Robust and Tunable Ferroelectricity in Ba/Co Codoped (K_(0.5)Na_(0.5))NbO_(3) Ceramics

The 0.98(K_(0.5)Na_(0.5))NbO_(3)-0.02Ba(Nb_(0.5)Co_(0.5))O_(3-δ) ceramics with doped Ba^(2+) and Co^(2+) ions are fabricated,and the impacts of the thermal process are studied.Compared with the rapidly cooled (RC) sample,the slowly cooled (SC) sample possesses superior dielectric and ferroelectric properties,and an 11 K higher ferroelectricparaelectric phase transition temperature,which can be attributed to the structural characteristics such as the grain size and the degree of anisotropy.Heat treatment can reversibly modulate the content of the oxygen vacancies,and in turn the ferroelectric hysteresis loops of the samples.Finally,robust and tunable ferroelectric property is achieved in SC samples with good structural integrity.

Microstructure Characteristics and Possible Phase Evolution of the Coal Gangue-Steel Slag Ceramics Prepared by the Solid-State Reaction Methods

Industrial wastes such as steel slag and coal gangue etc.were chosen as raw materials for preparing ceramic via the conventional solid-state reaction method.With steel slag and coal gangue mixed in various mass ratios,from 100%steel slag to 100%coal gangue at 10%intervals,microstructure and possible phase evolution of the coal gangue-steel slag ceramics were investigated using X-ray powder diffraction,scanning electron microscopy,mercury intrusion porosimetry and Archimedes boiling method.The experimental results suggest that the phase compositions of the as-prepared ceramics could be altered with the increased amount of coal gangue in the ceramics.The anorthite-diopside eutectic can be formed in the ceramics with the mass ratios of steel slag to coal gangue arranged from 8:2 to 2:8,which was responsible for the melting of the steel slag-coal gangue ceramics at relatively high temperature.Further investigations on the microstructure suggested that the addition of the proper amount of steel slag in ceramic compositions was conducive to the pore formation and further contributed to an increment in porosity.

Microstructure and Oxidation Behavior of ZrB_(2)-SiC Ceramics Fabricated by Tape Casting and Reactive Melt Infiltration

ZrB_(2)-based ceramics typically necessitate high temperature and pressure for sintering,whereas ZrB_(2)-SiC ceramics can be fabricated at 1500℃using the process of reactive melt infiltration with Si.In comparison to the conventional preparation method,reactive synthesis allows for the more facile production of ultra-high temperature ceramics with fine particle size and homogeneous composition.In this work,ZrSi_(2),B4C,and C were used as raw materials to prepare ZrB_(2)-SiC via combination of tape casting and reactive melt infiltration herein referred to as ZBC ceramics.Control sample of ZrB_(2)-SiC was also prepared using ZrB_(2) and SiC as raw materials through an identical process designated as ZS ceramics.Microscopic analysis of both ceramic groups revealed smaller and more uniformly distributed particles of the ZrB_(2) phase in ZBC ceramics compared to the larger particles in ZS ceramics.Both sets of ceramics underwent cyclic oxidation testing in the air at 1600℃for a cumulative duration of 5 cycles,each cycle lasting 2 h.Analysis of the oxidation behavior showed that both ZBC ceramics and ZS ceramics developed a glassy SiO_(2)-ZrO_(2) oxide layer on their surfaces during the oxidation.This layer severed as a barrier against oxygen.In ZBC ceramics,ZrO_(2) is finely distributed in SiO_(2),whereas in ZS ceramics,larger ZrO_(2) particles coexist with glassy SiO_(2).The surface oxide layer of ZBC ceramics maintains a dense structure because the well-dispersed ZrO_(2) increases the viscosity of glassy SiO_(2),preventing its crystallization during the cooling.Conversely,some SiO_(2) in the oxide layer of ZS ceramics may crystallize and form a eutectic with ZrO_(2),leading to the formation of ZrSiO_(4).This leads to cracking of the oxide layer due to differences in thermal expansion coefficients,weakening its barrier effect.An analysis of the oxidation resistance shows that ZBC ceramics exhibit less increase in oxide layer thickness and mass compared to ZS ceramics,suggesting superior oxidation resistance of ZBC ceramics.

