Ruby-spheres as pressure gauge for optically transparent high pressure cells

Abstract

Ruby is widely used as an in siru pressure gauge for optically transparent pressure cells up to the megabar range. Usually ruby chips cut from bulk crystals are used which are ill-characterized and inconvenient to handle and to identify visually. Here we present a systematic study on corundum samples doped with Cr³⁺ ions with concentration from 60 to 23500 ppm to determine the optimal conditions for the use as an accurate pressure marker. The influence of the excitation wavelength on the luminescence spectra was investigated. These studies led to the synthesis of small (1–50 micrometer) ruby spheres with 3000 ppm chromium concentration. After annealing and a heat treatment to avoid internal strains we find reproducible values of the position and the width of the fluorescence lines. These ruby spheres are not only well suited for a reliable and accurate pressure determination in experiments using diamond anvil cells, but can also be used as an in sihr micro-thermometer in high pressure-low temperature studies.     

Ruby under pressure

The ruby luminescence method is widely used for pressure measurement in the diamond anvil cell and other optically transparent pressure cells. With this application in mind, we briefly review the ground-state physical properties of corundum (α-Al₂O₃) with some emphasis on its behavior under high pressure, survey the effects of temperature and stress on the R-line luminescence of ruby (Cr-doped corundum), and address the recent efforts towards an improved calibration of the R-line shift under hydrostatic pressures beyond the 50 GPa mark.     

Exploiting optical properties of nanopolycrystalline diamond in high pressure experiments

ABSTRACT

We investigated the optical properties (absorption, luminescence and Raman spectra) of nanopolycrystalline diamond (NPD) aiming at exploring its capabilities as a pressure sensor and as a pressure-cell anvil for combined X-ray/neutron and optical studies. Notably, we analysed the Raman peak shift and broadening with pressure using a Moissanite Anvil Cell (MAC). The results are compared with those obtained in a DAC, where Raman signals from NPD chips and diamond anvils strongly overlap. Its pressure behaviour in the hydrostatic and non-hydrostatic regimes were investigated. We showed that the nanopolycrystalline structure induces remarkable differences in the peak shift and broadening between NPD and natural type IIa single-crystal diamond, making NPD suitable as pressure gauge for pressure determination and testing hydrostaticity of pressure transmitting medium.     

电驱动金刚石对顶砧低温连续加压装置

采用电驱动压电陶瓷取代传统机械螺丝给金刚石对顶砧施加压力,设计制备了低温下可连续增加流体静压的金刚石对顶砧压力装置,实现了低温(19±1)K连续加压达到4.41 GPa.该装置具有电驱动方便灵活、调谐精度高的低温连续加压功能.利用该装置实现了InAs单量子点发光与微腔腔模的共振耦合调谐过程.该装置将在原位压力精确调谐及测量样品信号跟踪等实验得到应用.     

用高压显微光谱系统研究非晶态As2S3的光学折射率随流体静压力变化的规律

用金刚石对顶砧高压显微光谱系统在高达66kbar的流体静压力和光谱波段为400—900nm范围内,用透射光干涉谱法测量了非晶态As₂S₃(a-As₂S₃)的光学折射率n与压力p以及波长λ的变化关系。a-As₂S₃的折射率对压力极为敏感,在波长为650nm,压力从1bar变到66kbar时,它增加35％。在计算机上用最小二乘法对实验点进行拟合的结果得到:对某一波长λ来说,遵循n(P)=n(0)+Ap+Bp²的非线性关系。其中n(p)和n(0)是p压和常压下的折射率,A和B是与波长有关的系数,文中给出了A和B的具体参数。这个关系与Weinstein和Galkiewicz等人公布的n(p)和p之间遵循线性关系不同。 关键词：     

Ruby fluorescence lifetime measurements for temperature determinations at high (p,T)

The lifetime of the ruby R₁ fluorescence line was measured as a function of pressure (up to about 20 GPa) and temperature (550 K) in an externally heated diamond anvil cell (DAC). At constant temperatures, the lifetime is increasing linearly with increasing pressure. The slope of the pressure dependence is constant up to a temperature of 450 K and it is decreasing at higher temperatures. At constant pressure, the lifetime is exponentially decreasing with increasing temperature. The (p, T)-dependence can be parametrized by the combination of a linear and an exponential function. This allows an accurate p, T-determination by the combination of fluorescence spectroscopy using Sm²⁺-doped strontium tetraborate and lifetime measurements of ruby, as the energy of the Sm²⁺ fluorescence is nearly temperature-independent.     

