共查询到16条相似文献,搜索用时 484 毫秒
1.
中国氦冷球床包层(CH HCSB TBM)初步采用Li 4SiO 4陶瓷小球作为氚增殖材料,实验研究了Li 4SiO 4陶瓷小球的中子辐照产氚性能。将冷冻成型法制备的Li 4SiO 4 陶瓷小球置于反应堆中辐照100min,然后在离线释氚实验平台上进行退火行为研究。实验结果表明,在用He +1% H 2为载气,流速为100mL•min -1,升温速率为5K•min -1的实验条件下,氚气(HT+T 2)是Li 4SiO 4陶瓷小球的主要释氚形态,占总氚的70%左右(不包括自由氚中的氚气),在400℃~700℃范围内出现两次释氚峰;氚化水(HTO+T 2O)所占比例小于20%,主要在300℃~500℃的低温段进行释放;氚在800℃前基本释放完,小球退火后的残氚量小于1%。冷冻成型干燥法制备的Li 4SiO 4陶瓷小球在300℃~700℃范围内有较好的释氚性能,氚残留量低,在聚变堆固态氚增殖包层设计中具有一定应用价值。 相似文献
2.
以Li 2CO 3、Nb 2O 5、TiO 2和Eu 2O 3为原料,采用固相法制备Eu 3+掺杂的5Li 2CO 3-1Nb 2O 5-5TiO 2(LNT)发光介质陶瓷。通过密度、XRD和荧光光谱测试,对0.2%(质量分数)Eu 2O 3掺杂的陶瓷片进行性能表征。结果表明:1 120℃烧结致密的陶瓷片,其晶相结构为“M-相”与Li 2TiO 3两相复合构成;在400 nm的近紫外光激发下,样品有较强的橙光(592 nm)和红光(615 nm)发射,分别属于Eu 3+的 5D 0→ 7F 1的磁偶极跃迁和 5D 0→ 7F 2的电偶极跃迁。 相似文献
3.
本文用X射线和差热分析方法对BaO-Li 2O-B 2O 3三元系中的两个截面:BaB 2O 4-Li 2B 2O 4和BaB 2O 4-Li 2O作了研究。在BaB 2O 4-Li 2B 2O 4赝二元系中发现了一个新的化合物4BaB 2O 4·Li 2B 2O 4。化合物在930±3℃由包晶反应形成,并与Li 2B 2O 4形成共晶反应。共晶温度为797±3℃,共晶点组分为79mol%Li 2B 2O 4。在BaB 2O 4-Li 2O截面中也存在化合物4BaB 2O 4·Li 2B 2O 4,其包晶反应温度从930±3℃随Li 2O含量增加下降到908±3℃。在组分60mol%Li 2O处形成另一个新的化合物2BaB 2O 4·3Li 2O。该化合物在630±3℃也是由包晶反应形成,并与Li 2O和Li 2CO 3分别形成共晶反应,共晶温度分别为400±3℃和612±3℃。在BaB 2O 4-Li 2B 2O 4和BaB 2O 4-Li 2O体系中都没有观察到固溶体。用计算机程序分别对化合物4BaB 2O 4·Li 2B 2O 4和2BaB 2O 4·3Li 2O的X射线粉末衍射图案进行了指标化,其结果:4BaB 2O 4·Li 2B 2O 4的空间群为Pmma,a=13.033?,b=14.630?,c=4.247?,每个单胞包含两个化合式单位;2BaB 2O 4·3Li 2O的空间群为Pmmm,a=4.814?,b=9.897?,c=11.523?,每个单胞也含有两个化合式单位。
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4.
采用溶胶-凝胶法制备Li 1.0Nb 0.6Ti 0.5O 3:Eu 3+红色荧光粉,讨论了煅烧温度、煅烧时间以及Eu 3+掺杂浓度对样品发光性能的影响。通过XRD、荧光光谱分别对样品的性能进行表征,结果表明:样品的晶相结构为"M-相(M-phase)"。在466 nm蓝光激发下,合成的荧光粉具有橙光(593 nm)和红光(612 nm)发射。发光强度随着煅烧温度的升高先增大后减小,最佳的煅烧温度为850℃。同时,随着煅烧时间的增加,发光强度先增大后减小,最佳煅烧时间为6 h。当Eu 2O 3掺入质量分数为2.5%时,样品的发光强度达到最大。Li 1.0Nb 0.6-Ti 0.5O 3:Eu 3+红色荧光粉在白光LED的应用中具有潜力。 相似文献
5.
