Regulating the dopant clustering in LiZnAs-based diluted magnetic semiconductor

Tuning of the magnetic interaction plays the vital role in reducing the clustering of magnetic dopant in diluted magnetic semiconductors(DMS).Due to the not well understood magnetic mechanism and the interplay between different magnetic mechanisms,no efficient and universal tuning strategy is proposed at present.Here,the magnetic interactions and formation energies of isovalent-doped(Mn) and aliovalent(Cr)-doped LiZnAs are studied based on density functional theory(DFT).It is found that the dopant–dopant distance-dependent magnetic interaction is highly sensitive to the carrier concentration and carrier type and can only be explained by the interplay between two magnetic mechanisms,i.e.,superexchange and Zener’s p–d exchange model.Thus,the magnetic behavior and clustering of magnetic dopant can be tuned by the interplay between two magnetic mechanisms.The insensitivity of the tuning effect to U parameter suggests that our strategy could be universal to other DMS.

Growth process,defects,and dopants of bulk β-Ga_(2)O_(3) semiconductor single crystals

β-gallium oxide(β-Ga2O3),as the typical representative of the fourth generation of semiconductors,has attracted increasing attention owing to its ultra-wide bandgap,superior optical properties,and excellent tolerance to high temperature and radiation.Compared to the single crystals of other semiconductors,high-quality and large-size β-Ga_(2)O_(3) single crystals can be grown with low-cost melting methods,making them highly competitive.In this review,the growth process,defects,and dopants ofβ-Ga_(2)O_(3) are primarily discussed.Firstly,the growth process(e.g.,decomposition,crucible corrosion,spiral growth,and development)ofβ-Ga_(2)O_(3) single crystals are summarized and compared in detail.Then,the defects of β-Ga_(2)O_(3) single crystals and the influence of defects on Schottky barrier diode(SBD)devices are emphatically discussed.Besides,the influences of impurities and intrinsic defects on the electronic and optical properties ofβ-Ga_(2)O_(3) are also briefly discussed.Concluding this comprehensive analysis,the article offers a concise summary of the current state,challenges and prospects ofβ-Ga_(2)O_(3) single crystals.

A review of Al-based material dopants for high-performance solid state lithium metal batteries

As the world transitions to green energy, there is a growing focus among many researchers on the requirement for high-efficient and safe batteries. Solid-state lithium metal batteries(SSLMBs) have emerged as a promising alternative to traditional liquid lithium-ion batteries(LIBs), offering higher energy density, enhanced safety, and longer lifespan. The rise of SSLMBs has brought about a transformation in energy storage, with aluminum(Al)-based material dopants playing a crucial role in advancing the next generation of batteries. The review highlights the significance of Al-based material dopants in SSLMBs applications, particularly its contributions to solid-state electrolytes(SSEs), cathodes, anodes,and other components of SSLMBs. Some studies have also shown that Al-based material dopants effectively enhance SSE ion conductivity, stabilize electrode and SSE interfaces, and suppress lithium dendrite growth, thereby enhancing the electrochemical performance of SSLMBs. Despite the above mentioned progresses, there are still problems and challenges need to be addressed. The review offers a comprehensive insight into the important role of Al in SSLMBs and addresses some of the issues related to its applications, endowing valuable support for the practical implementation of SSLMBs.

Heteroatom dopant strategy triggered high-potential plateau to non-graphitized carbon with highly disordered microstructure for high-performance sodium ion storage

Non-graphitized carbon(NGC)has been extensively utilized as carbonaceous anode in sodium-ion batteries(SIBs).However,more optimization to achieve competitive capacity and stability is still challenging for SIBs.In the study,the dopant strategy is utilized to construct nitrogen/sulfur-doped non-graphitized carbon(N-NGC or S-NGC)shell decorated on three-dimensional graphene foam(GF)as a self-support electrode.The highly disordered microstructures of heteroatom doped carbons are produced by applying a low-temperature pyrolysis treatment to precursors containing nitrogen and sulfur.The DFT calculations of Na-ion adsorption energies at diverse heteroatom sites show marginal-S,pyrrolic N and pyridinic N with more intensive Na-ion adsorption ability than middle-S,C=O and pristine carbon.The N-NGC with dominant small graphitic regions delivers adsorption ability to Na-ion,while the S-NGC with significant single carbon lattice stripes demonstrates redox reaction with Na-ion.Evidently,in comparison with only adsorption-driven slope regions at high potential for N-NGC,the redox reaction-generated potentialplateau enables non-graphitized S-NGC superior discharge/charge capacity and cycle-stability in the slope region.This work could provide deep insight into the rational design of non-graphitized carbon with rich microstructure and composition.

