Thermodynamic assessment of the CaO–Cu2O–FeO–Fe2O3 system

Thermodynamic assessment of the CaO–Cu₂O–FeO–Fe₂O₃ system is presented. Effects of temperature and P(O₂) on the phase equilibria involving slag, solubility of copper and the Fe³⁺/Fe²⁺ ratio in slag have been modeled using available experimental data. Subsolidus phase equilibria and concentration of iron in liquid copper were evaluated as well. Different ways of representing phase equilibria in a quaternary system are illustrated. The slag model, [Ca²⁺, Cu⁺, Fe²⁺, Fe³⁺][O²⁻], was developed using the Modified Quasichemical Model (MQM). Liquid metal phase is modeled using the MQM, but as a separate solution, (Cu^I, Fe^II, O^II). Spinel phase is modeled using the Compound Energy Formalism (CEF) and takes into account the solubility of copper and calcium. A thermodynamic database produced in the present study can be used for predictions in pyrometallurgical processing of copper involving calcium ferrite slags. The database is internally consistent with the binary and ternary sub-systems published earlier, as well as with higher-order systems. It works in the environment of FactSage, ChemApp, ChemSheet and SimuSage software packages.     

Thermodynamic optimization of the ZnO–FeO–Fe2O3–SiO2 system

Liquidus phase equilibria experimental data of the present authors for the ZnO–“Fe₂O₃”–SiO₂ system in air, ZnO–“FeO”–SiO₂ in equilibrium with metallic Fe, and ZnO–“FeO”–SiO₂–minor Cu₂O at p(O₂) ~10⁻⁷ … 10⁻⁸ atm (obtained as a part the research on the multicomponent PbO–ZnO–FeO–Fe₂O₃–Cu₂O–CaO–SiO₂ system), combined with phase equilibrium and thermodynamic data from the literature, have been used to obtain a self-consistent set of parameters of the thermodynamic models for all phases in the ZnO–FeO–Fe₂O₃–SiO₂ system for the whole range of compositions, p(O₂) between ~10⁻¹³ to 1 atm, and temperature range corresponding to liquid slag existence (1150–1700 °C). The modified quasichemical model is used for the liquid slag phase. From these optimized model parameters, the ternary phase diagrams are back calculated. The model based on the present set of parameters is in a good agreement with previous and new experimental data, and can be used for predictions of the ZnO–FeO–Fe₂O₃–SiO₂ phase equilibria over wide ranges of p(O₂), compositions and temperatures, as well as multicomponent systems.     

Thermodynamic optimization of the PbO–FeO–Fe2O3–SiO2 system

Liquidus phase equilibrium data of the present authors for the PbO–FeO–Fe₂O₃ system at various oxygen potentials, PbO–“Fe₂O₃”–SiO₂ system in air, and PbO–“FeO”–SiO₂ in equilibrium with metallic Pb, combined with phase equilibrium and thermodynamic data from the literature, have been used to obtain a self-consistent set of parameters of the thermodynamic models for all phases in the PbO–FeO–Fe₂O₃–SiO₂ system. The modified quasichemical model is used for the liquid slag phase. For the liquid phase, the PbO–FeO, PbO–Fe₂O₃, PbO–FeO–Fe₂O₃, PbO–FeO–SiO₂ and PbO–Fe₂O₃–SiO₂ parameters are optimized in the present study. From these model parameters, the optimized ternary phase diagram is back calculated. Present set of parameters describe previous and new experimental data well, and can be used for predictions of the PbO–FeO–Fe₂O₃–SiO₂ phase equilibria over wide ranges of oxygen partial pressured, compositions and temperatures, as well as multicomponent systems.     

Fe2O3/SnO2和SnO2/Fe2O3双层薄膜的XPS分析

用X光光电子能谱(XPS),结合Ar~+刻蚀对Fe_2O_3/SnO_2及Fe_20_3/SnO_2双层薄膜进行分析.结果表明:Fe_2O_3/SnO_2膜表面,晶格氧的结合能为529.85eV,热处理前有大量吸附氧存在,在600℃退火后,大部分羟基、羰基形态的吸附氧解吸;SnO_2/Fe_2O_3膜表面,热处理前后都只有少量的吸附氧,经热处理后表面吸附氧却略有增加.双层薄膜中锡向氧化铁层的扩散较铁向氧化锡层的扩散强.扩散的结果,形成了一个数十纳米的过渡层,对元件的气敏性质产生一定的影响.     

