共查询到19条相似文献,搜索用时 203 毫秒
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《高压物理学报》2018,(6)
系统地研究了层状二碲化钛在压力(至43.4GPa)作用下的电输运、晶格振动和结构性质。室温下样品的电阻率在6、13和22GPa附近表现出一系列的异常。为更好地研究二碲化钛的电子结构,测试了样品的低温电阻,在约6GPa处观察到超导转变。综合拉曼光谱和X射线衍射(XRD)实验结果发现:二碲化钛在6GPa附近可能发生拓扑相变;继续加压至约13GPa,样品发生从三角晶系到单斜晶系的结构相变,相变到22GPa附近完全结束。XRD数据与电输运结果相互印证,揭示了样品在压力诱导下的结构演变和电子结构变化。因此,二碲化钛为人们了解过渡金属二硫化物提供了一个全新的视角。 相似文献
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测定了在高压条件下两种金属(钙和锌)的8-羟基喹啉络合物的晶体粉末样品的发光行为和原位X光衍射光谱.结果表明,压力对其发光性质产生极大的影响.随着压力的增加,8—羟基喹啉钙的发光强度在3GPa以内时大大增加,随后发光强度快速下降.到7GPa左右时几乎为零,而8-羟基喹啉锌的发光强度随压力的增加而逐渐降低,到7GPa左右时约为常压的10%。高压下的原位X光衍射结果表明,8—羟基喹啉锌的晶体在3—4GPa开始发生非品化相变,在7GPa时该非晶化相变完成,样品的x光衍射完全消失.而8—羟基喹啉锌在压力的作用下(至16GPa)没有发生明显的相变。 相似文献
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研究了共聚物P(VDF-TrFE)(物质的量分数分别为80%、20%)在室温下、14GPa内的电容、电阻与压力的关系。实验结果表明,它在14GPa内存在两个相交:第一个相变发生在1.1GPa左右;而第二个相变发生在5~6GPa左右。 相似文献
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在室温条件下, 利用金刚石对顶砧超高压实验技术, 对液态的正庚烷进行了原位高压拉曼光谱研究, 采用红宝石荧光压标测压, 实验的最高压力为20.78 GPa。实验中发现, 当压力达到1.2 GPa左右时, 原本透明的样品腔内有小晶粒形成, 此时测量的拉曼谱上发现有许多新的拉曼峰出现。因此, 我们判断正庚烷在此压力下发生了一次相变; 当压力增加到3 GPa左右时, 在92.42 cm-1和2913.6 cm-1处又出现了2个新的拉曼峰, 并且拉曼频移随压力变化的曲线出现拐点, 我们推测在此压力下正庚烷可能又发生第二次相变; 当压力高于14.5 GPa时, 正庚烷发生了第三次压致相变; 而当压力介于7.5~14.5 GPa之间正庚烷处于两相共存的状态。我们给出了液体正庚烷在高压下的相变序列为: 液相-旋转相Ⅲ-旋转相Ⅳ-结晶相。该研究结果为进一步理解和研究其他正烷烃在高压下的结构、物理和化学特性提供了理论基础。 相似文献
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在金刚石压砧装置上,采用电阻和电容测量方法研究了Cd1-xZnxTe(x=0.04)在室温下、17 GPa内的电阻、电容与压力的关系。实验结果表明,它在3.1 GPa左右和5 GPa左右发生了两次电子结构相变,而在3.1 GPa以上和5.7 GPa左右发生了两次晶体结构相变。同时,还在活塞-圆筒测量装置上研究了Cd1-xZnxTe(x=0.04)在室温下、4.5 GPa内的p-V关系。实验结果表明它在3.8 GPa左右发生了相变。本工作还给出了它在相变前后的状态方程,以及它的Grüneisen参数γ0、体弹模量B0 与B0 的压力导数B0′。 相似文献
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Effects of high pressure on the Raman and fluorescence emission spectra of two novel 1,3,4-oxadiazole derivatives
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The effects of pressure on the fluorescence emission and Raman spectra of 1,4-bis[(4-methyloxyphenyl)-1,3,4-oxadiazolyl]- 2,5-bisheptyloxyphenylene (OXD-2) and on the fluorescence emission spectra of 1,4-bis[(4-methylphenyl)- 1,3,4-oxadiazolyl]phenylene (OXD-1) are investigated using a diamond anvil cell. With the increase of pressure, the intensity of the fluorescence emission increases and reaches maxima at 13GPa for OXD-1 and at 9.6GPa for OXD-2. The effect of pressure on the peak position of the emission shows a similar trend, red shift with the increase of pressure. But at higher pressures, the intensity of emission drops down dramatically. The Raman spectra of OXD-2 indicate that there appears a structural change at ca 3GPa. 相似文献
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Electron Transport Property of CdTe under High Pressure and Moderate Temperature by In-Situ Resistivity Measurement in Diamond Anvil Cell
