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For broad nanoscale applications, it is crucial to implement more functional properties, especially those ferroic orders, into two-dimensional materials. Here GdI$_3$ is theoretically identified as a honeycomb antiferromagnet with large $4f$ magnetic moment. The intercalation of metal atoms can dope electrons into Gd's $5d$-orbitals, which alters its magnetic state and lead to Peierls transition. Due to the strong electron-phonon coupling, the Peierls transition induces prominent ferroelasticity, making it a multiferroic system. The strain from undirectional stretching can be self-relaxed via resizing of triple ferroelastic domains, which can protect the magnet aganist mechnical breaking in flexible applications., Comment: 6 pages, 4 figures

The so-called interlayer-sliding ferroelectricity was recently proposed as an unconventional route to pursuit electric polarity in van der Waals multi-layers, which was already experimentally confirmed in WTe$_2$ bilayer even though it is metallic. Very recently, another van der Waals system, i.e., the ZrI$_2$ bilayer, was predicted to exhibit the interlayer-sliding ferroelectricity with both in-plane and out-of-plane polarizations [Phys. Rev. B \textbf{103}, 165420 (2021)]. Here the ZrI$_2$ bulk is studied, which owns two competitive phases ($\alpha$ \textit{vs} $\beta$), both of which are derived from the common parent $s$-phase. The $\beta$-ZrI$_2$ owns a considerable out-of-plane polarization ($0.39$ $\mu$C/cm$^2$), while its in-plane component is fully compensated. Their proximate energies provide the opportunity to tune the ground state phase by moderate hydrostatic pressure and uniaxial strain. Furthermore, the negative longitudinal piezoelectricity in $\beta$-ZrI$_2$ is dominantly contributed by the enhanced dipole of ZrI$_2$ layers as a unique characteristic of interlayer-sliding ferroelectricity, which is different from many other layered ferroelectrics with negative longitudinal piezoelectricity like CuInP$_2$S$_6$., Comment: 6 pages, 6 figures

Nowadays, designing and searching for materials with multiple functional characteristics are the key to achieving high-performance electronic devices. Among many candidates, two-dimensional multiferroic materials have great potential to be applied in highly-integrated magnetoelectric devices, such as high-density non-volatile memories. Here, we predict a two-dimensional material VOF2 monolayer to possess intrinsic ferroelectric and ferromagnetic properties. The VOF$_2$ monolayer own the largest in-plane ferroelectric polarization ($332$ pC/m) in the family of VO$X_2$ ($X$: halogen) oxyhalides. Different from other VO$X_2$ monolayers whose magnetic ground states are antiferromagnetic or noncollinear spiral textures, the VOF$_2$ monolayer owns a robust ferromagnetic ground state, which is rare but highly desirable. Our theoretical prediction provides a good candidate and starting point for the further pursuit of more two-dimensional multiferroic materials with high-performance magnetoelectricity., Comment: 5 figures

To improve thermal stability and reduce power dissipation of phase‐change memory (PCM), the oxygen‐doped Sn(15) Sb(85) (SS) thin film is proposed by magnetron sputtering in this study. Comparing to undoped Sn15Sb85(SS), the oxygen‐doped‐SS thin film has superior thermal stability and better data retention. Meanwhile, the electrical conductivity of crystallisation oxygen‐doped‐SS thin film is also lower than that of SS, which means its less power consuming in PCM. The electrical conductivity ratio between amorphous and crystalline states for oxygen‐doped SS reaches up to two orders of magnitude. After oxygen doping, the root‐mean‐square surface roughness from amorphous (0.29 nm) to crystalline (0.46 nm) state for oxygen‐doped‐SS thin films becomes smaller. The switching time of amorphisation process for the oxygen‐doped‐SS thin film (∼2.07 ns) is shorter than Ge(2) Sb(2) Te(5) (GST) (∼3.05 ns). X‐ray diffractometer is recorded to investigate the change of crystalline structure. Thus, the authors infer that oxygen‐doped SS is a promising phase‐change thin film for PCM.

Sb70Se30/SiO2 multilayer thin films were applied to improve the thermal stability by RF magnetron sputtering on SiO2/Si (100) substrates. The characteristics of Sb70Se30/SiO2 multilayer thin films were investigated in terms of crystallization temperature, ten years of data retention, and energy bandgap. It is observed that the crystallization temperature, 10-year data retention, and resistance of Sb70Se30/SiO2 multilayer composite thin films exhibited a higher value, suggesting that Sb70Se30/SiO2 multilayer composite thin films have superior thermal stability. The AFM measurement suggests that the SbSe (1 nm)/SiO (9 nm) multilayer thin films possess a smaller surface roughness (RMS = 0.23 nm). Besides, it was found that the phase-change time of SbSe (1 nm)/SiO (9 nm) multilayer thin films was shorter than that of GST in the process of crystallization and amorphization.

