Hysteretic phenomena in Xe-doped C₆₀ from x-ray diffraction
Polycrystalline fullerite С₆₀ intercalated with Xe atoms at 575 K and a pressure of 200 MPa was studied by powder x-ray diffraction. The integrated intensities of a few brighter reflections have been utilized to evaluate the occupancy of the octahedral interstitial sites in С₆₀ crystals, which turne...
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Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України
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irk-123456789-1214652017-06-15T03:03:49Z Hysteretic phenomena in Xe-doped C₆₀ from x-ray diffraction Prokhvatilov, A.I. Galtsov, N.N. Legchenkova, I.V. Strzhemechny, M.A. Cassidy, D. Gadd, G.E. Moricca, S. Sundqvist, B. Aksenova, N.A. Динамика кристаллической решетки Polycrystalline fullerite С₆₀ intercalated with Xe atoms at 575 K and a pressure of 200 MPa was studied by powder x-ray diffraction. The integrated intensities of a few brighter reflections have been utilized to evaluate the occupancy of the octahedral interstitial sites in С₆₀ crystals, which turned out to be (34±4) %, and in good agreement with another independent estimate. It is found that reflections of the (h00) type become observable in Xe-doped С₆₀. The presence of xenon in the octahedral sites affects both the orientational phase transition as well as the glassification process, decreasing both characteristic temperatures as well as smearing the phase transition over a greater temperature range. Considerable hysteretic phenomena have been observed close to the phase transition and the glassification temperature. The signs of the two hysteresis loops are opposite. There is reliable evidence that at lowest temperatures studied the thermal expansion of the doped crystal is negative under cool-down. 2005 Article Hysteretic phenomena in Xe-doped C₆₀ from x-ray diffraction / A.I. Prokhvatilov, N.N. Galtsov, I.V. Legchenkova, M. A. Strzhemechny, D. Cassidy, G.E. Gadd, S. Moricca, B. Sundqvist, N.A. Aksenova // Физика низких температур. — 2005. — Т. 31, № 5. — С. 585-589. — Бібліогр.: 27 назв. — англ. 0132-6414 PACS: 61.10.Nz, 81.05.Tp, 64.70.–p http://dspace.nbuv.gov.ua/handle/123456789/121465 en Физика низких температур Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України |
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Динамика кристаллической решетки Динамика кристаллической решетки |
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Динамика кристаллической решетки Динамика кристаллической решетки Prokhvatilov, A.I. Galtsov, N.N. Legchenkova, I.V. Strzhemechny, M.A. Cassidy, D. Gadd, G.E. Moricca, S. Sundqvist, B. Aksenova, N.A. Hysteretic phenomena in Xe-doped C₆₀ from x-ray diffraction Физика низких температур |
| description |
Polycrystalline fullerite С₆₀ intercalated with Xe atoms at 575 K and a pressure of 200 MPa was studied by powder x-ray diffraction. The integrated intensities of a few brighter reflections have been utilized to evaluate the occupancy of the octahedral interstitial sites in С₆₀ crystals, which turned out to be (34±4) %, and in good agreement with another independent estimate. It is found that reflections of the (h00) type become observable in Xe-doped С₆₀. The presence of xenon in the octahedral sites affects both the orientational phase transition as well as the glassification process, decreasing both characteristic temperatures as well as smearing the phase transition over a greater temperature range. Considerable hysteretic phenomena have been observed close to the phase transition and the glassification temperature. The signs of the two hysteresis loops are opposite. There is reliable evidence that at lowest temperatures studied the thermal expansion of the doped crystal is negative under cool-down. |
| format |
Article |
| author |
Prokhvatilov, A.I. Galtsov, N.N. Legchenkova, I.V. Strzhemechny, M.A. Cassidy, D. Gadd, G.E. Moricca, S. Sundqvist, B. Aksenova, N.A. |
| author_facet |
