K2Ln(NO3)5·2H2O(Ln=La,Ce,Pr,Nd,Sm)的晶体生长和热重-差热分析研究

本文生长出了K₂Ln（NO₃）₅·2H₂O（Ln=La；Ce；Pr；Nd；Sm）的单晶，并对其进行了晶体结构及差热-热重分析研究．结果表明，K₂Ln（NO₃）₅.2H₂O（Ln=La；Ce；Pr；Nd）的晶体属正交晶系，Fdd2空间群．首次生长出KPrN单晶并用直接法解出其晶体结构．解得KPrN的晶胞参数为：a=11．2210（10）A, b=21．411（3）A，c=12．208（2）A,Z=6；R=0．0240．对KLnN加热，则依次出现脱水、熔化、不可逆相变和NO的分解过程（K₂Ce（NO₃）₅·2H₂O除外）K₂Ln（NO₃）₅·2H₂O（Ln＝La；Nd；Sm）的NO分三步分解，K₂Ln（NO₃）₅·2H₂O（Ln=Ce；Pr）的NO分两步分解·KNO₃和Ln（NO₃）₃·nH₂O的混合物在225℃左右生成K₂Ln（NO₃）₅     

Synthesis and characterization of Cu–Co–Fe hydrotalcites and their calcined products

A series of new Cu–Co–Fe compounds with the general formula Cu _x Co_2−x Fe₁HT (x = 0, 0.5, 1, 1.5 and 2) has been prepared by hydrotalcite coprecipitation method. The presence of hydrotalcite phase is revealed by XRD analysis for x values of 0, 0.5 and 1. When the copper quantity is higher than 1, the malachite phase is preferentially formed. These results are confirmed by TG-DTA, FT-IR and XPS analysis. After calcination at 500 °C in air of all samples, XRD analysis reveals the presence of spinel phases such as Co₃O₄, CoFe₂O₄, CuFe₂O₄, Cu _x Co _y O₄ in the solids, monoclinic CuO phase when the copper content is greater or equal to 1 and haematite phase for the sample where x is equal to 2. The presence of these phases is also confirmed by XPS results. For comparison, a Co₂Fe₁OH sample has been synthesized by classical coprecipitation method and although Co₂Fe₁HT sample and Co₂Fe₁OH form a similar phase after calcination at 500 °C, Co₂Fe₁HT500 presents a higher BET value than Co₂Fe₁OH500 sample.     

K_2Ln(NO_3)_5·2H_2O(Ln=La,Ce,Pr,Nd,Sm)的晶体生长和热重-差热分析研究

本文生长出了K2Ln（NO3）5.2H2O（Ln=La；Ce；Pr；Nd；Sm）的单晶，并对其进行了晶体结构及差热-热重分析研究．结果表明，K2Ln（NO3）5.2H2O（Ln=La；Ce；Pr；Nd）的晶体属正交晶系，Fdd2空间群．首次生长出KPrN单晶并用直接法解出其晶体结构．解得KPrN的晶胞参数为：a=11．2210（10）,b=21．411（3），c=12．208（2）,Z=6；R=0．0240．对KLnN加热，则依次出现脱水、熔化、不可逆相变和NO的分解过程（K2Ce（NO3）5·2H2O除外）K2Ln（NO3）5·2H2O（Ln＝La；Nd；Sm）的NO分三步分解，K2Ln（NO3）5·2H。O（Ln=Ce；Pr）的NO分两步分解·KNO3和Ln（NO3）3·nH2O的混合物在225℃左右生成K2Ln（NO3）5     

Microstructure, thermal properties and hardness of the CeMO3 (M=Al,Ga) synthesized by arc-melting method

Synthesis of CeMO₃ (M=Al,Ga) was attempted by the arc-melting method. In the case of M=Al, the arc-melted sample consisted typically of three regions CeAlO₃, CeO₂ and eutectic, mainly Al₂O₃. A similar texture was also observed for the case of M=Ga. Both CeAlO₃ and CeGaO₃ are crystallized in a tetragonal system (space group:P4/mmm). Lattice parameters of the tetragonal cell for CeAlO₃ and CeGaO₃ are a=0.37669(9) nm, c=0.37967(7) nm and a=0.3873(1) nm, c=0.3880(1) nm, respectively. According to thermal analysis, decomposition of 2CeMO₃+1/2O₂→2CeO₂+M₂O₃ occurs for CeAlO₃ and CeGaO₃ at about 1275°C and 833°C, respectively. The TG curve shows that the onset-temperature of oxidation for CeAlO₃ is at 1170°C and for CeGaO₃ is at 720°C. After TG-DTA measurement, both compounds are completely decomposed to starting materials. The value of the micro-Vickers hardness for the CeAlO₃ and CeGaO₃ is 9.0 (±0.2) GPa and 7.2 (±0.4) GPa, respectively.     

