TEXTURAL EVOLUTION AND PHASE-TRANSFORMATION IN TITANIA MEMBRANES .1. UNSUPPORTED MEMBRANES
TEXTURAL EVOLUTION AND PHASE-TRANSFORMATION IN TITANIA MEMBRANES .1. UNSUPPORTED MEMBRANES
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DOI：
10.1039/jm9930301141
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发表时间：
1993-11-01
影响因子：
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通讯作者：
BURGGRAAF, AJ
中科院分区：
文献类型：
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作者：
KUMAR, KNP;KEIZER, K;BURGGRAAF, AJ
采用差示扫描量热法（DSC）、差示热分析（DTA）、热重法（TG）、x射线衍射（XRD）和氮气吸附法研究了溶胶-凝胶纳米结构无负载二氧化钛膜的结构演变。采用Avrami模型研究了锐钛矿-金红石相变动力学。前驱体凝胶的表面积约为165 m2 g-1，在600℃下热处理8 h后降为零。未掺杂的钛-凝胶层在600℃下煅烧8 h后转化为95%以上的金红石。转化过程中锐钛矿晶体的生长和金红石烧结的增强是导致表面积减少和孔洞增大的原因。氧化镧被认为是将相变温度提高到850℃的合适掺杂剂。与未掺杂的氧化镧相比，氧化镧掺杂的二氧化钛膜具有更好的多孔结构稳定性。
Textural evolution in sol-gel derived nanostructured unsupported titania membranes has been studied using differential scanning calorimetry (DSC), differential thermal analysis (DTA), thermal gravimetry (TG), X-ray diffraction (XRD) and N2 adsorption. The anatase-to-rutile phase transformation kinetics were studied using the Avrami model. The precursor gel had a surface area of ca. 165 m2 g-1, which after heat treatment at 600-degrees-C for 8 h reduced to zero. Undoped titania-gel layers transformed to more than 95% rutile after calcination at 600-degrees-C for 8 h. The causes of surface-area reduction and pore growth were anatase crystallite growth and the enhanced sintering of rutile during transformation. Lanthanum oxide was identified as a suitable dopant for shifting the transformation temperature to ca. 850-degrees-C. Lanthanum oxide doped titania showed an improved stability of porous texture compared to that of the undoped titania membranes.