Prokhvatilov, A.I. Galtsov, N.N. Legchenkova, I.V. Strzhemechny, M.A. Cassidy, D. Gadd, G.E. Moricca, S. Sundqvist, B. Aksenova, N.A. |
| author_sort |
Prokhvatilov, A.I. |
| title |
Hysteretic phenomena in Xe-doped C₆₀ from x-ray diffraction |
| title_short |
Hysteretic phenomena in Xe-doped C₆₀ from x-ray diffraction |
| title_full |
Hysteretic phenomena in Xe-doped C₆₀ from x-ray diffraction |
| title_fullStr |
Hysteretic phenomena in Xe-doped C₆₀ from x-ray diffraction |
| title_full_unstemmed |
Hysteretic phenomena in Xe-doped C₆₀ from x-ray diffraction |
| title_sort |
hysteretic phenomena in xe-doped c₆₀ from x-ray diffraction |
| publisher |
Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України |
| publishDate |
2005 |
| topic_facet |
Динамика кристаллической решетки |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/121465 |
| citation_txt |
Hysteretic phenomena in Xe-doped C₆₀ from x-ray diffraction / A.I. Prokhvatilov, N.N. Galtsov, I.V. Legchenkova, M. A. Strzhemechny, D. Cassidy, G.E. Gadd, S. Moricca, B. Sundqvist, N.A. Aksenova // Физика низких температур. — 2005. — Т. 31, № 5. — С. 585-589. — Бібліогр.: 27 назв. — англ. |
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Физика низких температур |
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| fulltext |
Fizika Nizkikh Temperatur, 2005, v. 31, No. 5, p. 585–589
Hysteretic phenomena in Xe-doped C60
from x-ray diffraction
A.I. Prokhvatilov1, N.N. Galtsov1, I.V. Legchenkova1, M. A. Strzhemechny1,
D. Cassidy2, G.E. Gadd2, S. Moricca2, B. Sundqvist3, and N.A. Aksenova4
1B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy
of Sciences of Ukraine, 47 Lenin Ave., Kharkov 61103, Ukraine
E-mail: galtsov@ilt.kharkov.ua
2Australian Nuclear Science and Technology Organisation, Private Mail Bag 1,
Menai, NSW 2234, Australia
E-mail: geg@ansto.gov.au
3Department of Physics, Umea University, S-901 87 Umea, Sweden
4Rail Way Transport Academy, 23 Moskovski Ave., Kharkov, Ukraine
Received August 4, 2004, revised August 10, 2004
Polycrystalline fullerite Ñ60 intercalated with Xe atoms at 575 K and a pressure of 200 MPa
was studied by powder x-ray diffraction. The integrated intensities of a few brighter reflections
have been utilized to evaluate the occupancy of the octahedral interstitial sites in Ñ60 crystals,
which turned out to be (34�4) %, and in good agreement with another independent estimate. It is
found that reflections of the (h00) type become observable in Xe-doped Ñ60. The presence of xenon
in the octahedral sites affects both the orientational phase transition as well as the glassification
process, decreasing both characteristic temperatures as well as smearing the phase transition over a
greater temperature range. Considerable hysteretic phenomena have been observed close to the
phase transition and the glassification temperature. The signs of the two hysteresis loops are oppo-
site. There is reliable evidence that at lowest temperatures studied the thermal expansion of the
doped crystal is negative under cool-down.
PACS: 61.10.Nz, 81.05.Tp, 64.70.–p
Introduction
The cubic crystals of fullerite C60 comprise almost
spherical molecules with a diameter of 10.2 Å. The
lattice has quite large interstitial cavities with octahe-
dral (4.12 Å) and tetrahedral (2.2 Å) point symmetry,
which can be stuffed with various atoms or molecules
with sizes comparable to the void diameters. This cir-
cumstance was utilized at the very beginning of the
fullerene era resulting in the high-Tc superconductiv-
ity of an organic crystal (C60 doped with alkali met-
als) [1]. Afterwards, C60 was intercalated with rare
gas atoms [2–7] and molecules of different symmetries
and sizes [8–14]. It is commonly accepted that
changes in the physical properties of fullerite C60
brought about by intercalation with neutral species
are mainly due to the doping-related change in the
molar volume. In the particular case under study the
doped crystal can be considered either to be under a
negative pressure or, in the opposite sense, to exhibit a
positive internal pressure.
