In order to explore new application opportunities of Barium Strontium Titanate (BST) ceramic composite by modifying the conventional ferroelectric properties of BST through La<sub>2</sub>O<sub>3</...In order to explore new application opportunities of Barium Strontium Titanate (BST) ceramic composite by modifying the conventional ferroelectric properties of BST through La<sub>2</sub>O<sub>3</sub> doping in BST matrix sintered at different temperature was investigated in this current study. Unadulterated Ba<sub>0.3</sub>Sr<sub>0.7</sub>TiO<sub>3</sub> (BST) matrix was prepared from BaTiO<sub>3</sub> (99.95%) and SrTiO<sub>3</sub> (99.95%) taken in stoichiometric extents which later doped by La<sub>2</sub>O<sub>3</sub> (99.99%) in varying extents (0.05 g, 0.10 g and 0.15 g) exploiting solid state reaction route. Doping caused drag effect for the penetration of impurities and sintering temperature helped the impurities migration to BST. Dielectric constant gets lower with rising of frequency, as electrons do not get enough time to polarize at high frequency. Dielectric constant and conductance are found maximum for the sample (0.1 g La<sub>2</sub>O<sub>3</sub> doped BST) sintered at 1460<span style="white-space:nowrap;">°</span>C and reverse is found in impedance analysis. These electrical properties showed visible frequency dependent response irrespective of sintering temperature and doping.展开更多
Composite ceramics of 0.7BaO·0.3SrO·(1-y)TiO2·yNb2O5 (BSTN) with coexistence of barium strontium titanate, Ba1-xSrxTiO3 (BST), and strontium barium niobate, SrxBa1-xNb2O6 (SBN) phases were successfully ...Composite ceramics of 0.7BaO·0.3SrO·(1-y)TiO2·yNb2O5 (BSTN) with coexistence of barium strontium titanate, Ba1-xSrxTiO3 (BST), and strontium barium niobate, SrxBa1-xNb2O6 (SBN) phases were successfully prepared in situ by controlling excess components according to a specially designed formula of 0.7BaO·0.3SrO·(1-y)TiO2·yNb2O5 and by using a traditional ceramic process. X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersion spectrometer (EDS) were used to characterize the phase composition, morphology and the micro-area chemical composition of the composite ceramics. The results showed that the SBN tungsten bronze phase appeared and coexisted stably with the BST perovskite phase when the excess content of Nb2O5 was >6mol%, whereas the BST perovskite phase formed and coexisted stably with the SBN tungsten bronze phase when the excess content of TiO2 was >5.3mol%. In the case of the two phases being equivalent to each other in BSTN composite ceramics, Nb2O5 was hard to be resolved into the perovskite phase, however, a few of TiO2 was easy to be resolved in the tungsten bronze phase. The microstructure of the composite ceramics were consisted of two kinds of grains. The smaller polygonal grains were belonged to the BST phase, and the larger ones to the SBN phase. The coexistence of the two phases inhibited the growth of the BST crystal. The density of microstructure of the composite ceramic was higher than that of both the pure BST and SBN calcined at the same temperature for the same time.展开更多
Perovskite Ba 0 5 Sr 0 5 Co 0 8 Fe 0 2 O 3- δ oxide is a novel stable oxygen permeable material, which can transfer oxygen by lattice oxygen and electrons. The membrane reactor made of perovskite Ba 0 5 Sr 0 5 Co 0 8...Perovskite Ba 0 5 Sr 0 5 Co 0 8 Fe 0 2 O 3- δ oxide is a novel stable oxygen permeable material, which can transfer oxygen by lattice oxygen and electrons. The membrane reactor made of perovskite Ba 0 5 Sr 0 5 Co 0 8 Fe 0 2 O 3- δ was applied to propane oxidative dehydrogenation (PODH), and it was found that the membrane material can increase the conversion of propane and the selectivity for propylene in the PODH reaction. At the same time, the PODH reaction can promote formation of more oxygen defects in the material and increase the oxygen permeability of the membrane at high temperature.展开更多
