Decomposition of single-source precursors under high-temperature high-pressure to access osmium–platinum refractory alloys

Article abstract of DOI:10.1016/j.jallcom.2019.152121

Thermal decomposition of (NH₄)₂[Os_xPt_1-xCl₆] as single-source precursors for Os–Pt binary alloys has been investigated under ambient and high pressure up to 40 GPa. Thermal decomposition of mixed-metal (NH₄)₂[Os_xPt_1-xCl₆] precursors in hydrogen atmosphere (reductive environment) under ambient pressure results in formation of β-trans-[Pt(NH₃)₂Cl₂] and α-trans-[Pt(NH₃)₂Cl₂] crystalline intermediates as well as single and two-phase Os–Pt binary alloys. For the first time, direct thermal decomposition of coordination compound under pressure has been investigated. A formation of pure metallic alloys from single-source precursors under pressure has been shown. Miscibility between fcc- and hcp-structured alloys has been probed up to 50 GPa by in situ high-pressure X-ray diffraction. Miscibility gap between fcc- and hcp-structured alloys does not change its positions with pressure up to at least 50 GPa.

Full text of DOI:10.1016/j.jallcom.2019.152121

Journal of Alloys and Compounds 813 (2020) 152121
Contents lists available at ScienceDirect
Journal of Alloys and Compounds
journal homepage: http://www.elsevier.com/locate/jalcom
Decomposition of single-source precursors under high-temperature
high-pressure to access osmiumeplatinum refractory alloys
Kirill V. Yusenko a , Kristina Spektor , Saiana Khandarkhaeva , Timofey Fedotenko ,
,
*
b
c
d
e
f
f
f
Anna Pakhomova , Ilya Kupenko , Arno Rohrbach , Stephan Klemme ,
b
g
g
Wilson A. Crichton , Tatyana V. Dyachkova , Alexander P. Tyutyunnik ,
Yurii G. Zainulin , Leonid S. Dubrovinsky , Sergey A. Gromilov
g
c
h, i
a
BAM Federal Institute of Materials Research and Testing, Richard-Willst a€ tter Str. 11, D-12489, Berlin, Germany
b
c
d
e
f
ESRF-The European Synchrotron, 71 Avenue des Martyrs, 38000, Grenoble, France
Bayerisches Geoinstitut, Universit a€ t Bayreuth, D-95440, Bayreuth, Germany
Material Physics and Technology at Extreme Conditions, Laboratory of Crystallography, University of Bayreuth, D-95440, Bayreuth, Germany
Photon Sciences, Deutsches Elektronen-Synchrotron, Notkestrasse 85, D-22607, Hamburg, Germany
Institut für Mineralogie, Westf a€ lische-Wilhelms-Universit a€ t Münster, Corrensstrasse 24, 48149, Münster, Germany
g
h
i
Institute of Solid State Chemistry, Pervomaiskaia str. 91, 620990, Ekaterinburg, Russia
Nikolaev Institute of Inorganic Chemistry, Lavrentiev ave. 3, 630090, Novosibirsk, Russia
Novosibirsk State University, Pirogova str. 2, 630090, Novosibirsk, Russia
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 18 July 2019
Received in revised form
Thermal decomposition of (NH ) [Os Pt Cl ] as single-source precursors for OsePt binary alloys has
4
2
x
1-x
6
been investigated under ambient and high pressure up to 40 GPa. Thermal decomposition of mixed-
metal (NH [Os Pt1-xCl ] precursors in hydrogen atmosphere (reductive environment) under ambient
pressure results in formation of -trans-[Pt(NH Cl ] and -trans-[Pt(NH Cl ] crystalline intermediates
4
)
2
x
6
29 August 2019
b
3
)
2
2
a
3
)
2
2
Accepted 1 September 2019
Available online 5 September 2019
as well as single and two-phase OsePt binary alloys. For the first time, direct thermal decomposition of
coordination compound under pressure has been investigated. A formation of pure metallic alloys from
single-source precursors under pressure has been shown. Miscibility between fcc- and hcp-structured
alloys has been probed up to 50 GPa by in situ high-pressure X-ray diffraction. Miscibility gap between
fcc- and hcp-structured alloys does not change its positions with pressure up to at least 50 GPa.
© 2019 Elsevier B.V. All rights reserved.
Keywords:
Osmium
Platinum
Alloys
Phase diagrams
Single-source precursors
High-pressure high-temperature
1. Introduction
Recent investigations suggested high phase stability of refractory
metals and their alloys up to extremely high-pressures reaching
Refractory alloys based on platinum group metals have been
proposed as materials for extreme environments such as high
mechanical impact, oxidative stress as well as high-temperature
high-pressure conditions. Phase diagrams, mechanical and func-
tional properties of refractory platinum group alloys were investi-
1 TPa [6,7]. Such finding makes refractory alloys as possible models
for investigation and development of ultra-incompressible mate-
rials [8]. Investigation of refractory binaries with hexagonal close
packed (hcp: Os, Re, Ru) and face centred cubic (fcc: Ir, Pt, Rh) re-
fractory metals allowed one to formulate general trend in their
phase stability under pressure as follows: along compression the
miscibility gap between hcp and fcc alloys shifts towards the metal
with larger atomic volume [9]. Previously we have confirmed this
tendency for IreOs and IrdRe alloys, where metals have close
atomic volumes and significantly different compressibility (IreOs
binary alloys) or different atomic volumes and nearly identical
compressibility (IrdRe binary alloys).
gated in many details by heating up to their melting temperatures
ꢀ
(
i.e. above 1500e3000 C). However, investigations under high
hydrostatic pressure were performed only for a limited number of
binary systems, mainly for FeeRu, IrdHf, IreOs, and IrdRe [1e5].
*
Corresponding author.
OsePt binary alloys have relevance not only as refractory
E-mail address: kirill.yusenko@bam.de (K.V. Yusenko).
https://doi.org/10.1016/j.jallcom.2019.152121
925-8388/© 2019 Elsevier B.V. All rights reserved.
0

2
K.V. Yusenko et al. / Journal of Alloys and Compounds 813 (2020) 152121
ꢀ
constructional system but also as functional materials with high
catalytic activity in CO oxidation [10e12]. It should be mentioned
that OsePt binaries for catalytic and mechanical tests were origi-
nally prepared using arc-melting which requires relatively large
amount of materials as well as cannot be considered as an effective
tool for preparation of supported metallic particles with high
porosity. Alternatively, materials for catalytic tests were prepared
12 C/min. Temperature was calibrated using the thermal expan-
sion of the cell parameters for silver powder as an external stan-
dard. The wavelength
distance were calibrated using CeO
(l
¼ 0.3086 Å) and sample-to-detector
2
powder as external standard.
Data were collected every 20 s (approximately every 4 K in the
temperature scale) using a Frelon2K 2D flat detector. The data were
converted, and diffracted intensitieswere integrated using custom
written Python-based algorithm. Temperature-dependent PXRD
patterns were plotted and analysed using the Powder3D software
[16].
High-pressure
(NH
loaded piston cylinder apparatus installed at the Institut für Min-
eralogie, WWU Münster [17]. (NH ] powder was
4
from water solutions using NaBH as reducing agent [13].