Si-Ti-B掺杂金刚石/硬质合金复合体的性能

金刚石粒度和掺杂量两因素对Si-Ti-B掺杂金刚石/硬质合金复合体的金刚石层的抗弯强度和耐磨性的综合影响,可以归结为平均自由程与机械性能的关系。在强度(或耐磨性)与平均自由程的关系曲线中,存在最大值。对于低掺杂量材料,强度随平均自由程(粘结相层厚度)的减少而降低。对于高掺杂量材料,强度随粘结相层厚度的增大而下降。Si-Ti-B掺杂烧结金刚石的耐热性高于钴粘结金刚石。

Si-Ti-B掺杂金剧石的烧结和显微结构

采用X射线衍射分析和透射电镜研究了Si-Ti-B掺杂金刚石的烧结过程和显微结构。其烧绪过程可分为四个阶段。Si、Ti与金刚石的表面碳或石墨反应生成碳化物,通过碳化物的烧结将金刚石晶粒结合起来。β-SiC是重要粘结相,为取向不同的层错型孪生组织,呈网状分布于金刚石晶粒之间。TiC呈颗粒状分布在金刚石和β-SiC晶粒之间。

铝掺杂氧化锌纳米粉末制备及其对PET的抗静电改性

采用化学共沉淀法制备了不同含量的Al单元掺杂氧化锌(AZO)纳米粉体,并将自制的纳米AZO粉末用于聚对苯二甲酸乙二酯(PET)制备,以提高PET的抗静电性能。利用X射线行射、扫描电子显微镜、热重分析、表面电阻测试仪等测试手段,探究了Al单元掺杂对AZO粉体结构、形貌及电性能的影响。在PET制备过程中加入AZO,探究AZO对PET抗静电性能的影响。结果表明:所制备的AZO纳米粉体为结晶度良好的六方纤锌矿结构。Al掺杂浓度影响AZO粉体形貌、晶体结构及电性能。随着Al掺杂浓度的增加,粉体的结晶质量降低,电性能先变好后变差,粉体尺寸变大,出现团聚、结块现象。适度的Al掺杂可使AZO电阻率达到最低,改善AZO的导电性能。在Al掺杂浓度为2%时,AZO纳米粉体的电性能最佳,电阻率为5.3×10^(4)Ω/m^(2)。使用制备的AZO纳米粉末作为导电填料能有效改善PET的抗静电性能,降低PET/AZO复合材料的表面电阻率,使材料由绝缘体转变为静电耗散体,抗静电性能增强。AZO填充量在0.005%时复合材料的表面电阻率最低,为1.16×10^(10)Ω/m^(2)。

碳类粒子对固体推进剂束流发散角度影响的实验研究

以石墨烯和碳粉两种碳类粒子作为掺杂剂定向改性固体推进剂,借助高速摄影技术和自搭建的束流发散角度测量系统,对比并分析不同掺杂比例和工作条件对改性推进剂束流发散角度的影响,确定了掺杂粒子的最优掺杂比例和工作条件。结果表明,石墨烯和碳粉的最优掺杂比例均为7%,且石墨烯的束流发散角度更小,生成稳定等离子体流的响应时间更短。同时,石墨烯更适配于小激光能量供给下的工作条件,而碳粉更适配于大激光能量供给下的工作条件。

利用掺杂层研究磁化靶中的能斯特效应

双层磁化套筒靶在内层采用高原子序数(Z)材料,减少了因能斯特效应导致的磁通损失并降低点火要求,为磁化靶聚变提供了一种备选方案。然而,添加高Z材料也可能增加由于物质混合而产生的辐射损失。通过在金属套筒中使用带有塑料掺杂的锗作为高Z替代物,初步分析了磁场能斯特输运和物质混合对磁化套筒惯性聚变的影响。与单层套筒相比,双层套筒靶展示出温度和磁通的显著增加,从而使聚变产额提高了154%。将碳氢掺杂剂添加到最内层的锗中,模拟了物质混合对聚变产额的影响。研究结果表明,锗与CH混合,保持较低的混合比例,能够显著提高聚变产额。

荧光碳量子点的低温快速合成及其性质研究

基于大多数碳量子点的合成对设备需求高、所需反应时间长或温度高,故探究一种简单、快速的碳量子点制备方法很有必要。研究以白砂糖(蔗糖)为碳源,浓磷酸为P掺杂剂和脱水剂,浓氨水为N掺杂剂,采用低温水浴加热的方法快速制备氮,磷共掺杂碳量子点(N,P-CDs);通过单因素优化实验法找到了N,P-CDs的最优合成条件:0.75g蔗糖和2.5mL浓磷酸经80℃水浴加热75min,冷却后加入9mL浓氨水;运用透射电子显微镜(TEM)、傅里叶红外光谱仪(FTIR)、紫外-可见分光光度计(UV-Vis)、荧光光谱仪对N,P-CDs的形貌、表面官能团和光学性质等进行了表征,其荧光量子产率为8%,并发现其对pH和金属离子的检测具有一定的应用潜力。

