Enthalpy of Fusion of PbO.2B2O3
Enthalpy of Fusion of PbO.2B2O3
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PbO.2B2O3 的熔化焓
DOI：
10.1111/j.1151-2916.1968.tb11907.x
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发表时间：
1968
期刊：
影响因子：
--
通讯作者：
R. Eagan
中科院分区：
文献类型：
--
作者：
J. M. Ricker;C. Bergeron;R. Eagan
He的熔化焓Pb 0. 2B203通过T定量差热分析b 2测定，使用铂样品架，每个样品架包含一个热电偶井，从底部突出到样品腔的中点。该装置用KC 1校准（mp 772 ° C，AHfusion = 84.5卡/克）。3通过测量试剂级NaCl和KI的熔化率来验证校准;测量值分别在公布值的± 2%内，± 116.4和33.7 cal/g。2B2O3晶体通过使组成为Pb0. BBe03处理4小时是其最大生长速率的温度。其他样品是从悬浮在过冷熔体中的铂丝中生长出的晶体聚集体。通过X-射线衍射分析确认了晶体种类。DTA单元以4.2 ℃/min的线性加热速率操作。所有样品研磨至-60 +100目。从热谱图中切下吸热峰下的面积，在分析天平上称重，并等同于与反应相关的焓变。Pb0. 2B208和KCl如图1所示。由粉末状玻璃制备的PbO * 2B2O3晶体的熔化焓的连续测定得到86.8和86.3 cal/g的值。由熔体生长的晶体得到87.6卡/克的值。平均值为86.9卡/克
HE enthalpy of fusion of Pb0. 2B203 was determined by T quantitative differential thermal analysisb2 using platinum sample holders each containing a thermocouple well which projected froin the bottom to the midpoint of the sample cavity. The apparatus was calibrated with KC1 (mp 772 “C, AHfusion= 84.5 cal/g). 3 The calibration was verified by measuring the enthalpies of fusion of reagent grade NaCl and KI; measured values agreed within i 2% of published value^,^ 116.4 and 33.7 cal/g, respectively.In one case the PbO. 2B203 crystals were prepared by devitrifying a finely-ground glass of the composition Pb0. BBe03 for 4 hr mar its temperature of maximum growth rate. Other samples were grown as an aggregate of crystals from a platinum wire suspended in the supercooled melt. Confirmation of the crystalline species was obtained by X-ray diffraction analysis. The DTA unit was operated at a linear heating rate of 4.2 ‘C/min. All samples were ground to-60+ lo0 mesh. The areas under the endotherms were cut from the thermogram, weighed on an analytical balance, and equated to the enthalpy changes associated with the reactions. The thermograms for Pb0. 2B208 and KCl are shown in Fig. 1. Successive determinations of the enthalpy of fusion of the PbO* 2B203 crystals prepared from powdered glass yielded values of 86.8 and 86.3 cal/g. A value of 87.6 cal/g resulted from the crystals which were grown from the melt. The average value was 86.9 cal/g