In our previous studies, an alternative strategy to access nano-
porous refractory alloys from solid or supported single-source
precursors has been reported [3e5]. So, OsePt alloys can be pre-
pared by reducing a solid single-source precursor in a hydrogen
flow according to the following chemical reaction:
high-temperature
decomposition
of
) [Os0.40Pt0.60Cl ] at 1 GPa has been performed in an end-
4 2 6
4 2 6
) [Os0.40Pt0.60Cl
ꢀ
(
NH
4
)
2
[Os
x
Pt1-xCl
6
] þ 2H
2
d600-800 C/ Os
x
Pt1-
enclosed in a 2 mm alumina crucible. The pressure assembly con-
sisted of a ½-inch talc-Pyrex cylinders, which contained an 8 mm
diameter graphite heater with inner parts of crushable Al
x
þ 4HCl þ 2NH
4
Cl;
2 3
O (TKF
or through thermal decomposition in inert atmosphere (He, Ar, or
):
GmbH, Kerschenbroich, Germany). Temperature was monitored
N
2
and controlled with a W97Re
3
eW75Re25 thermocouple. The sample
ꢀ
was compressed to 1 GPa with further heating up to 1000 C. After
80 min under compression and heating, the sample was quenched
to room temperature and subsequently decompressed for 2 h.
ꢀ
(
NH
4
)
2
[Os
x
Pt1-xCl
Cl.
6
] d600-900 C/ Os
x
Pt1-x þ 2/3N þ 16/
2
3
HCl þ 2/3NH
4
High-pressure
high-temperature
decomposition
of
Current strategy allows us to prepare OsePt alloys in the whole
(NH ) [Os0.40Pt0.60Cl ] at 8 GPa in H fluid was performed in the
4
2
6
2
range of concentrations using relatively low temperatures and
further probe their phase stability under high-pressure high-tem-
perature conditions.
large-volume 2000 tons MAVO press in a 6/8 mode with 25 mm
tungsten carbide anvils (ID06eLVP beamline, ESRF [18],
l
¼ 0.2254 Å). A linear pixelated GOS detector was used for in situ
In the current study, we report an investigation of Os
x
Pt1-x alloys
data collection (sequential exposure of 3.2 s at 10 Hz at 32 s interval,
mounted to intercept the downstream diffraction from the hori-
zontal anvil gap at ~2040 mm distance). The detector-beam normal
plane was mechanically corrected for tilt and rotation, the detector
position was corrected for zero-offset and calibrated against LaB6
(SRM660a). For this experiment, the sample was pressed into a
pellet (1.4 mm OD, 1.5 mm height) and sealed inside a NaCl capsule
(3 mm OD, 3.5 mm height) along with 2 pellets of NH BH
prepared from (NH [Os Pt1-xCl ] coordination compounds as
4
)
2
x
6
single-source precursors. Thermal decomposition of the precursors
in inert and reductive atmospheres at ambient and high pressure
up to 40 GPa has been investigated using in situ X-ray diffraction.
Phase stability and phase separation of Os
x
Pt1-x alloys have been
ꢀ
investigated under extreme conditions up to 50 GPa and 3000 C.
We report behaviour of OsePt binary alloys under high-pressure
high-temperature conditions to extend our knowledge with a
system where both atomic volumes and compressibilities for fcc-
and hcp-structured metals are significantly different. Thermal
3
3
(ammonia borane, 0.45 mm height, 1.4 mm OD). NH BH was
3
3
employed as a hydrogen source, providing ~6 times molar excess of
H fluid with respect to the metals. The sample capsule preparation
2
decomposition of (NH
4
)
2
[Os
x
Pt1-xCl
6
] compounds as single-source
was handled in an Ar-filled glove box. Afterwards, the NaCl capsule
precursors under high-pressure in inert and reductive environ-
ments gave us a possibility to extend our knowledge about
behaviour of coordination compounds under extreme conditions as
well as to show a possibility to decompose coordination salts under
high-pressure without formation of parasitic binary compounds.
was surrounded with a BN sleeve and along with carbon foil
resistance furnace and ZrO plugs was inserted into the 14 mm OEL
2
octahedral Cr:MgO assembly. The octahedron was further posi-
tioned between eight 25 mm WC anvils (Hawedia, ha7, 8 mm TEL)
equipped with pyrophyllite gaskets. Amorphous SiBCN rods (2 mm
OD) and 5 mm wide MgO rectangles served as X-Ray windows in
the octahedron and the gaskets, respectively, along the beam di-
rection. Pressures and temperatures were estimated using the NaCl
2
. Experimental section
Single-source precursors, (NH
4
)
2
[Os
x
Pt1-xCl
6
], were crystallized
Cl to a
[OsCl ] and
] (obtained from Acros Organics) [14,15]. Salts were
filtered, washed with diluted room temperature water solution of
NH Cl, absolute ethanol and dried in air. Elemental compositions
PeVdT equation of state [19]. The sample was compressed up to
ꢀ
by adding an excess of saturated water solution of NH
mixture of hot concentrated water solutions of (NH
NH [PtCl
4
9 GPa and carefully heated to 300 C to decompose NH
3
BH
3
and
4
)
2
6
2
release H . After hydrogen release though the pressure dropped to
ꢀ
8e8.5 GPa. Further heating in H fluid up to 600 C under quasi-
2
(
4
)
2
6
constant pressure was done in 60 min with further annealing
during 1 h. On compression, heating, cooling and decompression
PXRD data were simultaneously collected. Two-dimensional im-
ages were integrated to one-dimensional intensities as a function of
diffraction angle using the FIT2D [20].
4
were confirmed in 10 points using a Hitachi S-4800 Field Emission
scanning electron microscope (SEM) equipped with energy
dispersive X-ray (EDX) analyser and averaged for 10 points for each
sample.
High-pressure
(NH
high-temperature
] at 4 GPa and (NH
decomposition
of
] at
The thermal decomposition of (NH
4
)
2
[Os0.40Pt0.60Cl
6
]
at
4
)
2
[Os0.25Pt0.75Cl
6
4
)
2
[Os0.50Pt0.50Cl
6
ambient pressure was investigated in situ using the powder X-ray
diffraction (PXRD) set-up located at the ID11 beamline of the Eu-
ropean Synchrotron Radiation Facility (ESRF, Grenoble, France).
Samples in powder form were placed in 0.5 mm fused quartz mark
tubes (Hilgenberg GmbH, Germany). Capillaries were connected to
10 GPa has been performed in a standard toroid-type chamber of a
pressure apparatus at the Institute of Solid State Chemistry (Eka-
terinburg, Russia) [21]. Powdered salt was pressed inside a graphite
crucible with a boron nitride insulation. Stable compact tablets
with a diameter of 3 mm were obtained after 3e5 min treatment at
ꢀ
a 2 vol% H
2
/Ar or pure Ar flow (0.1e0.5 ml/min) and heated with hot
2000 C at 4 and 10 GPa. Graphite crucibles insulated with h-BN
were used to avoid any contact of the reaction mixture with oxygen
ꢀ
air stream from room temperature to 900 C with a ramp rate of

K.V. Yusenko et al. / Journal of Alloys and Compounds 813 (2020) 152121
3
atmosphere. No oxides, nitrides or carbides were detected after
high-temperature high-pressure treatment.