Low-firing and temperature stability regulation of tri-rutile MgTa_(2)O_(6)microwave dielectric ceramics

A glass frit containing Li_(2)O-MgO-ZnO-B_(2)O_(3)-SiO_(2)component was used to explore the low-temperature sintering behaviors and microwave dielectric characteristics of tri-rutile MgTa_(2)O_(6)ceramics in this study.The good low-firing effects are presented due to the high matching relevance between Li_(2)O-MgO-ZnO-B_(2)O_(3)-SiO_(2)glass and MgTa_(2)O_(6)ceramics.The pure tri-rutile MgTa_(2)O_(6)structure remains unchanged,and high sintering compactness can also be achieved at 1150℃.We found that the Li_(2)O-MgO-ZnO-B_(2)O_(3)-SiO_(2)glass not only greatly improves the low-temperature sintering characteristics of MgTa_(2)O_(6)ceramics but also maintains a high(quality factor(Q)×resonance frequency(f))value while still improving the temperature stability.Typically,great microwave dielectric characteristics when added with 2wt%Li_(2)O-MgO-ZnO-B_(2)O_(3)-SiO_(2)glass can be achieved at 1150℃:dielectric constant,ε_(r)=26.1;Q×f=34267 GHz;temperature coefficient of resonance frequency,τ_(f)=-8.7×10^(-6)/℃.

Clay Materials for Ceramics Application from N’Djamena in the Chad Republic: Mineralogical, Physicochemical and Microstructural Characterization

Herein, we report some characteristics of the clayey materials (CMs) collected from Kaliwa (C1), Kabé (C2) and Malo (C3) district in N’Djamena (Chad). Three samples were characterized applying XRF, XRD, FTIR, SEM. In addition, TGA/DSC were performed to control decomposition/mass loss and show phase transitions respectively of CMs. Geochemical analysis by XRF reveals the following minerals composition: SiO2 (~57% - 66%), Al2O3 (~13% - 15%), Fe2O3 (~6% - 10%), TiO2 (~1% - 2%) were the predominant oxides with a reduced proportion in C1, and (~7%) of fluxing agents (K2O, CaO, Na2O). Negligible and trace of MgO (~1%) and P2O5 was noted. The mineralogical composition by XRD shows that, C1, C2 and C3 display close mineralogy with: Quartz (~50%), feldspar (~20%) as non-clay minerals, whereas clays minerals were mostly kaolinite (~15%), illite (~5%) and smectite (~10%). FTIR analysis exhibits almost seemingly similar absorption bands characteristic of hydroxyls elongation, OH valence vibration of Kaolinite and stretching vibration of some Metal-Oxygen bond. SEM micrographs of the samples exhibit microstructureformed by inter-aggregates particles with porous cavities. TGA/DSCconfirm the existence of quartz (570˚C to 870˚C), carbonates (600˚C - 760˚C), kaolinite (569˚C - 988˚C), illite (566˚C - 966˚C), MgO (410˚C - 720˚C) and smectite (650˚C - 900˚C). The overall characterization indicates that, these clayey soils exhibit good properties for ceramic application.

Study on Acoustic Emission Characteristics of Deformation Damage Process of Zirconia Ceramics

Zirconia ceramics have become increasingly widely used in recent years and are favored by relevant enterprises. From the traditional dental field to aerospace, parts manufacturing has been used, but there is limited research on the deformation and damage process of zirconia ceramics. This article analyzes the acoustic emission characteristics of each stage of ceramic damage from the perspective of acoustic emission, and explores its deformation process characteristics from multiple perspectives such as time domain, frequency, and EWT modal analysis. It is concluded that zirconia ceramics exhibit higher brittleness and acoustic emission strength than alumina ceramics, and when approaching the fracture, it tends to generate lower frequency acoustic emission signals.

