Crystallographic characteristics and microwave dielectric properties of Ni-modified MgTa2O6 ceramics

Ni²⁺ modified MgTa₂O₆ ceramics with a trirutile phase and space group P4₂/mnm were obtained. The correlations between crystallographic characteristics and microwave dielectric performance of MgTa₂O₆ ceramics were systematically studied based on the chemistry bond theory (PVL theory) for the first time. The results indicate that the introduction of Ni²⁺ causes a change in polarizability and the Mg–O bond ionicity, which contributes to the variation of dielectric constant. Moreover, the lattice energy, and packing fraction, full width at half maximum of the Raman peak of Ta–O bond, as the quantitative characterization of crystallographic parameters, regulate the dielectric loss of MgTa₂O₆ ceramics in GHz frequency band. In addition, the study of sintering behavior shows that the densification and micromorphology are the crucial factors affecting the microwave dielectric performance. Typically, Ni²⁺ doping on the A-site of MgTa₂O₆ can effectively promote the Q × f values to 173,000 GHz (at 7.43 GHz), which ensures its applicability in 5G communication technology.     

Investigation of crystal characteristics,Raman spectra,and microwave dielectric properties of Mg1-xZnxTa2O6 ceramics

Mg_(1-x)Zn_xTa₂O₆ (x = 0.00?0.08) dielectric ceramics were synthesized via the traditional solid-state reaction method. We used XRD and Rietveld refinement to demonstrate that a pure Mg_(1-x)Zn_xTa₂O₆ phase with trirutile structure was formed. Zn²⁺ substitution helped to decrease the Raman full width at half width of the A_1g mode at 703 cm^?1, which resulted in an increase in the order and rigidity of the TaO₆ octahedron, this in turn contributed to improving the Q×f values. Additionally, the introduction of Zn²⁺ significantly promoted grain growth and increased the dense, and the molecular polarizability, these factors lead to a higher permittivity. Moreover, enhanced Ta-O bond energy resulted in a more stable TaO₆ octahedron in the Mg_(1?x)Zn_xTa₂O₆ system, which contributed to enhanced τ_f values via substitution of Zn²⁺ doped on the A-site. Correspondingly, the microwave dielectric properties were significantly improved for 0.04-doped samples, obtaining: ε_r = 27, Q × f = 185,000 GHz (at 7.47 GHz), τ_f =32 ppm/°C.     

PKI技术在社保电子政务中的应用

背景和意义劳动保障部门作为统一管理和组织协调社会劳动力,统筹城乡就业,规划、引导劳动力市场的发展,组织建立健全就业服务体系,负责社会保障基金的缴纳、记录、核算、支付的部门,运用信息技术来实现劳动保障管理工作的电子化、自动化和网络化,更科学、更迅速、更准确地汇集、加工、传递、运用各类信息,是社会保障电子政务系统建设的重要内容,也是加快由行政管理向社会服务转化的突破口。随着社会保障电子政务系统建设的不断深入以及网络技术的发展,基于Internet的网上应用已逐步开展。如参保单位的网上申报、网上缴费以及信息查询等。这…     

从事放射性个人剂量监测分析与防护调查

为了能及时了解放射性工作人员的受照剂量，以便能够更好地保障放射工作人员的健康与安全，采用热释光测量法对包头地区从事放射性工作的工作人员进行了个人剂量监测，并对他们的剂量当量频数分布进行了统计与分析，对工作环境的防护进行了调查对比，就今后的工作提出建议。     

金刚石薄膜异质外延的研究进展

主要介绍金刚石薄膜在Si上异质外延的研究状况。综述了外延金刚石薄膜的偏压形核 ,SiC过渡层的影响及一些实验参数对外延薄膜质量的影响等 ,并论述了发展方向     

羊皮服装革的压缩性能及其与丰满性的关系的研究

本文研究了羊皮服装革的压缩性能。对压缩系数（Ｋｃ）与羊皮服装革手感丰满性的关系进行了讨论。结果表明：压缩系数Ｋｃ反映出革的手感丰满程度。     

水平井眼轨迹对气井出砂趋势及工作制度的影响

出砂是影响油气井正常生产的重要因素之一。借助FEPG有限元程序自动生成平台，建立了三维应力场弹塑性地层出砂模型，并运用有限元法计算分析了不同轨迹的裸眼井井壁周围的有效塑性应变分布规律及出砂趋势，研究了气藏压力衰竭对完井方式的影响。研究表明，水平井眼轨迹对出砂有重要的影响，同一地应力环境下向不同方位延伸的水平井在投产时应该采取不同的生产压差和不同的生产制度，水平井眼轨迹对出砂的影响程度随着3个地应力差异的增大而加剧。气藏压力衰竭对井壁的稳定性和出砂趋势都有重要影响。随着气藏压力的衰竭，井壁稳定性将变得越来越差，最终导致井筒出砂。因此，对气井完井不仅应该考虑到气藏开发初期地层的稳定性状况，而且还应该考虑到气藏压力衰竭后可能出现的井壁失稳问题。     

信息社会世界峰会及其筹备进程

信息社会世界峰会是根据ITU的相关决议，在ITU的大力倡导下，在联合国和其他国际组织、国际机构的支持和配合下促成的。峰会的目的旨在通过召开尽可能高级别的会议，就信息社会建设问题达成全球共识，通过利用信息通信技术潜力。推动实现联合国《千年宣言》所确定的目标，促进全人类的进步。峰会的整个进程分为两个阶段，第一阶段于2003年12月在日内瓦举行，第二阶段于2005年在突尼斯举行。目前，峰会的主要议题和安排已基本确定，各国，尤其是发达国家和发展中国家在对信息社会的认识和未来的一些做法上还存在明显分歧。