排序方式: 共有29条查询结果,搜索用时 15 毫秒
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A new niobate compound with the chemical composition of Ba5LiTiNb9O30 was synthesized by doping Li^ into the system BaO-TiO2-Nb2O5 in conventional solid state reaction method. The crystalline structure was determined by X-ray diffraction analysis (XRD). The results showed that crystal structure of Ba5LiTiNb9O30 belongs to tetragonal tungsten bronze structure with space group P4bm and its unit cell parameters: a=b=1.2512(2) nm, c=0.4008(5)nm. The microstructure of reaction products was observed by scanning electron microscopy (SEM). 相似文献
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用改造的重叠模型多重散射X~α自洽场方法计算环芳类化合物[2~3]cyclophanes的电子结构, 分析该类分子中分子轨道通过空间和通过键的相互作用,单键连接桥.双键连接桥对通过键相互作用的影响, 用过渡态理论方法计算分子前线分子轨道的电离能,理论结果与紫外光电子能谙符合较好. 相似文献
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钨青铜结构Ba6Zn0.67M9.33O30(M=Nb,Ta)的合成与介电特性 总被引:1,自引:0,他引:1
Two compounds Ba6Zn0.67M9.33O3 and Ba6Zn0.67M9.33O30 with tungsten bronze structure were synthesized in the BaO-ZnO-Nb2O5/Ta2O5 systems by the conventional high temperature solid-state reaction.The structure and dielectric properties of Ba6Zn0.67M9.33O3 and Ba6Zn0.67M9.33O30 were determined by X-ray powder diffraction,scanning electron microscope and dielectric measurements.The results show that Ba6Zn0.67M9.33O30 belongs to paraelectric phase of fully filled tetragonal tungsten bronze structure at room temperature with unit cell parameters a:1.26256(4) nm, c:0.39698(2) nm. The room temperature dielectric constant (ε) of Ba6Zn0.67M9.33O30 ceramic reached 108 combined with a low dielectric loss of 0.005 at 1 MHz. While Ba6Zn0.67M9.33O3 belongs to fully filled tetragonal tungsten bronze structure at room temperature with the unit cell parameters a:1.25940 (3) nm, c=0.40008(2) nm. Ba6Zn0.67M9.33O30 ceramic shows significant relaxor behaviors, and the phase transition from ferroelectric to paraelectric occurred at 55℃ (at 1 MHz). The room temperature dielectric constant (ε) of ceramic reached 570 at 1 MHz. 相似文献
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熔盐法制备SrTiO3片状晶的研究 总被引:4,自引:0,他引:4
采用熔盐法(MSS)合成了片状SrTiO3晶体,主要由两个步骤来完成,首先在助熔剂KCl中合成片状前驱体Sr3Ti2O7,然后再通过SrTiO3生长基元在第一步获得的片状晶体Sr3Ti2O7上进行生长制备出片状SrTiO3.采用扫描电镜(SEM)、 X射线衍射(XRD)分析产物的显微结构,表明熔盐法制备的SrTiO3具有纯度高、明显的片状结构等特点,在1200℃下保温4 h,产物的衍射指标与钛酸锶的标准图谱基本上完全一致.1200℃下保温2 h获得的片状钛酸锶晶粒尺寸基本上符合要求(长10~15 μm),而时间延长后,在1200℃下保温4 h获得的钛酸锶晶粒尺寸达到40 μm以上.常规固相合成SrTiO3具有球状显微结构. 相似文献
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