Rietveld全谱拟合表征掺杂ZnO陶瓷

通过Rietveld全谱拟合对掺杂多物相ZnO陶瓷的物相定量组成,所含尖晶石相的化学配比、晶粒大小和残余应力等结构参数同时进行了表征,既快又准。研究结果表明,掺杂ZnO陶瓷以保持原晶格常数和没有其它元素掺杂的较大颗粒的ZnO相为主体,高分散的Bi₂O₃相与尖晶石相晶粒分散于ZnO晶粒间。尖晶石相的元素组成随原料的掺杂组分配比不同而不同,利用全谱拟合精修确定了它们的元素组成。     

Pr6O11对ZnO压敏材料显微结构的影响

研究了在ZnO压敏材料组分中以溶液方式加入稀土氧化物Pr6O11后其微观结构的变化。结果表明，Pr6O11的加入改变了ZnO尖晶石相的生成途径，使该材料在低于700℃时生成大量焦绿石相（Bi3Zn2Sb3O14）。当烧成温度高于900℃时，焦绿石相分解生成细小的二次尖晶石相（Zn7Sb2O12）。这种二次生成的细小尖晶石使材料晶粒尺寸减小，分布均匀；此外，Pr6O11的引入能生成含Pr物相，以及Pr氧化物相也有利于材料的晶粒细化。晶粒细化结果改善了ZnO压敏材料的压敏电压和非线性特性，与掺杂前相比，压敏电压提高了约60％。     

催化裂化USY／ZnO／Al2O3脱硫添加剂的高温水热失活

 对USY／ZnO／Al2O3汽油催化裂化脱硫添加剂经高温水热老化处理前后的脱硫性能进行了考察，发现老化后添加剂的脱硫性能大幅度下降．采用XRD和IR等技术对USY／ZnO／Al2O3添加剂在高温和高温水热条件下失活的原因进行了研究．结果表明，在高温下，ZnO可与USY沸石中的铝发生固相反应生成ZnAl2O4尖晶石，从而造成USY晶体结构崩塌，转变成无定形状态．在ZnO含量较高的条件下，ZnO可继续与USY晶体结构崩塌后生成的无定形的硅和铝的氧化物反应，生成Zn2SiO4硅锌矿和ZnAl2O4尖晶石结构．这一方面使添加剂失去了可形成硫化物吸附中心的ZnO，另一方面破坏了硫化物的裂化活性组分USY，从而造成添加剂脱硫性能下降甚至失去脱硫活性．ZnO对USY的破坏作用主要与温度有关．在USY／ZnO／Al2O3体系中，ZnO被ZnO与Al2O3之间形成的锌铝尖晶石膜固定并与USY隔离，单纯的高温条件对添加剂的破坏不显著，而水蒸气可以促进ZnO的移动，有利于ZnO与USY的接触，因此在高温和有水蒸气存 在的条件下添加剂的结构易遭到破坏．     

催化裂化USY／ZnO／A12O3脱硫添加剂的高温水热失活

对USY／ZnO／A12O3汽油催化裂化脱硫添加剂经高温水热老化处理前后的脱硫性能进行了考察，发现老化后添加剂的脱硫性能大幅度下降．采用XRD和IR等技术对USY／ZnO／A12O3添加剂在高温和高温水热条件下失活的原因进行了研究．结果表明，在高温下，ZnO可与USY沸石中的铝发生因相反应生成ZnAl2O4尖晶石，从而造成USY晶体结构崩塌，转变成无定形状态．在ZnO含量较高的条件下，ZnO可继续与USY晶体结构崩塌后生成的无定形的硅和铝的氧化物反应，生成Zn2SiO4硅锌矿和ZnAl2O4尖晶石结构．这一方面使添加剂失去了可形成硫化物吸附中心的ZnO，另一方面破坏了硫化物的裂化活性组分USY，从而造成添加剂脱硫性能下降甚至失去脱硫活性．ZnO对USY的破坏作用主要与温度有关．在USY／ZnO／Al2O3体系中，ZnO被ZnO与Al2O3之间形成的锌铝尖晶石膜固定并与USY隔离，单纯的高温条件对添加剂的破坏不显著，而水蒸气可以促进ZnO的移动，有利于ZnO与USY的接触，因此在高温和有水蒸气存在的条件下添加剂的结构易遭到破坏．     

