Infrared studies in the 1- to 15-micron region to 30,000 atmospheres

Abstract

A p ress ure ce ll ,--as constructed usin g a pair of type II d ia monds for sL ud y of infrare d spectra of solids in t he 1-to l5-micro n reg ion . Usin g co mme rcia l infra red equipme nt, spectra can be st ud ied routin ely to calculated press ures as high a s 30 ,000 atm osphe res. U nde r pressure, bands ge nerall y shif t to higher fr eque ncies a nd decrease in in ten s ity. The m agni t ude of bo th cha nges dep ends on the mode of vib ra t ion. Occasion a ll y m ajor cha nges in s pectra occur. In calcite the carbon -oxyge n symme t ri c st retchin g, m od e v" becomes a cti ve a t ele vated press ures while the do ubly dege nera te V3, sLretching, < Ind "4, bend ing, f,' (,-quencies spl it . F l'Om t he s hi ft in frequency of v, wiLh pr e~s ure the " compressibil it..v", [( -l / R o)(dR/dp)]' of the C-O bo nd le ngth, R, is calcula ted to bp 2.8 X IO-7/ atm os phere. :'Iia:i or spec tral ch a nges are no t observed in the sa me press ure ranges in other car bonates hav ing the calcite or aragonit e s t r uctu res. Thc rCR ult s for calcit e may be expla in ed by a shif t of the COs ion fr om the trigo na l axi s und e ,' press ure.

Deformation T-Cup: A new multi-anvil apparatus for controlled strain-rate deformation experiments at pressures above 18 GPa

“…1 With his apparatus Bridgeman performed experiments at pressures up to about 10 GPa. The subsequent development of the diamond-anvil cell 45 increased the pressure range over which experiments could be performed. Early attempts to deform samples at high pressure were conducted using the diamond cell as a deformation device; 23 a technique which is still used a) Electronic mail: simon.hunt@ucl.ac.uk at very high pressures.…”

Diamonds on Diamond: structural studies at extreme conditions on the Diamond Light Source

“…No evidence of the oS56 structure was found below 30 GPa, and indeed the tI56 phase was found to be quenchable back to ambient pressure. The discovery of the first non-cP7-type MB 6 compound quenched down to ambient pressure may help in the design of boron-based intermetallics with new electronic, magnetic and superconducting properties through a careful choice of the metal and the synthesis conditions. The complexity of the high-pressure tI56 structure is such that it could only have been determined through the use of powerful ab initio structure-searching algorithms.…”

“…The invention of the diamond anvil cell (DAC) in 1959 [5,6] was perhaps the pivotal development in high-pressure science. By using very small samples compressed within a pressure transmitting medium between the tips of two gem-quality diamonds (figure 1), the DAC allowed very high pressures to be obtained in a device small enough to hold in one's hand (and mount at a synchrotron!).…”

In situ temperature measurements through i-anvils in diamond anvil cells

“…Since the middle of the 20 th century, a number of devices have been developed to realize high pressure and high temperature experiments in two directions: either to study quench products at RC after equilibrium at P and T has been achieved; or to study the equilibrium in situ. Diamond anvils cells [1][2][3] (DAC) are probably the most powerful tools in experimentation thanks to the use of diamonds as anvils because (1) they cover a large range of pressures, from a few MPa to few hundreds of GPa, and temperatures from -180°C to a few thousands of °C, from the interior of planets up to their surfaces; (2) they permit direct observation of the processes through the transparent diamonds in real time, free of any quench effects; (3) in situ characterization at pressure and temperature during experiments is possible through various spectroscopical techniques (X-rays, FTIR, Raman...). However, the success of such investigations relies on the exact determination of the parameters of the experiments: pressure [4][5][6] and temperature.…”