施主掺杂对TiO2氧敏材料缺陷化学的影响

对施主V2O5掺杂TIO2材料的高温电导进行了详细的测试：XRD分析表明少量施主掺杂并未改变材料的金红石结构；施主掺杂样品在较高温度测试时，在高氧分压一侧，发生电导类型转变，从而使测氧范围变窄。运用缺陷化学分析法，解释了不同氧分压下的电导机制。     

TiO2薄膜氧敏特性研究

金属氧化物随氧分压不同而发迹其电导率这一性质被广泛地用来制作氧敏传感器，传统的传器大多是体材料或厚膜材料，工作时需加高温。文中描述的是ＴｉＯ２薄膜材料与Ｐｔ薄膜形成的肖特基势垒高度随氧分压不同而发迹的氧敏现象，测定了该肖特基有管的氧敏２，并讨论了其敏感机理。     

TiO_2薄膜氧敏特性研究

金属氧化物（如ZrO2，TiO2等）随氧分压不同而改变其电导率这一性质被广泛地用来制作氧敏传感器．传统的传感器大多采用体材料或厚膜材料，工作时需加高温．本文描述了TiO2薄膜材料与Pt薄膜形成的肖特基势垒高度随氧分区不同而改变的氧敏现象，测定了该肖特基二极管的氧敏特性，讨论了其敏感机理．     

不同金属掺杂对TiO2薄膜氧敏性能影响

该文讨论了TiO2对氧气的吸附过程及敏感机理、重点分析了掺铁和掺钨对氧敏特性的影响,并比较了两者的异同.制作了掺铁和掺钨的TiO2薄膜,并在400℃下对薄膜氧敏特性进行了测试.结果表明.TiO2具有低电阻的特点,在高温下能够有效感应氧气浓度的变化.     

SO4^2—掺杂对YFeO3电导和气敏性能的影响

用浸泡震荡分散法制备了ＹＦｅＯ３掺ＳＯ４＾２－半导体气敏材料,并对其电志和气敏性能进行了研究。结果表明：ＳＯ４＾２－的掺入改变了ｐ型ＹＦｅＯ３,半遐体材料的导电性能;少量ＳＯ４＾２－（≈１％）的存在,能提高材料的比表面积和表面吸附氧Ｏ２＾ｎ－数量,２５７℃下对乙醇有较好的选择性和灵敏度。有望开发为一类新型酒敏元件。     

掺铂TiO_(2-x)氧敏薄膜的制备和性能

以钛酸丁酯和无水乙醇分别为原料和溶剂,添加适量稳定剂制成稳定溶胶,用浸涂法在Ａｌ２Ｏ３基片上制备ＴｉＯ２薄膜,经１０００℃Ｈ２气氛下还原制得ＴｉＯ２－ｘ薄膜．最后在氯铂酸甲醛溶液中浸泡得到掺铂薄膜．实验结果表明掺铂薄膜在８００℃下具有良好的氧敏感性和重复性,薄膜在Ｎ２气氛下具有良好的电阻温度特性．本文分析了铂在薄膜中的作用原理．     

双施主对受主补偿的BaTiO3系PTCR材料的影响

采用过剩施主二次掺杂法，研究双施主二次掺杂时两种施主相对比例不同对于BaTiO3材料性能的影响，发现过剩施主二次掺杂对受主杂质进行补偿比一次掺杂效果好，在相同掺杂量的情况下，可获得更大的PTC效应和更低的室温电阻率。采用Sb、Y过剩双施主对受主进行补偿，当双施主相对比例变化时，存在PTCR材料α30℃=0．4℃^-1的极大值。采用过剩双施主对受主进行补偿，可获得升阻比〉7，温度系数α30℃〉0．30℃^-1的PTCR材料，有效地降低原料成本。     

TiO2高温电导及缺陷化学分析

对TiO2高温电导机制和缺陷化学进行了详细的理论分析和推导,计算了未掺杂样品的电导激活能。电导激活能不仅与温度有关,而且与载流子的特征有关。在低温高氧分压下,电导激活能大,氧缺位浓度较小,缺陷以一价氧缺位为主;而在高温低氧分压下,电导激活能小,氧缺位浓度较大,缺陷以二价氧缺位为主。     

TiO2-WO3纳米粉体的制备及氨敏性能研究

采用共沉淀法制得了w(TiO2)为0~10%的TiO2-WO3纳米粉体材料,利用X射线衍射仪、透射电镜等测试手段,分析了材料的微观结构,探讨了烧结温度、掺杂量、工作温度对WO3粉体材料气敏性能的影响。研究发现:TiO2的掺杂抑制了WO3晶粒的生长,提高了WO3粉体材料对氨气的灵敏度,其中,w(TiO2)为1%的烧结型气敏元件,在250~280℃的温度范围内,对氨有较高的灵敏度和较好的响应–恢复特性,并对其氨敏机理进行了探讨。     