钙钛矿太阳能电池中无掺杂聚合物空穴传输材料研究进展

基于传统空穴传输材料(HTM)的钙钛矿太阳能电池(PSC)已经实现了超过25%的能量转换效率,然而这些HTM通常需要添加吸湿性掺杂剂来实现高迁移率和可加工性,从而降低了器件稳定性。为解决该问题,无掺杂HTM受到广泛关注。总结了近年来用于高效PSC的无掺杂聚合物HTM的结构和性能,并分析了其中的构效关系,提出了高效无掺杂聚合物HTM的结构设计原理,并展望了未来的发展趋势。

Mg/Fe site-specific dual-doping to boost the performance of cobalt-free nickle-rich layered oxide cathode for high-energy lithium-ion batteries

Layer-type LiNi0.9Mn0.1O2is promising to be the primary cathode material for lithium-ion batteries(LIBs)due to its excellent electrochemical performance.Unfortunately,the cathode with high nickel content suffers from severely detrimental structural transformation that causes rapid capacity attenuation.Herein,site-specific dual-doping with Fe and Mg ions is proposed to enhance the structural stability of LiNi0.9Mn0.1O2.The Fe3+dopants are inserted into transition metal sites(3b)and can favorably provide additional redox potential to compensate for charge and enhance the reversibility of anionic redox.The Mg ions are doped into the Li sites(3a)and serve as O_(2)^(-)-Mg^(2+)-O_(2)^(-)pillar to reinforce the electrostatic cohesion between the two adjacent transition-metal layers,which further suppress the cracking and the generation of harmful phase transitions,ultimately improving the cyclability.The theoretical calculations,including Bader charge and crystal orbital Hamilton populations(COHP)analyses,confirm that the doped Fe and Mg can form stable bonds with oxygen and the electrostatic repulsion of O_(2)^(-)-O_(2)^(-)can be effectively suppressed,which effectively mitigates oxygen anion loss at the high delithiation state.This dual-site doping strategy offers new avenues for understanding and regulating the crystalline oxygen redox and demonstrates significant potential for designing high-performance cobalt-free nickel-rich cathodes.

Three-dimensional crystal defect imaging by STEM depth sectioning

One of the major innovations awaiting in electron microscopy is full three-dimensional imaging at atomic resolution.Despite the success of aberration correction to deep sub-angstrom lateral resolution,spatial resolution in depth is still far from atomic resolution.In scanning transmission electron microscopy(STEM),this poor depth resolution is due to the limitation of the illumination angle.To overcome this physical limitation,it is essential to implement a next-generation aberration corrector in STEM that can significantly improve the depth resolution.This review discusses the capability of depth sectioning for three-dimensional imaging combined with large-angle illumination STEM.Furthermore,the statistical analysis approach remarkably improves the depth resolution,making it possible to achieve three-dimensional atomic resolution imaging at oxide surfaces.We will also discuss the future prospects of three-dimensional imaging at atomic resolution by STEM depth sectioning.

无掺杂空穴传输材料在n-i-p型钙钛矿太阳能电池中的应用研究进展

钙钛矿太阳能电池(perovskite solar cells,PVSCs)因长期稳定性差和制造成本高难以实现工业化生产。其制备中最常用的空穴传输材料(hole-transporting materials,HTMs)为2,2′,7,7′-四[N,N-二(4-甲氧基苯基)氨基]-9,9′-螺二芴,需一定量吸湿添加剂以实现高效的空穴提取,导致对水敏感的钙钛矿层受到破坏。无掺杂HTMs避免了吸湿添加剂的使用,且成本低、合成步骤简单。综述了应用于n-i-p型PVSCs的YT5、M7-TFSI、P3HT、PBDB-Cz等高效率无掺杂有机小分子以及聚合物HTMs,提出了理想HTMs在器件性能、分子结构、合成条件、经济成本等方面的设计原则,并展望了无掺杂HTMs在PVSCs商业化过程中的应用前景。

Effect of Sb dopant amount on the structure and electrocatalytic capability of Ti/Sb-SnO_2 electrodes in the oxidation of 4-chlorophenol