High-pressure high-temperature
NH ] at 18.5 GPa has been performed in a 1000 t
decomposition
of
(
4 2 6
) [Os0.50Pt0.50Cl
multi-anvil press installed at the Institut für Mineralogie, WWU
Münster. 10/4 assemblies were used with chromium-doped MgO
octahedra, stepped LaCrO furnaces and pyrophyllite gaskets. The
3
assembly was pressure-calibrated at high temperatures using
olivine-wadsleyite-ringwoodite phase transitions [17]. The starting
powders were encapsulated into polycrystalline crushable Al
2 3
O
containers. The experiments were brought up to 18.5 GPa and
ꢀ
ꢀ
further heated to 1200 C at a rate of 10 C/min and then kept
constant for 5 min. Samples were quenched by turning off the
power supply, resulting in reducing the temperature to below
ꢀ
4
20 C in less than 1 s, and decompressed overnight.
Phase identity of recovered samples was investigated at ambient
conditions using PXRD without grinding at ID06-LVP (8 and 18 GPa
samples,
¼ 0.2296 Å) and ID15B beamlines (8 and 1 GPa samples,
¼ 0.4112 Å), as well as at in-house STADI-P (Stoe) diffractometer
10 GPa sample, slightly ground) in transmission geometry with a
Fig. 1. Phase diagram of OsePt binary system (right axis): experimental data from
Ref. [25] (stars) and modelled phase diagram using ideal solutions model (dashed line).
Hexagons (hcp-structured OsePt alloys) and squares (fcc-structured OsePt alloys)
correspond to atomic volumes of single-phase OsePt binary alloys according to Table 1
(left axis).
l
l
(
ꢀ
linear mini-PSD detector in the 2
q
range 5e120 with a step of
ꢀ
0
.02 . Focused CuK
a
1
(l
¼ 1.54059 Å) incident beam was obtained
using curved Ge(111) monochromator. Polycrystalline silicon
6
[OsBr ] were considered as single-source precursors for a single-
(
a ¼ 5.43075(5) Å) was used as external standard.
High-pressure high-temperature decomposition
NH ] above 20 GPa has been performed in a
phase fcceOs0.50Pt0.50. However, cell parameters of obtained equi-
atomic fcc-structured alloys were estimated much higher in com-
parison with other compositions. Recent investigations [29] sug-
gested a metastable nature of obtained fcc-Os0.50Pt0.50 alloy.
Originally formed fcc-Os0.50Pt0.50 under low temperature (below
of
(
4 2 6
) [Os0.50Pt0.50Cl
membrane Mao-type diamond anvil cell (DAC) with conically
supported Boehler Almax type anvils (150 m culet sizes) at the
P02.2. beamline [22], PETRA III, DESY in Hamburg (
¼ 0.2907 Å,
PerkinElmer XRD1621 (2048x2048 pixels, 200 ꢁ 200
m
l
ꢀ
2
600 C) with further high-temperature annealing decomposes with
m
m ) flat
2
a formation of fcc þ hcp two-phase mixture.
panel detector, beam size 3(v) ꢁ 3(h)
mm ). A powdered sample was
3
ꢂ1
At room temperature, atomic volumes (V/Z, Å $atom ) of
OsePt alloys correspond to two polynomial functions:
loaded in a hole drilled in the pre-indented rhenium gasket. Pres-
sure was determined using a ruby luminescence. Neon serving as a
pressure-transmitting medium was loaded at ~1.5 kbar using the
gas-loading system installed at the beamline. The diffraction im-
V/Zfcc ¼ 14.68(7) e 3(2)$10ꢂ3$xPt þ 7(1)$10ꢂ5$x 2P t
ages were recorded under continuous
u-rotation of the DAC
V/Zhcp ¼ 13.97(4) þ 7(7)$10ꢂ3$xPt þ 1(2)$10ꢂ4$x 2P t
;
ꢀ
from ꢂ3 to þ3 with 6 s acquisition time. After room temperature
compression up to 24 GPa, the sample was laser-heated online up
ꢀ
where xPt, at. % corresponds to the Pt atomic fraction in alloy. V/Zfcc
and V/Zhcp correspond to atomic volumes of fcc- (Z ¼ 4) and hcp-
to 2000e2300 C from both sides with simultaneous collection of
diffraction images. Temperature was estimated from the black body
radiation. Afterwards, cell was compressed to 34 GPa and heated up
(
Z ¼ 2) structured alloys. Both fits are quite close to the linear
ꢂ3
ꢀ
ꢀ
function: V/Z ¼ 13.95(1) þ 11.3(3)$10 $xPt. Linear function can be
used as a tool to obtain phase composition for two-phase samples
with known cell parameters.
to 1000e1200 C, then to 40 GPa and up to 1600 C and finally to
ꢀ
5
0 GPa and heated up to 850 C. PXRD for all steps was collected
after quenching to room temperature. Quenched unloaded sample
was also measured without DAC to confirm its phase composition.
Data were treated and integrated using DIOPTAS software [23]. Unit
cell, background, and line-profile parameters for sample and gold
internal standard as well as Ne diffraction lines were refined
simultaneously using model-free full-profile refinement imple-
mented in JANA2006 software [24].
Peritectic OsePt binary phase diagram can be reproduced based
on ideal solutions model (without mixing parameters) using CAL-
PHAD approach realised in PANDAT 8 software [30] with the SGTE v
4.4 thermodynamic database for pure elements [31]. Experimental
and modelled phase diagrams are quite close to each other for Pt-
rich alloys, but Os-rich part cannot be reproduced.
OsePt alloys under high-pressure. Two-phase OsePt alloys
annealed or formed from single-source precursor under high-
pressure represent a miscibility gap in the binary phase diagram
under compression. In current study, high-pressure high-temper-
3
. Results and discussion
OsePt alloys under ambient pressure. A peritectic OsePt
ꢀ
ature annealing up to 3000 C and 50 GPa has been performed to
ambient pressure binary phase diagram was investigated using
arc-melted samples [25] (Fig. 1). Peritectic temperature was esti-
probe dependence of a miscibility between fcc- and hcp-structured
alloys on pressure (Table 2, Fig. 2). All samples were investigated
after quenching and recovering at ambient pressure. According to
our previous knowledge, quenching and pressure unloading do not
change phase composition and phase amounts and recovered
samples correspond to high-pressure situation [3e5]. According to
our previous experimental observations for IreOs and IrdRe bi-
naries, miscibility gap in peritectic binary systems should shift to-
wards metal with higher atomic volume [3e5]. In the mentioned
binary systems, metals have close atomic volumes (14.155 vs.
ꢀ
mated at around 1955 C. The maximal solubilities of Pt in hcp-
structured (10 at. %) and Os in fcc-structured (20 at. %) alloys were
obtained by Rudman [26] using high-temperature sintering of fine
metallic powders (Table 1). Later, more concentrated alloys were
prepared using thermal decomposition of single source precursors:
hcpeOs0.75Pt0.25 was prepared from (NH
fcceOs0.30Pt0.70 was obtained from (NH
which suggests the narrower miscibility gap in the OsePt binary
3 4
metallic system. Of importance, [Pt(NH ][OsCl ] or [Pt(NH ) ]
4
)
2
[Os0.75Pt0.25Cl
6
] [14] and
4
)
2
[Os0.30Pt0.70Cl
6
] [15],
3
)
4
6

4
K.V. Yusenko et al. / Journal of Alloys and Compounds 813 (2020) 152121
Table 1
Single-phase OsePt alloys.