以CaF 2作为α-Si 3N 4粉末的烧结助剂,同时充当多孔氮化硅陶瓷的造孔剂,采用热压烧结工艺在较低温度下制备多孔氮化硅陶瓷。研究烧结助剂的含量对多孔氮化硅陶瓷显气孔率、抗弯强度的影响,分析材料的组分并观察断口结构。结果表明:在温度1 450℃,压力0.55T的条件下,当CaF 2添加量为6.0wt%时,多孔陶瓷的性能较为优异,其孔隙率为38.8%,α-Si 3N 4→β-Si 3N 4的相变程度为38.5%,抗弯强度为137.1 MPa。 相似文献
6.
我们用Raman光谱研究了Li 2O(LiCl) 2B 2O 3-Al 2O 3系玻璃的结构,着重研究了Al 2O 3的影响。对于Li 2O-B 2O 3系玻璃,Li 2O含量增加使玻璃中存在的BO 3三角体转变为BO 4四面体,
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7.
基于相图计算,制备了三种碳酸盐-氯盐体系混合盐,利用同步热分析仪对所配制熔盐的熔点、潜热、初晶点、分解温度进行了测定,选出性能较好的混合盐,进而对其进行比热测试、热循环稳定性测试和蓄热成本计算。结果表明,0.18K 2CO 3-0.14Na 2CO 3-0.68NaCl混合盐具有较低的熔点、较高的潜热与分解温度和良好的热循环稳定性,与Li 2CO 3-Na 2CO 3-K 2CO 3混合熔盐相比具有更低的相变蓄热成本。 相似文献
8.
采用高温还原法合成了一种新型无稀土掺杂Y 2O 2S:0.09Ti长余辉发光材料。基于助熔剂种类对长余辉发光材料特性的重要作用,选择了对余辉衰减初期和后期余辉强度有明显作用的Li 2CO 3和K 3PO 4两种助熔剂,研究了不同配比(以下用x表示,x=Li 2CO 3/(Li 2CO 3+K 3PO 4))的复合助熔剂对Y 2O 2S:0.09Ti磷光体晶体结构和发光性能的作用,以获得具有较好综合发光性能的Y 2O 2S:0.09Ti磷光体。采用PL光谱和余辉测试仪对材料的发光特性进行了表征,用XRD研究了其晶体结构的变化。XRD结果表明,在复合助熔剂范围内(x=0~1.0)均可获得单相性的Y 2O 2S:0.09Ti磷光体。同时发现复合助熔剂比例不同制备的样品中,Y 2O 2S:0.09Ti磷光体晶体择优取向也发生明显的变化,且高比例Li 2CO 3有助于Y 2O 2S:0.09Ti磷光体的晶体形成。复合助熔剂比例x对样品的激发峰与发射谱主峰位置(565nm)基本没有影响;但助熔剂比例x对发射峰强度则有明显影响,随着x增加,该磷光体的发光强度先增后减,在x=0.8时发光强度最大。 相似文献
9.
本文用阻抗谱方法研究了Li 3+xV 1-xT xO 4(T=Si,Ge)多晶的离子导电性,发现一些工艺条件如成型压强、烧结时间和烧结程序对电导率有很大影响。注意分析了这些影响的物理起因。最佳工艺条件是:在大约8t/cm 2压强下成型样品。在1000℃连续烧结5至6天,烧结过程中,应尽量避免温度波动。在此条件下制备的Li 3.5V 0.5Ge 0.5关键词: 相似文献
10.
具有巨介电常数的CaCu 3Ti 4O 12陶瓷是一种理想的高储能密度电容器材料.本文以草酸为沉淀剂、以乙酸铵为调节pH值的定量缓冲剂,获得制备CaCu 3Ti 4O 12陶瓷的简化共沉淀法.确定了pH=30为制备前驱粉料的最佳反应条件.通过显微分析和介电性能测量,发现在1040℃—1100℃范围内,随着烧结温度的提高,陶瓷的品粒尺寸增大,非线性系数上升,电位梯度和介电损耗下降,1100℃烧结的试样tanδ最低达到0.04.认为CaCu 3Ti 4O 12陶瓷介电损耗包含直流电导分量、低频松弛损耗和高频松弛损耗.低频松弛活化能为0.51 eV.,对应于晶界处的Maxwell-Wagner松弛极化;高频松弛过程活化能为0.10 eV,对应晶粒内部的氧空位缺陷.烧结温度的升高导致晶界电阻下降. 相似文献
11.
