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Journal ArticleDOI

Germanium telluride: specific heat and superconductivity

17 Aug 1964-Physical Review Letters (American Physical Society)-Vol. 13, Iss: 7, pp 233-234

AboutThis article is published in Physical Review Letters.The article was published on 1964-08-17 and is currently open access. It has received 22 citation(s) till now. The article focuses on the topic(s): Germanium telluride & Superconductivity.

Topics: Germanium telluride (70%), Superconductivity (52%)

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Lawrence Berkeley National Laboratory
Recent Work
Title
GERMANIUM TELLURIDE: SPECIFIC HEAT AND SUPERCONDUCTIVITY
Permalink
https://escholarship.org/uc/item/6fk8r321
Author
Finegold, Leonard.
Publication Date
1964-07-01
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UCRL-11534
University of California
Ernest
0.
Radiation
Lawrence
Laboratory
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copy,
call
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Info.
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Ext.
5545
GERJ\.1ANIUM
TELLURIDE:
SPECIFIC
HEAT
AND
SUPERCONDUCTIVITY
Berkeley, California

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GERMANIUM
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Leonard
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July
1964
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predictions,
certa~
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~;
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t
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semiconductors
and
semimetals
may be.
superconductors
at
experi-
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mentally
accessible
temperatures.
He
in
et
al.
have
examined germanium'·· . ,
·,,
·
·.
: _ .
;_
..
-.
.
tel_luride
containing
a
large
number
of
car:riers.
.
They
find
that
it
does.
'' -
··
· ·
. . . .
~
:
·:,
indeed
show
those
changes:\in
magnetic
s'usceptibility
with
temperature
~o
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::;···.·'
.
be
expected
of
a
superconductor.
However,
susceptibility
(and
.resisti-
_-
. :; .
vity)
mea_surements do
not
·exclude
the
possibility
of.
the
superconducti-
vity
being
confined
to
unrepresentative
regions
of
the
sample
(Hein
et
,I·_,
'•
..
al.).
The
heat
capacity
measurements
presented
here
show
that
at
least
· · . · : ·
·'
·
the
major
part
of
the
germanium
telluride
sample
was
superconducting,
and
hence
.that
the
superconductivity
observed
by
Hein
et
al.
is
a
true
:
''.
,.
bulk
effect.
,(
:
"'-,._
:
~
..
,
·'
-~
. .
·-'
..
'.
A
germani~
telluride
sample
of
the
type
used
by
Hein
et
al.
was
·,·.
kindly
supplied
to
me
by
Dr.
J.
K. Hulm.
It
was a
specially
prepared
·
·'
',
k
)
large
(one
grl;llll-mole)
cylinder
of
nominal
composition
Ge.
950
Te,
annealed·
,
....
'•
..
for
ten
days
at
485°C.
Attached
to
the
sample
were
a
carbon
(painted
-·,
·_:
· ·-: ·
·;
f :
colloidal
graphit~)
resistance
thermometer,
manganin
heater,
copper,
-
··
',
~-
varnish,
and'a
negiigibie
amount
(<.0.001
mole)
of
lead
in
a
super-
'
conducting
heat
switch
•.
The
apparatus
was
that
described
by
O'Neal
and
,'· .
Phillips
3
For
each
series
of
heat
capacity
measu;rements,
the
·sample·
.
.>
.
:--
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-··-·"
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..
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'-.
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:,_·

Citations
More filters

Book ChapterDOI
Abstract: Publisher Summary This chapter discusses rare earth pnictides. The rare earth elements are transitional in their chemical properties between the alkaline-earth elements, especially Ba, and the 5d transition elements Hf, Ta. With certain exceptions they behave like transition elements of the Sc group with additional f electrons in discrete levels. The exceptions are mainly because of the high stability of the empty, half- or completely-filled 4f shell. Certain compounds formed by Eu and Yb, in some cases also Sm and Tm, therefore, show close similarities with the corresponding alkaline-earth compounds whereas Ce and Tb in fluorides and oxides resemble Hf4+ and Th4+ compounds. The chapter discusses the preparation of the rare earth pnictides. All lanthanide elements react in the solid state with pnigogen vapors. Except for nitrogen, the chemical reaction takes place at temperatures below the melting point of the elementary pnigogen; therefore, they can be performed in fused-silica tubes. The reaction products are microcrystalline powders, which usually serve only as starting materials for single-crystal growth.

57 citations


Journal ArticleDOI
Abstract: The discoveries of superconductivity in the heavily-boron doped semiconductors diamond (C:B) in 2004 [Ekimov et al., Nature (London) 428, 542 (2004)] and silicon (Si:B) in 2006 [Bustarret et al., Nature (London) 444, 465 (2006)] have renewed the interest in the physics of the superconducting state of doped semiconductors. Recently, we discovered superconductivity in the closely related ``mixed'' system heavily boron-doped silcon carbide (SiC:B) [Ren et al., J. Phys. Soc. Jpn. 76, 103710 (2007)]. Interestingly, the latter compound is a type-I superconductor whereas the two aforementioned materials are type II. In this paper, we present an extensive analysis of our recent specific-heat study, as well as the band structure and expected Fermi surfaces. We observe an apparent quadratic temperature dependence of the electronic specific heat in the superconducting state. Possible reasons are a nodal gap structure or a residual density of states due to nonsuperconducting parts of the sample. The basic superconducting parameters are estimated in a Ginzburg-Landau framework. We compare and discuss our results with those reported for C:B and Si:B. Finally, we comment on possible origins of the difference in the superconductivity of SiC:B compared to the two ``parent'' materials C:B and Si:B.

51 citations


Journal ArticleDOI
Abstract: In order to optimize the binary Ge-Te system available experimental data were critically compiled from the literature. The cubic high-temperature β-phase and the rhomboedric room-temperature α-phase were described by a two-sublattice model with one kind of defect (vacancies on germanium sites). The room-temperature orthorhombic γ-phase was treated as a stoichiometric compound, as there is a lack of information about its solubility. The liquid phase was modelled by the the associate model with one kind of associate, namely ‘GeTe’. A set of thermodynamic parameters was obtained and the calculated phase diagram is presented.

49 citations



Journal ArticleDOI
J. E. Lewis1
Abstract: The measured transport properties of non-stoichiometric GeTe have been satisfactorily analysed on the basis of a two-carrier model and the various band parameters have been evaluated. In particular the variation of the carrier density of the system with composition has been obtained and then compared to the total number of excess atoms in the non-stoichiometric lattice. It is found that the defects occurring in GeTe due to these excess atoms are of a complex nature, except for compositions close to stoichiometry where singly ionized vacancies are the dominant defect.

41 citations