3
ꢂ1
, g/cm3
Composition
Ref.
a, Å
c, Å
V/Z, Å $atom
d
x
Preparation conditions
Reference material
3
hcp-phases (P6 \mmc)
hcp-Os [[27], N 6e662]
ꢀ
2.7341(2)
13.98
14.00
14.02
14.11
14.17
14.23
22.587
22.587
22.585
22.440
22.401
22.336
4
.3197(4)
2.7350(7)
.322(12)
2.7361(7)
.3247(12)
2.738(2)
.346(3)
2.735(2)
.375(3)
2.736(1)
.391(2)
ꢀ
hcp-Os0.95Pt0.05 [26]
Sintering 1 h, 2500 C
4
ꢀ
hcp-Os0.90Pt0.10 [26]
Sintering, 1 h, 2500 C
4
ꢀ
hcp-Os0.90Pt0.10 [14]
Thermal decomposition of (NH
Thermal decomposition of (NH
Thermal decomposition of (NH
4
)
4
)
4
)
2
2
2
[Os0.90Pt0.10Cl
[Os0.80Pt0.20Cl
[Os0.75Pt0.25Cl
6
6
6
], 550 С, H
2
2
2
4
ꢀ
hcp-Os0.80Pt0.20 [14]
], 550 С, H
4
ꢀ
hcp-Os0.75Pt0.25 (Sample A) [15]
], 550 С, H
4
fcc-phases (Fm3m)
ꢀ
fcc-Os0.50Pt0.50 [28]
fcc-Os0.50Pt0.50 [28]
fcc-Os0.50Pt0.50 [14]
fcc-Os0.30Pt0.70 [14]
fcc-Os0.25Pt0.75 (Sample B) [14]
fcc-Os0.20Pt0.80 [26]
fcc-Os0.10Pt0.90 [26]
3.899(3)
3.899(3)
3.91(1)
3.898(3)
3.902(3)
3.9049(7)
3.9127(7)
3.9231(2)
14.82
14.82
14.98
14.81
14.85
14.89
14.98
15.09
21.586
21.586
21.356
21.713
21.673
21.652
21.577
21.460
Thermal decomposition of [Pt(NH
Thermal decomposition of [Pt(NH
Thermal decomposition of [Pt(NH
3
3
3
)
)
)
4
4
4
][OsCl
][OsBr
][OsCl
6
], 600 С, He
ꢀ
6
], 500 С, H
2
ꢀ
6
], 500 С, Не
ꢀ
Thermal decomposition of (NH
Thermal decomposition of (NH
4
)
)
2
[Os0.30Pt0.70Cl
[Os0.25Pt0.75Cl
6
], 500 С, H
], 500 С, He
2
ꢀ
4
2
6
ꢀ
Sintering, 1 h, 1700 C
ꢀ
Sintering, 1 h, 1700 C
ꢀ
fcc-Pt [27, N 4e802]
Reference material
Table 2
Thermobaric treatment of OsePt alloys and (NH
4
)
2
[Os
x
6
Pt1-xCl ] single-source precursors.
Nominal composition
Phase composition after
thermobaric treatment
a, Å
c, Å
V/Z,
Å $atom
Experimental conditions
3
ꢂ1
Os0.40Pt0.60
EDX 30/70 [33]
hcp-Os0.89Pt0.71
2.737(2)
4.370(4)
3.898(2)
2.739(2)
4.372(4)
3.895(2)
2.741(4)
4.374(8)
3.897(3)
2.740(2)
4.347(4)
3.920(2)
2.737(2)
4.340(4)
3.888(2)
3.895(2)
14.18(4)
(NH
400 C, 15 min
4
ꢀ
)
2
[Os0.40Pt0.60Cl
6
6
6
] ambient pressure, H
2
flow,
flow,
flow,
fcc-Os0.89Pt0.71
hcp-Os0.76Pt0.24
14.82(5)
14.20(4)
Os0.50Pt0.50
EDX ¼ 40/60 [33]
(NH
4
)
2
[Os0.50Pt0.50Cl
], ambient pressure, H
2
ꢀ
400 C, 15 min
fcc-Os0.37Pt0.63
23 at. % hcp-Os0.73Pt0.27
14.77(5)
14.23(8)
Os0.60Pt0.40
EDX ¼ 55/45 [15,33]
(NH
4
)
2
[Os0.60Pt0.40Cl
] ambient pressure, H
2
ꢀ
400 C, 15 min
77 at. % fcc-Os0.32Pt0.68
14.80(8)
Os0.40(3)Pt0.60(3)
13 at. % hcp-Os0.82Pt0.18
14.132(5) Decomposition of (NH
4
)
2
[Os0.40Pt0.60Cl
6
],
ꢀ
EDX Os/Pt ¼ 40(3)/60(3)
1 GPa, 1000 С, 80 min
[Current study]
87 at. % fcc-Os0.02Pt0.98
41 at. % hcp-Os0.87Pt0.13
15.059(5)
14.08(4)
hcp-Os0.75Pt0.25 (EDX:
Os/Pt ¼ 69/31) [15]
Annealing hcp-Os0.75Pt0.25 Sample A, 1.5e2 GPa,
2000 C, 3 min
ꢀ
59 at. % fcc-Os0.54Pt0.46
14.69(5)
14.77(5)
ꢀ
Os0.25Pt0.75 [Current
study]
fcc-Os0.25Pt0.75
Pt0.75Os0.25
(
а
¼ 3.902(3) Å) Sample B, 4 GPa, 2000 С, 3 min
Os0.40(3)Pt0.60(3)
EDX Os/Pt ¼ 40(3)/60(3)
5 at. % hcp-Os0.73Pt0.27
2.741(2)
4.374(4)
3.896(1)
14.230(2) Decomposition of (NH
4
)
2
[Os0.40Pt0.60Cl
6
]
H
2
fluid 8.5e9 GPa,
ꢀ
[
Current study]
95 at. % fcc-Os0.35Pt0.65
24 at. % hcp-Os0.89Pt0.11
14.784(2) 600 С, 30 min
Os0.5Pt0.5 [Current
study]
2.73592(9) 14.071(2) Decomposition of (NH
4.34134(19)
4
)
2
[Os0.50Pt0.50Cl
6
],
ꢀ
10 GPa, 2000 С, 5 min
76 at. % fcc-Os0.41Pt0.59
3.88136(10) 14.618(2)
Os0.5Pt0.5 [Current
study]
Os0.5Pt0.5 [Current
study]
85 at. % fcc-Os0.43Pt0.57
15 at. % fcc-Os0.82Pt0.18
5 at. % hcp-Os0.74Pt0.26
3.879(2)
3.840(2)
2.742(2)
4.378(4)
3.888(2)
14.591(5) Decomposition of (NH
14.156(5) 18 GPa, 1200 С, 2 min
14.252(5) Decomposition of (NH
4
4
)
2
2
[Os0.50Pt0.50Cl
[Os0.50Pt0.50Cl
6
6
],
ꢀ
ꢀ
)
] at 24 GPa and 2300 С, further laser-heating at
ꢀ
30, 40 and 50 GPa up to 2000, 1600 and 850 C, respectively
95 at. % fcc-Os0.35Pt0.65
14.689(5)
3
ꢂ1
1
3.971 Å $atom ) and significantly different compressibility (341
4 2 x 6
(NH ) [Os Pt1-xCl ] precursors in inert conditions (10 GPa, 18 GPa
vs. 399 GPa) for IreOs binary alloys or different atomic volumes
and above) and in hydrogen fluid (8.5 GPa) show similar results
which suggests formation of equilibrium phases under all observed
pressures. At the same time, annealing of pre-synthetized metallic
powders as well as precursors under relatively low hydrostatic
pressure (below 2 GPa) results in a formation of alloys with less
amount of second metal, which might be a result of low inter-
diffusion or separate formation of metals in the thermal decom-
position process. In the sample annealed at 18 GPa, cell parameters
for hexagonal phase are masked under diffraction lines of assembly.
