Diamond Anvil Cell Manual Cell Preparation, ac Susceptibility and electrical Resistivity Measurements, Accessory Equipment (version: November 2011) Washington University Physics Schilling High Pressure Lab March 24, 2014 Contents 1 Operation of the Diamond Anvil Cell 8 1.1DescriptionoftheDiamondAnvilCell............. 8 1.2ChecklistforPerformingaDACExperiment.......... 8 1.3CareoftheDiamondAnvilCell................. 11 1.3.1 Diamond Care and Installation of New Diamonds . 11 1.3.2 DiamondAlignment................... 13 1.3.3 BackingPieces...................... 18 1.3.4 CleaningtheDiamondAnvilCell............ 22 1.3.5 GasketPreparation.................... 23 1.4UsingtheApparatus....................... 30 1.4.1 PreparingtheDACforaMeasurement......... 30 1.4.2 InitialProcedures..................... 33 1.4.3 CoolingDown....................... 37 1.4.4 Controlling Temperature . .............. 45 1.4.5 Preparing the Cell for Loading with Liquid He . 47 1.4.6 LoadingtheCellwithLiquidHe............. 48 1.4.7 ChangingPressure.................... 50 1 2Measurements 53 2.1MeasuringSusceptibility..................... 53 2.2MeasuringPressureusingRubyFluorescence.......... 56 2.2.1 RubyFluorescence.................... 56 2.2.2 Measurement....................... 57 2.2.3 Lasers........................... 59 2.2.4 OpticalSystem...................... 60 2.3 Measuring Pressure using the Raman Diamond Vibron . 64 2.4MeasuringtheDiamondSeparation............... 67 2.5ProblemswithRubyMeasurements............... 69 3 Problems with the Equipment and Maintenance Info 71 3.1LaserPowerSupplyBoard.................... 71 3.2PhotomultiplierTube....................... 71 3.3 Pickup Coil ............................ 72 3.4 Capillary Line Connection .................... 72 3.5Thermometers........................... 73 3.6 Laser Power ............................ 73 4 The Coil System 75 4.1WindingtheTissenSide-by-SideCoilSystem......... 75 4.2 WindingtheCornelius/KlotzCoilSystem......... 82 4.2.1 Cornelius/KlotzSecondary(Pickup)Coils....... 82 4.2.2 Cornelius/KlotzPrimary(Field)Coil.......... 85 4.2.3 MiniaturizedCoils(Andy)................ 85 2 4.2.4 Epoxies.......................... 86 4.3CommonPitfalls......................... 86 5 Micro Spot Welder Guide 88 5.1Overview.............................. 88 5.2 Components ............................ 88 5.2.1 PowerSupply....................... 89 5.2.2 TungstenElectrode.................... 89 5.2.3 LowerElectrode...................... 90 5.2.4 Gold/PlatinumWire................... 90 5.3 Preparations ............................ 90 5.4Welding.............................. 93 5.5References............................. 95 6 Quick Guide for using the Current Ramping Control Unit 96 6.1Overview.............................. 96 6.2 Connections ............................ 96 6.3Startuptutorial......................... 96 6.4Controls.............................. 99 6.4.1 MaxOutputDial..................... 99 6.4.2 RateDial......................... 99 6.4.3 SweepToggleSwitch................... 99 6.4.4 SetButton......................... 99 6.4.5 StartButton.......................100 6.4.6 PauseButton.......................100 3 6.5DialPositionValues.......................100 6.6Programming...........................101 7 Vickers Hardness Indenter 102 7.1Background............................102 7.2Instructions............................102 7.3Results:..............................104 8 Copper Plating 107 9 Resistivity Measurments in the DAC 109 10 Making an Insulated Gasket 121 10.1InsulatingtheGasket.......................121 10.2MakingaSampleChamber....................121 10.3Makingtheelectrodes......................124 10.4Puttingelectrodesonthegasket.................125 10.5 Making insulation materials for resistance measurements in DAC127 10.5.1Diamondpowder+Epoxyglue.............127 10.5.2OtherMaterials......................128 4 List of Figures 1.1DiamondAnvilCellcomponents................. 9 1.2 Jigs for supporting diamonds during gluing process. 14 1.3Jigusedforremovingthebackingpieces............. 19 1.4 PPMS measurement on gasket and backing piece materials. 20 1.5 PPMSmeasurementsontheWCsample from Kennametal . 21 1.6 Gasket punch ........................... 25 1.7 Oxford “flow”cryostat....................... 38 1.8 Oxford “flow”cryostat....................... 39 1.9NewliquidHetranfertube.................... 40 1.10TheoldliquidHetransfertube................. 42 1.11Plotofmembranevs.samplepressure............. 51 2.1OriginalDACopticalsetup.................... 61 2.2 Schematic of modifiedopticalsetup................ 63 2.3Ramanscattering......................... 65 2.4Ramanmeasurementsetup.................... 66 2.5Ramandiamondvibronspectrum................ 68 2.6Heliumdensity.......................... 