共查询到18条相似文献,搜索用时 375 毫秒
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在BaF2-InF3系统中存在一个萤石型固溶体Ba1-xInxF2+x(03(InF6)2和BaInF5。测定了系统中各个相的电导率并和BaF2-BiF3系统进行比较。讨论了阳离子极化性和晶体共价性对电性能的影响。
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用固相反应法、X射线粉末衍射技术和复平面阻抗谱测量研究了BaF2-BiF3系统的相组成和离子电导。在此系统中发现了两种类型的Ba1-xBixF2+x固溶体:萤石型(0s≈0.5(141/2)aF,cs<
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系统研究了铁磁性形状记忆合金Mn2 -xNiGa1+x的结构、磁性和有序化转变. 研究表明: 随着Ga含量的增加, Mn2 -xNiGa1+x的母相结构由Hg2CuTi 型逐渐转变到Cu2MnAl型Heusler结构. 母相的晶格常数先增加后降低, 当x=0.3时达到最大值. 0.3 ≤x ≤0.8时, 材料除呈现Heusler结构的主相之外, 还出现了Ni2In型六角相. 过渡金属中3d电子之间交换相互作用的减弱, 导致Mn2-xNiGa1+x主相的居里温度由Mn2NiGa的590 K逐渐降低至Ga2MnNi的220 K左右; 当x=0.6–0.8时, Ni2In型六角相的居里温度与主相的居里温度出现分离. Ga对Mn的替代引起合金中原子间耦合作用的变化, 导致低温下Mn2 -xNiGa1+x的饱和磁化强度先增加后降低, 即x≤0.4时呈上升趋势, x>0.4时急剧下降. 差热分析结果显示, 随着x从0增加到1, 样品熔化温度逐渐降低, B2相到Heusler相的转变温度先降低后增加. 相似文献
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采用高温固相法,通过阳离子替代的实验策略,制备出系列窄带发射且颜色可由深黄色调至绿色的K2-xNaxZn0.94SiO4∶0.06Mn2+(0≤x≤2)荧光粉。用X射线粉末衍射仪对样品的物相进行表征,通过扫描电子显微镜和能量色散谱测试对样品的形貌和元素分布进行分析。结果表明,成功地合成了纯相且元素分布均匀的K2-xNaxZn0.94SiO4∶0.06Mn2+(0≤x≤2)荧光粉。在蓝光激发下,随着Na+离子逐渐代替K+离子,K2-xNaxZn0.94SiO4∶0.06Mn2+(0≤x≤2)荧光粉的发光强度逐渐增强,原荧光粉的发光强度得到有效提高的同时发光颜色由深黄色调至绿色。在427 nm激光的激发下:当x=0.8时,... 相似文献
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本文研究了a-Fe90-xCoxZr10(x=4,10,20,…,70)和Fe90-yCryZr10(y=0,4,7,16,20)系列合金的M?ssbaner谱。实验结果表明a-Fe90-yCoyZr10和富Fe区(x<30)的a-Fe90-xCoxZr10
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以Nd(Ⅲ)作为放射性核素An(Ⅲ)的模拟替代物,以Gd2O3和ZrO2粉体为原料,通过高温固相反应法(1500℃,保温72 h)合成了Gd2-xNdxZr2O7(0≤x≤2.0)微米级的钆锆烧绿石固化An(Ⅲ)的模拟固化体.利用X射线衍射仪、显微硬度计和扫描电子显微镜等对所制备样品的物相、密度、维氏硬度和微观形貌进行了表征.结果表明:Gd2-xNdxZr2O7(0≤x≤2.0)系列固化体样品多呈板状,均为烧绿石相;其密度值随固溶量x值的增加,呈逐渐下降趋势,但均≥5.76 g·cm-3.固化体的维氏硬度值(Hv)随x值的递增呈逐渐减小趋势,x值与维氏硬度值之间满足Hv=695.18636-162.64091 x的线性关系,但维氏硬度值均≥400kg·mm-2以上. 相似文献
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本文研究了C-15结构化合物(Zr0.5Hf0.5-xTax)V2(x≤0.2)和(Hf0.5Zr0.5-xNbx)V2(x≤0.2)的超导转变温度Tc及其压力效应?Tc/?P。报道了实验方法与结果。与(Hf1-xTax)V2和(Zr1-xTax)V2的情况不同,在(Zr0.5Hf0.5-xTax)V2中Ta的引入使常压下的Tc下降,然而(?)Tc/(?)P却大为提高。因此高压下Zr0.5Hf0.45Ta0.05V2的Tc反而比Hf0.5Zr0.5V2更高。导出了一个基于角动量分波表象能带论方法的描述压力效应的新关系式。它指出导带电子波函数中的高角动量成分变化对Tc的压力效应影响比较重要。这个公式有助于理解上述复杂的实验现象,并能合理地解释某些元素(如Cs,Ba,La等)的Tc随压力剧增的事实。
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在-100—200℃温度范围内,测量了(Pb0.97La0.02)(Zr0.65< /sub>Sn0.35-xTix)O3(PZST,0.1≤x≤0.14)反铁电陶 瓷的热膨胀性质.实验结果表明,组分在0.1 ≤x≤0.12的试样室温下为反铁电(AFEt)四方相,热膨胀系数(α)在低温段发生 “弯曲” ,而变温x射线衍射谱(XRD)显示材料保持四方相结构;当Ti含量在0.125≤x≤0.14时,室温 下是铁电三方相(FER),温度升高时FER→AFEt相变体 积收缩,AFEt→立方顺电(PE c)相变体积增大;变温XRD谱证明了材料相结构随温度的转变过程.用多元复杂 化合物存在 纳米线度组分非均匀的观点解释了热膨胀性质随Ti含量演化的物理机理,并得到了该系统的 温度-Ti(x)含量相图.
