Laser Heated Diamond Anvil Cell

Thomas Duffy, Princeton University

Guoyin Shen, GSECARS, University of Chicago

Dion Heinz, University of Chicago

Andy Campbell, University of Chicago/University of Maryland

Acknowledgements: A. Kubo, S. Shieh, B. Kiefer, V. Prakapenka

COMPRES annual meeting June 2005

Laser heating facilities in wide use at synchrotrons:

-- Advanced Photon Source: GSECARS, HPCAT, SRICAT

-- ESRF, SPring-8, ALS, NSLS

Mainly variants of near-IR laser, double-sided heating design of G. Shen and colleagues, RSI, 2001.

CO2 laser heating systems:

-- Advantages: large focal spot, no absorber so avoid chemical reactions and diffraction interference

-- Problems: heating limited to <40 GPa?, diamond damage, mainly 1-side only

Sample environment (Laser heating workshop: March 2004):

-Temperature gradients

- Design of heating geometry

-Thermal pressure effects

- P/T standards

Selected Activities for 2004-2005

3/04 Laser heating workshop at APS (~60 participants)

7/04 Andy Campbell joins project as research associate (50%)

8/04-4/05 Completion of system design and procurement of components including CO2 laser

11/04; 3/05 Princeton/Chicago collaborative beamtime at 13-ID-D

2/05 Safety features completed and protocol finalized for CO2 laser system in GSCEARS laser lab

2/05-6/05 Testing of system design and benchtop experimentation with optical layouts

7/05 Andy Campbell becomes Asst. Prof. U. of Maryland; Search for replacement ongoing

GSECARS single-sided CO2 laser heating plan

Design goals for CO2 system: CO2 laser heating system for in situ use at APS beamline 13-ID-DStatus: heating system established and tested in lab, almost ready for hutch installation

Power adequate for heating Fe-free silicates in the DACStatus: 230 W laser more than adequate. 50 µm spot in olivine heats at ~90 W at 38 GPa with Type I diamonds; Heating can be carried out using either Type 1 or Type II diamonds.

Robust, reliable system without alignment driftStatus: Negligible drift in short term heating. High laser power will require better DAC cooling to be implemented.

Power stability as great as achievableStatus: CO2 laser can be operated in CW mode. External power modulation is done using a polarizer/attenuator. Motorization of attenuator and feedback loop for stabilization will be implemented

Facilitate hutch installation by using existing components wherever appropriateStatus: CO2 beam delivery has been designed to be single-sided; viewing optics and temperature measurement will occur on the other side of the DAC, and will utilize the system currently in place for YLF laser heating.

Conform to safety requirements at APSStatus: Laboratory system interlocked, keyswitched, and shielded. Guidelines for alignment and operation have been established and implemented. Shielding material has been installed also as a liner to laser enclosure in 13-ID-D hutch.

Description of CO2 laser heating components: CO2 laser: Synrad model f201. 230 W output power at 10.6 µm; 5-25 kHz or CW; Linearly polarized, extinction ratio ~150:1; high mode quality (TEM00 98%)

Diode alignment laser: Edmund. 633 nm; Class I (0.9 mW)

Beamcombiner: Laser Research Optics. Transmits 10.6 µm 99%; reflects 633 nm 85%; ZnSeBeam expander: Infrared Optical Products. 2X; ZnSe; Used to limit beam divergence

Mirrors: Ophir and Laser Research Optics. Au/Cu or Au/Si; high reflectivity (>99.8%); warm up by only 2-3 °C at 100 W

Attenuator: II-VI Inc. Polarizing attenuator exploits high extinction ratio of laser; consists of 2+2 ZnSe brewster windows; 200:1 extinction; water-cooled; negligible beam deflection when rotated; currently manual operation but planned for motorized operation in hutch

Laser focussing lens: Ophir or Laser Research Optics. ZnSe; plano-convex, meniscus, and diffractive lenses have been tested; 1.0” dia, 2.5” f.l. PCX lens currently used; spot size in DAC ~50 µm

Final mirror: Under development. Have been using Ophir Au/Si, 3 mm thick. Testing custom Au/C mirror, made by Au coating (APS metrology lab) on glassy carbon substrate

Viewing optics: On opposite side of DAC from CO2 laser beam delivery. Negligible CO2 beam transmitted through DAC using type I diamonds; thin silicate glass slide can be installed to block beam if measureable transmission detected with type II diamonds

After CO2 laser heating at 37 GPaol -> pv + mw

100 m

Future:

--Further bench top testing of CO2 heating system;Some modification of design to adapt to constraints of 13-ID-D diffractometer setup

--By May 06, installation of CO2 laser heating system in 13-ID-D complete

--Commissioning of the system during the APS 2006-2 run

-- Open to general users for 2006-3 run.

Other Ongoing Projects

-- Finite element simulations of thermal structure in the laser-heated diamond cell (Kiefer and Duffy, J. Appl. Phys., 2005)

--Systematic study of thermal pressure effects and development of new in situ standards at ~20-40 GPa

-- Sample environment

-- X-ray fluorescent crystals for x-ray/heating alignment

-- ultrahigh P-T capabilities

Laser heating to 2 MBar

Kiefer and Duffy, J. Appl. Phys. 2005

Double Hot Plate Single Hot Plate

Micro Furnace

Y3Al5O12 doped with 0.05% Ce (YAG:Ce)

YAG:Ce fluoresces in visible in response to x-ray excitation

~3 m positioning of x-ray beam and heating spot center

Shieh et al., ESPL, 2005

A. Kubo, S. Shieh, T. Duffy, G. Shen, V. Prakapenka

10 15 20

?

?

Pt1

11

Pt2

00

Pt2

20

Pt3

11

Pt2

22

Pt3

31

Ar4

22

Pt4

20

Pt4

00+

Ar4

20

Ar3

31

Ar3

11

Ar2

20

Ar2

00

Ar1

11

Mg

O4

22

Mg

O4

20

Mg

O3

31

Mg

O40

0

Mg

O2

22

Mg

O3

11

+A

r22

2

Mg

O22

0

Mg

O2

00

Inte

nsi

ty (

a.u

.)

2Theta / degrees (lambda=0.3311A)

before laser heating after laser heating

Mg

O1

11

MgO+Pt (in argon)

~18GPa

Thermal pressure

-- MgO, Pt, Ar, and ruby

-- P=18-25 GPa, T ~ 2000 K

--Good agreement between MgO and Pt pressures during and after heating

--thermal pressure in sample heated at ~1400 K was 2 GPa at 23 GPa

--After heating, pressure outside sample (ruby) was 2-3 GPa higher than pressure in heated area

A. Kubo, T. S. Duffy, G. Shen, and V. B. Prakapenka