借助典型的固相反应烧结机制，研究了MgO含量对微波高品质因数瓷介材料微观结构与介电性能参数影响的规律。结果表明：高温烧结的镁钛系瓷介质中，随着MgO含量增加，Mg 2 TiO 4晶相的含量逐渐降低、瓷体晶粒由尖晶石型演变为氯化钠型结...借助典型的固相反应烧结机制，研究了MgO含量对微波高品质因数瓷介材料微观结构与介电性能参数影响的规律。结果表明：高温烧结的镁钛系瓷介质中，随着MgO含量增加，Mg 2 TiO 4晶相的含量逐渐降低、瓷体晶粒由尖晶石型演变为氯化钠型结构，对应的微波介电常数出现缓慢降低，在10.10~13.37范围连续可调。当x=16时，在1525℃/2 h烧成，可获得性能优良的（2＋x）MgO-TiO2陶瓷，其ρ=3.49g·cm–3，εr=10.37，Q·f=118747 GHz（f=10.47 GHz），τf=–53.35×10–6℃–1。展开更多
Novel TiO2/BiVO4 microfiber heterojunctions were constructed using cotton as biomorphic templates. The as-synthesized samples were characterized by scanning electron microscope, X-ray diffraction, X-ray photoelectron ...Novel TiO2/BiVO4 microfiber heterojunctions were constructed using cotton as biomorphic templates. The as-synthesized samples were characterized by scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy, UV-Vis diffuse reflectance spectra and photocatalytic experiment. The morphology of the as-synthesized TiO2/BiVO4 composites was consisted of a large quantity of microfiber structures with diameter from 2.5 gm to 5 μm, and the surface of samples became more coarse and compact with the increase of weight ratio of TiO2. The TiO2/BiVO4 samples with proper content （10.00wt%） showed the highest pho- tocatalytic degradation activity for methylene blue （MB） degradation among all the samples under visible light, and 88.58%MB could be degraded within 150 min. The enhancement of photocatalytic activity was mainly attributed to the formation of n-n heterojunction at the contact interface of TiO2 and BiVO4, which not only narrowed the band gap of BiVO4 for extending the absorption range of visible light, but also promoted the transfer of charge carriers across interface. A possible photodegradation mechanism of MB in the presence of TiO2/BiVO4 microfibrous photocatalyst was proposed.展开更多
基金This work was supported by Program Funded by Sha.anxi Department （No.2013JK0690）, the Scientific Research Provincial Education Fundamental Research Funds of Xianyang Normal University （No. 14XSYK011, No.12XSYK025）, Shaanxi Province Natural Science Foundation （No.2015JQ5188）.
文摘Novel TiO2/BiVO4 microfiber heterojunctions were constructed using cotton as biomorphic templates. The as-synthesized samples were characterized by scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy, UV-Vis diffuse reflectance spectra and photocatalytic experiment. The morphology of the as-synthesized TiO2/BiVO4 composites was consisted of a large quantity of microfiber structures with diameter from 2.5 gm to 5 μm, and the surface of samples became more coarse and compact with the increase of weight ratio of TiO2. The TiO2/BiVO4 samples with proper content （10.00wt%） showed the highest pho- tocatalytic degradation activity for methylene blue （MB） degradation among all the samples under visible light, and 88.58%MB could be degraded within 150 min. The enhancement of photocatalytic activity was mainly attributed to the formation of n-n heterojunction at the contact interface of TiO2 and BiVO4, which not only narrowed the band gap of BiVO4 for extending the absorption range of visible light, but also promoted the transfer of charge carriers across interface. A possible photodegradation mechanism of MB in the presence of TiO2/BiVO4 microfibrous photocatalyst was proposed.
