Diamond Anvil Cell Technology Research Articles

Pressure-Induced Tunable Charge Carrier Dynamics in Mn-Doped CsPbBr3 Perovskite.

All-inorganic perovskite materials (CsPbX3) have attracted increasing attention due to their excellent photoelectric properties and stable physical and chemical properties. The dynamics of charge carriers affect the photoelectric conversion efficiencies of perovskite materials. Regulating carrier dynamics by changing pressure is interesting with respect to revealing the key microphysical processes involved. Here, ultrafast spectroscopy combined with high-pressure diamond anvil cell technology was used to study the generation and transfer of photoinduced carriers of a Mn-doped inorganic perovskite CsPbBr3 material under pressure. Three components were obtained and assigned to thermal carrier relaxation, optical phonon–acoustic phonon scattering and Auger recombination. The time constants of the three components changed under the applied pressures. Our experimental results show that pressure can affect the crystal structure of Mn-doped CsPbBr3 to regulate carrier dynamics. The use of metal doping not only reduces the content of toxic substances but also improves the photoelectric properties of perovskite materials. We hope that our study can provide dynamic experimental support for the exploration of new photoelectric materials.

Structure and Dynamics of Low-Density and High-Density Liquid Water at High Pressure.

Liquid water has a primary role in ruling life on Earth in a wide temperature and pressure range as well as a plethora of chemical, physical, geological, and environmental processes. Nevertheless, a full understanding of its dynamical and structural properties is still lacking. Water molecules are associated through hydrogen bonds, with the resulting extended network characterized by a local tetrahedral arrangement. Two different local structures of the liquid, called low-density (LDW) and high-density (HDW) water, have been identified to potentially affect many different chemical, biological, and physical processes. By combining diamond anvil cell technology, ultrafast pump-probe infrared spectroscopy, and classical molecular dynamics simulations, we show that the liquid structure and orientational dynamics are intimately connected, identifying the P-T range of the LDW and HDW regimes. The latter are defined in terms of the speeding up of the orientational dynamics, caused by the increasing probability of breaking and reforming the hydrogen bonds.

Approaching the “cold curve” in laser-driven shock wave experiment of a matter precompressed by a partially perforated diamond anvil

AbstractThis paper suggests a novel route to approach the cold compression curve in laser-plasma induced shock waves. This effect is achieved with a precompression in a diamond anvil cell (DAC). In order to keep the necessary structure of one dimensional shock wave it is required to use a diamond anvil cell with a partially perforated diamond anvil. Precompression pressures of about 50 GPa, that are an order of magnitude higher than the currently reported pressures, are possible to obtain with presentley existing diamond anvil cell technology. The precompressed Hugoniot of Al was calculated for different precompression pressures and it was found that at precompression pressure of 50 GPa the Hugoniot follows the “cold curve” up to about 2 Mbar and 5.2 g/cc. Furthermore, the thermal relative contribution on the Hugoniot curves is calculated.

Invited Article: High-pressure techniques for condensed matter physics at low temperature

Condensed matter experiments at high pressure accentuate the need for accurate pressure scales over a broad range of temperatures, as well as placing a premium on a homogeneous pressure environment. However, challenges remain in diamond anvil cell technology, including both the quality of various pressure transmitting media and the accuracy of secondary pressure scales at low temperature. We directly calibrate the ruby fluorescence R1 line shift with pressure at T=4.5 K using high-resolution x-ray powder diffraction measurements of the silver lattice constant and its known equation of state up to P=16 GPa. Our results reveal a ruby pressure scale at low temperatures that differs by 6% from the best available ruby scale at room T. We also use ruby fluorescence to characterize the pressure inhomogeneity and anisotropy in two representative and commonly used pressure media, helium and methanol:ethanol 4:1, under the same preparation conditions for pressures up to 20 GPa at T=5 K. Contrary to the accepted wisdom, both media show equal levels of pressure inhomogeneity measured over the same area, with a consistent DeltaP/P per unit area of +/-1.8 %/(10(4) microm(2)) from 0 to 20 GPa. The helium medium shows an essentially constant deviatoric stress of 0.021+/-0.011 GPa up to 16 GPa, while the methanol:ethanol mixture shows a similar level of anisotropy up to 10 GPa, above which the anisotropy increases. The quality of both pressure media is further examined under the more stringent requirements of single crystal x-ray diffraction at cryogenic temperature. For such experiments we conclude that the ratio of sample-to-pressure chamber volume is a critical parameter in maintaining sample quality at high pressure, and may affect the choice of pressure medium.