3
ꢂ1
(
(
14.155 vs. 14.730 Å $atom ) and very close compressibility values
341 vs. 353 GPa) for IrdRe binary alloys. But on the contrary, Pt
and Os have significantly different atomic volumes (15.094 vs.
3
ꢂ1
1
3.971 Å $atom ) and bulk moduli (273.5 vs. 399 GPa) [7,32]. For
OsePt alloys miscibility gap does not change with pressure or just
slightly shifts towards osmium below 50 GPa, which suggests high
structural stability of discussed refractory binary system.
Two-phase alloys obtained by thermal decomposition of

K.V. Yusenko et al. / Journal of Alloys and Compounds 813 (2020) 152121
5
[34]. It has been proposed that both compounds decompose with a
formation of several intermediates which can be detected using
spectroscopic techniques but invisible in PXRD. trans- and/or cis-
[
Pt(NH
termediates. However, several previous ex situ investigations of
NH [PtCl ] did not give much insight into its thermal decom-
position in H flow while the most data were obtained in an inert
3 2 2 4 n
) Cl ] and polymeric {OsCl } were proposed as key in-
(
4
)
2
6
2
gas atmosphere [34e39].
In the current study, we chose (NH
sentative example of bimetallic compounds within (NH
Cl
4
)
2
[Os0.40Pt0.60Cl
6
] as repre-
[Os
6
] series. Metallic products as well as thermal decomposition
4
)
2
x
Pt1-
x
process seem to be similar for all other compositions. Similar
assumption was used for our previous studies of thermal decom-
position of (NH ) [Ir Os1-xCl ] and (NH ) [Ir Re1-xCl ] in H -flow
4 2 x 6 4 2 x 6 2
where Ir(III)-containing intermediate was detected [4,5]. Fig. 3
summarizes temperature-dependent PXRD data collected upon
heating in inert and reducing atmosphere under ambient pressure.
In Ar flow (inert atmosphere), (NH
4
)
2
[Os0.40Pt0.60Cl
6
] forms directly
ꢀ
single-phase fcc-Os0.40Pt0.60 above 400 C. Single-phase alloy de-
composes with a formation of fcc þ hcp mixture with further
4 2 6
heating (Table 2). Such decomposition of (NH ) [Os0.40Pt0.60Cl ]
Fig. 2. Pressure dependence of the phase miscibility for OsePt alloys with pressure
below 20 GPa at temperature above 1000 C. Hexagons (hcp-structured OsePt alloys)
ꢀ
without a formation of any crystalline intermediates detectable by
and squares (fcc-structured OsePt alloys) correspond to Table 2, circles correspond to
starting composition before heat-treatment. Open hexagons and squares correspond to
annealed two-phase samples.
PXRD was expected based on data obtained for pure (NH
and (NH [OsCl ].
4 2
Surprisingly, thermal decomposition of (NH ) [Os0.40Pt0.60Cl
4
)
2
[PtCl
6
]
4
)
2
6
6
]
in 2 vol% H
termediates. Above 200 C, (NH
2
/Ar flow occurs with a formation of several in-
ꢀ
4
)
2
[Os0.40Pt0.60Cl
6
] forms
b-trans-
As a result, only cubic phase can be refined.
[
Pt(NH
3
)
2
Cl
2
]
(isostructural with
b
-trans-[Pd(NH Cl ]: Pbam,
3
)
2
2
Data obtained under low pressure (below 2.5 GPa) has low
reproducibility due to a number of experimental factors. Samples
releases relatively large number of volatile products which provoke
large stress and gradients in large assemblies. As a result, large
assemblies should have high temperature and pressure gradients
upon heating. Short reaction and temperature annealing times
a ¼ 8.1415(6), b ¼ 8.1459(7), c ¼ 7.7888(5) Å, Z ¼ 4 [40]), NH
4
Cl and
ꢀ
fcc-structured metallic phase. Further heating above 250 C results
in the transformation of
trans-[Pt(NH Cl ] (isostructural with
b
-trans-[Pt(NH
3
)
2
2
Cl ] intermediate to a-
3
)
2
2
a
-trans-[Pd(NH
3
)
2
Cl
2
]: P1,
ꢀ
a ¼ 6.299(4), b ¼ 6.554(4), c ¼ 6.819(4) Å,
a
¼ 100.900(18) ,
ꢀ
ꢀ
ꢀ
b
¼ 102.82(3) ,
g
¼ 102.068(12) , Z ¼ 2 [41]). Above 300 C, only
(
several minutes) probably do not give equilibrium samples. High-
fcceOs0.40Pt0.60 can be detected. Further annealing results in a
formation of fcc þ hcp alloys mixture. It is important to note that
pressure experiments (above 10 GPa) can be considered as more
reproducible due to relatively small sample volumes with fast re-
action times and low temperature and pressure gradients.
Pressure dependence of phase diagrams for refractory ultra-
incompressible metals was never modelled using CALPHAD as
well as ab initio approaches. Nevertheless, our data gives an
experimental basis for further construction of such phase diagrams
using compressibility data for pure metals and their alloys as well
as pressure dependence of miscibility gaps in binary systems. We
hope to perform theoretical modelling to support our experimental
studies in the nearest future.
3 2 2
cis-[Pt(NH ) Cl ] was not detected as crystalline product at any
temperatures. Both polymorphs,
Pt(NH Cl ], are well-known for Pd but were not previously
described for Pt. Both Pd polymorphs, -trans-[Pd(NH Cl ] and
trans-[Pd(NH Cl ], were synthetized and characterized structur-
ally. -trans-[Pd(NH Cl ] is less stable and easily irreversibly
transforms to -trans-[Pd(NH Cl ] with heating in a solid-state. It
seems that less symmetric structure, -trans-[Pt(NH Cl ], is more
3 2 2
b-trans-[Pt(NH ) Cl ] and a-trans-
[
3
)
2
2
b
3
)
2
2
a-
3
)
2
2
a
3
)
2
2
b
3
)
2
2
a
3
)
2
2
stable. Since only the strongest diffraction lines characteristic for
Pt-containing intermediates were detected, detailed crystal struc-
tures of detected intermediate crystalline phases could not be
extracted from such relatively poor X-ray diffraction data.