The most interesting phenomena caused by inter-
calation are observed within the regions where the
orientational phase transition (Tc = 260 K) occurs or the
orientational glass forms (Tg = 90 K). Usually, when
the voids are filled with the larger rare gas atoms such as
Xe or with simpler closed-shell molecules, the ani-
sotropic interaction between C60 molecules weakens;
and the rotation of the C60 molecules loosens up, result-
ing in lower critical temperatures for both transforma-
tions [6,7]. Moreover, when the dopant species are cer-
tain molecules, for example, CO or NO, there are
indications [15,16] that no freezing into an orientational
© A.I. Prokhvatilov, N.N. Galtsov, I.V. Legchenkova, M. A. Strzhemechny, D. Cassidy, G.E. Gadd, S. Moricca, B. Sundqvist,
and N.A. Aksenova, 2005
glass state was observed. In regards to doping with rare
gas species, both large negative expansivity as well as
temperature hysteresis of the thermal expansion are ob-
served at low temperatures [17].
In this paper, we report detailed powder x-ray studies
of the structural characteristics of Xe-doped C60, with a
temperature cycling around the orientational phase tran-
sition (150–300 K) as well as in the region where
orientational glass states tend to form, (7 to 100 K).
Experimental
C60 powder was saturated with xenon at a pressure
and temperature of about 200 MPa and 575 °C, re-
spectively, for a period of 36 hours. When intercalated
at high pressure but at 300 °C, only 10% of octahedral
voids are filled; the filling can reach 66% if C60 is
saturated at 575 °C [6]. In the present case, thermo-
gravimetric analysis (TGA) showed a weight loss
between 6 and 7% indicative of a stoichiometry of
Xe0.39–0.45C60. The powder of Xe-doped C60 was
subsequently compacted for dilatometric studies in
cylindrical dies by quasi-hydrostatic compression with
pressures of up to 1 GPa, as described elsewhere [17].
The sample used in our x-ray experiments was a chunk
taken from the larger compacted specimen, the smooth
surface of which served as the reflection plane in the
x-ray experiments.
Powder x-ray studies were carried out on a
DRON-3M diffractometer equipped with a special liq-
uid-helium cryostat. The temperature of samples was
varied over the range of 7 to 300 K. The temperature
was stabilized to within �0.05 K at every measurement
point. In the orientational glass domain (T � 70 K)
and below the orientational phase transition point
(Tc � 260 K), the temperature was varied in warm-up
and cool-down regimes with the intention of looking
for possible hysteretic phenomena of the lattice pa-
rameters and thermal expansivities. The intensities,
widths, and angular positions of the relevant reflec-
tions as functions of temperature were used for analy-
sis of the phenomena under study. The lattice parame-
ter error was �0.02 % and the intensity of the x-ray
reflections was measured to within 1 %.
Results and discussion
A typical x-ray pattern is shown in Fig. 1. It can be
seen that our fine-grain samples, in addition to the fcc
phase of Xe-doped fullerite C60, contain about 10% of
another phase which could in no way be indexed as
fcc. It should be noted that in the «as-prepared»
Xe-doped powder samples, no other than but fcc phase
was detected [6] either in x-ray or neutron diffraction
experiments. The reflections belonging to this new
phase are indicated in Fig. 1 with arrows. It is possible
that the new phase is a result of a partial polymeriza-
tion caused by the previous compacting. Notwith-
standing the known polymerization-related structure
[18,19] we failed to find a space group that could fit
the extra reflections mentioned.
We observed substantial changes in the scattered
intensities compared to pure fullerite. To mention
first, the reflections of the type (h00) became clearly
distinguishable (in pure C60 their intensities are virtu-
ally zero because of the specific molecule /lattice size
relation and the shape of C60 molecule [20]). Some
other reflections, such as (111) and (220), are lower
in intensities as compared to pure C60, while others
such as (420) and (422), are brighter.
The absolute lattice parameter values as a function
of temperature were determined as follows. At two
reference points, viz., at room temperature and at 7 K,
full-profile diffraction patterns have been recorded in
order to obtain the rms averaged reference cubic lat-
tice parameter values for those two reference points
and in each case with the lattice parameter averaged
over all the observed reflections. Then, between those
two reference points, the lattice parameters at other
temperatures was determined from the (311) reflec-
tion and scaled appropriately to the reference values.