氧化铝基表层镁铝尖晶石的研究──Ⅰ．表层镁铝尖晶石的相结构、孔结构、表面酸性及负载钯的化学状态

对＜１０００℃焙烧的γ－Ａｌ２Ｏ３载镁体系进行了相表征，发现在基质氧化铝上形成了表层镁铝尖晶石，具有“原尖晶石结构”的γ－Ａｌ２Ｏ３则在＜１０００℃保持物相不变．进一步研究了这种氧化铝基表层镁铝尖晶石的孔结构、表面酸性以及负载耙的分散与化学状态，结果表明：氧化铝基表层尖晶石的孔结构和表面酸性由构成的氧化铝基决定，并随温度变化，表层尖晶石仅可稳定氧化铝基的物相，与其孔性质和酸性无关；负载在氧化铝基表层尖晶石上的钯，主要分布在表层镁铝尖晶石上，有强的载体一金属相互作用，以Ｐｄ０和Ｐｄ２＋两种状态存在．     

锌基复合脱硫剂脱硫性能的研究

采用共沉淀法和机械混合法制备了Zn-Cu-Mn复合氧化物和ZCM(Z=ZnO、C=CuO、M=MnO2)复合氧化物，并对两种氧化物的脱硫能力进行了分析，同时也将这二种氧化物与单一的ZnO、MnO2和CuO的脱硫能力进行比较。利用XRD和FPD(火焰光度计)分别对复合氧化物的物质组成、结构和脱硫性能进行了分析。实验证明，Zn-Cu-Mn在250℃～350℃具有良好的脱硫能力，且300℃的脱硫能力最佳；空速为7799h-1时穿透硫容较高。煅烧温度为400℃时，Zn-Cu-Mn的脱硫能力高于ZnO。煅烧温度升高，Zn-Cu-Mn复合氧化物的比表面积和脱硫能力下降，且生成了具有尖晶石结构的CuMn2O4。与Zn-Cu-Mn复合氧化物和ZnO相比，ZCM复合氧化物的脱硫能力较低。煅烧温度为550℃时，ZCM体系中的MnO2分解为Mn2O3，当温度升至750℃时Mn2O3相消失，生成了具有尖晶石结构的CuMn2O4。     

ZnCr基催化剂煅烧温度对异丁醇合成性能的影响

研究了煅烧温度对ZnCr基催化剂合成异丁醇性能的影响。结果表明,随着煅烧温度的升高,催化剂的活性和产物分布都发生了较大的变化。催化剂在较低的温度下煅烧,液相产物中醇主要是甲醇和异丁醇;在较高的温度下煅烧,液相产物醇的分布符合A-S-F方程。用BET、XRD、H₂-TPR、XPS等技术手段对催化剂织构参数、体相结构、还原性能、表面组成进行表征。结果表明,在300℃煅烧时,催化剂中的ZnO和Cr₂O₃未完全形成非计量尖晶石Zn_xCr_2/3(1-x)O;400℃煅烧时,催化剂中形成了最多量非计量尖晶石Zn_xCr_2/3(1-x)O;当煅烧温度高于400℃时,随着煅烧温度进一步升高,非计量尖晶石Zn_xCr_2/3(1-x)O逐步发生了分解,生成了更多量的ZnO和Cr₂O₃,导致催化剂的活性随之下降。进一步证明了非计量尖晶石Zn_xCr_2/3(1-x)O是该催化反应活性相。     

Bi基化合物膜包覆ZnO的制备和电化学性能

为提高锌镍电池ZnO的循环充放电性能,采用Bi(NO3)3水解沉积法对ZnO包覆Bi基化合物膜,系统研究了包覆ZnO的微结构和电化学性能。TEM,XRD和EDS表明由Bi6(NO3)4(OH)2O6·2H2O,BiO和Bi2O3组成的Bi基化合物膜包覆在ZnO表面。表面包覆能提高ZnO的循环性能和放电容量,含5.1wt%Bi的包覆ZnO循环性能稳定,平均放电容量为509mAh·g-1,利用率为78%,性能有较大改善。充放电曲线和循环伏安结果均表明包覆Bi基化合物膜能降低锌镍电池的充电平台,加宽放电平台,提高ZnO的电化学活性。包覆Bi基化合物膜能有效减小活性材料与碱性电解液的接触,抑制ZnO的溶解,提高循环稳定性;而包覆膜的微孔结构又可使活性材料接触到电化学反应必须的H2O和OH-,保证了高的放电容量。     

