Synthesis, characterization and thermal studies on solid compounds of 2-chlorobenzylidenepyruvate of heavier trivalent lanthanides and yttrium(III)
                                
                                    
                                        作者:G Bannach、E Schnitzler、O Treu Filho、V H S Utuni、M Ionashiro                                    
                                    
                                        DOI:10.1007/s70973-005-6972-y
                                    
                                    
                                        日期:2006.1
                                    
                                    Solid-state compounds of general formula LnL3⋅nH2O, where Ln represents heavier lanthanides and yttrium and L is 2-chlorobenzylidenepyruvate, have been synthesized. Chemical analysis, simultaneous thermogravimetry-differential analysis (TG-DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry, elemental analysis and infrared spectroscopy have been employed to characterize and to study the thermal behaviour of these compounds in dynamic air atmosphere. On heating these compounds decompose in four (Gd, Tb, Ho to Lu, Y) or five (Eu, Dy) steps. They lose the hydration water in the first step and the thermal decomposition of the anhydrous compounds up to 1200°C occurs with the formation of the respective oxide, Tb4O7 and Ln2O3 (Ln=Eu, Gd, Dy to Lu and Y) as final residue. The dehydration enthalpies found for these compounds (Eu, to Lu and Y) were: 65.77, 55.63, 86.89, 121.65, 99.80, 109.59, 131.02, 119.78, 205.46 and 83.11 kJ mol-1, respectively.
                                    具有通式LnL3⋅nH2O的固体化合物已被合成,其中Ln代表较重的
镧系元素和
钇,L是2-
氯苯亚甲基
丙酮酸酯。通过
化学分析、同步热重-差热分析(TG-DTA)、差示扫描量热法(
DSC)、X射线粉末衍射、元素分析和红外光谱来表征这些化合物并研究它们在动态空气气氛中的热行为。在加热时,这些化合物分解成四个(Gd、Tb、Ho至Lu、Y)或五个(Eu、Dy)步骤。它们在第一步失去结晶
水,然后在高达1200°C的温度下无
水化合物的分解过程中形成相应的氧化物,最终残留物为Tb4O7和Ln2O3(Ln=Eu、Gd、Dy至Lu和Y)。这些化合物(从Eu到Lu和Y)的脱
水焓分别为:65.77、55.63、86.89、121.65、99.80、109.59、131.02、119.78、205.46和83.11 kJ mol-1。