Using these lattice parameters, we calculated how
the intercalation with Xe has changed the room-tem-
perature diffraction intensity ratios for specifically
chosen reflections compared to the most intense (311)
reflection, as a function of the occupancy of octahe-
dral voids by Xe atoms and assuming a uniform distri-
bution of the dopant throughout the sample. In the
calculations we used the following expression for the
scattering amplitude of reflection (hkl):
586 Fizika Nizkikh Temperatur, 2005, v. 31, No. 5
A.I. Prokhvatilov et al.
10 15 20 25 30 35
0
1
2
3
4
5
293 Ê
2 , deg�
1
1
1
2
0
0
2
2
0
2
2
2
4
0
0
3
1
1
3
3
1
4
2
0
4
2
2
5
1
1
4
4
0
5
3
1
6
0
0
Ñ – Xe60
In
te
n
si
ty
,
im
p
/s
1
0
3
Fig. 1. A typical x-ray diffraction pattern from poly-
crystalline C60–Xe samples, recorded at room temperature.
The indexed reflections belong to the orientationally disor-
dered fcc phase of Xe-doped fullerite C60. The arrows indi-
cate reflections of an unknown phase.
F q f qr/qr f XC RG RG
h k l( ) ( )( ( ) ( )� � �
� �60 1q qsin .
(1)
Equation (1) generally applies for the case of atoms
of any rare gas randomly distributed over octahedral
cavities. The first term in the right-hand side of Eq.
(1) is the contribution from the randomly rotating C60
molecules; the second term is the contribution from
the interstitial rare gas (RG) atoms. The quantities
fC( )q and fRG( )q , both functions of the momentum
transfer vector, are respectively the carbon and RG
atomic scattering factors and fXe ( )q will be used for
the latter. The absolute magnitude of the vector q is
given by 4�
sin( )/ , where 2 is the deflection angle
of the incident x-rays with wavelength
. Finally,
XRG is the rare gas occupancy of the octahedral voids,
which is assumed to be uniform throughout the sample.
The square of F( )q in Eq.(1) is proportional to the in-
tensity of the actual x-ray reflections at the respective
angles 2 , the values were calculated using the lattice
parameter determined as described from the room-tem-
perature value a � (14.246±0.003) Å. Integrated inten-
sities were determined using the Gaussian function
which turned out to be a little better than the
Lorentzian one. All calculated integrated intensities
were normalized to that of the brightest reflection
(311). The experimentally determined integrated in-
tensity ratios for the chosen reflections are plotted in
Fig. 2 to evaluate the occupancy of octahedral voids
by xenon. Using the four occupancies thus found (see
Fig. 2), we calculated the weighted average of the oc-
cupancy to be XXe = (34±4)%, in good agreement
with previously found TGA data (41.5 ± 2.5)%, see
above in the Experimental Section). We ascribe the
uncertainty in the value to two factors, viz., the
inhomogeneity of the distribution of Xe over the grain
volume and the errors in absolute intensity values for
the weaker lines (see Fig. 2).
Variations of the lattice parameter a T( ) of Xe-doped
C60 with temperature under warm-up and cool-down
are plotted in Fig. 3. One can see that the path a T( ) de-
pends essentially on the direction of temperature varia-
tion. Two hysteresis loops were observed and it is
noteworthy that the signs of the warmup/cooldown
hystereses are opposite to each other. At temperatures
below the orientational phase transition in pure
fullerite ( )Tc � 260K , the cool-down lattice parame-
ters are appreciably higher than those found with
warm-up. In the temperature range where the orien-
tational glass is observed in pure C60 the hysteresis
loop has a narrower span and, as mentioned above, its
sign is opposite to that of the hysteresis at higher tem-
peratures, or in other words, the cool-down lattice pa-
rameter values are smaller than the warmup ones.