Cr对钙钛矿型氧敏材料性能的影响

利用固相合成法制备了不同Cr含量的氧敏陶瓷样品,研究了添加剂Cr对钙钛矿型氧敏材料性能的影响,测量了不同氧分压下的阻–温特性和氧敏特性。结果表明:在SrTiO3中Cr离子替钛位可使SrTiO3实现p型掺杂;Cr掺杂促进了氧空位的产生,加强环境氧与晶格氧的交换,提高了氧灵敏度,使其达到9;Cr离子变价增加了空穴载流子浓度,提高了材料的电导率,使电阻值降低到几千欧。     

TiO_2高温电导及缺陷化学分析

对 Ti O2 高温电导机制和缺陷化学进行了详细的理论分析和推导 ,计算了未掺杂样品的电导激活能。电导激活能不仅与温度有关 ,而且与载流子的特性有关。在低温高氧分压下 ,电导激活能大 ,氧缺位浓度较小 ,缺陷以一价氧缺位为主 ;而在高温低氧分压下 ,电导激活能小 ,氧缺位浓度较大 ,缺陷以二价氧缺位为主     

一维掺杂光子晶体缺陷模的全貌特征

通过一维掺杂光子晶体缺陷模的三个不同角度的立体图以及它们对应的俯视切面图,全面地研究了缺陷模随杂质光学厚度、杂质折射率以及光子晶体折射率的变化关系,得出了一维掺杂光子晶体缺陷模的全貌特征,并得到以下重要结论:缺陷模透射峰随杂质光学厚度变化呈周期性的出现,在同一周期上缺陷模的波长随杂质光学厚度呈线性变化;缺陷模透射峰的半高宽度随杂质折射率的增加而减小,但陷模透射峰的高度不受杂质折射率变化的影响;光子晶体的折射率对缺陷模透射峰的峰高和半高宽度都有显著的影响.     

偶联剂处理PZT压电陶瓷效果研究

研究了硅烷偶联剂和钛酸酯偶联剂对PZT压电陶瓷的表面处理,通过红外光谱和扫描电镜照片对比了不同偶联剂的处理效果,同时与未经偶联剂处理的陶瓷进行对比。进一步研究了偶联剂处理前、后陶瓷与高分子树脂之间的结合力,经硅烷偶联剂KH-550处理后,陶瓷与高分子树脂间互相浸润、渗透,增加了二者的结合力。     

In Situ Electrical Characterization of Anatase TiO2 Quantum Dots

A novel method for performing in situ characterization of the electrical properties of pristine, ultrafine nanopowders is reported. A modified dilatometer, with a spring‐loaded push rod and electrodes, allows for the simultaneous monitoring of the packed nanopowder's lateral displacement as well as its complex impedance spectroscopy as a function of temperature within a controlled environment. Anatase TiO₂ quantum dots of 2 nm diameter, on average, are examined and found to simultaneously shrink and become more resistive upon initial heating. The resistance changes by approximately 3 orders of magnitude upon heating, associated with the desorption of adsorbed water, demonstrating the need for sample preconditioning. Subsequent electrical resistivity measurements, as a function of oxygen partial pressure, over approximately 40 orders of magnitude, at temperatures between 300 °C and 400 °C, exhibit nearly 9 orders of magnitude change in conductivity. The data are consistent with a Frenkel‐based defect disorder model characterized by an enthalpy of reduction of 5.5 ± 0.5 eV.     

掺铁TiO2的X-射线衍射和表面光电压谱研究

以溶胶一凝胶法制备了不同掺铁比例的TiO2膜光催化剂，分别以X-射线衍射和场诱导表面光电压谱进行表征。结果表明，在掺铁量小于0．007(Fe／Ti摩尔比)范围内，随着掺铁比的逐渐提高，催化剂粒径逐渐增大，催化剂的带隙宽度加大，光电压响应阈值蓝移，预示着实际应用中催化剂的催化活性的提高。但随着催化剂掺铁比例的进一步提高，Fe2O3，相的出现将导致光催化剂在长波处出现光伏响应，不利于催化剂光活性的提高。     

Highly Efficient n-Doping via Proton Abstraction of an Acceptor1-Acceptor2 Alternating Copolymer toward Thermoelectric Applications

