RevSciInstrum_75_5022

8/8/2019 RevSciInstrum_75_5022

1/4

High pressure cells for magnetic measurementsDestructionand functional tests

J. Kamard,a) Z. Machtov, and Z. Arnold Institute of Physics AS CR, Na Slovance 2, 182 21 Praha 8, Czech Republic

(Received 19 May 2004; accepted 30 August 2004; published 2 November 2004)

The design of nonmagnetic CuBe and multilayer CuBe+MP35N hydrostatic pressure cells for

magnetization and magnetostriction measurements in a pressure range up to 2 GPa at temperaturesdown to 5 K and in fields up to 14 T is presented. The safety operation of the cells is based on

destruction tests described in this work. An influence of the pressure cells on measured magnetic

magnitudes and the temperature induced pressure changes in the clamped cells have been carefully

studied in a temperature range from 350 K down to 5 K using different pressure transmitting

media. 2004 American Institute of Physics. [DOI: 10.1063/1.1808122]

I. INTRODUCTION

During the last decade, pronounced magnetovolume and

magnetoelastic phenomena have been discovered in the f-

and d-electron systems at multiextreme conditionsunderhigh pressures at low temperatures and in high magnetic

fields. A systematic study of the general dependencies of

magnetic moments and magnetic interactions on interatomic

distances in the rare earth and transition elements alloys and

intermetallic compounds has brought basic information for

understanding of the Invar-phenomena, the huge magneto-

crystalline anisotropy and crystal electric field effects.1

Using

advantages of commercial measurement systems with super-

conducting quantum interference device (SQUID) magneto-

meters the generation of small or miniature high pressure

cells has been developed for measurements of magnetization

and magnetocrystalline anisotropy,14

magnetostriction, and

magnetotransport properties5,6

at hydrostatic pressures up to

2 GPa, magnetic fields up to 20 T, and temperatures down to

4 K.

Our pressure study of magnetic moments and noncol-

linear magnetic structures in the Fe-rich R-Fe intermetallics7

and study of magnetotransport properties of the U-based

intermetallics6

awoke specific demands on the high pressure

technique. We designed and tested two types of nonmagnetic

pressure cells for magnetization, magnetostriction, and mag-

netotransport measurements. The CuBe and multilayer

CuBe+MP35N hydrostatic pressure cells were fitted to usein a SQUID magnetometer (MPMS-5S) and in the physical

property measurement system (PPMS-14T) both from aproduction of Quantum Design Ltd., San Diego, CA (QD).

Using these tailor-made cells, magnetic studies in a pressure

range up to 2 GPa at temperatures down to 2.5 K and in

fields up to 14 T can be performed. A guarantee of their

safety operation is based on destruction tests of the construc-

tion materials presented below. An influence of the cells on

magnetic magnitudes measured in the QD measurement sys-

tems and temperature induced changes of pressure inside the

clamped cells are mentioned in the last part of the article.

II. PRESSURE CELLS

The hydrostatic pressure cells with a liquid pressure-

transmitting medium were designed to ensure a compression

of studied single crystals without their damage or plastic

deformation. The dimensions of the CuBe cell for magneti-

zation measurements (Fig. 1) were limited by a sample space

in the SQUID magnetometer. The standard Bridgman-type of

seal is used on a piston. The plug with a sample holder is

sealed by a set of Cu- and plastic rings. An orientation of the

studied single crystals fixed on the sample holder can be

easily checked by the x-ray Laue method. A connection of

the holder with the plug by a screw ensures that a misalign-

ment of crystal axes and SQUID axes is smaller than 3.

So, an uncertainty in a determination of magnetization is less

than 0.3%. Pressure is determined at a low temperature re-

gion from a pressure shift of the critical temperature TC of

superconducting transition in Pb. The spindle oil (OL3) has

been used as a pressure-transmitting medium.

The two-layer CuBe+MP35N high pressure cell (Fig.2) was constructed for direct electrical measurements includ-

ing magnetoresistance. Compressibility, thermal expansion,

and anisotropy of spontaneous and forced magnetostriction

can be measured with help of micro-strain gauges fixed on

the studied single crystals. Cu-antiextrusion rings seal the

Teflon container with pressure transmitting medium only.Twelve Cu wires are lead out of the pressure cell through the

plug and fixed on the standard electric QD connector that is

firmly attached to this plug. Thanks to this construction, the

pressure cell can be used in the PPMS-14T by a standard

way as the other QD inserts. Three four-wire resistivity out-

puts enable continual measurement of pressure by the Man-

ganin sensor and, e.g., simultaneous measurements of strains

of the sample in two directions by strain gauges. The pres-

sure and temperature effects on properties of the strain

gauges and their relevant calibration were described earlier.9a)