Formation of OsePt alloys from single-source precursors. All
binary OsePt alloys were prepared from (NH ) [Os Pt1-xCl ] as
4 2 x 6
single-source precursors. In all previous reports, alloys were pre-
pared under ambient pressure and further annealed under
compression. However, single-source precursor already contains
reducing agent and can be thermally decomposed under pressure
with easy formation of metallic alloys. In other words, thermal
decomposition of the precursor under compression also results in a
formation of equilibrium metallic composition and can be used to
probe miscibility gap in the phase diagram under high-pressure
similarly to ambient pressure trials.
4 2 6
Thermal decomposition of (NH ) [Os0.40Pt0.60Cl ] in hydrogen
ꢀ
flow under ambient pressure starts already at 200 C and can be
schematically summarized as follows:
(
[
NH
4
)
2
[Os0.40Pt0.60Cl
6
] /
Cl þ fccePt
b
-trans-
Os1-x þ “OsCl
Pt(NH
3
)
2
Cl
2
] þ NH
4
x
4
”
b
-trans-[Pt(NH Cl
3
)
2
2
] / -trans-[Pt(NH
a
3
)
2
2
Cl ];
To shed the light on the thermal behaviour of (NH
Cl ] bimetallic compound, its thermal decomposition in hydrogen
6
4 2 x
) [Os Pt1-
fcc-Pt
x
Os1-x þ “OsCl
4
” þ
a
3 2 2
-trans-[Pt(NH ) Cl ] / fccePt0.60Os0.40;
x
and helium under ambient pressure as well as in hydrogen fluid
under compression (8.5e9 GPa) was monitored in situ using X-ray
diffraction.
y
fccePt0.60Os0.40 / fccePt Os1-y (major phase) þ hcpePt
nor phase)
z
Os1-z (mi-
Previously, thermal decomposition of (NH
mosphere (He) and (NH [OsCl ] in reducing (H
He) atmospheres was investigated using in situ PXRD and EXAFS
4
)
2
[PtCl
6
] in inert at-
In
NH
inert
[Os0.40Pt0.60Cl
atmosphere,
thermal
decomposition
of
4
)
2
6
2
in Ar) and inert
(
4
)
2
6
] under ambient pressure occurs at much
(
ꢀ
higher temperatures and starts above 400 C with a direct

6
K.V. Yusenko et al. / Journal of Alloys and Compounds 813 (2020) 152121
Fig. 3. Thermal decomposition of (NH
resentations of possible crystal structures of
containing analogues (see text for details).
4
)
2
[Os0.40Pt0.60Cl
6
] (shown as s) (ambient pressure, ESRF-ID-11, Ar (A) and 2 vol% H
Cl ] (shown as bt) along b-axis (C) and -trans-[Pt(NH
2
/Ar flow (B), 12 K/min heating rate,
Cl ] (shown as at) along c-axis (D) based on their Pd-
2
l
¼ 0.3086 Å). Rep-
b-trans-[Pt(NH
3
)
2
2
a
3
)
2
formation of fccePt0.60Os0.40 without any crystalline intermediates.
Thermal decomposition of (NH [Os0.40Pt0.60Cl ] under high-
pressure in inert (self-generated atmosphere without an addition
of extra reducing agent) or reducing (H fluid) environment can be
considered as an alternative routine to synthesise of OsePt alloys.
In all previous studies, alloys pre-synthetized from single-source
precursors under ambient conditions were further heat-treated
reaction of single-source precursors with hydrogen fluid under
high-pressure allows us to access reduction and equilibration un-
der relatively low temperature due to high reactivity of in statu
nascendi generated nanostructured porous metastable bimetallic
particles. Hydrogen formed in the reaction vessel also should have
higher reactivity and might improve reaction kinetic and
equilibration.
4
)
2
6
2
under high-pressure. Nevertheless, (NH
4
)
2
[Os0.40Pt0.60Cl
6
] can be
4 2 6
High-pressure decomposition of (NH ) [Os0.40Pt0.60Cl ] in
ꢀ
directly decomposed under compression in piston-cylinder press,
multi-anvil press, or in diamond anvil cells (Table 2). Equilibrium
OsePt alloys were found in all experiments without a formation of
any nitrides or chlorides as crystalline products. Thermal decom-
position of compressed (NH ) [Os0.40Pt0.60Cl ] powder under high
4 2 6
hydrostatic pressure without adding any reducing agents can be
considered as thermal decomposition in inert conditions. Decom-
hydrogen fluid occurs between 500 and 600 C (maximal experi-
mental temperature) without a formation of any metastable in-
termediate hydrides, nitrides, or chlorides. Initially formed pure
fcc-structured phase with annealing decomposes with a formation
of fcc þ hcp two-phase mixture (Fig. 4b, Table 2).
High-pressure high-temperature treatment of single-source
precursors as well as pre-synthetized binary or multicomponent
alloys may allow to prepare material unavailable under ambient
pressure. Treatment under high-pressure changes thermal
decomposition mechanism and increases decomposition temper-
ature. As a result, unstable highly reactive intermediates might
form. Changes of phase equilibrium in metallic systems under high-
pressure should be also considered.
ꢀ
position and further annealing at 1000e2300 C under compres-
sion results in a formation of fcc þ hcp two-phase mixture. No signs
of fcc / hcp or hcp / fcc transformations under compression were
found below 50 GPa. Quenched unloaded sample gives an estima-
tion for the miscibility gap under compression which does not
significantly change from ambient pressure to 50 GPa (Table 2,
Figs. 2 and 4a).
3 3
Alternatively, ammonia borane, NH BH , as a hydrogen source,
4. Conclusions
can be used for easy release of hydrogen with a formation of inert
heBN-like products [42]. The reaction can be reproducibly per-
formed in a large-volume press [42]. An encapsulation of the
pelletized initial single-source precursor surrounded by two
ammonia borane pellets inside a NaCl capsule was performed as
NaCl is inert and impermeable for hydrogen. According to the
hydrogen phase diagram, hydrogen exists as supercritical fluid at
OsePt binary alloys have been investigated in the whole range
of compositions. Existing experimental data suggest that published
OsePt binary phase diagram should be corrected to be able to
explain all experimental data. Thermal decomposition of
NH ) [Os Pt1-xCl ] under ambient and high pressure in inert and
4 2 x 6
reductive atmosphere results in a formation of single and two-
(
8
GPa above 375 K and at 9 GPa above 400 K [43,44]. As a result, the
phase OsePt binary alloys. Alloys recovered from annealing

K.V. Yusenko et al. / Journal of Alloys and Compounds 813 (2020) 152121
7
Fig. 4. Thermal decomposition of (NH
4
)
2
[Os0.40Pt0.60Cl
6
] under high-pressure in diamond anvil cell (Left: PETRA III e P02.2 PETRA III, 20e40 GPa, Ne as pressure-transmitting
ꢀ
medium,
l
¼ 0.2907 Å, s stands for (NH
4
)
2
[Os0.40Pt0.60Cl
6
] precursor salt, g stands for Re gasket) and in the large-volume press in hydrogen fluid at 8.5 GPa from 300 C to
[Os0.40Pt0.60Cl ] precursor salt, fcc e corresponds to fcc-Os0.40Pt0.60, other diffraction lines correspond to assembly).
ꢀ
6
00 C (ESRF e ID06-LVP,
l
¼ 0.2254 Å, s corresponds to (NH
4
)
2
6
correspond to equilibrium phase diagram and can be used for
mapping a miscibility gap between fcc- and hcp-structured alloys.
