Photon Factory Activity Report 2019 #37 (2020)

AR-NE5C/2018G583

A Brand-New 6-6 Assembly for a Cubic-type of Multianvil Apparatus
Kazuhiro FUCHIZAKI1,*, Tomoyuki Wada2, Hiroki NARUTA1, Masamichi Tanaka2,Akio SUZUKI3, and Kazuo IRINO4
1
Department of Physics, Ehime University, Matsuyama 790-8577, Japan
2
Shinkou Kouki Corporation, Iyo 791-3131, Japan3
Department of Earth Science, Tohoku University, Sendai 980-8578, Japan
4
Institute for Collaborative Relations, Ehime University, Matsuyama 790-8577, JapanWe developed a new way of assembling a second stage, which includes a frame bundling a set of second-stage anvils
when loading a high-pressure cell using a DIA-6 type of multianvil apparatus. A newly developed tool can assemble awhole set within 4 minutes with a precision required for high-pressure experiments.
1 Introduction
Nowadays, science under extremely high pressures
beyond 100 GPa is mainly developed using a diamondanvil cell. However, a multianvil apparatus has still been
a powerful tool with which to generate high pressures inmaterial and Earth sciences and technology. Here, we
focus on a cubic-type apparatus, often referred to as amultianvil-6 (MA-6), consisting of six anvils. MA-6s
have been installed in not only laboratories but alsosynchrotron x-ray and neutron beam facilities worldwide
to carry out in situ experiments. For example, MAX-80
and MAX-III installed in beamlines NE5C and NE7A,
respectively, are of this type. The mechanism ofgenerating high pressure is simple; the external load
exerted on the main ram is transmitted to the anvils
equipped with an anvil guide of an MA-6. The anvils thenpush a sample embedded in a cubic pressure-transmitting
medium. Here, we call such a traditional method onestage compression.
Instead of this one-stage compression, many
apparatuses have begun to adopt a two-stage compression
method since around 2010[1,2]. The outer set of anvils
compresses the six small anvils bundled with a frame.
The second-stage assembly (SSA), consisting of the set of
inner anvils holding a sample cell, is removable uponexchanging a sample. The portability of the SSA
facilitates replacing the anvils by those with a different
truncation edge length (TEL), depending on a pressure
range desired, thus taking optimal advantage of thebeamtime available when a user plans to use sets of anvils
with different TELs.
However, when users perform their experiments using
a set of inner anvils of the same TEL, a two-stagecompression is not necessarily efficient; it instead
produces extra loss time much unless more than one SSA
is available. An SSA is composed of a set of inner anvils,
stuck together by TeflonTM chips of a particular size,
which is held in a metal frame wrapped up by a Kapton®
tape to ensure electric insulation. A set of chips withappropriate height, such as pieces of balsa sheets with aspecific thickness, must be stuck on the corners of theframe to center exactly the SSA (see Fig. 1 left panel).
The Teflon chips and the balsa pieces are required tomake the virtual center of the inner anvils coincide withthat of the outer anvils. We call this adjustment‘centering’ here. A situation in which preparing the SSA
cannot proceed in parallel to the experiment results in asevere loss of efficiency of the whole experiment. Weshould mention that purchasing these specific parts and aset of inner anvils is burdens on the user side.
Our project has started to address these issues and set
the following goal: A user alone can set up the SSA andrestart-up compression within 15 min upon a sample
change. Although this time will be much less than a usual
time duration of more than 1 hour when the conventional
assembling method is adopted, we will aim the same
degree for the accuracy of centering as attained by theordinary method.

Fig. 1: The SSA mounted in the first-stage outer anvils of
MAX-80 installed in BL NE5C, KEK-AR. It takes morethan one hour to assemble a conventional SSA, i.e., anelectrically insulated metallic frame bundling inner anvils,
which support a sample cell (left). In contrast, the newassembly consisting of a POM frame (right) allows asingle user to finish setting within 4 min using the uniquetool devised.
2 New Development
To this end, we first paid attention to the roles of aframe supporting a set of inner anvils: (i) It must help theinner anvils to ensure the precise centering. Most of theusers use a metallic frame because of the excellent
workability of metals. (ii) Therefore, a frame must be
electrically insulated for electric current to flow through aheater enclosing the sample (container) because weusually measure samples at high temperatures underpressure.