热分析在耐火材料上的应用

用热重-差热分析法分析了特种浇注料Al2O3、SiO2的干燥特性，找出了炉底爆裂的原因，提出了炉底改进意见，应用于马鞍山钢铁公司收到良好的效果。     

Characterization of Al18B4O33 ceramic synthesized by the sol-gel,precipitation, and combustion methods

In this study, Al₁₈B₄O₃₃ aluminum borate is synthesized by the sol-gel, precipitation, and combustion methods, which use similar starting materials. Simultaneous thermal analyzer and Fourier transform infrared spectroscopy are employed to determine the thermal behavior and the chemical bonding structures. In addition, the crystal structure and microstructure are identified by X-ray diffraction and scanning electron microscope. The results reveal that Al₁₈B₄O₃₃ nanorods are produced by sol-gel method and citric acid controls the morphology of powders. Additionally, Al₁₈B₄O₃₃ phase is obtained by decomposing Al₄B₂O₉ unstable phase at 1000°C by sol-gel method. However, Al₁₈B₄O₃₃ phase is immediately obtained from calcination of an amorphous phase at 1000°C by precipitation and combustion methods.     

Rhodium-incorporated faujasite prepared at 80 °C

Rhodium-incorporated zeolites were synthesized from orthosilicate, aluminum nitrate, and rhodium chloride at 80 °C. Crystal phase diagram (zeolite types as functions of rhodium feed ratio and reaction period) showed that pure faujasite was formed in a wide range, but prolonged reaction caused partial transformation from faujasite to cancrinite at the rhodium feed ratio Rh/(Al + Rh) ≤ 0.02 and to gismondine at Rh/(Al + Rh) ≥ 0.4. X-ray diffraction analysis illustrated that an increase in the rhodium feed ratio caused appreciable decreases in the d-spacings, suggesting that rhodium was incorporated into the faujasite framework. ICP-OES analysis for the products showed that the rhodium content increased almost linearly with the increase in the rhodium feed ratio with an upper limit of the analyzed Rh content Rh/(Al + Rh) = 0.183 at the Rh feed ratio of 0.3. The products were almost quantitatively ion-exchanged using an ammonium chloride aqueous solution to study the ammonia desorption profiles on TG-DTA/MS analysis in the heating process. Considerably sharp exothermic peaks were observed at 245 °C simultaneously in the heating process. These peaks are probably related to catalytic decomposition of ammonia and desorption of ammonia, nitrogen, and water in the zeolite. A hypothesis was proposed for this mechanism: rhodium can be abruptly eliminated at an elevated temperature from the zeolite framework toward the micropores to form its hydroxides or oxides, then they triggered a catalytic decomposition of the adsorbed ammonia. The effect of calcination on crystallinity of the products and catalytic reactivity for hydrogen peroxide decomposition supported the proposed mechanism.     

1-L-丙氨酸-1-脱氧-D-果糖的热裂解分析

采用热重/差热(TG-DTA)和在线裂解气相色谱/质谱联用(Py-GC/MS)分析技术对1-L-丙氨酸-1-脱氧-D-果糖(Ala-Fru)的热裂解进行了研究.TG-DTA分析结果显示,Ala-Fru的初始裂解温度为147.47℃,600℃时样品质量损失至原重的25%;在350℃,450℃,550℃,650℃,750℃和850℃这6个温度下的Py-GC/MS结果显示,裂解产物的种类和数量随裂解温度的升高而增多,其裂解产物主要为吡嗪类、吡啶类、吡咯类和呋喃类等杂环类化合物以及少量酮类化合物,这些物质是卷烟烟气中重要的香味成分.