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In situ resistivity measurement has been performed to investigate the electron transport property of powered CdTe under high pressure and moderate temperature in a designed diamond anvil cell. Several abnormal resistivity changes can be found at room temperature when the pressure increases from ambient to 33 GPa. The abnormal resistivity changes at about 3.8 GPa and 10 GPa are caused by the structural phase transitions to the rock-salt phase and to the Cmcm phase, respectively. The other abnormal resistivity changes at about 6.5 GPa, 15.5 GPa, 22.2 GPa and about 30 GPa never observed before are due to the electronic phase transitions of CdTe. The origin of the abnormal change occurred at about 6.5 GPa is discussed. The temperature dependence of the resistivity of CdTe shows its semiconducting behaviour at least before 11.3 GPa. 相似文献
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Ito M Hori J Kurisaki H Okada H Perez Kuroki AJ Ogita N Udagawa M Fujii H Nakamura F Fujita T Suzuki T 《Physical review letters》2003,91(7):077001
We performed resistivity measurements in CuRh2S4 under quasihydrostatic pressure of up to 8.0 GPa, and found a pressure-induced superconductor-insulator transition. Initially, with increasing pressure, the superconducting transition temperature T(c) increases from 4.7 K at ambient pressure to 6.4 K at 4.0 GPa, but decreases at higher pressures. With further compression, superconductivity in CuRh2S4 disappears abruptly at a critical pressure P(SI) between 5.0 and 5.6 GPa, when it becomes an insulator. 相似文献
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Muramatsu T Takeshita N Terakura C Takagi H Tokura Y Yonezawa S Muraoka Y Hiroi Z 《Physical review letters》2005,95(16):167004
High-pressure effects on the superconducting transitions of beta-pyrochlore oxide superconductors AOs(2)O(6) (A = Cs,Rb,K) are studied by measuring resistivity under high pressures up to 10 GPa. The superconducting transition temperature T(c) first increases with increasing pressure in every compound and then exhibits a broad maximum at 7.6 K (6 GPa), 8.2 K (2 GPa), and 10 K (0.6 GPa) for A = Cs, Rb, and K, respectively. Finally, the superconductivity is suppressed completely at a critical pressure near 7 GPa and 6 GPa for A = Rb and K and probably above 10 GPa for A = Cs. Characteristic changes in the coefficient A of the T(2) term in resistivity and residual resistivity are observed, both of which are synchronized with the corresponding change in T(c). 相似文献
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Pressure-Induced Metallization and Electrical Phase Diagram for Polycrystalline CaB_6 under High Pressure and Low Temperature
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《中国物理快报》2016,(8)