Electronic mail: [email protected]

REVIEW OF SCIENTIFIC INSTRUMENTS VOLUME 75, NUMBER 11 NOVEMBER 2004

0034-6748/2004/75(11) /5022/4/$22.00 5022 2004 American Institute of Physics

Downloaded 29 Mar 2010 to 157.92.44.72. Redistribution subject to AIP license or copyright; see http://rsi.aip.org/rsi/copyright.jsp
http://dx.doi.org/10.1063/1.1808122


2/4

III. EXPERIMENT AND RESULTS

To ensure the safety operation of the cells, we performed

the destruction tests of the CuBe and MP35N parts of cells

(identified as No. 1 in Fig. 2) after their standard temperature

treatment. The CuBe (Berylco Co., Oberursel, Germany)

parts were annealed at 315 C for 2 h and the MP35N (La-

trobe Steel Co., Latrobe, PA) parts were heated at 590 C for

4 h, both in argon atmosphere. During this heat treatment,

the parts were packed in Ta sheets. The resultant hardnesses

were 60510 HV and 4205 HV in the case of the MP35N

alloy and the CuBe bronze, respectively. The strain gauges

were glued on the outer surface of the tested cells in a tan-

gential direction to measure R/R0. The cells were filled by

indium and closed by tungsten carbide (WC) pistons that

were sealed by the Cu-antiextrusion rings. Pressure in in-

dium is almost hydrostatic and a friction of the WC pistons is

sufficiently low to determine pressure P inside cells from

force of a hydraulic press. Pressure was enhanced repeatedly

and very slowly by steps of 0.03 GPa (with pause 20 s be-

tween steps) up to destruction of the cells. The destruction

tests were analyzed by a use of the simple Lam Eqs. (A1)

(with K2 =5.44). The equations are mentioned in the Appen-

dix. The deformation curves of the MP35N alloy and the

CuBe bronze are presented in Figs. 3 and 4, respectively. The

limit pressure Pmax of elastic deformation was derived from

the linear part of the deformation curve in the first cycle of

the loading. The received values, Pmax =1 GPa for MP35N

and Pmax =0.8 GPa for CuBe, are in very good agreement

with relation (A2) in the Appendix. The yield stresses in

tension Yt of both materials were derived from the measured

hardnesses. The values of Youngs modulus E calculated

from the linear parts of the deformation curves [with the help

of Eq. (A3) in the Appendix] agree well with the data of the

producers, EMP35N =235 GPa and ECuBe=127 GPa. An autof-

rettage of the cells is clearly seen in the next cycles of load-ing. During the last one, the cells were loaded up to destruc-

tion. A process of the destruction of the CuBe cell was very

quick and a crack went through all length of the cell. In the

case of the MP35N alloy, an enormous deformation preceded

the destruction and the crack appeared in the central loaded

part of the cell only, i.e., both ends of the cell with the WCpistons inside remained undamaged.

We have used the deformation curves to determine limits

of load of cells to their autofrettage. After the heat treatment,

the cells were filled by indium and loaded by force that in-

duces a plastic deformation. A limit of the plastic part of

deformation, Rplast/R5*104, was chosen to keep the

cells in the elastic deformation regime during their operation

up to pressure 1 GPa in the CuBe cells and up to 1.5 GPa in

the MP35N single-layer cells. The elastic limit of pressure in

the outer CuBe layer at a contact with the MP35N cell is

0.41 GPa and this pressure should not be exceeded when the

maximum pressure inside the two-layer cell is reached. In

that case, the elastic behavior of the two-layer CuBe+MP35N high pressure cell can be ensured up to pressure2 GPa.

IV. FUNCTIONAL RESULTS AND CONCLUSIONS

The influence of both the pressure cells and the pressure

medium on measured magnetic magnitudes were carefully

FIG. 1. Miniature CuBe pressure cell with inner diameter 2.5 mm and outer

diameter 8.6 mm; 1, 9upper and lower pressure clamping bolts, 2plug

with 3sealing, 4sample on a holder, 5pressure cell, 6lead pressure

sensor, 7piston with Bridgman mushroom-type seal, 8piston backup.

FIG. 2. Multilayer CuBe+MP35N high pressure cell with inner diameter7 mm and outer diameter 25 mm; 1inner cell from MP35N, 2outer

CuBe supporting sheet, 3plug with electrical leads, 4piston,

5Manganin, 6 and 7CuBe fixing screw, 8capsule, 9sample space,

10QD connector (fixed to plug 3).