Ti/Sb-SnO2 anodes were prepared by thermal decomposition to examine the influence of the amount of Sb dopant on the structure and electrocatalytic capability of the electrodes in the oxidation of 4-chlorophenol. The physicochemical properties of the Sb-SnO2 coating were markedly influenced by different amounts of Sb dopant. The electrodes, which contained 5% Sb dopant in the coating, presented a much more homogenous surface and much smaller mud-cracks, compared with Ti/Sb-SnO2 electrodes containing 10% or 15% Sb dopant, which exibited larger mud cracks and pores on the surface. However, the main microstructure remained unchanged with the addition of the Sb dopant. No new crystal phase was observed by X-ray diffraction （XRD）. The electrochemical oxidation of 4-chlorophenol on the Ti/SnO2 electrode with 5% Sb dopant was inclined to electrochemical combustion; while for those containing more Sb dopant, intermediate species were accumulated. The electrodes with 5% Sb dopant showed the highest efficiency in the bulk electrolysis of 4-chlorophenol at a current density of 20 mA/cm^2 for 180 min; and the removal rates of 4-chlorophenol and COD were 51.0% and 48.9%, respectively.

The conductive mechanisms of a titanium oxide memristor with dopant drift and a tunnel barrier

Nano-scale titanium oxide memristors exhibit complex conductive characteristics, which have already been proved by existing research. One possible reason for this is that more than one mechanism exists, and together they codetermine the conductive behaviors of the memristor. In this paper, we first analyze the theoretical base and conductive process of a memristor, and then propose a compatible circuit model to discuss and simulate the coexistence of the dopant drift and tunnel barrier-based mechanisms. Simulation results are given and compared with the published experimental data to prove the possibility of the coexistence. This work provides a practical model and some suggestions for studying the conductive mechanisms of memristors.

Influences of anionic and cationic dopants on the morphology and optical properties of PbS nanostructures

Selenium and zinc are used as anionic and cationic dopant elements to dope PbS nanostructures. The undoped and doped PbS nanostructures are grown using a thermal evaporation method. Scanning electron microscopy （SEM） results show similar morphologies for the undoped and doped PbS nanostructures. X-ray diffraction （XRD） patterns of three sets of the nanostructures indicate that these nanostructures each have a PbS structure with a cubic phase. Evidence of dopant incorporation is demonstrated by X-ray photoelectron spectroscopy （XPS）. Raman spectra of the synthesized samples con- firm the XRD results and indicate five Raman active modes, which relate to the PbS cubic phase for all the nanostructures. Room temperature photoluminescence （PL） and UV-Vis spectrometers are used to study optical properties of the undoped and doped PbS nanostructures. Optical characterization shows that emission and absorption peaks are in the infrared （IR） region of the electromagnetic spectrum for all PbS nanostructures. In addition, the optical studies of the doped PbS nanos- tructures reveal that the band gap of the Se-doped PbS is smaller, and the band gap of the Zn-doped PbS is bigger than the band gap of the undoped PbS nanostructures.

DASP: Defect and Dopant ab-initio Simulation Package

In order to perform automated calculations of defect and dopant properties in semiconductors and insulators, we developed a software package, the Defect and Dopant ab-initio Simulation Package(DASP), which is composed of four modules for calculating:(ⅰ) elemental chemical potentials,(ⅱ) defect(dopant) formation energies and charge-state transition levels,(ⅲ) defect and carrier densities and(ⅳ) carrier dynamics properties of high-density defects. DASP uses the materials genome database for quick determination of competing secondary phases when calculating the elemental chemical potential that stabilizes compound semiconductors. DASP calls the ab-initio software to perform the total energy, structural relaxation and electronic structure calculations of the defect supercells with different charge states, based on which the defect formation energies and charge-state transition levels are calculated. Then DASP can calculate the equilibrium densities of defects and electron and hole carriers as well as the Fermi level in semiconductors under different chemical potential conditions and growth/working temperature. For high-density defects, DASP can calculate the carrier dynamics properties such as the photoluminescence(PL) spectrum and carrier capture cross sections which can interpret the deep level transient spectroscopy(DLTS). Here we will show three application examples of DASP in studying the undoped GaN, C-doped GaN and quasi-one-dimensional SbSeI.

Effect of Some Metal Ion Dopants on Electrochemical Properties of Ni(OH)_2 Film Electrode

The Ni(OH) 2 film electrodes doped respectively with alkali-earth metal aluminum, lead, partial transition metal and some rare-earth metal(altogether 17 kinds of metals) ions were prepared by cathode electrodeposition. The electrode reaction reversibility, the difficult extent of oxygen evolution, the proton diffusion coefficient, the discharge potential of middle value and the active material utilization of the Ni(OH) 2 film electrode were compared with those of the ones doped with the metal ions by means of cyclic voltammetry, potential step and constant current charge-discharge experiments. It was found that Ca 2+ , Co 2+ , Cd 2+ , Al 3+ etc. have obviously positive effect.

Dopant Implantation into the Silicon Substrate with Non-Planar Surface

The influence of technological process parameters (aiming angle and implantation energy) on the distributions of dopant concentrations in a silicon substrate is investigated by computer modeling.