Miscibility gap between fcc- and hcp-structured alloys does not
change its positions with pressure up to at least 50 GPa.
Ruthenium alloys under high pressure, Acta Metall. 13 (1965) 533e541,
https://doi.org/10.1016/0001-6160(65)90104-5.
2] I. Halevy, S. Salhov, M.L. Winterrose, A. Broide, A.F. Yue, A. Robin, O. Yeheskel,
J. Hu, I. Yaar, High pressure study and electronic structure of the super-alloy
[
HfIr
3
, J. Phys. Conf. Ser. 215 (1) (2010), 012012, https://doi.org/10.1088/
1742-6596/215/1/012012.
Thermal decomposition of (NH
pressure in an inert (self-generated atmosphere without adding
additional reducing agent) or reducing (H fluid) medium can be
considered as alternative procedure for the synthesis of OsePt al-
loys. Thermal decomposition of mixed-metal (NH [Os Pt1-xCl
precursor in hydrogen atmosphere (reductive environment) can be
associated with a formation of -trans-[Pt(NH Cl ] and -trans-
Pt(NH Cl ] crystalline intermediates. Fcc-structured intermedi-
4 2 x 6
) [Os Pt1-xCl ] under high
[
3] K.V. Yusenko, E. Bykova, M. Bykov, S.A. Gromilov, A.V. Kurnosov, C. Prescher,
V.B. Prakapenka, M. Hanfland, S. van Smaalen, S. Margadonna,
L.S. Dubrovinsky, Compressibility of IreOs alloys under high pressure, J. Alloy.
Comp. 622 (2015) 155e161, https://doi.org/10.1016/j.jallcom.2014.09.210,
2
155.
4
)
2
x
6
]
[
4] K.V. Yusenko, E. Bykova, M. Bykov, S.A. Gromilov, A.V. Kurnosov, C. Prescher,
V.B. Prakapenka, W.A. Crichton, M. Hanfland, S. Margadonna, L.S. Dubrovinsky,
High-pressure high-temperature stability of hcp-Ir
alloys, J. Alloy. Comp. 700 (2017) 198e207, https://doi.org/10.1016/
x
Os1-x (x ¼ 0.50 and 0.55)
b
3
)
2
2
a
[
3
)
2
2
j.jallcom.2016.12.207.
ate metallic phase with further heating or annealing decomposes
with a formation of two-phase (fcc þ hcp) mixture.
[5] K.V. Yusenko, E. Bykova, M. Bykov, S. Riva, W.A. Crichton, M.V. Yusenko,
A.S. Sukhikh, S. Arnaboldi, M. Hanfland, L.S. Dubrovinsky, S.A. Gromilov, IrdRe
binary alloys under extreme conditions and their electrocatalytic activity in
methanol oxidation, Acta Mater. 139 (2017) 236e243. https://doi.org/10.
1016/j.actamat.2017.08.012.
Detailed investigation of the thermal decomposition of pure
4 2 6
compound (NH ) [PtCl ] in hydrogen atmosphere using in situ X-
ray diffraction and X-ray spectroscopy will give more insight into
the decomposition process of mixed-metal compounds with
[6] L. Dubrovinsky, N. Dubrovinskaia, V.B. Prakapenka, A.M. Abakumov, Imple-
mentation of micro-ball nanodiamond anvils for high-pressure studies above
6
Mbar, Nat. Commun.
3 (1163) (2012) 1e7, https://doi.org/10.1038/
2
-
2-
2-
chemically similar anions such as [PtCl
6
] , [PtBr
6
]
6
and [PdCl ] .
ncomms2160.
Simultaneous presence of anions with different chemical proper-
[7] L. Dubrovinsky, N. Dubrovinskaia, E. Bykova, M. Bykov, V. Prakapenka,
C. Prescher, K. Glazyrin, H.-P. Liermann, M. Hanfland, M. Ekholm, Q. Feng,
L.V. Pourovskii, M.I. Katsnelson, J.M. Wills, I.A. Abrikosov, The most incom-
pressible metal osmium at static pressures above 750 gigapascals, Nature 525
2
-
2-
2-
ties and thermal stability such as [OsCl
6
] , [IrCl
6
]
6
and [ReCl ]
might drastically change thermal decomposition process.
(2015) 226e229, https://doi.org/10.1038/nature14681.
[
8] B.K. Godwal, J. Yan, S.M. Clark, R. Jeanloz, High-pressure behaviour of osmium:
an analog for iron in Earth's core, J. Appl. Phys. 111 (2012), 112608, https://
doi.org/10.1063/1.4726203.
Acknowledgements
[
9] R.O.C. Fonseca, V. Laurenz, G. Mallmann, A. Luguet, N. Hoehne, K.P. Jochum,
New constraints on the genesis and long-term stability of Os-rich alloys in the
Earth's mantle, Geochem. Cosmochim. Acta 87 (2012) 227e242, https://
doi.org/10.1016/j.gca.2012.04.002.
The authors thank the ID11 and ID06-LVP beamlines at the ESRF,
and P02.2 beamline at the PETRA III for providing us measurement
time and technical support. We also thank Dr. Michael Hanfland
(
ESRF) for the help with measurements of recovered samples at the
[10] N. Dimakis, F.A. Flor, N.E. Navarro, A. Salgado, E.S. Smotkin, Adsorption of
carbon monoxide on PlatinumꢂRuthenium, PlatinumꢂOsmium, Plati-
numꢂRutheniumꢂOsmium, and Platinumꢂ RutheniumꢂOsmiumꢂIridium
alloys, J. Phys. Chem. C 120 (2016) 10427e10441. https://doi.org/10.1021/acs.
jpcc.6b02086.
beamline ID15B, and Dr. Harald Müller (ESRF) for his kind assis-
tance with the Chemistry Laboratory facilities at ESRF. The work
was partly carried out in accordance with the state assignment for
the Institute of Solid State Chemistry of the Ural Brunch of the
Russian Academy of Sciences (theme No АААА-А19-
[
11] Renxuan Liu, Iddir Hakim, Qinbai Fan Gouyan Hou, Aili Bo, K.L. Ley,
E.S. Smotkin, Y.-E. Sung, H. Kim, S. Thomas, A. Wieckowski, Potential-
dependent infrared absorption spectroscopy of adsorbed CO and X-ray
photoelectron spectroscopy of arc-melted single-phase Pt, PtRu, PtOs, PtRuOs,
and Ru electrodes, J. Phys. Chem. B 104 (2000) 3518e3531. https://doi.org/10.
1
19031890025-9).
1
021/jp992943s.
References
[12] Ho-Cheng Tsai, Yu-Chi Hsieh, T.H. Yu, Yi-Juei Lee, Yue-Han Wu, B.V. Merinov,
Pu-Wei Wu, R.R. San-Yuan Chen, W.A. Adzic, Goddard III, DFT study of oxygen
reduction reaction on Os/Pt coreeshell catalysts validated by electrochemical
[1] L.D. Blackburn, L. Kaufman, M. Cohen, Phase Transformations in Iron-

8
K.V. Yusenko et al. / Journal of Alloys and Compounds 813 (2020) 152121
experiment, ACS Catal.
cs501020a.