采用碳酸锂(Li2CO3)为n型掺杂剂,苝四甲酸二酐(3,4,9,10 perylenetetracarboxylic dianhydride,PTCDA)为母体材料,通过真空热蒸发方式制备了n型掺杂的PTCDA复合材料,将其作为电子注入材料应用到NPB/Alq3异质结有机电致发光器件中.研究发现,同LI2CO3:BC... 相似文献
12.
The Li oxides species formed on Li over-deposited V 2O 5 thin film surfaces have been studied by using X-ray and UV induced photoelectron spectroscopy (XPS and UPS). The photoelectron spectroscopic data show that the Li over-deposited V 2O 5 system itself is not stable. Further chemical decomposition reactions are taken place even under UHV conditions and lead to form Li 2O and Li 2O 2 compounds on the surface. The formation of Li 2O 2 causes to arise an emission line at about 11.3 eV in the valence band spectra. 相似文献
13.
The solid–solid interactions between cobalt and ferric oxides to produce CoFe 2O 4 were followed up using XRD investigation. The effect of Li 2O-doping on the ferrite formation was also studied. The electrical and dielectric parameters of pure and doped mixed solids precalcined at 1273 K were measured using d.c and a.c instruments.The dopant concentration was varied between 0.5 and 6 mol% Li 2O. The results obtained revealed that Li 2O doping much enhanced the ferrite formation due to an increase in the mobility of the reacting species. The addition of the smallest amount of Li2O (0.5 mol%) resulted in measurable variations in the electrical constants (ρ, Ea, ′, ″ and tan δ). Resistivity increased upon increasing the dopant concentration up to 1.5 mol% exceeding the values measured for the undoped sample. Furthermore, the presence of 6 mol% Li2O brought about a significant decrease of electrical resistivity. Also, the activation energy decreased with increasing the dopant concentration. The dielectric constant behaves according to ε=const. 1/ρ1/2. The Li2O-doping modified the values of different dielectric constants, the change in these constants was found to be strongly dependent on the amount of Li2O added.These results have been discussed in terms of the potentiality of Li2O in increasing the mobility of the reacting species involved in the ferrite formation. 相似文献
14.
The possibilities of inductively coupled plasma-atomic emission spectrometry (ICP-AES) for the chemical characterization (dopants, impurities, and macroconstituents) of perovskite ceramic semiconductors (PTC thermistors, varistors, manganites, cobaltites) are shown. The dissolution of the samples is achieved by five methods: (a) decomposition with HCl in a Teflon-lined pressure vessel, (b) decomposition with HF + H 2SO 4 in a Teflon-lined pressure vessel, (c) decomposition with (NH 4) 2SO 4 + H 2SO 4 in a platinum dish, (d) fusion with Na 2CO 3 + Na 2B 4O 7 in a platinum crucible, (e) fusion with Li 2B 4O 7 in a graphite crucible. The spectral interferences and the inter-element effects are studied and corrected. The detection limits are comprised, approximately, between 0.00001% and 0.1%. High sensitivity and good precision are attained. 相似文献
15.
Adsorption of N 2 and N 2O at various sites on Ni(7 5 5) has been investigated by density functional theory (DFT) method (periodic DMol 3). Several possible adsorption structures (attaching the nitrogen atom to the surface, or lying parallel) are found for both molecules. There is a clear binding energy preference of N 2 and N 2O for step sites in contrast to the case of CO. It is revealed that the decomposition of N 2O occurs exclusively near the step, but not on the terrace. Two decomposition channels can be considered; dissociative adsorption and spontaneous decomposition during TPD ramp. Three possible candidates for the precursor of the spontaneous decomposition of N 2O during TPD ramp are discussed. 相似文献
16.
利用 11B的核磁共振谱研究了锂、硼、硅酸盐(Li 2O·B 2O 3·SiO 2)三元玻璃体系,测量并分析了BO 4单元与对称和非对称的BO 3单元的比例。分析结果表明,三元体系的结构单元亦可适用于锂、硼玻璃的二元体系的FDB模型说明,其差异在于前者中的Li 2O由B 2O 3与SiO 2按比例分享。 相似文献
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