FIG. 3. Pressure vs strain dependence measured by strain-gauge fixed on

outer surface of the tested MP35N pressure cell.

FIG. 4. Increase of outer diameter of the tested CuBe pressure cell in de-

pendence on internal pressure. Deformation was measured by a strain gauge.

Rev. Sci. Instrum., Vol. 75, No. 11, November 2004 Destruction tests of pressure cells 5023



3/4

tested in a temperature range from 350 K down to 5 K in

fields up to 5 T using the SQUID magnetometer. Contrary to

a very slight temperature dependence of diamagnetic suscep-

tibility of pure Cu, the nonmagnetic CuBe bronze Berylco

25 exhibits a substantial increase of paramagnetic volume

susceptibility at low temperature region (Fig. 5) due to anadmixture of magnetic elements (Co and Ni). However, the

miniature CuBe cell is long enough to remain all in the

SQUID measuring coils during the magnetization measure-

ments. Hence, a signal originated from the CuBe cell is not

simply addable to the SQUID response. The effect of pres-

sure cell on measured magnetization is demonstrated by

comparative measurements of magnetization of paramag-

netic palladium placed in the pressure cell and in the stan-

dard straw, see Fig. 6. It is seen that we met a serious prob-

lem to measure a total magnetization (samplecell) smaller

than 103 emu with this type of the pressure cell. On the

other hand in the case of ferromagnetic materials, a differ-

ence between values of magnetization measured in the cell

and in the straw can be caused by relatively strong forces

originated from magnetocrystalline and/or shape anisotropy

that act on the sample in the straw in higher magnetic fields.

We observed the differences up to 1% of a nominal value of

magnetization. For this reason, we measure magnetization of

samples inside the pressure cell even at ambient pressure.

This allows us to detect even very small pressure changes of

magnetization. The very weak pressure dependence of the Fe

moment was measured on the single crystal (body centered

cubic crystal structure) of pure Fe (4N) in the principal di-

rection. Values of the relevant pressure parameter,

dln M/dp =4.40.6*103 GPa1 at 5 K and dln M/dp

=4.80.8*103 GPa1 at 300 K, can be considered as a

limit of sensitivity of the pressure experiments in the de-

scribed cell.

We determine pressure inside the CuBe cells by Pb-

pressure sensors as mentioned above. The values of TC at

ambient and high pressures are derived from temperature de-

pendence of ac susceptibility of lead measured with low fre-

quency ac current f=2.2 Hz and very slow temperaturesweep 0.005 K/min. in the SQUID magnetometer, see Fig.7. Using a relation PGPa=TCK/0.405K/GPa,

8pres-

sure can be calculated with an accuracy 0.015 GPa. Due toa strong field dependence of TC, a precision of this pressure

determination is very sensitive to magnetic field residua.

Hence, an extraordinary attention should be paid to the pres-

sure determination in the case of samples with a high value

of remanent magnetization that can produce a significant re-

sidual magnetic field even after the magnet reset. A competi-

tive measurement of pressure dependence of the critical field

HC of superconducting state in Pb does not bring a substan-

tial profit due to the strong temperature dependence of HC.

Significant changes of pressure inside the clamp hydro-

static cells during their cooling or heating are caused by a

difference between thermal expansions of the pressure trans-

mitting media and construction materials of the cells.6,10

Wehave tested three pressure media-spindle oil OL3, Fluorinert

FC-77 and Daphne 7373in a pressure range up to 1.2 GPa

at temperatures from 350 K down to 5 K. The first one is a

light mineral oil and the last one is the Japan pressure me-

dium (olefin oligomers).11

Both the thermal volume expan-

sion and the compressibility of the pressure media are usu-

ally of about one order higher than ones of the metallic

construction materials (or metallic samples). So, the tem-

perature induced changes of pressure inside the clamped

cells are given mainly by relation P =T*m/m, where

m is volume expansion and m compressibility of the pres-

sure medium. In the case of the tested pressure media, the

FIG. 5. Temperature dependence of volume susceptibility of CuBe bronze

and Cu.

FIG. 6. Comparative measurements of magnetization of Pd placed in straw

and in pressure cell in SQUID magnetometer.

FIG. 7. Temperature dependence of ac susceptibility of Pb under different

pressures.

5024 Rev. Sci. Instrum., Vol. 75, No. 11, November 2004 Kamard, Machtov, and Arnold



4/4

values of m/m are close to value 103 GPa/K, see Fig. 8.

