扫描法固体低温比热测量系统及其分析

介绍了扫描法测量固体低温比热的实验系统及其出现的问题和解决方法.用此实验系统对纯度为99.7%电介铜的比热测量结果表明,它与美国国家标准参考数据相比,在80K—260K范围内偏差小于7%.     

充液航天器姿态稳定分析的Casimir方法

充液航天器中的液体燃料晃动将可能导致航天器姿态不稳定性现象的发生．本文采用哈密顿动力学方法研究了半充液航天器姿态运动的稳定性问题．首先将晃动液体等效为弹簧质量块力学模型,建立了液体晃动与航天器姿态多体耦合动力学系统的哈密顿方程,并进一步推导了与耦合动力学系统相关的Casimir函数;借助于Casimir函数并采用李亚普诺夫稳定性理论推导出耦合系统的稳定性和非稳定性条件,最后给出了数值仿真结果及相关结论．     

高压对NiCr—NiCu热电偶的温度影响

在室温和液氮温度下,压强在0—20kbar(1bar=10~5Pa)变化范围内,测量了NiCr-NiCu热电偶的压力热电势随压强的变化关系.测量结果表明:在室温和液氮温度下,压力热电势均随压强增高,在0.1K的温度测量精度、0—20kbar的压强范围内,压力热电势不会对温度测量带来影响.     

One-step synthesis route of the aligned and non-aligned single crystalline α-Si_3N_4 nanowires

This paper reports the bulk synthesis route of the aligned and non-aligned high-qualityα-Si 3 N4 nanowires(NWs) which were grown directly from the Si substrate by vapor phase deposition at 1050℃.The as-grown products were characterized by employing XRD,SEM,HRTEM and photoluminescence.The microscopic results revealed that the products consist of single crystalline aligned and non-alignedα-Si 3 N4 NWs having a same diameter range of 30-100 nm and different lengths of about hundreds of microns.The XRD observation revealed that the products consist ofα-phase Si 3 N4 NWs.The room temperature PL spectra indicated that the NWs have good emission property.The non-aligned NWs were formed at lower temperature as compared with aligned NWs.Our method is a simple and one-step procedure to synthesize the bulk-quantity and high-purity aligned and non-alignedα-Si 3 N4 NWs at a relatively low temperature.The possible growth mechanism was also briefly discussed.