C. Y. Ban
,
J.Z. Cui
,
Q.X. Ba
金属学报(英文版)
The structures and macro-segregation of 2124 Al-alloy were studied when a pulsedmagnetic field (PMF) was applied during solidification. It is found through experi-ments that a remarkable change occurs in the solidification structures of 2124 Al-alloyunder pulsed magnetic field. The eutectic phase at grain boundaries change from thickcontinuous eutectic network to thin discontinuous one, and the distribution of soluteelements was also homogenized. The typical negative segregation phenomenon of Cu incommon solidification condition was restrained, and the segregation of Mg decreased.
关键词:
aluminium alloy
,
null
,
null
,
null
Journal of Applied Physics
The crystal structure and superconducting properties of RuSr(2-x)Ba(x)GdCu(2)O(8) (0less than or equal toxless than or equal to0.1) have been investigated. X-ray powder diffraction (XRD) patterns show that the solid solution range is 0less than or equal toxless than or equal to0.1. The superconducting transition temperature was raised up to 35 K (zero) and 62 K (onset) for x=0.07, from 16 K (zero) and 45 K (onset) for x=0.0, and then T(C) decreases with x when x>0.07. Rietveld refinement for XRD data of RuSr(2-x)Ba(x)GdCu(2)O(8) show that the apical Cu-O(1) bond length increases with an increase of x, while the Ru-O(1) bond length decreases, This may account for the enhancement of the superconducting transition temperature. (C) 2004 American Institute of Physics.
关键词:
dc magnetization;rusr2gdcu2o8;ferromagnetism;coexistence;gd
刘林
,
方有维
,
邓新峰
,
庄文东
,
唐斌
,
张树人
无机材料学报
doi:10.3724/SP.J.1077.2012.00281
采用固相反应法制备了(Ba1-xSrx)La4Ti4O15(x=0.8~0.95)复合体系微波介质陶瓷, 并对其进行物相组成、晶体结构分析以及微波介电性能的研究. 研究结果表明, (Ba1-xSrx)La4Ti4O15陶瓷主晶相为SrLa4Ti4O15, 并伴随有第二相SrLa8Ti9O15. SEM观察表明, Ba0.2Sr0.8La4Ti4O15陶瓷内部微观结构致密, 晶粒尺寸在10~20 μm之间, 晶界清晰. 随着x值逐渐增大, (Ba1-xSrx)La4Ti4O15陶瓷中晶粒形态发生变化, 气孔增多. 在x=0.8时, (Ba1-xSrx)La4Ti4O15陶瓷具有优良的微波介电性能, 即εr =40.86, Q×f≈62806 GHz, τf =-20×10-6/℃. 随着Ba2+的含量逐渐增加, 该陶瓷的介电常数εr单调上升, 品质因子Q×f值增加, 说明适量的Ba2+替代Sr2+能改善陶瓷的微波介电性能.
关键词:
微波介质陶瓷
,
perovskite-like structure
,
microwave dielectric property
,
SrLa4Ti4O15
刘林
,
方有维
,
邓新峰
,
庄文东
,
唐斌
,
张树人
无机材料学报
doi:10.3724/SP.J.1077.2012.00281
采用固相反应法制备了(Ba1-xSrx)La4Ti4O15(x=0.8～0.95)复合体系微波介质陶瓷,并对其进行物相组成、晶体结构分析以及微波介电性能的研究.研究结果表明,(Ba1-xSrx)La4Ti4O15陶瓷主晶相为SrLa4Ti4O15,并伴随有第二相SrLa8Ti9O15.SEM观察表明,Ba0.2Sr0.8La4Ti4O15陶瓷内部微观结构致密,晶粒尺寸在10～20 μm之间,晶界清晰.随着x值逐渐增大,(Ba1-xSrx)La4Ti4O15陶瓷中晶粒形态发生变化,气孔增多.在x=0.8时,(Ba1-xSrx)La4Ti4O15陶瓷具有优良的微波介电性能,即εr=40.86,Q×f≈62806 GHz,τf=-20×10-6/℃.随着Ba2+的含量逐渐增加,该陶瓷的介电常数εr单调上升,品质因子Q×f值增加,说明适量的Ba2+替代Sr2+能改善陶瓷的微波介电性能.
关键词:
微波介质陶瓷
,
类钙钛矿结构
,
微波介电性能
,
SrLa4Ti4O15
原子核物理评论
研究了高电荷态离子~(40)Ar~(q+)(q＝7-14)轰击金属Au表面产生的特征X射线谱.实验结果表明,在弱束流(nA量级)的情况下,对于动能相同的入射离子,当电荷态比较高(q＝11)时,便能有效地激发靶原子的特征X射线,单离子的X射线产额高达10~(-8)量级.分析结果显示,入射离子的势能、动能和这种相互作用特有的镜像相互作用势能沉积在靶表面,使靶原子内壳层电子激发和电离,形成空穴和产生外壳层电子填充空穴辐射特征X射线,特征X射线的产额随入射离子的势能(电荷态)的增加而增加.