69 4.1Side-by-sidecoilsystem...................... 76 4.2Coilformforwindingside-by-sidecoil.............. 77 5 4.3Explodedviewofthecoilwindingsprig............. 77 4.4 Coil winding configuration.................... 78 4.5Sparkweldingcircuit....................... 81 4.6 Typical delrin coil form used for winding pickup coils. 83 5.1 Micro spot welding power supply and micromanipulator. 89 5.2 Pulse profilesformicrospotwelder............... 90 5.3Flattenedtipofthegoldwire.................. 91 5.4 Layout of components for bonding wires to small samples . 92 5.5Weldedgoldwires......................... 94 5.6 Examples of samples wired with the micro spot welding unit. 95 6.1Controlsforcurrentrampingdevice............... 97 6.2 One of the power supplies used with the current ramping device. 98 7.1Vickershardnessindenter....................103 7.2Diamondindentationformeasuringhardness..........103 7.3SteelhardnessconversiontableforVickersHV0.5.......105 8.1SetupforcopperplatingtheDACpiston.............108 9.1 Hole drilled in Rhenium gasket with EDM. .........110 9.2 The insulation tape cur out in the preindented area. 111 9.3 Diamond powder filledinthepreindentedarea.........112 9.4Insulationlayerafterbeingpressed................113 9.5 Crazy glue on the perimeter of the preindented circle. 114 9.6Samplechamber..........................115 6 9.7Initialelectrodeposition......................116 9.8Resistivitymeasurementelectrodearrangement........117 9.9Resistivitysamplespaceunderpressure.............118 9.10Finalpositionoftheelectrodesoverthehole...........119 9.11Clampinresistivitymeasurements...............120 10.1Preparationofinsulatinggasket.................122 10.2Insulatingpowderforinsulatinggaskets.............122 10.3Insulatinglayerofpowderongasket...............122 10.4Samplespacefornon-hydrostaticmeasurements........123 10.5Electrodesandsamplechamber.................123 10.6Resistivitymeasurementsamplechamber............124 10.7Cuttingplatinumelectrodes...................125 10.8Culetandpre-indendentedareawithelectrodes........126 10.9Placingelectrodes.........................126 10.10Pressingelectrodes........................127 10.11Keepingelectrodesinplace....................128 10.12Gasketwithelectrodesinplace.................129 10.13Gasketandwiresonthegasketholder..............130 10.14Diamondpowderandepoxymixture..............131 7 1. OperationoftheDiamondAnvilCell 1.1 Description of the Diamond Anvil Cell The diamond anvil cell (DAC) described herein (pictured in Figure 1.1) was designed by Jim Schilling in 1982 and machined at the U. of Delaware. The original drawings are included in the DAC binder. The DAC is designed to reach pressures greater than 1 Mbar. In March 2011, Narelle Hillier reached a pressure of approximately 200 GPa, the highest pressure attained to date. Stefan Klotz designed the experimental setup and more detail can be found in his thesis (in German), in his papers, and in the theses of later students. The following students have used the DAC for substantial portions of their Ph.D. work: Stefan Klotz (1992), Andrew Cornelius (1996), Craig Looney (1997), Sascha Sadewasser (1999), Shanti Deemyad (2004), James Hamlin (2007), Mathiewos Debessai (2009), and Wenli Bi (2011). 1.2 Checklist for Performing a DAC Experiment This section gives a step-by-step checklist for performing a DAC experiment. The starting point assumes that the cell is still together after the completion of an experiment. The procedure is then: 1. Make sure that the capillary line coming from the He gas bottle to the topofthecryostatissecuredandnotverybent. Iftoomuchstrainis placed on the capillary, especially at the joint with the membrane, it might break. 2. Take the clamp apart and store all of the components in a safe location. Ensure that the capillary line for the diaphragm is securely stored. 3. Clean the diamonds and inside of the clamp thoroughly with ethanol or methanol. (Do not use acetone as it could attack the glue holding the diamonds and coil system in place.) 8 Figure 1.1: The DAC. In addition to the piston and body, the force plate (which sits on top of the diaphragm, not shown), the retaining ring, and the torquing tool for the retaining ring are pictured from left to right in the foreground. 9 4. Ensure that the diamonds are still aligned. 5. Punch out a gasket and pre-indent to the desired thickness. 6.Drilltheholeinthegasket.Makesurethattheholeiscenteredonboth sides!!!!! This is also an indication of how well the diamonds are aligned and whether the piston is wobbling at all. If required (for hydrostatic measurements), sputter gold onto the gasket. 7. If you have previously removed the coil system (usually this is not necessary) or are installing a new one, mount the coil system in the cell