Experimental study and thermodynamic optimization of the ZnO–FeO–Fe2O3–CaO–SiO2 system

Liquidus phase equilibrium experimental data from the present study for the ZnO-“Fe₂O₃”-CaO-SiO₂ system in air, combined with phase equilibria and thermodynamic data from the literature on the ZnO-“Fe₂O₃”-CaO system in air and ZnO-“FeO”-CaO-SiO₂ system in equilibrium with metallic Fe, have been used to obtain a self-consistent set of parameters of the thermodynamic models for all phases in the ZnO–FeO–Fe₂O₃–CaO–SiO₂ system. The modified quasichemical model is used for the liquid slag phase; spinel (Fe,Zn,Ca)^tetr (Fe,Zn,Ca,Va)^oct₂O₄, melilite Ca₂(Fe²⁺,Fe³⁺,Zn)(Fe³⁺,Si)₂O₇ and olivine (Fe,Zn,Ca)^I(Fe,Zn,Ca)^IISiO₄ are described with compound energy formalism; lime and wustite (monoxide) (Ca,Fe,Zn)O, zincite (Zn,Fe,Ca)O_1+x, calcium-zinc ferrites Ca₂Fe₂O₅-“CaZnO₂” and CaFe₄O₇-“ZnFe₄O₇”, α- and α′-dicalcium silicate (Ca,Fe,Zn)₂SiO₄ and tricalcium silicate (Ca,Fe,Zn)₃SiO₅ and silicoferrite of calcium (SFC) Ca₉Fe₄₆SiO₈₀–Ca₁₂Fe₄₀Si₄O₈₀ are described within Bragg-Williams formalism; for other phases, previous assessments have been adopted. The phase diagrams are back calculated with the optimized model parameters. Present study is a part of research program on the characterization of the multicomponent PbO–ZnO–FeO–Fe₂O₃-“Cu₂O”-CaO-SiO₂ system.     

高选择性 Fe2O3元件的研制􀀁

利用共沉淀法合成& 一?( )? ? 敏感基料, 通过+ , ) ? ? 的掺杂研制出具有高选择性, 灵敏 度, 抗湿性和穗定性的. /0 气敏元件     

Thermodynamic modeling of the Co–Fe–O system

As a part of the research project aimed at developing a thermodynamic database of the La–Sr–Co–Fe–O system for applications in Solid Oxide Fuel Cells (SOFCs), the Co–Fe–O subsystem was thermodynamically re-modeled in the present work using the CALPHAD methodology. The solid phases were described using the Compound Energy Formalism (CEF) and the ionized liquid was modeled with the ionic two-sublattice model based on CEF. A set of self-consistent thermodynamic parameters was obtained eventually. Calculated phase diagrams and thermodynamic properties are presented and compared with experimental data. The modeling covers a temperature range from 298 K to 3000 K and oxygen partial pressure from 10⁻¹⁶ to 10² bar. A good agreement with the experimental data was shown. Improvements were made as compared to previous modeling results.     

Fe2O3-In2O3复合薄膜光波导传感元件检测二甲苯气体的研究

摘 要：本文采用溶胶-凝胶法(sol-gel)制备出氧化铁-氧化铟复合材料,利用提拉法将复合材料固定在锡掺杂玻璃光波导表面研究出能够检测二甲苯气体的Fe2O3-In2O3复合薄膜/锡掺杂玻璃光波导气敏元件。将气敏元件固定在气体检测系统中对挥发性有机气体进行检测。实验结果表明,Fe2O3-In2O3复合薄膜/锡掺杂玻璃光波导气敏元件对二甲苯气体具有较好的响应,其响应浓度范围为1×10-3～1×10-5(V/V)。在常温下该敏感元件对于浓度为1×10-5(V/V)的二甲苯蒸汽有比较明显响应,其响应和恢复时间分别为5s和20s。Fe2O3-In2O3复合薄膜/锡掺杂玻璃光波导气敏元件具有灵敏度高、响应速度快、制作工艺简单和可逆性好等特点。     

Fe2O3的CO气敏特性的研究

本文研究了γ-Fe_2O_3材料的制备和掺杂对CO气敏特性的影响。实验表明用硫酸盐制备的γ-Fe_2O_3材料具有相对高的灵敏度,进行适当的Ti-Rh复合氧化物掺杂又明显提高了γ-Fe_2O_3材料对CO的灵敏度。讨论了该掺杂的量对CO灵敏度的影响,及相应元件的基本性质。     