关键词:
高电荷态离子
,
X射线
,
产额
刘丽华
,
宋奔升
,
栗峰
,
王镇
,
潘浩瀚
,
李阳
无机材料学报
doi:10.15541/jim20140403
采用电弧炉熔炼、球磨、放电等离子烧结的方法合成了系列第 I 类笼状化合物 Ba8Ga15XSi30(X=Ga、Zn、Cu)。研究了Zn、Cu对Ga的替代对材料结构以及热电性能的影响。结果表明,相比于Ba8Ga16Si30, Zn、Cu的掺杂使得样品的晶格常数减小,热导率降低, Seebeck系数的绝对值增大,ZT值有明显的升高。
关键词:
I类笼状化合物
,
晶格常数
,
热电性能
孙彩霞
,
高景霞
,
张金平
,
王二萍
,
张洋洋
硅酸盐通报
采用固相反应制备了（1－x）Ba3（VO4）2-xLi2MoO4微波介质陶瓷，研究了掺入不同质量比的Li2MoO4对Ba3（VO4）2的微观结构和微波介质性能影响，X线衍射（XRD）测试结果表明，Ba3（VO4）2和Li2MoO4二者兼容性良好，无第二相产生。添加具有低熔点及相反（负）频率温度系数的Li2 MoO4能有效降低Ba3（ VO4）2的烧结温度，并随着添加剂Li2 MoO4的增加，此复合陶瓷的相对体密度、介电常数εr 和品质因数Q ×f呈现出先增加随后又降低的趋势，而谐振频率里面温度系数τf逐渐降低。当烧结温度为660℃且添加量30wt％Li2 MoO4的复合微波介质陶瓷获得了最佳的微波介电性能：εr ＝11．99， Q ×f＝39700 GHz，τf ＝－24 ppm／℃。
关键词:
低温烧结
,
Ba3(VO4)2
,
Li2MoO4
,
微波介质陶瓷
Physical Review B
We prepare a series of polycrystalline Sr(0.9-x)Ba(0.1)Ca(x)TiO(3) (SBCT) with relatively low Ba- and Ca-doping levels, and their microstructural, ferroelectric, dielectric, and lattice dynamic properties are investigated. It is surprisingly found that a proper Ca(2+) doping, which usually favors the antiferroelectric state in SrTiO(3), can remarkably enhance the ferroelectricity of SBCT. The coupling and competition between the ferroelectric state induced by Ba(2+) doping and antiferroelectric state induced by Ca(2+) doping lead to a sequence of multipolarized states, such as the enhanced polarization state, the cooperative polarization state, and the antiferroelectric state.
关键词:
strontium-titanate;phase-diagram;sr1-xcaxtio3;perovskites
Applied Physics a-Materials Science & Processing
The Pr(1+x)Ba(2-x)Cu(3)O(7+/-delta) solid solution was investigated by means of X-ray powder diffraction combined with Rietveld analysis. A Pr123 single phase could be synthesized under Pr-rich conditions by sintering at 950 degreesC in air. The solubility range of Pr(1+x)Ba(2-x)Cu(3)O(7+/-delta) solid solution is 0.08 less than or equal to x less than or equal to 0.80. The structure of Pr(1+x)Ba(2-x)Cu(3)O(7+/-delta) for 0.08 less than or equal to x less than or equal to 0.30 is orthorhombic. The structure transforms into tetragonal for 0.30 less than or equal to x less than or equal to 0.80. To form the Pr123 single phase, the Ba sites in the Pr123 structure must have partial Pr ions, and the least amount is x = 0.08. Ba ions cannot occupy the sites of Pr ions. In the Pr123 structure, Ca ions can replace Pr ions; the highest value is x = 0.4 in the PrBa(2-x)Ca(x)Cu(3)O(7+/-delta) system under our experimental conditions. However, Ca ions cannot replace B a ions. The ionic radius plays a more important role than the chemical properties in the substitution between Pr, Ba and Ca ions in the Pr123 structure.
关键词:
cu-o system;approximately 950-degrees-c;superconductivity;diagram;pr;growth;nd;prba2cu3o7-delta;praseodymium;property
高旭芳
,
丘泰
中国有色金属学报
采用传统固相反应法制备Ba6-3x(La1-mBim)8+2x(Ti0.95Zr0.05)18O54(x=2/3)微波介质陶瓷,研究Bi掺杂对Ba6-3xLa8+2x(Ti0.95Zr0.05)18O54(x=2/3)陶瓷的烧结性能、微观结构以及介电性能的影响.结果表明:当0＜m＜0.4时,Bi3+取代A1位的La3+生成单相类钨青铜型固溶体;当Bi3+的掺杂量超过这个范围时,La0.176Bi0.824O1.5作为第二相出现在固溶体中;Bi3+的掺入使Ba6-3xLa8+2x(Ti0.95Zr0.05)18O54(x=2/3)陶瓷的烧结温度从1 400 ℃降低到1 300 ℃,同时,其介电常数大幅度提高,谐振频率温度系数减小,但品质因数急剧减小;当m=0.05时,1 350 ℃下保温2 h烧结获得的陶瓷具有微波介电性能,εr=88.63,Q·f=4 395 GHz,τf=6.25×10-6/℃.
关键词:
介电性能
,
Bi掺杂
,
微波介质陶瓷
,
类钨青铜结构
