Novel Materials and Ground States

PRESSURE - I

590B F18

Sergey L. Bud’ko

units and scales

pressure measurements

uniaxial and biaxial pressure

Novel Materials and Ground States

Clayton A. Swenson

1923-2018

Distinguished Professor Emeritus, Department of Physics and Astronomy

~ 50 publications on high pressure physics (equations of state, superconductivity, etc.)

Novel Materials and Ground States

Clayton A. Swenson

1923-2018

Distinguished Professor Emeritus, Department of Physics and Astronomy

His father was Nels Swenson, who owned the Swenson and Redeen Grocery Store, which operated on Walker Street in St. Louis Park from 1923 to 1952. The story of this early Park business can be found in Clayton’s brother Don Swenson‘s book Something in the Water, available from the SLP Historical Society.Clayton received a scholarship to Harvard, where he studied physics. In his senior year at Harvard, Los Alamos was looking for scientists to work on the A-bomb. This was his first job. After the war, he was a new graduate student in Physics at Harvard, ready to do Nuclear Physics. He was awarded a fellowship to go to Oxford and work in the relatively new field of Low Temperature Physics. After his Oxford D. Phil. (Ph.D). he went back to Harvard to set up a low temperature program, then went to MIT to work for three years before finally ending up at the Department of Physics at Iowa State University and then Ames Laboratory of the Atomic Energy Commission. Each of these activities involved an abrupt change in life direction, often not expected. He both taught and did significant published research. He was named a Distinguished Professor and chaired the Department of Physics for seven years. He spent sabbatical years in Australia at their Standards Laboratory and in England at the National Physical Laboratory and more recently six months at Los Alamos (not on nuclear physics) For 25 years, he was the only non-Standards Laboratory member on the Consultative Committee on Thermometry of the International Committee on Weights and Measures in Paris.

http://slphistory.org/swensonclayton/

Novel Materials and Ground States

Pressure units

pascal

(Pa)

bar

(bar)

technical

atmosphere

(at)

atmosphere

(atm)

torr

(Torr)

pound-force per

square inch

(psi)

1 Pa ≡ 1 N/m2 10−5 1.0197×10−5 9.8692×10−6 7.5006×10−3 145.04×10−6

1 bar 100,000 ≡ 106 dyn/cm2 1.0197 0.98692 750.06 14.5037744

1 at 98,066.5 0.980665 ≡ 1 kgf/cm2 0.96784 735.56 14.223

1 atm 101,325 1.01325 1.0332 ≡ 1 atm 760 14.696

1 torr 133.322 1.3332×10−3 1.3595×10−3 1.3158×10−3 ≡ 1 Torr; ≈ 1 mmHg 19.337×10−3

1 psi 6,894.76 68.948×10−3 70.307×10−3 68.046×10−3 51.715 ≡ 1 lbf/in2

1 kbar ~ 1000 atm

1 GPa = 10 kbar

Novel Materials and Ground States

Why pressure?

500 TPa380 GPa 500 MPa

10 GPa1 GPa

CaFe2As2

Berthold Schwarz

Novel Materials and Ground States

Pressure around us - low

Novel Materials and Ground States

Pressure around us - highP

ressu

re in

CM

P la

bs

Novel Materials and Ground States

Pressure inside the Earth

Novel Materials and Ground States

Liquid column (1661, Huygens)

Bourdon gauge - 1849

Δp = gloc(ρl – ρg) H

How to measure pressure

Novel Materials and Ground States

Pressure measurements - Piston - cylinder

Friction (but can rotate the piston)

Up to 5 GPa (better below 1 GPa)

p1S1 = p2S2

p = F/S

Novel Materials and Ground States

Pressure measurements - Equation of State (EOS)

p = p(V,T)

p = [3K0(1-x)]/x5 . exp[c0(1-x)]

x = a/a0 = (V/V0)1/3

c0 = 3/2 (K0’ - 3)

a – lattice parameter, K0 – bulk modulus, K0’ – its pressure derivative

Structural measurements (neutrons, x-rays) on “simple solids”. Measure below 5 GPa, use above 5 GPa.

Linear temperature dependencies using:

α – thermal expansion and δ = d (ln α)/d (ln V)|T

Can use models for EOS

Novel Materials and Ground States

Pressure measurements – Fixed points

Can measure resistively (if no optical/x-ray access)

Sharp, with little hysteresis

Temperature-dependent

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Pressure measurements – resistance

Manganin (86% copper, 12% manganese, and 2% nickel)

1/R dR/dP = 2.5 x 10-11 Pa-1

“small” temperature dependence“moderate” stress dependence“some” batch to batch differenceageing (pressure) preferredgood reproducibility within the batch

Less ubiquitous:Zeranin (Cu-Mn-Sn alloy) n-InSb (UNIPRESS, Warsaw)

Room temperature resistance derivatives of elements or semiconductors (Pb, In, …)

Novel Materials and Ground States

Pressure measurements – superconducting manometers

[P in GPa]

Easy to get high purity materialsRelatively easy to measure

Low Hc – care about remnant fieldExtrapolation may be problematic

Novel Materials and Ground States

Pressure measurements – luminescence

Need optical access

Preferred for DAC

Huge pressure range

Pressure scales are moving target

Novel Materials and Ground States

Hydrostatic and uniaxial pressure

P

P=0P=0

How to check?

pressure sensor (small! and sensitive!)

pi = pj

and everything in between

one can use any pressure/stress pattern as long as it is known and well described

Novel Materials and Ground States

Are my pressure medium and pressure cell good enough? (Operational approach)

Can get similar results on several runs (reproducibility)

Transitions are not broadening under pressure (homogeneity/hydrostaticity)*

Consistent data on increase and decrease of pressure (reversibility – no plastic deformations)

Am I consistent with anybody else? Can I rationalize my data?

*assuming homogeneous, preferably single-crystalline, sample

(Beware of the case of CaFe2As2 in a piston-cylinder cell)

Novel Materials and Ground States

Pressure generation

Media:

gas

liquid

solid

Novel Materials and Ground States

Uniaxial pressure devices

- anvils F

sampleanvils

Force: - screw (+spring)- gas membrane- press/rod (from RT)

can be simple and compact

• parallelicity of the anvils and the sample• desire for thin samples • no voids/inclusions• pressure determination?• limited number of measurement techniques (?)

Novel Materials and Ground States

Uniaxial pressure devices

anvils - example

Novel Materials and Ground States

Uniaxial pressure devices - tension

F

F

simplecan calculate tension

uniform, small cross-section sample

vice like devices

Novel Materials and Ground States

Uniaxial pressure devices – tension - piezo

Novel Materials and Ground States

Biaxial pressure – epitaxial films

film-substrate mismatch

Novel Materials and Ground States

Biaxial pressure – epitaxial films on piezo

LSCOBa122-Co

Novel Materials and Ground States

Biaxial pressure – glue your sample on a piezo stack

See multiple publications from the group of Ian Fisher (Stanford) and references therein

Beware of glue, sample thickness, etc.