锂掺杂ZnO陶瓷靶材制备及其掺杂引起的缺陷

采用燃烧合成和放电等离子烧结方法制备锂掺杂ZnO陶瓷靶材. 利用XRD, SEM, TEM和激光粒径分析等手段分析合成粉体与陶瓷的显微结构. 结果表明, 锂掺杂ZnO粉体与陶瓷均为纤锌矿结构, 无其他相存在; 粉体的粒径分布为0.18-1.7 μm, 烧结体致密度较高, 晶粒尺寸为1-3 μm. 此外, 分析锂元素在烧结过程中引起掺杂缺陷变化, 锂元素由ZnO晶格的间隙位置转移为替代锌晶格位置, 实现受主掺杂, 为实现p型ZnO薄膜的制备奠定基础.     

氧化铝基表层镁铝尖晶石的研究Ⅰ.表层镁铝尖晶石的相结构、孔结构、表面酸性及负载钯的化学状态

对＜１０００℃焙烧的的ｒ－ＡＬ２Ｏ３载镁体系进行了相表征，发现在基质氧化铝上形成了表层镁铝尖晶石 ，具有“原晶石结构”的ｒ－Ａｌ２Ｏ３则在＜１０００℃保持物相不变。进一步研究玻了这种氧化铝基表层镁铝晶石的孔结构，表面酸性以及负载钯的分散与化学状态，结果表明：氧化铝基表层晶石的孔结构和表面酸性由构成的氧化铝基决定，并随温度变化；表层尖晶石仅可稳定氧化铝基的物相，与其孔性质和酸性无关；负载在氧化铝基表     

Thermal Study of the Ceramic Pigments CoxZn(7−x)Sb2O12

Using the Pechini method, pigments with spinel structure (Zn₇Sb₂O₁₂)were synthesized by substitution of the cation Zn²⁺ by Co²⁺, in compounds with different concentrations of Sb₂O₃. The doping resulted in Co_xZn_(7–x)Sb₂O₁₂ phases(x=1–7) that were isomorphs to spinel, denominated as samples A and B. After thermal treatment at 400°C for 1 h, the powders were characterized by thermogravimetry(TG) and differential thermal analysis (DTA). The results indicate a different behavior whena higher amount of Sb₂O₃ is used, due to the presence of a secondary phase (ilmenite). This revised version was published online in July 2006 with corrections to the Cover Date.     

微波加热液相均匀沉淀法制备纳米Sb2O3阻燃剂(英)

Antimonyoxide(Sb2O3)isanimportantadditiveflameretardant.Itisextensivelyusedinflameretar鄄danttreatmentofpolyolefine,polyvinylchloride,polyesterandtextiles.TheefficiencyofhalogenatedflameretardantcanbeenhancedbycooperatingwithSb2O3.ThesizeofSb2O3hasgreatef…     

Crystal structure, conductivity and reversible water uptake of new layered potassium antimonates KxL(1+x)/3Sb(2−x)/3O2 (L=Ni, Mg, Co)

Novel mixed potassium antimonates K_0.59Mg_0.53Sb_0.47O₂, K_0.5Ni_0.5Sb_0.5O₂, K_0.5Co_0.5Sb_0.5O₂ (rhombohedral P3-type structure), K_0.56Ni_0.52Sb_0.48O₂ and K_0.86Co_0.62Sb_0.38O₂ (hexagonal P2 type) have layered structures based on brucite-like (L,Sb)O_6/3 sheets of edge-shared octahedra and interlayer K⁺ cations in trigonal prismatic coordination. The preference to form P2 and P3 structures rather than closely related O3 type is dictated by the large radius of K⁺ and the value of unit cell parameter a, restricted by average size of the cations randomly distributed in the octahedral sites within (L,Sb)O_6/3 layer. The new phases reversibly absorb atmospheric moisture leading to the formation of hydrates with ca. 11% larger interlayer distances. The impedance spectroscopy of P2-type K_0.56Ni_0.52Sb_0.48O₂ and P3-type K_0.59Mg_0.53Sb_0.47O₂ ceramics shows relatively high ionic conductivity, presumably due to potassium cationic transport, with activation energies of 35±2 and 33±1 kJ/mol, respectively. At 573 K, the conductivity values are 0.016 S/cm for K_0.56Ni_0.52Sb_0.48O₂ and 0.021 S/cm for K_0.59Mg_0.53Sb_0.47O₂. Interaction with water vapor leads to increasing total conductivity.     

