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
Novel Materials and Ground States
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.