X-ray studies of the semiconductors snas,InTe, TlS and TISe UP TO 43 GPa

Abstract

The structures of the semiconductors SnAs, InTe, TlS and TlSe have been investigated using high-pressure (HP) diffraction technique-a gasketed diamond anvil cell (DAC)'. The pressure was measured by ruby fluorescence technique. The first order reversible transition from NaCl to CsCl structure was found in SnAs with volume discontinuity 5% the two-phase area extends from 32 to 43 GPa. The volume change V/v,(P) of the SnAs is shown in Figure 1. In agreement with the gomology rule3, the same pressure effect has been found in Sn_xSb1?x atP=9 GPa2.     

Dependence of the annihilation pressure of ruby R-line fluorescence on the laser exciting wavelength

Abstract

Using solid argon as pressure medium, quasi-hydrostatic pressure was obtained at room temperature in the diamond cell up to 90 GPa. The mechanism of the disappearance of ruby R lines and the applicability of ruby pressure scale under quasi-hydrostatic pressure above 100 GPa was discussed. The deviation of every pressure measured at nine positions in the cell per mean pressure was less than 1.5% at pressure below 80 GPa.     

百万大气压下的压强校准及5.5 Mbar静压强的获得

进行了百万大气压下,静水压和非静水压条件下的压力校准,同时观察到金刚石砧容器中红宝石R线红移至830nm处,由校准公式算得对应的压强为5.5Mbar。 关键词：     

90 GPa（准）静水压力的产生及压力分布的测量

 本文使用固态氩做传压介质，在自制的Mao-Bell型金刚石对顶砧装置中获得了90 GPa的准静水压。通过测量样品室内不同位置上红宝石荧光R₁线的频移来确定压力分布。实验结果表明在80 GPa以下，样品室内不同位置上的压力与平均压力（p）的差Δp很小，最大的Δp/p不超过1.5%。在90 GPa时，红宝石的荧光R线与常压的很相似。这表明利用固态氩做传压介质可以获得接近100 GPa的准静水压。此外，对红宝石荧光光谱中位置在14 938 cm^-1和14 431 cm^-1两条谱线随压力的变化情况也作了讨论，并由此得出结论，14 938 cm^-1这条线也可用来标定压力。     

超高压下红宝石荧光R线的猝灭压力与入射激发线波长的关系

 分别使用固态氩和体积比为4∶1的甲醇-乙醇混合溶液做传压介质，测量红宝石在这两种介质中的荧光光谱随压力的变化。首先发现在超高压下红宝石荧光R线的压致猝灭与入射激发线波长以及高压样品室内的静水压程度有关。实验结果表明：入射激发线的波长越长，荧光R线的猝灭压力越低；对同一激发线波长，静水压程度差，猝灭压力高。这一现象归因于红宝石吸收谱中U带和Y带随压力的蓝移。     

High-pressure optical studies on R-line fluorescence lifetime in Al2O3:V2+

The effect of high hydrostatic pressure (up to 10.3?GPa) at room temperature on fluorescence lifetime τ for R line (²E→⁴A₂ transition) in ruby Al₂O₃:V²⁺ was studied. The performed studies show the linear increase of τ with increasing pressure. At 10.3?GPa, τ is about 1.36 times higher than at ambient pressure. The obtained trend was explained by a model which considered the effect of pressure on τ through an induced change of line position, inter-ionic distance, compressibility, and molecular polarizability. A good agreement between the calculated and experimental values for τ was obtained.     