Physics-embedded machine learning search for Sm-doped PMN-PT piezoelectric ceramics with high performance

Pb(Mg_(1/3)Nb_(2/3))O_(3)–PbTiO_(3)(PMN-PT)piezoelectric ceramics have excellent piezoelectric properties and are used in a wide range of applications.Adjusting the solid solution ratios of PMN/PT and different concentrations of elemental doping are the main methods to modulate their piezoelectric coefficients.The combination of these controllable conditions leads to an exponential increase of possible compositions in ceramics,which makes it not easy to extend the sample data by additional experimental or theoretical calculations.In this paper,a physics-embedded machine learning method is proposed to overcome the difficulties in obtaining piezoelectric coefficients and Curie temperatures of Sm-doped PMN-PT ceramics with different components.In contrast to all-data-driven model,physics-embedded machine learning is able to learn nonlinear variation rules based on small datasets through potential correlation between ferroelectric properties.Based on the model outputs,the positions of morphotropic phase boundary(MPB)with different Sm doping amounts are explored.We also find the components with the best piezoelectric property and comprehensive performance.Moreover,we set up a database according to the obtained results,through which we can quickly find the optimal components of Sm-doped PMN-PT ceramics according to our specific needs.

Porous high-entropy rare-earth phosphate(REPO_(4),RE=La,Sm,Eu,Ce,Pr and Gd)ceramics with excellent thermal insulation performance via pore structure tailoring

Thermal insulation materials play an increasingly important role in protecting mechanical parts functioning at high temperatures.In this study,a new porous high-entropy(La_(1/6)Ce_(1/6)Pr_(1/6)Sm_(1/6)Eu_(1/6)Gd_(1/6))PO_(4)(HE(6RE_(1/6))PO_(4))ceramics was prepared by combining the high-entropy method with the pore-forming agent method and the effect of different starch contents(0–60vol%)on this ceramic properties was systematically investigated.The results show that the porous HE(6RE_(1/6))PO_(4)ceramics with 60vol%starch exhibit the lowest thermal conductivity of 0.061 W·m^(-1)·K^(-1)at room temperature and good pore structure stability with a linear shrinkage of approximately1.67%.Moreover,the effect of large regular spherical pores(>10μm)on its thermal insulation performance was discussed,and an optimal thermal conductivity prediction model was screened.The superior properties of the prepared porous HE(6RE_(1/6))PO_(4)ceramics allow them to be promising insulation materials in the future.

新《公司法》若干重要问题解读(笔谈)

新《公司法》修订所涉及的内容非常丰富,修订内容包括公司登记制度、股东出资责任、公司治理制度、公司资本制度、控股股东义务、董监高信义义务等方面。赵旭东教授指出,本次《公司法》修订在公司登记与信息公示制度、股东出资责任和法律后果、公司资本制度、公司治理制度、股东权益保护和控股股东义务这五个关键领域实现了重大突破和创新。周林彬教授集中解析了“国家出资公司组织机构的特别规定”一章,认为新《公司法》的亮点之一是通过新设这一章积极回应了我国国有企业治理的“本土实践”与“中国问题”,给出新时期国有企业治理的“中国方案”,推进了中国特色的国有企业治理制度的设计,重塑了国有企业的规范体系。刘凯湘教授对本次《公司法》修订中与公司资本制度相关的若干条文展开解析,包括限期认缴制、新增有限公司股东出资义务加速到期制度、股东违反出资义务的责任承担规则、董事会的催缴出资义务、股东失权制度、董监高对股东抽逃出资的连带责任、类别股的规定、授权资本制等。赵万一教授深入探讨了这次《公司法》修改的主要特点,认为新《公司法》既坚持了其商法属性,同时又充分考虑了《民法典》的既有制度内容,适当兼顾了与《民法典》之间的制度衔接关系,从而既为科学解决民法与商法的关系提供了理念和制度支持,也为中国式法律制度体系的创建提供了完美的立法实践样本。周友苏教授深入解析了新《公司法》在完善股东出资制度方面增加的股东出资缴纳、股东出资“加速到期”、股东失权、股东出资责任这四条新规定,认为新《公司法》在完善股东出资制度方面增加的这些新规定,积极回应了我国自2013年以来公司数量大幅增长所带来的股东盲目认缴、天价认缴、期限过长的现象突出,损害债权人利益的纠纷案件呈明显上升态势等问题,极大地强化了保护债权人的力度。李建伟教授深入解析了《公司法》修订中与法定代表人制度相关的若干条文,认为新《公司法》关于法定代表人的规定较之以往更加体系化,并有望基本解决困扰公司实践许多年的诸多难题,但其中亦存在不完全规范的问题。