Thermal study of CoxZn7-xSb2O12 spinel obtained by pechini method using different alcohols

With the aim of obtaining materials with applications in pigments, Co_xZn_7-xSb₂O₁₂ spinels were synthesized using the Pechini method. This method consists in the formation of a polymeric net, where the metallic cations are homogeneously distributed. In this work, two types of alcohol (ethyl glycol and ethylene glycol) were used for the synthesis of a zinc antimoniate spinel, Co_xZn_7-xSb₂O₁₂ (x=0-7). The materials were characterized by termogravimetry (TG) and differential thermal analysis (DTA). TG results indicated a decrease in total mass loss when cobalt was added to the solution substituting zinc, for samples prepared using the two different alcohols. Decomposition temperatures, obtained by TG and DTA, presented a decreasing behavior as cobalt was added to the material. In relation to the alcohols, all results indicated a better polymerization of the resin when ethylene glycol was used, being the most indicated one for cation immobilization. X-ray diffraction did not show differences between the two alcohols - both presented the spinel phase (Co, Zn)_2.33Sb₀.₆₇O₄. Samples with higher quantity of cobalt also presented ilmenite phase (Co, Zn)Sb₂O₆. This revised version was published online in August 2006 with corrections to the Cover Date.     

Observation of Sb2O3 Nanocrystals in SiO2 after Sb Ion Implantation

 Antimony nanocrystals were formed in thin SiO₂ films using low-energy ion implantation of Sb followed by annealing. Using Fourier transform laser microprobe mass spectrometry (FT LMMS), we observed for the first time the presence of antimony oxide in the intermediate phase (as-implanted layer of Sb) by means of signals referring to the intact Sb₂O₃ molecules. Only SbO⁺ fragments, but no adduct ions of Sb₂O₃ could be detected in annealed samples. The size and the distribution of the nanocrystals formed around the initial depth of implantation were studied in the as-implanted samples by high-resolution electron microscopy (HREM). The crystalline structure of these nanocrystals was also studied and the presence of antimony trioxide Sb₂O₃ in the form of valentinite was proven. After the annealing step, the implanted material had spread into a wider band. The method introduced here, based on combining TEM (transmission electron microscopy) and FT LMMS results, offers the possibility of studying the evolution of the phases in Sb nanocrystal formation.     

Micro-sized Sb2O3 octahedra fabricated via a PEG-1000 polymer-assisted hydrothermal route

The micro-sized Sb₂O₃ octahedra can be synthesized on a large scale via a simple PEG-1000 polymer-assisted hydrothermal route (PAHR) in the temperature range of 160-180 °C for 10-14 h. The structures, compositions, and morphologies of the as-synthesized products are derived from X-ray power diffraction pattern, X-ray photoelectron spectra, and field emission scanning electronic microscope. Meanwhile, the optical properties of the micro-sized Sb₂O₃ octahedra are studied by their photoluminescene spectroscopy and Raman spectrum. Furthermore, the possible growth mechanism of the micro-metered Sb₂O₃ octahedra is discussed on the basis of a series of supplementary experiments. And it has been found that PEG-1000, sodium tartrate, the reaction temperature, and the reaction time have considerable effects on the final morphology of Sb₂O₃, while the pH value has an influence on the formation of the Sb₂O₃ crystals.     