Repeated cooldown of the sample virtually did not
change the situation and the lattice parameter a T( ) fol-
lowed the same path as found during the first cool-down
run. What is striking is the strong «smearing» and shift
of the orientational transition to lower temperatures, as
compared to that for pure C60, as well as the huge tem-
perature span of the hysteresis loop, which stretches
from 150 K up to room temperature. The largest lattice
parameter difference at 230 K amounts to �a � 0 055. Å,
which exceeds by far the experiment error in a T( ) . The
hysteretic effect observed at lower temperatures affects
the crystal lattice to a lesser extent. The loop is found to
be far from symmetric; the upper bifurcation point is at
T = (60±5) K; whilst the maximum lattice parameter
difference �a � (0.007±0.003) Å is reached at � 20 K. A
pronounced instability was observed for the cool-down
regime, which manifested itself in a greater scatter of
lattice parameter values. The cool-down curve is steeper
than the warm-up curve at the high-temperature end of
Hysteretic phenomena in Xe-doped C60 from x-ray diffraction
Fizika Nizkikh Temperatur, 2005, v. 31, No. 5 587
20 30 40 50
0
0.1
0.2
0.3
0.4
0.5
0.6
Xe occupancy, %
I
/I
h
kl
3
1
1
Fig. 2. Calculated intensity ratios for a few fcc reflections
versus the Xe occupancy of octahedral voids at room tem-
perature with the lattice parameter equal to a = 14.246 Å:
220 (�), 222 (�), 420 (�), 200 (�). The solid symbols
indicate the corresponding experimental intensity ratios.
0 50 100 150 200 250 300
14.00
14.05
14.10
14.15
14.20
14.25
14.30
TG
T, K
Ñ + Xe60
a
,Å
Tc
Fig. 3. Temperature dependence of the lattice parameter of
the C60–Xe sample, as measured under cool-down or warm-up
regimes: warm-up (�), (�); cool-down (�), (�), (�); pure
C60 (–). The lower solid curve is for pure fullerite C60 [22].
the hysteresis loop. What is equally striking is that at
the low-temperature end there is a definite indication
that the thermal expansivity has become negative. A
very rough estimate from the three lowest points yields
unusually large negative expansivities of the order of
–5
10–4 K–1. Negative linear thermal expansion coeffi-
cients at low temperatures have already been docu-
mented for pure fullerite [21] and also for fullerite inter-
calated with neon, argon, and krypton [17,23] and now,
in conjunction with this work, with Xe as well [23]. The
dilatometric measurements of thermal expansion coeffi-
cients in the orientational glass region of the C60–Xe
system have been carried out up to 28 K. Which allowed
comparison between dilatometric of Ref. 24 and x-ray
data, as shown in Fig. 4. The solid curves are drawn
through dilatometry points and smoothly extrapolated
to higher temperatures. A good qualitative agreement is
evident.
We tried to observe relaxation processes in the do-
main of the high-temperature hysteresis at fixed tem-
peratures of 150, 180, 220 and 250 K on both the
warm-up and cool-down branches. Contrary to our ex-
pectations, no changes in lattice parameter values
were recorded and this was even after quite long (10
hours) waiting times.
The cause behind the anomalies observed in this re-
port (two hystereses, large negative expansivities at
low temperatures) is not completely clear. A qualita-
tive explanation of both low-temperature anomalies
(the hysteresis and the negative expansivities) was
suggested by Aleksandrovskii et al. [24]. The negative
expansion coefficients, found dilatometrically at low
temperatures [24], are related to the tunnel nature of
the low-energy levels. The hysteresis is ascribed to a
polyamorphic phase transition between two different
orientational glass phases, in which case the
non-ergodic character of the glass system can lead to
hysteretic phenomena. As regards the high-tempera-
tures hysteresis, we can make the following remarks.
Of course, since the orientational phase transition is a
first-order one, it is quite natural that it occurs with a
hysteresis. We understand but well that because the
distribution of Xe atoms inside the crystallites should
be, most likely, highly inhomogeneous, the span of the
hysteresis could be much larger than in pure C60 [22].
However, first, the temperature span is too broad and,
second, the high-temperature bifurcation point is
(contrary to expectations) above Tc in the pure mate-
rial. So, the nature of the high-temperature hysteresis
is not completely understood.
Considering the lattice parameter of C60 doped with
Xe as a function of the occupancy XXe (see Fig. 5) we
note that the specific occupancy as estimated from our
x-ray diffraction data (Fig.2) falls close to the points
from other reports [6] that dealt with the C60–Xe sys-
tem. However, if taken in their completeness the points
of the a X( )Xe dependence do not fall on a straight line.