中国式员工持股计划与公司违规:监督者抑或合谋者

以我国员工持股计划重启为背景,以2011—2019年A股上市公司为样本,验证员工持股计划对公司违规的影响。结果显示,员工持股计划降低了公司违规概率与频率。机制检验发现,员工持股计划一方面通过促进中小股东投票与委派董事涉入公司内部治理,另一方面通过信息传递提升独立董事履职效率并增加分析师跟踪。进一步地,区分违规类型后发现,员工持股计划的抑制作用主要存在于信息披露违规与一般违规;区分员工持股计划方案后发现,员工持股规模高、锁定期长、高购买折价、无杠杆、无控股股东担保或兜底、无业绩条件的员工持股计划对公司违规的抑制更显著。经济后果分析发现,员工持股计划对公司违规的监督能够抑制股价崩盘风险。研究结论从公司违规角度验证了员工持股计划的监督者角色,为我国员工持股计划实施效果提供了新的经验证据。

我国农业上市公司资本结构对财务绩效影响研究

农业在我国国民经济中发挥着至关重要的作用,农业上市公司良好的绩效水平对产业结构调整具有一定导向作用,而资本结构既影响企业的财务绩效,也影响农业企业价值的提升。文章以资本结构为切入点,研究我国农业上市公司资本结构与财务绩效之间的关系,选取农业上市公司2017—2022年数据作为研究样本,建立评价我国农业上市公司财务绩效的多元线性回归模型,以揭示其资本结构与财务绩效的关系。研究结果表明,我国农业上市公司的资产负债率与财务绩效之间呈显著负相关关系,流动负债率与财务绩效之间呈线性负相关关系但不显著,第一大股东持股比例与财务绩效之间呈显著正相关关系。根据研究结果,提出优化农业上市公司资本结构,提高企业财务绩效的相关建议。

国际能源化工公司生物化工业务发展策略分析

生物化工通常以生物质为原料,或采用相对温和的生物发酵过程,具有典型的绿色特征,已成为“净零碳”目标下国际能源化工公司战略布局的重点之一。巴斯夫、道达尔能源、杜邦、埃克森美孚4家公司生物化工业务入局较早,且非常重视技术创新,结合自身优势各有侧重地部署新业务。巴斯夫推出生物质平衡方案,重视关键中间体的生物替代,围绕工业生物技术超前布局;道达尔能源以生物燃料为切入点,上下游统筹布局,不断强化产品优势;杜邦公司敏锐捕捉市场机遇,持续追求差异化竞争优势;埃克森美孚坚持油品业务主线,适时调整生物燃料布局重点,保持技术的领先性。我国企业可借鉴国际主要能源化工公司的发展模式及经验,结合公司业务定位,加速科技创新向产业应用转变。