Thermal decomposition of antimony oxyhalides

The thermal decomposition of SbOCl, Sb₄O₅Cl₂ and Sb₈O₁₁Cl₂ has been studied by thermogravimetry with identification of the products resulting in the condensed phase by X-ray diffraction and infrared technique. It is shown that in nitrogen SbOCl undergoes progressive stepwise thermal disproportionation to Sb₂O₃ and SbCl₃ with formation of Sb₄O₅Cl₂ and Sb₈O₁₁Cl₂ and as intermediates. It is thus confirmed that Sb₃O₄Cl, suggested to be formed instead of Sb₈O₁₁Cl₂, is not an intermediate of this process. An identical mechanism is observed in air but with oxidation of Sb₂O₃ to Sb₂O₄.

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Zusammenfassung Mittels TG wurde die thermische Zersetzung von SbOCl, Sb₄O₅Cl₂ und Sb₈O₁₁Cl₂ untersucht und die entstehenden Produkte der kondensierten Phase mittels Röntgendiffraktionsuntersuchungen und IR-Spektroskopie identifiziert. Es wurde gezeigt, daß SbOCl in Stickstoff einer stufenweise thermische Disproportionierung unterliegt, bei der über die Zwischenprodukte Sb₄O₅Cl₂ und Sb₈O₁₁Cl₂ zuletzt Sb₂O₃ und SbCl₃ entstehen. Es wurde weiterhin bewiesen, daß das anstelle von Sb₈O₁₁Cl₂ vorgeschlagene Sb₃O₄C_l kein Zwischenprodukt dieses Zersetzungsvorganges ist. Ein ähnlicher Mechanismus gilt für die Zersetzung in Luft, jedoch mit der Oxidation von Sb₂O₃ zu Sb₂O₄.

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This work was carried out with the financial support of the Progetto Finalizzato Chimica Fine II del Consiglio Nationale delle Ricerche.     

Study of ceramic pigments based on cobalt doped Y2O3–Al2O3 system

Ceramic pigments based on Y₂O₃–Al₂O₃ system doped by cobalt as a colourant agent were synthesized by solid-state reaction at temperatures up to 1,400 °C. The reactivity of initial mixtures of components was improved by the mineralizer LiF and the mechanical activation in a planetary ball mill. The temperature region of the product formation was followed by the method of thermal analysis. The effect of the synthetic method on the phase composition of the products was studied by X-ray diffraction analysis. Studied pigment-application properties of the product include the measurement of optical properties in the visible region of light and particle size distribution. The simple solid-state reaction led to the formation of turquoise samples that contain mainly blue CoAl₂O₄ spinel and next to it also YAlO₃ perovskite and Y₃Al₅O₁₂ garnet phases. The mineralizer LiF promotes the formation of yttrium aluminium double oxides of sandy-yellow to grey–brown colour hue, although the samples also contain small amount of blue CoAl spinel phase. Intensive milling process did not results in CoAl spinel phase and the samples contain yttrium aluminium perovskite and cobalt oxide. Evaluation of Kubelka–Munk absorption as a function of the pigment concentration was found that hiding is complete by adding of 5 mass% of pigment to the ceramic glaze. Resulting colour hue of all pigment applications into ceramic glaze is blue. The size of particles lies in the range of 7–26 μm.     

Preparation and crystallographic investigation of the spinel series: Mn1 + 2sCr2 − 3sSbsO4 (0.05 ⩽ , s ⩽ 0.30)

Mn_{1 + 2s}Cr_{2 ? 3s}Sb_sO₄, a new series of spinels, have been prepared and studied using X-ray powder data. For s going from 0.05 to 0.30, a gradually increases from 8.441(1) to 8.472(1) Å, and u slightly decreases, from 0.262 to 0.258. Interatomic distances are given. The Mn_{1 + 2s}Cr_{2 ? 3s}Sb_sO₄ (0.05 < s < 0.30) series may be conceived as the result of partial substitution of Cr^{3 +} by 2/3Mn^{2 +} + 1/3Sb^{5 +} in the normal spinel, MnCr₂O ₄.     

超声场中均匀沉淀法制备纳米Sb2O3阻燃剂(英)

Sb2O3isanessentialsynergistofalmostallthehalogenatedflameretardants.Themechanicalproper-tiesandflameretardancyofflameretardingmaterialsaregreatlyinfluencedbythesizeofSb2O3.WhennanosizedSb2O3isappliedtotheflameretardingpolymericmaterials,themechanicalprope…