Photon Factory Activity Report 2019 #37 (2020)

The condition (ii) is satisfied if we use insulators as aframe at the outset. Indeed, Dr. Kikegawa of IMSS, KEK,
has used a plastic frame made of PEEK to bundle theinner anvils. According to his suggestion, we first
replaced a metal frame by a PEEK frame. Nevertheless, atthe same time, we started to look for other plastic
materials, which have similar workability but are lessexpensive. Finally, we encountered POM, which canoffer comparative performance though the melting point
is about half as high as that of PEEK. To meet thecondition (i), we devised a unique tool with which toattain the centering within 4 min with the required
precision. The anvils are finally clamped with six small
screws to the frame. Such works as shielding a frame withKapton® tape, adjusting the position of a frame withbalsa pieces, and joining the anvils with TeflonTM chips
are now no longer required (Fig. 1 right panel). We are
now free from such a laboring job and the extra cost.
The development was accelerated since 2018 andfinished at the end of FY2019. The Ehime Industrial
Promotion Foundation supported us financially during theperiod.
3 Verification Experiment
We examined for plastic frames made of PEEK and
POM a series of necessary tests such as the extent ofdeformation before and after holding them under 40
degrees centigrade, which is the expected temperature
they experience when placed in an MA-6 on actualexperiments. We confirmed no quantitative or qualitativechanges in the plastic frames against those tests.
We applied for the experiment at KEK because weneed to check our SSA can be used safely in highpressure experiments. Besides, we have to confirm in situ
that the centering is satisfied with the desired accuracy.
We conducted verification experiments using MAX-80
installed at NE5C from 2018 through 2019. Four
opportunities were given to the experiments. We used
TEL of 4, 6, and 8 mm as the internal anvils. A W-Re
wire piece of diameter 0.125 mm and length 1 mm wasused as a dummy sample. A typical compression anddecompression cycle are as follows: We first applied 30
tons of load at room temperature and then heated adummy sample to 1000 or 1500 K. We loaded up to 100
or 120 tons at that temperature. We measured pressure at
the sample position using a pressure standard, NaCl, at
every addition of 20 tons of load. We also took a photo of
the transmission image of the dummy sample at thosepressures. The diameter of the sample was almost
comparable to the width of a gap between the anvils at thehighest load applied when using anvils of TEL 4 mm.
3 Results and Discussion
The temperature of the frame was monitored during
each experiment. While the sample was held at 1500 K, aPEEK frame position never exceeded forty degrees
centigrade. In the same situation, the temperature of a
POM frame stayed even several degrees lower.
We are planning to make a detailed report elsewhere on
the results of the verification experiment, including such atemperature history, together with the precise design of
the assembling tool we developed [3]. We only show here
in a visually appealing fashion that the tool can bringabout satisfactory centering.
As an example, we show in Fig. 2 a situation weobserved when we compressed the sample using a set of
inner anvils of TEL 6 mm. We can easily confirm that adummy sample (a bit of wire) always centers the anvil
gap until the highest load applied. The situation remained
the same even when the conditions became severer, i.e.,
when the inner anvils of TEL 4 mm were employed.

Fig. 2: A transmission image of the dummy sample in ananvil gap when a POM frame was employed is shown. (a)Anvil gap 2.11 mm at ambient conditions, (b) 0.99 mm at
5.0 GPa and room temperature, (c) 0.94 mm at 3.0 GPa
and 1500 K, and (d) 0.78 mm at 5.8 GPa and 1500 K.
We could thus reach our goal held up when this R&D
project has started. However, we could uncover a problem
within a series of verification experiments, in which weexperienced blowouts. We found that a blowout at a hightemperature altered the surface conditions of a POMframe. This alteration makes the slip characteristics of theframe change inhomogeneously. Therefore, even though
the size of a frame is unaffected by a blowup, and it holds
the inner anvils at the right position, the anvils would notslide uniformly upon loading. This unsynchronized
movement of the inner anvils would cause a rotation of asample cell, thereby making beams miss the sample. We
confirmed a similar alteration of a PEEK frame, which
experienced a blowout under elevated temperatures.
Resolving the issue is our next concern.
4 Summary
We confirmed that our newly designed POM frame,
which is less expensive than a PEEK frame, can safely
and stably hold a sample at high temperatures andpressure. The assembly tool devised allows us to quickly(within 4 min) center the sample with the desired
precision. However, we cannot recommend reusing aPOM (PEEK) frame if it experiences a blowout.
Acknowledgement
This work was supported by the Ehime Industrial
Promotion Foundation and Institute for Collaborative
Relations, Ehime University. Preparations for theexperiments were carried out using the facility at theGeodynamics Research Center, Ehime University.
References[1] N. Nishiyama et al., High Press Res. 28, 307 (2008).
[2]A. Sano-Furukawa et al., Rev. Sci. Instrum. 85, 113905(2014).
[3] K. Fuchizaki, T. Wada, H. Naruta, A. Suzuki, K. Irino,
in preparation.

Photon Factory Activity Report 2019 #37 (2020)

Research Achievements
For both the frame and assembling kit, we shall not
apply for a patent nor for a design right, which may
prevent high-pressure science from extending its reach.
Shinkou Kouki Co. has just released a whole set of tools
at a reasonable price.
* fuchizak@phys.sci.ehime-u.ac.jp