基于机器学习的上市公司审计风险识别

审计风险的准确识别有助于提高会计师事务所执业质量、规范上市公司行为,对于促进资本市场健康运行至关重要。因此,本文提出了一种机器学习框架,主要由因变量增强、自变量筛选和LightGBM模型训练三部分组成,以准确识别上市公司的审计风险水平。通过利用沪深两市A股上市公司2005—2019年的28918个样本进行实证分析,结果表明本文所提出的机器学习框架在高审计风险样本中的识别准确性达到94%,显著优于传统的审计风险识别方法,并且发现真实盈余管理、市场化程度、会计稳健性、预付账款和其他应收款占总资产的比重、每股经营活动现金流量等变量对于准确识别审计风险起到重要作用。

上市公司ESG报告“漂绿”行为治理

“双碳”目标提出以来,社会各界对生态环境保护和经济绿色转型发展的关切与日俱增,但是上市公司ESG报告的披露质量良莠不齐,“漂绿”问题成为我国生态文明建设中极不和谐的音符。文章首先介绍了影响上市公司“漂绿”ESG报告的内外部因素,再结合我国ESG信息披露的要求和治理现状,从公司内部治理的角度出发,提出将党组织融入公司治理体系、贯彻“高层承诺原则”、加强董事会能力建设、强化监事会权责、培养绿色诚信的公司文化、主动披露ESG鉴证报告等治理措施。从公司内部治理角度加强对“漂绿”的研究和治理,完善公司内部治理机制,有助于从长远提高公司环境和经济绩效、提高ESG报告的质量。

商业银行设立理财子公司能够实现风险隔离吗?

本文以中国商业银行设立理财子公司为准自然实验,基于2018—2021年84家银行的季度财务数据,采用渐进双重差分模型(DID)考察商业银行设立理财子公司的风险隔离效应。研究发现:设立理财子公司显著降低了母公司商业银行的风险承担,能够实现理财业务与其他业务的风险隔离,且设立时间越长,风险隔离效应越显著。异质性检验和机制分析表明,这种风险隔离效应在城商行与农商行中最弱;“去嵌套、降杠杆”和“去池化、缓错配”是实现风险隔离的主要机制。对母公司商业银行和理财子公司并表的进一步分析发现,设立理财子公司不能降低银行控股集团的整体风险承担,仅能实现风险隔离。这些研究发现对于完善商业银行内部控制和外部监管具有重要启示。

ESG表现如何赋能企业绿色技术创新?--来自中国上市公司的微观证据

经济新发展阶段下ESG是可持续导向下企业运营的重要理念。在绿色发展导向下,如何将企业环境、社会与公司治理(ESG)等多重责任嵌入到企业创新体系之中,驱动传统创新向绿色创新与绿色发展转型,成为了学界关注的焦点议题。本文以2011年—2019年中国沪深A股上市公司为研究样本,考察了上市公司ESG表现对企业绿色技术创新的影响及其内在作用机制。研究结果表明:(1)企业ESG表现驱动了企业绿色技术创新,对企业绿色技术创新具有显著的促进效应,在考虑内生性问题后研究结论依然稳健;区分ESG表现各类维度,企业环境责任、社会责任与公司治理表现对企业绿色技术创新均产生显著的促进效应。(2)内在机制检验结果表明,ESG表现主要通过强化企业环保投入、缓解企业融资约束以及提高企业内部控制质量以促进企业绿色技术创新。(3)调节机制检验结果表明,外部环境规制(环保补助与排污收费)与内部高管激励(薪酬激励与股权激励)在ESG表现与企业绿色技术创新之间产生显著的正向调节效应,即在ESG表现驱动企业绿色技术创新过程中,外部环境规制与内部高管激励制度具有外部的资源补偿效应、合法性倒逼效应以及内部激励效应。(4)异质性分析结果表明,ESG表现对企业绿色技术创新的驱动效应在国有企业、通过国际ISO14001环境认证企业与制造业企业中更为明显。而且经济效应检验结果表明,ESG表现驱动企业绿色技术创新有助于企业改善经济绩效。本研究为绿色发展导向下强化企业ESG理念,基于可持续导向与企业社会责任融入企业创新体系驱动企业绿色转型发展,最终实现企业与社会环境的共生融合发展提供政策启示。