溅SnO2/Fe2O3 薄膜的敏感特性研究

薄膜元件应用前景广阔, 为进一步探索多层薄膜元件的性能廷“ , 我们对? % . / 及 / % . 体系作了分析研究, 得到了双层膜在灵敏度与选择性方面都明显优于单层膜的结论 01 ?? 本文介绍? % . / ? 2 一( ) / . 。体系的实验结果     

复合氧化物Fe2O3-SnO2 的气敏特性研究

1962年清山哲郎提出ZnO薄膜的气敏特性后,研究目标较集中于以ZnO,SnO_2,γ-Fe_2O_3和α-Fe_2O_3为基质的氧化物半导体陶瓷材料,并已有商品出售.氧化铁基气敏材料与氧化锌、氧化锡相比,它有无需添加贵金属催化剂便可达到实用气敏灵敏度的优点.我们也曾从催化活性、磁学性能和气敏特性等方面,对α-Fe_2O_3基气敏材料的气敏机制进行了研究,得到满意的结果.本文旨在探讨α-Fe_2O_3-SnO_2配比和氧化铁粒度与气敏性能间关系,并且也浅析了气敏机制,以期为此复合材料实用化提供依据.     

掺Sb2O3 的SnO2与Fe2O3厚膜的 电学行为及气敏特性

介绍掺入Sb_2O_3后的SnO_2和FeO_3(由γ-Fe_2O_3-热处理得到)气敏厚膜元件电阻和灵敏度的变化规律:对于SnO_2基元件,Sb_2O_3具有低掺杂(<4%wt)电阻变小,高掺杂电阻增大的作用,但气敏性降低;对于Fe_2O_3基元件,掺入Sb_2O_3后不但能降低电阻、提高气敏性,而且对丙酮的选择性也增强.指出Sb~(3+)→Sb~(5+)变化对上述效应起着重要作用,并探讨了Fe_2O_3基元件表面化学吸附增强的原因.     

Stability and formability of complex oxides in M2O3–M′2O3 systems

Based on fundamental thermodynamics and a simple energy model for solid M₂O₃ oxides, two atomic parameters of their constituent elements are identified that govern the solid phase stability in an M₂O₃–M₂′O₃ binary system. They are P₁=|r_A−r_B| and P₂=(r_A+r_O)(r_B+r_O)(r_A+r_B+2r_O), where, r_A, r_B and r_O are the ionic radii of ion A, ion B and oxygen, respectively. Using 237 known M₂O₃–M₂′O₃ systems and these two parameters (P₁ and P₂), new rules were obtained not only on the formability of stable complex oxides but also on the conditions that these compounds being of MM′O₃ stoichiometry and further of ABO₃-type perovskite structure. The classification accuracy of such rules reaches respectively 98.7% for formability of complex oxides, 97.9% for the MM′O₃ stoichiometry test, and 100% for the ABO₃-type perovskite structure prediction. Thirty seven new systems are used to validate these empirical rules, and the prediction is in good agreement with experiment. The influence of ionic size difference on the phase stability is further discussed based on the proposed energy model. The new rules may help material scientists to practically predict new complex compounds as well as to further theoretically study phase stability in M₂O₃–M₂′O₃ systems.     

V2O3—聚乙烯复合材料PTC热敏电阻的研究

对V_2O_3-聚乙烯复合物新型PTC热敏电阻进行了探索性研究.当加入(40～60)%vol的聚乙烯时,V_20_3基复合材料具有较显著的PTC效应,其特点是加入量适当可获得室温电阻率较低的热敏材料.还研究了V_2O_3颗粒大小对V_2O_3-聚乙烯热敏电阻电性能的影响.     

V2O3一聚乙烯复合材料PTC热敏电阻的研究

对, ? . & 一聚乙烯复合物新型? ( ) 热敏电阻进行了探索性研完? 当加入?!% # /% + 0 ? 12 的聚乙烯时, , ? . , 基复合材料具有较显著的? ( ) 效应, 其特点是 加入量适当可获得室温电阻率较低的热敏材料? 还研究了, ? . & 颗粒大小对, ? . & 3 聚乙烯热敏电阻电性能的影响?