For other rare gas species as dopants of C60, and where
the lattice parameter vs. occupancy is known it appears
to follow a linear a XRG( ) relationships. This is clearly
seen in Fig. 5 for Ne [25]. Indirect evidence from our
findings on the C60–He system [26,27], also suggests is
a linear function, whereas for Ar the span of XAr is too
narrow to make a sound judgment at this stage. The
588 Fizika Nizkikh Temperatur, 2005, v. 31, No. 5
A.I. Prokhvatilov et al.
0 10 20 30 40 50 60 70
T, K
�
L/
L,
1
0
–
3
1.5
1.0
0.5
–0.5
0
Fig. 4. Relative elongation versus temperature polycrystal-
line C60–Xe samples under warm-up and cool-down, accor-
ding to dilatometric [24] and x-ray diffraction measure-
ments; cool-down: this work (�), [24] (�); warm-up: this
work (�), [24] (�)..
0 20 40 60 80 100
14.10
14.15
14.20
14.25
14.30
14.35
14.40
He
Ne
293 K
Ar
Kr
Xe
Occupancy, %
a
,
Å
Fig. 5. The lattice parameter of RG-doped cubic fullerite
C60 as a function of the RG occupancy of octahedral
voids. The corresponding references are: the solid circles
[6] and the empty overturned triangle is from this study
for Xe; the solid rhombs [3] for Ne; the empty rhombs [6]
for Kr; the solid [5,6] and empty (this work, see text)
squares for Ar; the tilted cross [26,27] for He; the open
circle for pure C60 [22].
reason behind the nonlinearity of the a X( )Xe relation-
ship is not clear at present.
Conclusions
We have performed x-ray powder diffraction stud-
ies of a Xe-doped C60 sample over the temperature
range from 7 to 300 K.
The sample is found to contain two phases. One is
the fcc phase, quite common for fullerite C60 but with
the lattice parameter slightly increased due to xenon
present. The structure of the other phase (of approxi-
mately 10% content) was not determined. Its presence
might result from partial polymerization brought
about by sample preparation handling.
The room temperature reflection intensities al-
lowed us to evaluate the weight averaged Xe occu-
pancy as (34�4) mol %, in good agreement with the
TGA estimates performed upon saturation.
The variation of the fcc lattice parameter with tem-
perature depends strongly on the sign of the tempera-
ture increment. Two hysteresis loops have been ob-
served in the temperature dependence of the lattice
parameter. The wider and more pronounced one is be-
low the orientational transition point; the other hys-
teresis loop is below the orientational glassification
point ( )Tg � 70K . The nature of the hysteresis, espe-
cially of the high-temperature one, is not completely
clear.
The lattice parameters measured in the lowest tem-
perature points under cooldown give indication of un-
usually large negative thermal expansivities.
The authors thank A.N. Aleksandrovskii and V.G.
Manzhelii for valuable discussions and for providing
us with their experimental results prior to publica-
tion. This work was partially supported by the STCU,
Grant No 2669.
1. O. Zhou and D.E. Cox, J. Phys. Chem. Solids 11,
1373 (1992).
2. J.E. Schirber, G.H. Kwei, J.D. Jorgensen, R.L. Hit-
terman, and B. Morosin, Phys. Rev. B51, 12014
(1995).
3. B. Morosin, J.D. Jorgensen, S. Short, G.H. Kwei, and
J.E. Schirber, Phys. Rev. B53, 1675 (1996).
4. G.E. Gadd, P.J. Evans, S. Moricca, and M. James, J.
Mat. Res. 12, 1 (1997)
5. G.E. Gadd, S.J. Kennedy, S. Moricca, C.J. Howard,
M.M. Elcombe, P.J. Evans, and M. James, Phys. Rev.
B55, 14794 (1997).
6. G.E. Gadd, S. Moricca, S.J. Kennedy, M.M. Elcombe,
J. Evans, M. Blackford, D. Cassidy, C.J. Howard, P.
Prasad, J.V. Hanna, A. Burchwood, and D. Levy, J.
Phys. Chem. Solids 58, 1823 (1997).
7. M. Gu and T.B. Tang, J. Appl. Phys. 93, 2486 (2003).
8. J.E. Schirber, R.A. Assink, G.A. Samara, B. Morosin,
and D. Loy, Phys. Rev. B51, 15552 (1995).
9. S.A. Meyers, R.A. Assink, J.E. Schirber, and D. Loy,
Mat. Res. Soc. Symp. Proc. 359, 505 (1995).
