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近红外激发下得到了不同温度下缬氨酸在金纳米颗粒上的SERS光谱。温度的变化范围为373~100 K,从373 K到273 K整体强度变强,峰数量也很多。263 K到193 K的温度区间内强度比较弱,到173 K时峰强度和数量又有所增加,接着降低到100 K时强度又变低,同时峰的位置也有一些移动。文章对SERS的部分峰位给予了适当的归属,并对上述变化给予了初步解释。 相似文献
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我们测量了Nb_3Sn从4.2K到273K的绝对热电势率,结果表明在18 K以上,Nb_3Sn的热电势率都是正的.在60K左右,观察到由于声子曳引引起的平坦的峰.第一次观察到在超导临界温度附近,热电势率也有一个明显的转变过程. 相似文献
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采用紧密结合的分子动力学模型,对Na(n)(5<=n<=10)小团簇的键长涨落、势能、热容量等熔化性质在50K到1500K温区进行了模拟研究,结果表明:它们发生两次相变,一种在230K到300K的温度范围内,依次有块体玻璃态转变;一种在550K到870K温度段,依次经历了熔化相变.同时也得到随着团簇体系的减小,势能由下向上排列的曲线,即体系的势能由低变高. 相似文献
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本文介绍一种供分度热电偶用的低温恒温器.实验得出:从室温到20K,恒温器的恒温精度可达±0.005K,从20K到4.2K,恒温器的恒温精度可达±0.01K. 相似文献
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铬/氢/氧燃烧火焰中的热力学参数计算和平衡分析 总被引:4,自引:3,他引:1
为研究含铬废物在焚烧过程的氧化行为,用Gaussian98软件计算了七个气态铬氧化物和氢氧化物从200K到6000K的热力学参数,焓差和熵。并对燃氧比分别为0.95,0.80和0.60的三个焚烧工况进行了热力学平衡分析,火焰温度从800K到2500K。计算结果表明,随着燃氧比的降低,高温下六价铬的含量增加,在2100K左右达到最大值。 相似文献
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本文报道了在 Bi-Sr-Ca-Cu-O 体系中发现120K 相的实验结果.样品的电阻在130K 时开始超导转变,在120K 时下降到约为130K 时的8%,最后在98K 出现零电阻.文中对样品进行了相分析和显微结构观察. 相似文献
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在K原子密度约为0.5-5×1016cm-3的样品池中,脉冲激光710nm线双光子激发K2基态到高位1∧g 态,研究了K2( 1∧g)+ K(4S)碰撞转移过程。K原子密度由测量KD2线蓝翼对白光的吸收得到。测量不同K密度下 1∧g态发射的时间分辨荧光强度,它是一条指数衰减曲线,由此得到1∧g态的有效寿命,从描绘出的有效寿命倒数与K原子密度关系直线的斜率得到1∧g 态总的碰撞猝灭截面为 ,从截距得到的辐射寿命为 。测量了K的6S →4P3/2和4D→4P3/2 在不同K密度下的时间积分荧光强度,得到了K2( )+K→K2( )+K(6S,4D)碰撞转移截面为 (对转移到6S)和 (对转移到4D)。 相似文献
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使用日本原子能研究开发机构里设置的高分解能粉末中子衍射装置, 在 15 K 和 294 K 温度下对 PbS 进行了中子衍射实验。在 15 K 和 294 K 温度里观察到了明显的振动形状的热漫散射。 所观察到的漫散射强度可由原子间热振动相关效应的影响来解释。在 294 K 下从原子间相关效应和德拜—劳厄因子的温度参数中获得了 PbS 相邻原子间的力常数。 相似文献
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The electrical resistivity of a hydrogenated LaNi5 thin film has been investigated as a function of temperature in vacuum and in hydrogen. While the film was heated in vacuum for the first time, the change in resistivity exhibited different characteristics during different ranges of temperatures due to the competition of two effects owing to the lattice scattering of conductive electrons and the number of them. The resistivity had a sharp drop near 600 K, which originates from the formation of high conducting lanthanum hydride and nickel due to a reaction between the dissolved hydrogen and LaNi5. The change in resistivity was not repeatable during the successive heating and cooling processes. When the film was heated under a hydrogen atmosphere, a drop in resistivity occurred near 700 K due to the reaction between LaNi5 and the hydrogen atmosphere. The film showed a linear temperature dependence of receptivity with completeness of the reaction. It was found that the reaction was irreversible. The film lost the ability of hydrogen absorption after the reaction, and it had a phase change from LaNi5 to LaH and Ni. This result was supported by X-ray diffraction patterns. 相似文献
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The electrical resistivity of a hydrogenated LaNi5 thin film has been investigated as a function of temperature in vacuum and in hydrogen. While the film was heated in vacuum for the first time, the change in resistivity exhibited different characteristics during different ranges of temperatures due to the competition of two effects owing to the lattice scattering of conductive electrons and the number of them. The resistivity had a sharp drop near 600 K, which originates from the formation of high conducting lanthanum hydride and nickel due to a reaction between the dissolved hydrogen and LaNi5. The change in resistivity was not repeatable during the successive heating and cooling processes. When the film was heated under a hydrogen atmosphere, a drop in resistivity occurred near 700 K due to the reaction between LaNi5 and the hydrogen atmosphere. The film showed a linear temperature dependence of receptivity with completeness of the reaction. It was found that the reaction was irreversible. The film lost the ability of hydrogen absorption after the reaction, and it had a phase change from LaNi5 to LaH and Ni. This result was supported by X-ray diffraction patterns. 相似文献
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Nb2O5掺杂的氧化锌陶瓷导电特性研究 总被引:2,自引:0,他引:2
研究了Nb2O5掺杂的ZnO陶瓷在低温下导电特性,结果表明,低温状态下,随着Nb2O5掺杂量的增加,ZnO电阻率降低,不同温度下烧结的ZnO样品,烧结温度越高,电阻率愈小,同一烧结温度下,不同烧结时间的ZnO样品,随着烧结时间的增加,电阻率愈小. 相似文献
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本文在20°—300°K研究了室温载流子浓度2×1012—1×1020cm-3含硼或磷(砷)Si的电学性质。对一些p-Si样品用弱场横向磁阻法及杂质激活能法进行了补偿度的测定,并进行了比较。从霍尔系数与温度关系的分析指出,对于较纯样品,硼受主能级的电离能为0.045eV,磷施主能级为0.045eV,在载流子浓度为1018—1019cm-3时发现了费米简并,对载流子浓度为2×1017—1×1018cm-3的p-Si及5×1017—4×1018cm-3的n-Si观察到了杂质电导行为。从霍尔系数与电导率计算了非本征的霍尔迁移率。在100°—300°K间,晶格散射迁移率μ满足关系式AT-a,其中A=2.1×109,α=2.7(对空穴);或A=1.2×108,α=2.0(对电子)。另外,根据我们的材料(载流子浓度在5×1011—5×1020cm-3间),分别建立了一条电阻率与载流子浓度及电阻率与迁移率的关系曲线,以提供制备材料时参考之用。 相似文献
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研究了(Fe1-xWx)84.5B15.5(x=0—0.1)非晶态合金的电阻率ρ与温度T(4.2—300K)的关系。实验结果表明,在所研究浓度区域内均出现电阻率与温度关系的极小值,电阻率极小值的温度Tmin在x=0.06时出现峰值。用x=0.02—0.1浓度区域内,当Tmin时,又出现了电阻率与温度关系的极大值,电阻率极大值的温度Tmax在26—35K之间。低温电阻率反常现象与类Kondo效应及局域磁矩之间RKKY相互作用有关。
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