The electrical properties of polycrystalline CaB_6 are revealed by in-situ resistance measurements under high pressure and low temperature.Due to the existence of grain boundaries,polycrystalline CaBe behaves with semiconducting transport properties,which is different from the semimetallic CaBe single crystals.The temperaturedependent resistance measurement results show that before the structural phase transition at 12.3 GPa the high pressure first induces the metallization at 6.5 GPa for CaBe.Moreover,the phase diagram for CaB_6 is drawn based on the investigated electric conducting properties and at ieast three different conducting phases are found even at moderate high pressure and low temperature,indicating that the electric nature of CaBe is very sensitive to the environment. 相似文献
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Chunyuan He Yanzhang Ma Ming Li Aimin Hao Dongmei Zhang Guangtian Zou 《Journal of Physics and Chemistry of Solids》2008,69(9):2227-2229
In situ electrical resistivity measurement of CdSe was performed under high pressure and moderate temperature using a diamond anvil cell equipped with a microcircuit. With the pressure increasing, a sharp drop in resistivity of over two orders of magnitude was observed at about 2.6 GPa, it was caused by the transition to the rock-salt CdSe. After that, the resistivity decreased linearly with pressure. However, in different pressure range, the decreasing degree was obviously different. This attributed to the different electron structures. By fitting to the curve of pressure dependence of resistivity in different pressure range, the relationship of the band gap to pressure was given and the metallization pressure was speculated to be in the range of 70-100 GPa. The temperature dependence of resistivity showed that in the experimental temperature and pressure range the resistivity had a positive temperature coefficient. 相似文献
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高压下的电学性质测量是获得材料物理性质的有效手段。利用集成在金刚石对顶砧上的薄膜微电路,测量了高压下Fe3O4/β-CD(β-糊精)的电导率,并分析了电导率随压力的变化关系。在0~39.9 GPa范围内,Fe3O4/β-CD的电导率随压力的增加而逐渐增大,并呈半导体的特征;而在17.0 GPa处其电导率发生突变,表明样品发生了高压相变。在卸压过程中,电导率随压力的变化呈线性关系,并且卸压后样品的电导率不能回到最初的状态,推测这是一个不可逆的高压结构相变。 相似文献
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利用在金刚石压砧上集成的微电路,原位测量了CdSe多晶粉末在温度为300~450 K、压力达到23 GPa时电阻率随温度和压力的变化关系。实验结果表明:在加压过程中,电阻率在2.6 GPa压力时出现的异常改变,对应着CdSe从纤锌矿向岩盐矿结构的转变,而在6.0、9.8、17.0 GPa等压力处出现的电阻率异常,则是由CdSe中的电子结构的变化所引起的;在卸压过程中,只在约14.0和3.0 GPa压力下观察到了两个电阻率异常点。通过对电阻率随压力变化曲线的模拟,得出了CdSe高压相的带隙随压力的变化关系,据此预测CdSe金属化的压力应在70~100 GPa之间。变温实验结果表明,在实验的温度和压力范围内,CdSe的电阻率均随温度的增加而升高。 相似文献
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金红石高温高压相变的Raman光谱特征 总被引:3,自引:2,他引:1
以Ar作压力介质,在准静水压力条件下,利用激光加热DAC技术和显微Raman光谱原位测试技术,在0~35 GPa压力范围开展金红石的高温高压相变研究。在室温条件下,金红石结构TiO2于13.4 GPa开始转变成斜锆石相,于21 GPa时转变完全,并直到35 GPa时斜锆石相稳定存在。在压力分别为29.4和35.0 GPa时,用YAG激光器发出的波长为1.064 μm的红外激光束扫描加热样品,TiO2斜锆石高压相转变成另一Pbca结构高压相。卸压时,Pbca相于26.3 GPa时转变成斜锆石相。斜锆石相转变成Pbca相需要加热才能发生,而卸压时却在较小的压力区间即迅速转变完全,两相转变压力边界在28 GPa左右。进一步卸压,斜锆石相直到11 GPa仍稳定,在7.6 GPa时斜锆石相与α-PbO2相两相共存,5 GPa时完全转变成α-PbO2相,并直到常压该相以亚稳定态存在。 相似文献