SiO 2 -doped Sb material is proved to be a promising candidate for phase change memory (PCM) use because of its high crystallization temperature (∼239 °C), large crystallization activation energy (4.05 eV), and good data retention ability (162 °C for 10 years). The band gap is broadened and the grain size is refined by SiO 2 doping. The reversible resistance transition can be achieved by an electric pulse as short as 5 ns for the PCM cell based on SiO 2 -doped Sb material. A lower operation power consumption (the energy for RESET operation 1.1 × 10 −11 J) is obtained. In addition, SiO 2 -doped Sb material shows a good endurance of 2.5 × 10 5 cycles.

Cu–Sn–Se material was prepared by magnetron sputtering to investigate its potential application in phase change memory. The amorphous-to-crystalline transition was studied by in situ film resistance measurements. Cu–Sn–Se material had lower activation energy for crystallization (1.60 eV) and higher crystallization resistance than SnSe. The amorphous Cu–Sn–Se had more narrow band gap compared to SnSe. After the adding of Cu, the crystallization of Cu–Sn–Se material was inhibited and the grain structure became more compact. The picosecond laser pulse measurement indicated that Cu–Sn–Se material had a fast phase change speed (3.36 ns). The results demonstrated that Cu–Sn–Se material was a promising phase change material which had low power and high speed application in phase change memory.

The GeTe/Sb superlattice-like thin films are systematically investigated for the potential application in phase change memory. Compared with GeTe, GeTe/Sb film has lower crystallization temperature and activation energy. Besides, the internal stress of GeTe/Sb is less than GeTe during the crystallization. The superlattice-like structure is observed by transmission electron microscopy. The polycrystalline phase is confirmed by selected area electron diffraction. The reversible resistance switching can be realized for GeTe/Sb-based phase change memory device with an electric pulse of 8 ns width. In addition, GeTe/Sb shows a good endurance of 6.3 × 106 cycles.

The thermal stability of phase change films is a key parameter in phase change memory (PCM) applications. Here, we find that the Sm doped Sn15Sb85 films have a higher crystallization temperature and a better data retention ability in comparison with those of pure amorphous SnSb films, revealing a potential candidate for PCM applications. In addition, it demonstrated that the Sm doping was also propitious to reduce the power consumption and decrease the change of roughness in the crystallization process. Finally, the data storage capability of the Sm0.015(Sn15Sb85)0.985-based PCM cell was obtained with a reversible phase change process between high and low resistance states.

Al-doped Sn2Se3 phase change material has higher crystallization temperature and lower conductivity than Ge2Sb2Te5 material. A series of optical constants of Al-doped Sn2Se3 materials are measured by spectroscopic ellipsometry measurement. The energy band gap is broadened after Al doping and the grain size becomes smaller. The optical reflectivity is reduced while the reflectivity contrast is enhanced. The phase transition speed between the amorphous and crystalline states is investigated by the picosecond laser pulses. A fast phase change speed is observed for Al-doped Sn2Se3 material.

In this paper, the following questions were investigated: the proportion of mass loss, the mass fraction of oil, the structure, composition and ultimate analysis of solid residues and gas products. By comparing the treatment effect of using both microwave and electric as the source of heat to dispose the oil-based drilling cuttings (OBDC), the advantages of microwave heating treatment were demonstrated. Meanwhile, the composition of liquid products by microwave pyrolysis was analyzed. The results show that the microwave heating is better than electric heating and the former can promote the pyrolysis of petroleum hydrocarbons. The results of component analysis of the liquid products from OBDC by microwave pyrolysis show that C12∼C20 components pyrolyze at 500 °C. At the same time, a mass of C21∼C24 components volatilize. At the temperature above 500 °C, the thermal cracking reactions of >C25 components occur and a maximum content of paraffin in liquid products is obtained. As the temperature increases, the components obtained by pyrolysis become more and more complex.

In this article, Ge10Sb90/SiO2 multilayer thin films were prepared to improve thermal stability and data retention for phase change memory. Compared with Ge10Sb90 monolayer thin film, Ge10Sb90 (1 nm)/SiO2 (9 nm) multilayer thin film had higher crystallization temperature and resistance contrast between amorphous and crystalline states. Annealed Ge10Sb90 (1 nm)/SiO2 (9 nm) had uniform grain with the size of 15.71 nm. After annealing, the root-mean-square surface roughness for Ge10Sb90 (1 nm)/SiO2 (9 nm) thin film increased slightly from 0.45 to 0.53 nm. The amorphization time for Ge10Sb90 (1 nm)/SiO2 (9 nm) thin film (2.29 ns) is shorter than Ge2Sb2Te5 (3.56 ns). The threshold voltage of a cell based on Ge10Sb90 (1 nm)/SiO2 (9 nm) (3.57 V) was smaller than GST (4.18 V). The results indicated that Ge10Sb90/SiO2 was a promising phase change thin film with high thermal ability and low power consumption for phase change memory application.