10. B. Morosin, R.A. Assink, R.G. Dunn, T.M. Massis,
and J.E. Schirber, Phys. Rev. B56, 13611 (1997).
11. M. James, S.J. Kennedy, M.M. Elcombe, and G.E.
Gadd, Phys. Rev. B58, 14780 (1998).
12. G.H. Kwei, F. Troun, B. Morosin, and H.F. King, J.
Chem. Phys. 113, 320 (2000).
13. S.A. FitzGerald, T. Yildirim, L.J. Santodonato, D.A.
Neuman, J.R.D. Copley, J.J. Rush, and F. Trouw,
Phys. Rev. B60, 6439 (1999).
14. I. Holleman, G. von Helden, A. van der Avoird, and
G. Meijer, Phys. Rev. Lett. 80, 4899 (1998).
15. S. Van Smaalen, R. Dinnebier, I. Holleman, G. von
Helden, and G. Meijer, Phys. Rev. B57, 6321 (1998).
16. M. Gu, T.B. Tang, and D. Feng, Phys. Rev. B66,
073404 (2002).
17. A.N. Aleksandrovskii, A.S. Bakai, A.V. Dolbin, G.E.
Gadd, V.G. Gavrilko, V.G. Manzhelii, S. Moricca, B.
Sundqvist, and B.G. Udovidchenko, Fiz. Nizk. Temp.
29, 432 (2003) [Low Temp. Phys. 29, 324 (2003)].
18. S. Amelinks, C. Van Henrich, D. van Dyck, and G.
Van Tendeloo, Phys. Status Solidi A131, 589 (1992).
19. B. Sundqvist, Adv. Phys. 48, 1 (1999).
20. R. Moret, P. Launois, T. Wagberg, B. Sundqvist, V.
Agafonov, V.A. Davydov, and A.V. Rakhmanina, Eur.
Phys. J. B37, 25 (2004).
21. A.N Aleksandrovskii, V.B. Esel’son, V.G. Manzhelii,
A.V. Soldatov, B. Sundqvist, and B.G. Udovidchenko,
Fiz. Nizk Temp. 23, 1256 (1997) [Low Temp. Phys.
23, 943 (1997)]; Fiz. Nizk. Temp. 26, 100 (2000)
[Low Temp. Phys. 26, 75 (2000)].
22. N.A. Aksenova, A.P. Isakina, A.I. Prokhvatilov, M.A.
Strzhemechny, Fiz. Nizk. Temp. 25, 964 (1999) [Low
Temp. Phys. 25, 724 (1999)].
23. A.N. Aleksandrovskii, V.G. Gavrilko, V.B. Esel’son,
V.G. Manzhelii, B.G. Udovidchenko, and V.P. Malets-
kiy, Fiz. Nizk Temp. 27, 1401 (2001) [Low Temp. Phys.
27, 1033 (2001)].
24. A.N. Aleksandrovskii, A.S. Bakai, A.V. Dolbin, V.B.
Esel’son, G.E. Gadd, V.G. Gavrilko, V. G. Manzhelii,
S. Moricca, and B. Sundqvist, Fiz. Nizk. Temp.
565 (2005).
25. B. Morosin, J.D. Jorgensen, S. Short, G.H. Kwei, and
J.E. Schirber, Phys. Rev. B53, 1675 (1996).
26. I.V. Legchencova, A.I. Prokhvatilov, Yu.E. Stetsenko,
M.A. Strzhemechny, K.A. Yagotintsev, A.A. Avdeenko,
V.V. Eremenko, P.V. Zinoviev, V.N. Zoryansky, N.B.
Silaeva, and R.S. Ruoff, Fiz. Nizk. Temp. 28, 1320
(2002) [Low Temp. Phys. 28, 942 (2002)].
27. Yu.E. Stetsenko, I.V. Legchenkova, K.A. Yagotintsev,
A.I. Prokhvatilov, and M.A. Strzhemechny, Fiz. Nizk.
Temp. 29, 597 (2003) [Low Temp. Phys. 29, 445 (2003)].
Hysteretic phenomena in Xe-doped C60 from x-ray diffraction
Fizika Nizkikh Temperatur, 2005, v. 31, No. 5 589
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