采用直接沉淀法制备了顺电体钛酸锶钡(Ba_(0.6)Sr_(0.4)TiO_3)纳米粉体,用钛酸酯偶联剂将Ba_(0.6)Sr_(0.4)TiO_3纳米粉体改性后与聚偏氟乙烯(PVDF)进行物理共混制备Ba_(0.6)Sr_(0.4)TiO_3/PVDF复合材料薄膜。XRD图谱分析表明,Ba_(0.6)Sr...采用直接沉淀法制备了顺电体钛酸锶钡(Ba_(0.6)Sr_(0.4)TiO_3)纳米粉体,用钛酸酯偶联剂将Ba_(0.6)Sr_(0.4)TiO_3纳米粉体改性后与聚偏氟乙烯(PVDF)进行物理共混制备Ba_(0.6)Sr_(0.4)TiO_3/PVDF复合材料薄膜。XRD图谱分析表明,Ba_(0.6)Sr_(0.4)TiO_3粉体晶相皆为立方相,经TEM分析发现颗粒形貌呈球形,粒径约为50 nm,分散性好。在低比例纳米Ba_(0.6)Sr_(0.4)TiO_3粉体掺入下,复合材料的介电常数和击穿场强与纯PVDF相比有显著提高,在粉体的含量约为7vol%时,材料的介电常数为12,击穿场强达到289 k V/mm,储能密度最大。展开更多
文摘In order to explore new application opportunities of Barium Strontium Titanate (BST) ceramic composite by modifying the conventional ferroelectric properties of BST through La<sub>2</sub>O<sub>3</sub> doping in BST matrix sintered at different temperature was investigated in this current study. Unadulterated Ba<sub>0.3</sub>Sr<sub>0.7</sub>TiO<sub>3</sub> (BST) matrix was prepared from BaTiO<sub>3</sub> (99.95%) and SrTiO<sub>3</sub> (99.95%) taken in stoichiometric extents which later doped by La<sub>2</sub>O<sub>3</sub> (99.99%) in varying extents (0.05 g, 0.10 g and 0.15 g) exploiting solid state reaction route. Doping caused drag effect for the penetration of impurities and sintering temperature helped the impurities migration to BST. Dielectric constant gets lower with rising of frequency, as electrons do not get enough time to polarize at high frequency. Dielectric constant and conductance are found maximum for the sample (0.1 g La<sub>2</sub>O<sub>3</sub> doped BST) sintered at 1460<span style="white-space:nowrap;">°</span>C and reverse is found in impedance analysis. These electrical properties showed visible frequency dependent response irrespective of sintering temperature and doping.
文摘Composite ceramics of 0.7BaO·0.3SrO·(1-y)TiO2·yNb2O5 (BSTN) with coexistence of barium strontium titanate, Ba1-xSrxTiO3 (BST), and strontium barium niobate, SrxBa1-xNb2O6 (SBN) phases were successfully prepared in situ by controlling excess components according to a specially designed formula of 0.7BaO·0.3SrO·(1-y)TiO2·yNb2O5 and by using a traditional ceramic process. X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersion spectrometer (EDS) were used to characterize the phase composition, morphology and the micro-area chemical composition of the composite ceramics. The results showed that the SBN tungsten bronze phase appeared and coexisted stably with the BST perovskite phase when the excess content of Nb2O5 was >6mol%, whereas the BST perovskite phase formed and coexisted stably with the SBN tungsten bronze phase when the excess content of TiO2 was >5.3mol%. In the case of the two phases being equivalent to each other in BSTN composite ceramics, Nb2O5 was hard to be resolved into the perovskite phase, however, a few of TiO2 was easy to be resolved in the tungsten bronze phase. The microstructure of the composite ceramics were consisted of two kinds of grains. The smaller polygonal grains were belonged to the BST phase, and the larger ones to the SBN phase. The coexistence of the two phases inhibited the growth of the BST crystal. The density of microstructure of the composite ceramic was higher than that of both the pure BST and SBN calcined at the same temperature for the same time.
文摘Perovskite Ba 0 5 Sr 0 5 Co 0 8 Fe 0 2 O 3- δ oxide is a novel stable oxygen permeable material, which can transfer oxygen by lattice oxygen and electrons. The membrane reactor made of perovskite Ba 0 5 Sr 0 5 Co 0 8 Fe 0 2 O 3- δ was applied to propane oxidative dehydrogenation (PODH), and it was found that the membrane material can increase the conversion of propane and the selectivity for propylene in the PODH reaction. At the same time, the PODH reaction can promote formation of more oxygen defects in the material and increase the oxygen permeability of the membrane at high temperature.
文摘采用直接沉淀法制备了顺电体钛酸锶钡(Ba_(0.6)Sr_(0.4)TiO_3)纳米粉体,用钛酸酯偶联剂将Ba_(0.6)Sr_(0.4)TiO_3纳米粉体改性后与聚偏氟乙烯(PVDF)进行物理共混制备Ba_(0.6)Sr_(0.4)TiO_3/PVDF复合材料薄膜。XRD图谱分析表明,Ba_(0.6)Sr_(0.4)TiO_3粉体晶相皆为立方相,经TEM分析发现颗粒形貌呈球形,粒径约为50 nm,分散性好。在低比例纳米Ba_(0.6)Sr_(0.4)TiO_3粉体掺入下,复合材料的介电常数和击穿场强与纯PVDF相比有显著提高,在粉体的含量约为7vol%时,材料的介电常数为12,击穿场强达到289 k V/mm,储能密度最大。
