极性钙钛矿氧化物BiInO 3和BiZn 1/2 Ti 1/2 O 3之间的固溶体,以Bi 3+和B位(In和Zn 1/2 Ti 1/2)的原子位移为自发电研究了极化。观察到极性正交于非极性斜方转变伴随着具有恒定体积收缩负热膨胀(NTE)X在BiIn中≤0.3 1- X的Zn X / 2的Ti X / 2 ö 3。电极化相对于A位Bi 3+的相对位移到B位离子降低了转变温度,并在较宽的温度范围内实现了NTE,同时抑制了温度滞后。此外,新的的LiNbO 3被发现为0.4≤型相X ≤0.8与铁弹和压电行为,具有一个非常高的开关应变,并展示用于增强的磁畴壁的移动性的潜力。
in the nanocomposites was proved by Fourier-transforming infrared spectroscopy. UV–Vis diffusive reflection spectra indicated that the absorption edge of the nanocomposites shifted towards the visible region. The photocatalytic activity of the composites was tested through the photocatalytic degradation of methyl blue under simulated solar irradiation. The results showed that the photocatalytic activity
Chromenopyridines are an important class of compound because of their diverse biological activities. In the present work, we have developed convenient route for the synthesis of chromeno[4,3-b] pyridine derivatives (3a–e, 5a–e, and 7a–d) by Friedlander condensation of 4-amino-2-oxo-2H-chromene-3-carbaldehyde with various activemethylenecompounds. We have used mixed metal oxide catalyst such as nanomaterial
Chromenopyridines 是一类重要的化合物,因为它们具有多种生物活性。在目前的工作中,我们已经开发了便利的途径用于合成色烯并[4,3-的b ]吡啶衍生物(3a中- ë,5A - ë,和图7a - d由4-氨基-2-氧代的弗里德兰德缩合) 2小时-色烯-3-甲醛与各种活性亚甲基化合物。我们使用了混合金属氧化物催化剂,如纳米材料钛酸锌。反应是针对各种溶剂体系进行的,我们也改变了催化剂的浓度。就收率和反应速率而言,2-丙醇/水溶剂体系和5 mol%催化剂浓度是最佳的。合成化合物的结构经1 H NMR、13 C NMR、质谱和元素分析确证。
Aerogel processing of MTi2O5 (M=Mg, Mn, Fe, Co, Zn, Sn) compositions using single source precursors: synthesis, characterization and photocatalytic behavior
作者:P.N. Kapoor、S. Uma、S. Rodriguez、K.J. Klabunde
DOI:10.1016/j.molcata.2004.11.008
日期:2005.3
source precursor by the condensation reaction of Ti(OPrn)4 with M(OAc)2, followed by their (M[OTi(OPrn)3]2) hydrolysis and drying under supercritical conditions by a modified aerogel process. Product compositions, oxide structure types, and morphology were characterized by powder X-ray diffraction, scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDXA), and BET surface area measurements
通常使用基于TiO 2(带隙为3.2 eV)的氧化物半导体光催化剂在UV照射下破坏有机物。目前,我们一直致力于纳米晶体光催化剂的气凝胶合成,其将利用可见光和紫外线辐射破坏诸如乙醛之类的有机化合物。本文中,我们报告了尝试合成MTi 2 O 5型(M = Mg,Mn,Fe,Co,Zn和Sn)混合金属氧化物的结果。制备方法涉及通过Ti(OPr n)4与M(OAc)2的缩合反应,然后是它们的(M [OTi(OPr n)3 ] 2的形成,形成单一来源的前体)通过改进的气凝胶工艺在超临界条件下水解和干燥。通过粉末X射线衍射,具有能量色散X射线分析(EDXA)的扫描电子显微镜(SEM)和BET表面积测量来表征产品组成,氧化物结构类型和形态。仅对于Mg,获得了具有化学假板钛矿结构类型的化学计量MgTi 2 O 5,而对于M = Fe,Co和Zn,获得了复合材料MTiO 3 / TiO 2。这些复合氧化物的光催化行为是通过在紫外光(320
Synthesis and Characterization of (Zn,Cd)TiO<sub>3</sub>by a Modified Sol–Gel Method
Ilmenite‐type (Zn1−xCdx)TiO3 (0≤x≤0.15 and 0.8≤x≤1.0) was synthesized by a modified sol–gel route including the Pechini process via two‐step heat treatments. The thermal stability of (Zn1−xCdx)TiO3 depended on the amount of cadmium content. The as‐synthesized (Zn1−xCdx)TiO3 (0≤x≤0.15 and 0.8≤x≤1.0) showed higher thermal stability than that of ZnTiO3. The variation of the dielectric constant of all synthesized (Zn1−xCdx)TiO3 samples for all measurement frequencies showed a similar tendency. The dielectric constant of each (Zn1−xCdx)TiO3 sample decreased first with increasing frequencies and then increased slightly when the frequency was up to 107 Hz. Moreover, the dielectric loss tangent of all synthesized (Zn1−xCdx)TiO3 samples for all measurement frequencies also changed in similar patterns. The dielectric loss tangent decreased with increasing measurement frequencies. The microwave dielectric properties of (Zn1−xCdx)TiO3 were changed with the cadmium doping content in the range of microwave frequency.
**颜色类型 (Zn1−xCdx)TiO3 (0 ≤ x ≤ 0.15 和 0.8 ≤ x ≤ 1.0) 是通过一种改进的溶胶-凝胶法(包括Pechini过程)通过两步热处理合成的。Zn1−xCdx TiO3的热稳定性取决于镉含量的多少。所合成的 (Zn1−xCdx)TiO3 (0 ≤ x ≤ 0.15 和 0.8 ≤ x ≤ 1.0)表现出比 ZnTiO3更高的热稳定性。所有合成的 (Zn1−xCdx)TiO3样品的介电常数随测量频率的变化显示出相似的趋势。每个 (Zn1−xCdx)TiO3样品的介电常数随频率增加而首先减小,然后在频率达到 107 Hz 时略微增加。此外,所有合成的 (Zn1−xCdx)TiO3样品的介电损耗角正切随测量频率的变化也呈现出相似的规律。介电损耗角正切随测量频率的增加而减小。微波频率范围内镉掺杂含量的变化会影响 (Zn1−xCdx)TiO3的微波介电性能。**
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Sol–gel synthesis of ZnTiO3 using a single-source precursor based on p-carboxybenzaldehyde oxime as a linker
ZnTiO3 was synthesized by solâgel processing using a single-source precursor in which the two metal atoms are linked by means of p-carboxybenzaldehyde oxime. According to spectroscopic investigations, the COOH group is coordinated to Zn2+ and the oximate group to a Ti(OiPr)3 moiety. The temperature-dependent structure evolution of ZnTiO3 was investigated to illustrate the advantage of this approach compared to materials prepared from two individual precursors (zinc benzoate and oximate-modified Ti(OiPr)4). ZnTiO3 prepared from the single-source precursor has a more homogeneous structure through all stages of the synthesis process and a higher surface area. The latter results in a higher activity in the photocatalytic degradation of methylene blue.