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热膨胀性质
铁电/反铁电相界
反铁电陶瓷
PZST 相似文献
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We have measured the effect of varying the mobile ion concentration on the sodium ion conductivity in the Hf-Nasicon system, Na1+xHf2SixP3-xO12, for 1.4 ? x ? 2.8. The conductivity is greatest for Na3.2Hf2Si2.2 P0.8O12: σ25°C = 2.3 × 10?3 (ω cm)?1, and σ250°C = 1.7 × 10?1 (ω cm)?1. These values are approximately 50% greater and worse, respectively, than the values reported for the best Zr-Nasicon. We have characterized the variation of lattice parameters with composition and found the behavior to be similar to that of Zr-Nasicon. A small distortion from rhombohedral to monoclinic symmetry occurs for compositions 1.8 ? x ? 2.2. 相似文献
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Materials with the formula Yb2-xAlxMo3O12 (x = 0.1, 0.2, 0.3, 0.4, 0.5, 0.7, 0.9, 1.0, 1.1, 1.3, 1.5, and 1.8) were synthesized and their structures, phase transitions, and hygroscopicity investigated using X-ray powder diffraction, Raman spectroscopy, and thermal analysis. It is shown that Yb2-xAlxMo3012 solid solutions crystallize in a single monoclinic phase for 1.7 〈 x 〈 2.0 and in a single orthorhombic phase for 0.0 〈 x 〈 0,4, and exhibit the characteristics of both monoclinic and orthorhombic structures outside these compositional ranges. The monoclinic to orthorhonlbic phase transition temperature of A12Mo3012 can be reduced by partial substitution of A13+ by Yb3+, and the Yb2-zAlxMo3012 (0.0 〈 x 〈 2.0) materials are hydrated at room temperature and contain two kinds of water species. One of these interacts strongly with and hinders the motions of the polyhedra, while the other does not. The partial substitution of A13+ for Yb3+ in Yb2Mo3012 decreases its hygroscopicity, and the linear thermal expansion coefficients after complete removal of water species are measured to be -9.1 x 10-6/K, -5.5 x 10-6/K, 5.74 x 10-6/K, and 9.5 x 10 6/K for Ybl.sAlo.2(MoO4)3, Yb1.6Alo.4(MoO4)3, Ybo.4All.6(Mo04)3, and Ybo.2Al1.8(MoO4)3, respectively. 相似文献
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X-ray powder diffraction,resistivity and magnetization studies have been performed on polycrystalline Nd(FexMn1-x)2Si2 (0 ≤ x ≤ 1) compounds which crystallize in a ThCr2Si2-type structure with the space group I4/mmm.The field-cooled temperature dependence of the magnetization curves shows that,at low temperatures,NdFe2Si2 is antiferromagnetic,while the other compounds show ferromagnetic behaviour.The substitution of Fe for Mn leads to a decrease in lattice parameters a,c and unit-cell volume V .The Curie temperature of the compounds first increases,reaches a maximum around x = 0.7,then decreases with Fe content.However,the saturation magnetization decreases monotonically with increasing Fe content.This Fe concentration dependent magnetization of Nd(FexMn1-x)2Si2 compounds can be well explained by taking into account the complex effect on magnetic properties due to the substitution of Mn by Fe.The temperature’s square dependence on electrical resistivity indicates that the curve of Nd(Fe0.6Mn0.4)2Si2 has a quasi-linear character above its Curie temperature,which is typical of simple metals. 相似文献
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A detailed study of the transport properties of the disordered fluorite-type solid solution Pb1-xInxF2+x (0 < × < 0.25) and of the ordered fluorite-type related Pb2InF7 (x = 0.333) and Pb7In5F29 (x = 0.417) has been carried out. For x = 0.25 the conductivity is shown to decrease when disordering diminishes as a consequence of annealing. The disordered Pb0.88In0.12F2.12 phase is a fairly good anionic conductor. 相似文献