金刚石压砧内单轴应力场对物质状态方程测量的影响

金刚石压砧的几何结构使得在高压下封垫内的样品通常处于单轴应力场中：压砧轴向加载应力最大,径向应力最小.由于金刚石压砧内非静水压单轴应力场的影响,用传统的高压原位X射线衍射方法测得的物质压缩曲线一般位于理想静水压压缩曲线之上.利用金刚石压砧径向X射线衍射技术以及晶格应变理论,结合最近的钨、金刚石和硼六氧样品的高压原位同步辐射径向X射线衍射实验结果,从宏观差应力、样品强度、标压物质和待测物质强度的关系三个方面分析讨论了金刚石压砧内单轴应力场对物质状态方程测量的影响及解决方案. 关键词： 金刚石压砧 单轴应力场 高压原位X射线衍射 状态方程     

Pressure calibration in high pressure EXAFS experiments

Abstract

To avoid glitches due to Bragg reflection we use boron carbide anvils for our high pressure EXAFS experiments. Since boron carbide precludes the ruby fluorescence pressure calibration we use the EXAFS of selected materials to measure the reduction with pressure of the nearest neighbor distance and infer the pressure from an isothermal equation of state. The requirements for a good pressure calibrant and the difficulties in EXAFS data analysis are discussed. Cu, NaBr and RbCl have successfully been tested as pressure calibrants.     

Behavior of antimony above solid solubility in silicon produced by implantation and laser annealing

Abstract

Antimony implantation into <111> silicon was carried out at RT with a dose of 4.5 × 10¹⁵ cm^?2, energy 75 keV. For the annealing of the sample pulses of a Q-switched ruby laser were used with energy density of ～ 1.5 Joule/cm² and duration of 15–20 nsec. Hall effect measurement was applied to determine the electrical activity of the layers. Lattice location and the depth profile of Sb was studied by RBS and channeling technique. Measurements show that after laser annealing Sb occupies mostly substitutional sites in Si with 84% electrical activity. It has been shown that after laser annealing the concentration of Sb in lattice sites is almost an order of magnitude higher than the limit of solid solubility. Isochron and isothermal annealing of these samples up to 1150°C was carried out to study the kinetics of reverse annealing of antimony.     

Theoretical calculations of the R1 red shift of ruby under high pressure

The essentials of the pressure-dependent shifts of the ruby fluorescence lines can be understood by the concept of electron cloud expansion under pressure. By using this concept the relevant formulas for the red shift are derived. The calculated results for red shifts of the ruby R₁ line are in good agreement with the experimental data up to 1700 kbar.     

用高压显微光谱系统研究(Zn0.85Cd0.15)S:Cu,Al磷光体在流体静压力下施主-受主对的发光

用金刚石对顶砧高压显微光谱系统在室温和1bar—66kbar的流体静压力范围内研究了(Zn_0.85Cd_0.15)S:Cu,Al磷光体的发光峰位置和相对发光强度随压力而变化的规律。随着压力的增加,发射峰值波长迅速移向短波方向,而发射峰值对应的光子能量随压力增加的速率为4.7meV/kbar(38cm^-1/kbar)。这个值比该材料的吸收边随压力增加的速率要小。随着压力的增加,该磷光体的发光峰值相对强度急骤下降,当压力从常压升到66kbar时,发光峰值相对强度下降到原值的6％。这些结果可以用Al³⁺-Cu⁺的施主-受主对模型来解释。本文还估计施主(Al³⁺)和受主(Cu⁺)的激活能之和随压力增加的速率为3.7meV/kbar(30cm^-1/kbar)。 关键词：     

High pressure investigations on amorphous selenium

We report the diamond anvil cell (DAC) high pressure powder X-ray diffraction studies on amorphous selenium (a-Se) under truly hydrostatic pressure condition up to 20 GPa. Amorphous selenium exhibits a sharp and irreversible transition to a hexagonal structure at 10.6 ± 0.1 GPa. It is also known that metallization occurs in a-Se around this pressure. Some plausible arguments are provided to suggest that the amorphous to crystalline transition may be driven by metallization.     

Phase transition of samarium under high pressure

Abstract

The DAC X-ray power photograph method was employed for studing the phase transition of samarium up to 26.3 GPa. The experimental results show that the dhcp and fcc high pressure phase of Sm appeared at about 4.0 and 12.5 GPa and room temperature respectively. The dhcp phase was kept until 19.6 GPa. A model for Sm-type -? dhcp -? fcc phase transition is provided in this paper.     

Pressure effects on bacteriophage T4

Abstract

The conformational changes which occur in bacteriophage T4 during infection can be simulated by hydrostatic pressure. The kinetics of the pressure induced process is measured by the decrease of the virus infectivity. Experimental results are explained by assuming that the virus population is composed of three parts which differ in their pressure sensitivity. It is shown that the phages which are the highly sensitive part lose this feature when they are alawly accustomed to pressure.