系统重要性金融科技公司的法律规制

随着金融科技的加速应用,金融科技的系统性风险已成为监管重点。金融科技巨头以关键技术服务商、金融基础设施和互联网金融控股集团等样态深度参与金融活动,在规模性、复杂性、可替代性和关联性等方面开始具备系统重要性特征,成为金融科技时代的“大而不能倒”。有必要参考系统重要性金融机构的监管经验,并结合金融科技公司系统性风险的生成机理,对系统重要性金融科技公司予以特殊规制。在有效识别系统重要性金融科技公司的基础上,整合金融监管、数据治理、网络安全和市场竞争等四大规制场域,建立以协调性为目标的监管体制、以可靠性为目标的审慎监管体系、以可承受性为目标的风险处置机制,构建系统重要性金融科技公司的监管框架和规制方案,有效防范其运行失灵给金融稳定带来的冲击。

地区空气污染的“压力”与企业绿色转型的“动力”——基于城市PM2.5和公司并购的实证发现

地区空气污染会影响域内各类市场主体行为,包括微观企业决策。碳达峰、碳中和的提出要求各地加强空气污染治理,推动企业绿色转型,而绿色并购是企业绿色转型的重要方式。利用2013—2018年我国A股上市的污染企业发起的并购为样本,并手动搜集整理确定绿色并购样本,实证研究地区空气污染对域内企业绿色转型的影响。研究发现,地区空气污染加剧会提升域内污染企业绿色并购的意愿。在此基础上,通过并购前后企业信息披露质量和社会责任承担变化,研究发现地区空气污染加剧下的企业绿色转型并非源于自主绿色转型发展的内生“动力”,更多是外部“压力”下的“工具主义”行为。从影响路径来看,地区空气污染引致的压力会通过行业竞争和融资约束这两个途径影响污染企业绿色转型的“动力”。最后,异质性检验发现在市场化程度高和非国有企业样本,地区空气污染加剧对企业绿色并购的促进作用更为显著。

明星分析师关注、企业投资行为与公司价值

企业投资行为对于中国经济高质量发展与“双循环”国家战略实施发挥重要作用。通过手工搜集2016—2021年明星分析师研究报告数据,研究明星分析师对公司投资行为的影响。研究发现,明星分析师通过缓解融资约束、增强股票流动性、解读研发行为,促进企业投资行为,而且明星分析师在管理层持股比例较低、大股东持股比例低、成长性水平较低、公司透明度较低的样本中,结果更加显著,体现其较好的专业胜任能力。进一步分析发现,明星分析师能够解读不同盈利分组的投资行为,不存在明显的选择性偏好;与没有明星分析师跟踪的样本相比,明星分析师跟踪对投资行为具有更强的影响;明星分析师通过正向解读投资行为途径,对公司价值挖掘,发挥积极作用。研究结论对发挥明星分析师信息中介作用,优化投资结构与提升投资绩效,提供经验参考。

财务公司内部控制体系优化模型构建与运用——基于三层架构视角

近年来,财务公司违规以及因集团公司暴雷牵连财务公司的危机事件频繁爆发。不断优化内部控制体系是财务公司稳定发展的重要命题。由于财务公司特殊的业务特点和风险特征,内部控制体系不仅受到内部控制具体环节实施情况的影响,还受到内部环境以及外部监管和金融环境、所属集团公司管控要求和产业环境的影响,这就要求财务公司需及时根据环境的变化而不断调整和优化自身的内部控制体系。如何优化财务公司的内部控制体系是实操中企业所经常所面临的管理难点。文章以某财务公司为例,在充分调研的基础上,构建了基于三层架构的内部控制优化体系模型,并依据该模型对某财务公司的内部控制体系进行了完善。