50MeV/u~(20)Na+~(208)Pb→p+~(19)Ne+~(208)Pb反应的探测效率模拟

用半经典模型考虑20Ｎａ＋２０８Ｐｂ→ｐ＋１９Ｎｅ＋２０８Ｐｂ的Ｃｏｕｌｏｍｂ解离过程。用ＭｏｎｔｅＣａｒｌｏ方法计算前角放置的望远镜阵列对Ｃｏｕｌｏｍｂ解离碎片的探测效率。讨论了天体环境下ｐ＋１９Ｎｅ→２０Ｎａ俘获反应道的低能级共振截面测量的可行性。

Cross-correlation of excitation functions for different fragments and different scattering angles in Al-27(F-19, x)y reactions

Excitation functions have been measured for different projectile-like fragments produced in Al-27(F-19,x)y reactions at incident energies from 110.25 to 118.75 MeV in 250 keV steps. Strong cross section fluctuations of the excitation functions are observed. The cross- correlation coefficients of the excitation functions for different atomic number Z and for different scattering angle theta(cm) have been deduced. These coefficients are much larger than the statistical theoretical calculated ones. This indicates that there are strong correlations between different exit channels in the dissipative heavy ion Collision of Al-27(F-19,x)y.

Largely deformed dinuclear system formed in F-19+Al-27 dissipative collision

Excitation functions are measured for different charge products of the F-19+(27) Al reaction in the laboratory energy range 110.25-118.75MeV in steps of 250keV at theta(lab) = 57 degrees, 31 degrees and -29 degrees. The coherence rotation angular velocities of the intermediate dinuclear systems formed in the reaction are extracted from the cross section energy autocorrelation functions. Compared the angular velocity extracted from the experimental data with the ones deduced from the sticking limit, it is indicated that a larger deformation of the intermediate dinuclear system exists.

Rotation and deformation of the dinuclear system formed in dissipative reaction of F-19+Al-27

Excitation functions of the reaction products B, C, N, O, F and Ne emitted from the dissipative reaction of (19) F+(27) Al have been measured at incident energies from 110.25MeV to 118.75MeV in steps of 250keV. The moments of inertia of the intermediate dinuclear system formed in the reaction are extracted from the energy autocorrelation functions of the products. Comparing the moment of inertia extracted from the experimental data with the calculated one by using the sticking limit, it indicates that the formed dinuclear system has a large deformation in the reaction process.

Non-reproducibility of the cross sections of the products induced from dissipative reaction of F-19+Al-27

The differential cross sections of the dissipative products B, Q N, O, F, Ne, Na and Mg induced from the reactions of F-19+Al-27 at two incident energies have been measured at the HI-13 tandem accelerator, Beijing. In the case of a fixed beam incident energy 114MeV or 118.75MeV respectively, identical reaction system and the same detection system, 20 target points in steps of 2mm on(.)a 10mmx50mm rectangular Al foil have been bombarded. The experimental results indicate that the probability distribution of the cross sections is much wider than a standard Gaussian distribution. This non-reproducibility of the cross sections can't be interpreted by the statistical property of a finite count rate.

Thermal-shock resistance of LnMgAl(11)O(19) (Ln = La, Nd, Sm, Gd) with magnetoplumbite structure

Lanthanide hexaaluminates including LaMgAl11O19, NdMgAl11O19, SmMgAl11O19 and GdMgAl11O19 were synthesized via Sol-Gel method. Due to the anisotropic crystal growth, these oxides crystallize in the form of platelets and the platelet thickness increases with the decrease of rare-earth ionic radius. It was observed that the thermal-shock resistances of LaMgAl11O19, NdMgAl11O19 and SmMgAl11O19 oxides were superior to 8YSZ as proved by water quenching tests. In addition, the thinner the platelet. the more interstices are retained in the sintered specimen, and the better thermal-shock resistance the oxide has. Based on SEM images, it can be seen that the SmMgAl11O19 sample exhibits a mixture of the intergranular and transgranular fracture after thermal cycling failure.

Microstructures and mechanical properties of extruded Mg-8Gd-0.4Zr alloys containing Zn

Microstructures and mechanical properties of the Mg-8Gd-xZn-0.4Zr (x = 0, 1 and 3 wt.%) alloys in the as-cast, as-extruded and extruded-T5 conditions, have been investigated. The peak-aged Mg-8Gd-1Zn-0.4Zr alloy during isothermal ageing at 423 K acquires highest mechanical properties, with the highest ultimate tensile strength and yield tensile strength of 314 and 217 MPa, respectively. Addition of Zn has obvious effect on age hardening responses, especially for 1 wt.% Zn addition. It is due to a uniform distribution of beta' phase which can impede the movement of dislocations. However, addition of 3 wt.% Zn to the Mg-8Gd-0.4Zr alloy leads to a precipitation of Mg3Zn3Gd2 phase (W-phase). This phase is incoherent with interface of the matrix and becomes cores of the fracture in tensile test at room or elevated temperature.

