
Florin Bobaru Ph.D.
We propose a computational method for a homogenized peridynamics description of fiber-reinforced composites and we use it to simulate dynamic brittle fracture and damage in these materials. With this model we analyze the dynamic effects induced by different types of dynamic loading on the fracture and damage behavior of unidirectional fiber-reinforced composites. In contrast to the results expected from quasi-static loading, the simulations show that dynamic conditions can lead to co-existence of and transitions between fracture modes; matrix shattering can happen before a splitting crack propagates. We observe matrix–fiber splitting fracture, matrix cracking, and crack migration in the matrix, including …
Cause And Prevention Of Moisture-Induced Degradation Of Resistance Random Access Memory Nanodevices, Albert Chen
Cause And Prevention Of Moisture-Induced Degradation Of Resistance Random Access Memory Nanodevices, Albert Chen
Albert B Chen
Dielectric thin films in nanodevices may absorb moisture, leading to physical changes and property/performance degradation, such as altered data storage and readout in resistance random access memory. Here we demonstrate using a nanometallic memory that such degradation proceeds via nanoporosity, which facilitates water wetting in otherwise nonwetting dielectrics. Electric degradation only occurs when the device is in the charge-storage state, which provides a nanoscale dielectrophoretic force directing H2O to internal field centers (sites of trapped charge) to enable bond rupture and charged hydroxyl formation. While these processes are dramatically enhanced by an external DC or AC field and electron-donating electrodes, …
Demonstration And Modeling Of Multi-Bit Resistance Random Access Memory, Albert Chen
Demonstration And Modeling Of Multi-Bit Resistance Random Access Memory, Albert Chen
Albert B Chen
Although intermediates resistance states are common in resistance random access memory (RRAM), two-way switching among them has not been demonstrated. Using a nanometallic bipolar RRAM, we have illustrated a general scheme for writing/rewriting multi-bit memory using voltage pulses. Stability conditions for accessing intermediate states have also been determined in terms of a state distribution function and the weight of serial load resistance. A multi-bit memory is shown to realize considerable space saving at a modest decrease of switching speed.
Size-Dependent Metal-Insulator Transition In Pt-Dispersed Sio2 Thin Film: A Candidate For Future Non-Volatile Memory, Albert B. Chen
Size-Dependent Metal-Insulator Transition In Pt-Dispersed Sio2 Thin Film: A Candidate For Future Non-Volatile Memory, Albert B. Chen
Albert B Chen
Non-volatile random access memories (NVRAM) are promising data storage and processing devices. Various NVRAM, such as FeRAM and MRAM, have been studied in the past. But resistance switching random access memory (RRAM) has demonstrated the most potential for replacing flash memory in use today. In this dissertation, a novel RRAM material design that relies upon an electronic transition, rather than a phase change (as in chalcogenide Ovonic RRAM) or a structural change (such in oxide and halide filamentary RRAM), is investigated. Since the design is not limited to a single material but applicable to general combinations of metals and insulators, …
Purely Electronic Switching With High Uniformity, Resistance Tunability, And Good Retention In Pt-Dispersed Sio2 Thin Films For Reram, Albert Chen
Albert B Chen
Resistance switching memory operating by a purely electronic switching mechanism, which was first realized in Pt-dispersed SiO2 thin films, satisfies criteria including high uniformity, fast switching speed, and long retention for non-volatile memory application. This resistive element obeys Ohm's law for the area dependence, but its resistance exponentially increases with the film thickness, which provides new freedom to tailor the device characteristics.
Environmentally Benign Synthesis Of Nanosized Aluminophosphate Enhanced By Microwave Heating, Eng-Poh Ng, Luc Delmotte, Svetlana Mintova
Environmentally Benign Synthesis Of Nanosized Aluminophosphate Enhanced By Microwave Heating, Eng-Poh Ng, Luc Delmotte, Svetlana Mintova
Eng-Poh Ng
The problem addressed with our paper is on the efficient utilization of reacting materials for enhanced syntheses of nanosized aluminophosphate molecular sieve by microwave heating, and decreasing or almost eliminating the related waste. The synthesis procedure deals with the environmental issues concerning the future manufacture re-use and disposal of non-reacted chemicals associated with the production of nanosized aluminophosphate. Nanosized AlPO-18 has been prepared by a multicycle synthesis approach via re-using non-reacted compounds from precursor suspensions with minimal requirement of chemical compensation after recovering of crystalline nanoparticles from each step. This approach is implied as environmentally benign and results in almost …