Yield strength of molybdenum at high pressures

In the diamond anvil cell technology, the pressure gradient approach is one of the three major methods in determining the yield strength for various materials at high pressures. In the present work, by in situ measuring the thickness of the sample foil, we have improved the traditional technique in this method. Based on this modification, the yield strength of molybdenum at pressures has been measured. Our main experimental conclusions are as follows: (1) The measured yield strength data for three samples with different initial thickness (100, 250, and 500 microm) are in good agreement above a peak pressure of 10 GPa. (2) The measured yield strength can be fitted into a linear formula Y=0.48(+/-0.19)+0.14(+/-0.01)P (Y and P denote the yield strength and local pressure, respectively, both of them are in gigapascals) in the local pressure range of 8-21 GPa. This result is in good agreement with both Y=0.46+0.13P determined in the pressure range of 5-24 GPa measured by the radial x-ray diffraction technique and the previous shock wave data below 10 GPa. (3) The zero-pressure yield strength of Mo is 0.5 GPa when we extrapolate our experimental data into the ambient pressure. It is close to the tensile strength of 0.7 GPa determined by Bridgman [Phys. Rev. 48, 825 (1934)] previously. The modified method described in this article therefore provides the confidence in determination of the yield strength at high pressures.

Probing hydrogen-rich molecular systems at high pressures and temperatures

Information on the behavior of hydrogen-containing simple molecular systems at high pressures and temperatures is central to many problems in chemistry and allied sciences. The combination of increasing pressure and temperature causes a redistribution of the electronic density, and the resulting alterations in interatomic interactions give rise to changes in macroscopic properties. Experimental studies of hydrogen-rich systems under extreme conditions have advanced considerably in recent years as a result of improvements in diamond anvil cell technology in combination with resistive- and laser-heating techniques. These experimental methods are combined with spectroscopic and diffraction techniques, and the results interpreted with the aid of molecular simulations. In this tutorial review we discuss recent findings in hydrogen, water, and other selected hydrogen-rich systems including compounds formed from these materials. The results are examined in terms of the evolution of effective potentials and interatomic vibrational coupling, molecular dissociation and recombination, ionization and polymerization, quantum effects, and order-disorder phenomena.

New condensed matter probes for diamond anvil cell technology

An overview of several new developments in diamond anvil cell techniques is presented. Thenovel techniques developed in our laboratory address fundamental properties of compressedmaterials, e.g. vibrational, electronic and spin excitations. We focus on the techniques madepossible by third-generation synchrotron x-ray sources and by the development of themagnetic susceptibility probes in diamond anvil cells. A brief list of topics is given below:Application of nuclear resonant inelastic x-ray scattering technique to themeasurements of the phonon density of states and elastic properties ofiron-containing materials at megabar pressures.Magnetic collapse and high-spin to low-spin transitions probed by the x-rayK β emission process in transition metal compounds.Superconductivity in multi-megabar pressure range studied by the magneticsusceptibility technique.Selected applications of these techniques will be covered, including elastic properties ofcompressed hcp-Fe, insulator–metal transition in FeO and superconductivity in Li.

High Pressure X-Ray Crystallography With the Diamond Cell at NIST/NBS.

Scientists in the Crystallography Section at NIST/NBS made several outstanding contributions which greatly promoted the development and advancement of high pressure x-ray crystallography during the second-half of the 20th century. These milestone achievements or “firsts” included: (1) the invention of the lever-arm type diamond anvil cell (DAC) in 1958; (2) the development of DAC technology for powder x-ray diffraction at high pressure in 1960; (3) the introduction of DAC methodology for single crystal x-ray diffraction at high pressure in 1964; (4) the invention of the optical fluorescence ruby method of pressure measurement in 1971; and (5) the discovery of hydrostatic pressure-transmitting media useful to unprecedented pressures for that time. These achievements provided the spark that ignited the explosion of activity in high pressure research that occurred in laboratories throughout the world during the latter part of the 20th century. It is still going on, unabated, today. An estimated 5000 DACs were built during the last 40 years.

Theoretical stability limit of diamond at ultrahigh pressure.

Based on density-functional total-energy pseudopotential calculations, we find that diamond structure carbon becomes energetically unstable relative to a highly distorted tetrahedrally coordinated structure at pressures above 5.0 Mbar. This distorted phase has a rhombohedral crystal structure containing eight atoms (denoted as the R8 structure) and has recently been identified experimentally as a pressure-induced metastable phase of silicon. This result has profound implications for ultrahigh pressure experimentation as it places a substantially lower limit on the maximum pressures attainable with diamond-anvil cell technology than was believed to exist previously.

Prospects of using synchrotron radiation facilities with diamond-anvil cells: High-pressure research applications in geophysics

Diamond-anvil pressure cells have proven versatile and useful for conducting high pressure research in the submegabar range. The interfacing of diamond-anvil cell technology with synchrotron facilities seems a logical new step for carrying out in situ X-ray diffraction studies of materials under extreme conditions of combined high pressure and temperature. The conventional film method of X-ray diffraction has definite limitations which call for the energy dispersive analysis techniques. Various potential high pressure-temperature studies in geophysics and related fields involving the use of diamond-anvil cell, synchrotron facilities and energy dispersive techniques are exemplified. For geophysical studies the conditions prevailing in 86% of the Earth's volume are capable of being simulated completely in pressure, and partially in pressure and temperature, simultaneously.