To reduce the influence of the pressure media, metallic or

ceramic inserts were put into pressure cells.4

However with

increasing viscosity of the pressure media, this can lead to aformation of undesirable pressure gradients, especially at

lowered temperatures.

The data given in Fig. 8 represent the results of direct

measurements in both the presented types of the pressure

cells. They were derived from four types of simultaneous

measurements. The standard determination of pressure have

been based on a continuous measurement of electrical resis-

tivity the Manganin sensor. To compensate a nonlinear tem-

perature dependence of the Manganin pressure coefficient

below 130 K, strain gauges were glued on the outer surfaces

of the cells to measure internal pressure at lowered tempera-

tures using Hooks law. Simultaneously, the earlier data on

the pressure dependence of Nel temperature, TN=275 K, inLu2Fe17 intermetallics were used to determine pressure at

this temperature range (open symbols in Fig. 8). Measure-

ments of the critical temperature TC of superconducting state

in Pb under pressure served as the second fix point for the

determination of pressure at low temperature range (open

symbols in Fig. 8). From the point of view of the smallest

decrease of pressure with decreasing temperature, the best

pressure medium for the clamped cells seems to be Daphne

7373, at least in pressure range above 0.7 GPa. In agreement

with work,11

the observed decrease of pressure from initial

pressure 1.5 GPa at 300 K to final pressure at 5 K is smaller

than 0.2 GPa. However, we detected substantial changes of

pressure in the cells with Daphne inside in a pressure rangebelow 0.5 GPa. The dependence of the pressure variations on

the starting pressure clamped in cell at 300 K is much less

pronounced in OL3. Taking into account the presented pres-

sure corrections, all three tested pressure media are fully ac-

ceptable for the use in the pressure cells in wide temperature

range.

ACKNOWLEDGMENTS

This work is a summary of knowledge received during

the last years, when a continual attention has been paid to

both the design and the fabrication of pressure equipment in

the framework of the projects of the Grant Agency of the

Czech Republic and the Grant Agency of the Academy of

Sciences of the Czech Republic (No. 202/02/0739 and No.

A1010315, respectively).

APPENDIX

In diagram 1,

R0 =outer radius of the cell; Ri =inner radius of the cell; K

=R0/Ri; oR= tangential stress; rR= radial stress; l= axial stress; P =pressure in the cell=rRi; P0 =outerpressure=rR0=0; Lam equations:

oR = P/K2 1 + P * R0

2/K2 1 * R2 ,

rR = P/K2 1 P * R0

2/K2 1 * R2, A1

1 = P/K2 1 .

When Yt is the yield stress in tension, E is Youngs modulus

and is Poissons constant, the maximum pressure Pmax at

elastic regime is

Pmax = Yt*K2 1/3 * K2 A2and

R/R = 1/E * oR * rR . A3

1J. Kamard, in Encyclopedia of Materials: Science and Technology

(Elsevier Science, Oxford, 2001), pp. 49764982.2

S. Reich and T. Godin, Meas. Sci. Technol. 7, 1079 (1996).3

K. Koyama, S. Hane, K. Kamishima, and T. Goto, Rev. Sci. Instrum. 69,

3009 (1998).4

Y. Uwatoko et al., Rev. High Pressure Sci. Technol. 7, 1508 (1998).5

G. Oomi and T. Kagayama, Physica B 239, 191 (1997).6

F. Honda, V. Sechovsk, O. Mikulina, J. Kamard, A. H. Lacerda, and H.

Nakotte, Int. J. Mod. Phys. B 16, 3330 (2002).7

Z. Machtov, J. Kamard, A. V. Andreev, Z. Arnold, and O. Prokhnenko,High Press. Res. 23, 165 (2003).

8B. Bireckoven and J. Wittig, J. Phys. E 21, 841 (1988).

9J. Kamard, K. V. Kamenev and Z. Arnold, in High Pressure in Science

and Technology, edited by W. A. Trzeciakowski (World Scientific, Sin-

gapore, 1996), pp. 5153.10

J. D. Thompson, Rev. Sci. Instrum. 55, 231 (1984).11

K. Murata, H. Yoshino, H. Om Yadav, Y. Honda, and N. Shirakawa, Rev.

Sci. Instrum. 68, 2490 (1997).

FIG. 8. Temperature induced pressure variations in clamped cell for three

pressure transmitting media.

Rev. Sci. Instrum., Vol. 75, No. 11, November 2004 Destruction tests of pressure cells 5025


Documents

RevSciInstrum_75_5022