In this study, a nickel oxide (NiO)-based resistive random-access memory (RRAM) was demonstrated with multistate data storage. The NiO thin film was fabricated by solution procession combined with UV irradiation at a low temperature of 200 °C. The device exhibited a high on/off resistance ratio (>10 5 ), as well as good endurance and excellent retention characteristics. It is important that multistate data storage was obtained by adjusting the RESET stop voltage, which resulted in a multilevel cell (MLC) to increase storage density. Unintentionally doped carbon (C) was distributed in the NiO thin film with periodic fluctuation. C-related filaments formation and multistate rupture were suggested as the resistive switching mechanism.

Nickel hydroxide [Ni(OH) 2 ] thin films were synthesized by a solution process and characterized by x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and time-of-flight secondary-ion mass spectrometry. Unlike nickel oxide (NiO) memristors, which exhibit only nonvolatile memory properties, the Ag/Ni(OH) 2 /Pt memristor can be operated in volatilethreshold resistive-switching mode with the compliance current (I cc ) varying from 10 nAto 100 μA. When I cc exceeds 1 mA, the nonvolatile switching mode is triggered. The resistiveswitching mechanism of Ag ion diffusion in Ni(OH) 2 is discussed by combining experimental analysis and density functional theory calculations. The results provide a useful guideline for designing volatile-threshold memristor.

This paper studies the traceability of the certified value of the reference material with the equivalent water content of nitrogen tetroxide(NTO) and green nitrogen tetroxide(MON), which lays the foundation for the certified value of the reference material. The purity of bibenzyl was measured by differential scanning calorimetry(DSC), the water content of deuterium acetonitrile(DAN) was measured by Karl Fischer method, the proton content and water content of deuterium acetonitrile(DAN) were measured by nuclear magnetic resonance spectroscopy(NMR), and the equivalent water content of deuterium acetonitrile(DAN) - nitrous oxide system was measured. All of these three methods can be directly traced to SI units, which are internationally recognized potential reference measurement methods. Therefore, the fixed value of equivalent water content reference material has metrological traceability.

In this study, an Ag-doped Ni(OH) 2 (Ag:Ni(OH) 2 ) thin film is fabricated by solution process with Ag concentration of 2% at 200 • C and applied to threshold switching selector devices. X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy analysis confirm that the matrix contains 72% Ni(OH) 2 and 28% NiO, while the Ag is doped as ion state. As the processing temperature increases, the Ni(OH) 2 matrix changes to NiO, and the doped Ag tends to metal state. Selector devices with Pt bottom and top electrodes were fabricated and measured. Compared with a Pt/Ag:NiO/Pt device, which shows non-volatile resistive switching characteristics, bi-directional threshold switching behavior is demonstrated in the Pt/Ag:Ni(OH) 2 /Pt device. The selectivity is larger than 10 4 . The high/low resistance state cycles have been measured by half-bias pulse stimulation without obvious deterioration. Since Ag ion in Ni(OH) 2 matrix shows fast diffusion, a thin Ag filament could be formed at low voltage, which then disperses and fractures after the voltage is removed. It corresponds to the main mechanism of bi-directional threshold switching. For the Pt/Ag:NiO/Pt device, the formation of thicker Ag filaments at higher electric fields leads to non-volatile resistive switching.