LaMgAl_(11)O_(19)∶R(R=Tb,Mn)的真空紫外光谱特性

采用高温固相反应法合成了LaMgAl11O19∶R(R=Mn,Tb)荧光体,测量了荧光体的真空紫外激发光谱和相应的发射光谱,观察到基质吸收带位于170nm附近,Mn2+离子的吸收位于170～510nm范围,Tb3+离子的4f 5d吸收位于170～250nm范围。在147nm激发下,它们发射绿光。真空紫外光谱特性的研究表明,基质与激活离子之间存在较好的能量传递。

镧六方铁氧体Ba_(1-x)La_xFe_(12)O_(19)的电磁性能与吸波特性

研究了掺稀土六方铁氧体Ba1-xLaxFe12O19的合成条件,测试了其结构、形貌、电磁性能与吸波特性.结果表明,稀土离子La3+的加入,降低了钡铁氧体的磁化强度、矫顽力和顽磁性,其磁特性接近软磁铁氧体材料;在1.65～2.95GHz的频率范围内,具有良好的吸波性能.

La_2CaB_(10)O_(19)∶Eu~(3+)的VUV-VIS范围光谱的研究

研究了La2CaB10O19∶Eu3+红色发光材料的高分辨发射光谱和UV VUV激发光谱。根据发射光谱和荧光寿命,认为进入晶格的Eu3+占据了两种格位,一种Eu3+占据了与O2-离子十配位的La3+的格位,另一种Eu3+则占据了与O2-离子八配位的Ca2+的格位。又从激发光谱的分析中,得到Eu3+的电荷迁移带(CTB)是峰值位于244nm的宽带,而位于130～170nm之间的成份复杂的宽带包括硼酸盐基质的吸收带和Eu3+的f d跃迁的结论。

LaMAl_(11)O_(19)(M=Mg,Fe)的化学键性质和穆斯堡尔谱研究

利用复杂晶体化学键的平均能带模型研究了LaMAl11O19(M =Mg ,Fe)晶体的化学键性质。结果表明 ,La O键只有 3%的共价性 ,4f1格位却具有很强的共价特征。晶体中各格位共价次序为 :La O

助熔剂对发光体BaAl_(12)O_(19):Mn结构及发光的影响

在几种不同的助熔剂的作用下合成了BaAl12O19：Mn发光体，XRD谱显示助熔剂不仅有利于基质的结晶成核，而且对基质的不同晶面的生长也有影响.其UV光谱表明不同的助熔剂对其发光的影响不一样，H3Bo3不利于其发光，AIF3对其发光的提高不大，BaF2则可以较大地增加其发光强度．其VUV光谱显示在150nm附近有较强的激发证实了其可成为用于PDP的荧光粉之一．

甲烷与二氧化碳重整制取合成气反应的研究 (I)Sr_(1-x)La_xNiAl_(11)O_(19)催化剂的物理化学性质表征

合成了具有磁铅石结构的Ｓｒ１－ｘＬａｘＮｉＡｌ１１Ｏ１９系列催化剂，并用ＸＲＤ、ＵＶ－ＤＲＳ、Ｈ２－Ｏ２滴定及Ｐｙ－ＩＲ等方法对其体相及表面性质进行了表征．结果表明，Ｌａ３＋离子能够同晶取代Ｓｒ２＋离子进入催化剂晶格内部；随着Ｌａ３＋含量增加，催化剂的结晶度提高，从而降低了镍的还原性，并使金属镍在表面上的分散度略有提高；在ＳｒＮｉＡｌ１１Ｏ１９中掺入Ｌａ３＋离子，能够抑制晶体沿ｃ轴方向的生长，提高其比表面积；同时Ｌａ３＋离子对Ｓｒ２＋离子的调变，减少了表面的酸中心数目

甲烷与二氧化碳重整制取合成气反应的研究 (I)Sr_(1-x)La_xNiAl_(11)O_(19)催化活性表征

对具有磁铅石结构的Ｓｒ１－ｘＬａｘＮｉＡｌ１１Ｏ１９对甲烷与二氧化碳重整反应的催化活性、积炭量和稳定性进行了研究．不同还原温度下催化剂的ＸＲＤ和催化活性的实验结果表明，金属镍是ＣＨ４＋ＣＯ２重整反应的活性组分，金属镍含量越大，反应活性越高．反应后催化剂积炭量的分析结果说明，在相同镍含量和分散度的情况下，Ｌａ３＋离子对Ｓｒ２＋离子调变，可以降低催化剂的表面酸性，提高催化剂的抗积炭能力．ＬａＮｉＡｌ１１Ｏ１９是一种具有较好催化活性、稳定性和抗积炭性能的催化剂.