Electron transporting (n-type) polymers are the coveted complementary counterpart to more thoroughly studied hole transporting (p-type) semiconducting polymers. Besides intrinsic stability issues of the doped form of n-type polymer toward ubiquitous oxidizing agents (H₂O and O₂), the choice of suitable n-dopants and underlying mechanism of doping is an open research field. Using a low LUMO, n-type unipolar acceptor₁-acceptor₂ copolymer poly(DPP-TPD) in conjunction with bulk n-doping using Cs₂CO₃ these issues can be addressed. A solid-state acid-base interaction between polymer and basic carbonate increases the backbone electron density by deprotonation of the thiophene comonomer while forming bicarbonate, as revealed by NMR and optical spectroscopy. Comparable to N-DMBI hydride/electron transfer, Cs₂CO₃ proton abstraction doping shifts the poly(DPP-TPD) work function toward the LUMO. Thereby, the anionic doped state is resilient against O₂ but is susceptible toward H₂O. Based on GIWAXS, Cs₂CO₃ is mostly incorporated into the amorphous regions of poly(DPP-TPD) with the help of hydrophilic side chains and has minor impact on the short-range order of the polymer. Cs₂CO₃ proton abstraction doping and the acceptor₁-acceptor₂ copolymer architecture creates a synergistic n-doped system with promising properties for thermoelectric energy conversion, as evidenced by a remarkable power factor of (5.59 ± 0.39) × µW m⁻¹ K⁻².     

Electronic Conductivity and Defect Chemistry of Heterosite FePO4

Electrochemical investigations on polycrystalline orthorhombic FePO₄ (heterosite), the lithium‐poor part of the LiFePO₄/FePO₄ redox couple, gives insight into its charge‐carrier chemistry. The material obtained by chemical delithiation exhibits a predominant electronic conductivity. A residual lithium content of 0.03 wt% was found and has to be considered as lithium interstitials in the FePO₄ ground structure. Compensation by electrons induces n‐type conduction, confirmed by the pO₂ dependence of the electronic conductivity. The pO₂ dependence is primarily ascribed to the formation of an oxidic surface composition leading to bulk depletion of lithium, rather than to filling of oxygen vacancies.     

Synergistically Improved Molecular Doping and Carrier Mobility by Copolymerization of Donor–Acceptor and Donor–Donor Building Blocks for Thermoelectric Application

In this work, it is demonstrated that random copolymerization is a simple but effective strategy to obtain new conductive copolymers as high‐performance thermoelectric materials. By using a polymerizing acceptor unit diketopyrropyrrole with donor units thienothiophene and oligo ethylene glycol substituted bithiophene (g₃2T), it is found that strong interchain donor–acceptor interactions ensure good film crystallinity for charge transport, while donor–donor type building blocks contribute to effective charge transfers. Hall effect measurements show that the high electrical conductivity results from increased free carriers with simultaneously improved mobility reaching over 1 cm² V^?1 s^?1. The synergistic effect of improved molecular doping and carrier mobility, as well as a high Seebeck coefficient ascribed to the structural disorder along polymer chains via random copolymerization, results in an impressive power factor up to 110 µW K^?2 m^?1 which is 10 times higher than that of solution‐processed polythiophenes.     

Tuning Fermi Levels in Intrinsic Antiferromagnetic Topological Insulators MnBi2Te4 and MnBi4Te7 by Defect Engineering and Chemical Doping

MnBi₂Te₄ and MnBi₄Te₇ are intrinsic antiferromagnetic topological insulators, offering a promising materials platform for realizing exotic topological quantum states. However, high densities of intrinsic defects in these materials not only cause bulk metallic conductivity, preventing the measurement of quantum transport in surface states, but may also affect magnetism and topological properties. In this paper, systematic density functional theory calculations reveal specific material chemistry and growth conditions that determine the defect formation and dopant incorporation in MnBi₂Te₄ and MnBi₄Te₇. The large strain induced by the internal heterostructure promotes the formation of large-size-mismatched antisite defects and substitutional dopants. The results here show that the abundance of antisite defects is responsible for the observed n-type metallic conductivity. A Te-rich growth condition is predicted to reduce the bulk free electron density, which is confirmed by experimental synthesis and transport measurements in MnBi₂Te₄. Furthermore, Na doping is proposed to be an effective acceptor dopant to pin the Fermi level within the bulk band gap to enable the observation of surface quantum transport. The defect engineering and doping strategies proposed here should stimulate further studies for improving synthesis and for manipulating magnetic and topological properties in MnBi₂Te₄, MnBi₄Te₇, and related magnetic topological insulators.