13] B. Gurau, R. Viswanathan, Renxuan Liu, T.J. Lafrenz, K.L. Ley, E.S. Smotkin,
E. Reddington, A. Sapienza, B.C. Chan, T.E. Mallouk, S. Sarangapani, Structural
and electrochemical characterization of binary, ternary, and quaternary
platinum alloy catalysts for methanol electro-oxidation, J. Phys. Chem. B 102
5
(2015) 1568e1580. https://doi.org/10.1021/
А
в
т
о
реферат д
21 C.)
[29] T.I. Asanova, I.P. Asanov, M.-G. Kim, S.V. Korenev, In situ X-ray spectroscopic
investigation of thermal decomposition of double complex salt [Pt(NH
[OsCl ], J. Struct. Chem. 58 (2017) 901e910. https://doi.org/10.1134/
S0022476617050079.
иссертации на соискание ученой степени к.х.н. Новосибирск, 2003.
[
3 4
) ]
6
(
1998) 9997e10003. https://doi.org/10.1021/jp982887f.
14] I.V. Korolkov, A.I. Gubanov, K.V. Yusenko, I.A. Baidina, S.A. Gromilov, Synthesis
of non-equilibrium Pt Os1-x solid solutions. Crystal structure of [Pt(NH
OsCl ], J. Struct. Chem. 48 (3) (2007) 486e493, https://doi.org/10.1007/
[30] S.-L. Chen, S. Daniel, F. Zhang, Y.A. Chang, X.-Y. Yan, F.-Y. Xie, R. Schmid-
Fetzer, W.A. Oates, The pandat software package and its applications, Calphad
26 (2002) 175e188. https://doi.org/10.1016/S0364-5916(02)00034-2.
[31] A.T. Dinsdale, SGTE data for pure elements, Calphad 15 (1991) 317e425.
https://doi.org/10.1016/0364-5916(91)90030-N.
[
[
x
3 4
) ]
[
6
s10947-007-0073-1.
15] S.A. Gromilov, T.V. D’yachkova, A.P. Tyutyunnik, YuG. Zainulin, A.I. Gubanov,
[32] K. Mibe Chang-Sheng Zha, W.A. Basset, O. Tschauner, R.J. Hemley Ho-Kwang
Mao, PdVdT equation of state of platinum to 80 GPa and 1900 K from in-
ternal resistive heating/x-ray diffraction measurements, J. Appl. Phys. 103
(2008), 054908. https://doi.org/10.1063/1.2844358.
S.V. Cherepanova, The product of thermobaric treatment of Pt0.25Os0.75
J. Struct. Chem. 49 (2008) 382e385. https://doi.org/10.1007/s10947-008-
138-9.
,
0
[
[
16] P. Rajiv, R. Dinnebier, M. Jansen, Powder 3D Parametric: a program for
automated sequential and parametric Rietveld refinement using Topas, Mater.
Sci. Forum 651 (2010) 97e104.
17] T. Grützner, S. Klemme, A. Rohrbach, F. Gervasoni, J. Berndt, The effect of
fluorine on the stability of wadsleyite: implications for the nature and depths
of the transition zone in the Earth's mantle, Earth Planet. Sci. Lett. 482 (2018)
[33] S.A. Gromilov, YuV. Shubin, A.I. Gubanov, E.A. Maksimovskii, S.V. Korenev, X-
4 2 6 x 6
ray study of the thermolysis products of (NH ) [OsCl ] [PtCl ]1ex, J. Struct.
Chem. 50 (2009) 1121e1125. https://doi.org/10.1007/s10947-009-0164-2.
[34] Q. Kong, F. Baudelet, J. Han, S. Chagnot, L. Barthe, J. Headspith, R. Goldsbrough,
F.E. Picca, O. Spalla, Microsecond time-resolved energy-dispersive EXAFS
4 2 6
measurement and its application to film the thermolysis of (NH ) [PtCl ], Sci.
236e244. https://doi.org/10.1016/j.epsl.2017.11.011.
Rep. 2 (2012) 1018, https://doi.org/10.1038/srep01018.
[
18] J. Guignard, W.A. Crichton, The large volume press facility at ID06 beamline of
the European synchrotron radiation facility as a High Pressure-High Tem-
perature deformation apparatus, Rev. Sci. Instrum. 86 (8) (2015), 085112,
https://doi.org/10.1063/1.4928151.
[35] H. Rumpf, J. Hormes, A. Moller, G. Meyer, Thermal decomposition of
(NH [PtCl ] e an in situ X-ray absorption spectroscopy study, J. Synchrotron
Radiat. 6 (1999) 468e470, https://doi.org/10.1107/S0909049598015994.
[36] G. Meyer, A. Moller, Thermolysis of ternary ammonium chlorides of rhenium
and the noble-metals, J. Less Common. Met. 170 (1991) 327e331. https://doi.
org/10.1016/0022-5088(91)90336-3.
[37] G. Matuschek, K.H. Ohrbach, A. Kettrup, Simultaneous thermal-analysis mass-
spectrometric investigations on the thermal behaviour of noble-metal com-
plexes, Thermochim. Acta 190 (1991) 125e130. https://doi.org/10.1016/0040-
6031(91)85238-D.
4
)
2
6
[
[
19] F. Birch, Equation of state and thermodynamic parameters of NaCl to 300 kbar
in the high-temperature domain, JGR Solid Earth 91 (1986) 4949e4954.
https://doi.org/10.1029/JB091iB05p04949.
20] A.P. Hammersley, S.O. Svensson, M. Hanfland, A.N. Fitch, D. H €a usermann,
Two-dimensional detector software: from real detector to idealised image or
two-theta scan, High Press. Res. 14 (1996) 235e248, https://doi.org/10.1080/
0
8957959608201408.
[38] Y. Verde-Gomez, G. Alonso Nunez, F. Cervantes, A. Keer, Aqueous solution
reaction to synthesize ammonium hexachloroplatinate and its crystallo-
graphic and thermogravimetric characterization, Mater. Lett. 57 (2003)
4667e4672. https://doi.org/10.1016/S0167-577X(03)00381-1.
[
[
21] K. Anbukumaran, C. Venkateswaran, N.V. Jaya, S. Natarajan, Piston-cylinder
apparatus for high-pressure and high-temperature studies, High-Press. Sci.
Techn. 1e2 (1994) 1585e1588.
22] H.-P. Liermann, Z. Konopkova, W. Morgenroth, K. Glazyrin, J. Bendarchik,
E.E. McBride, S. Petitgirard, J.T. Delitz, M. Wendt, Y. Bican, A. Ehnes, I. Schwark,
A. Rothkirch, M. Tischer, J. Heuer, H. Schulte-Schrepping, T. Kracht, H. Franz,
The extreme conditions beamline P02.2 and the extreme conditions science
infrastructure at PETRA III, J. Synchrotron Radiat. 22 (2015) 908e924, https://
doi.org/10.1107/S1600577515005937.
[39] R.D. Weir, E.F. Westrum, Thermodynamics, phase transitions and crystal
structure of ammonium hexahalides: comparative study of the heat capacity
and thermodynamic properties of (NH
4
)
2
PtCl
(NH
6
,
)
(ND
TeCl
4
)
,
2
PtCl
(ND
6
,
4
(NH
TeCl
4
)
6
2
,
PtBr
and
6
,
(ND
(NH
4
)
2
PtBr
RuCl
6
,
6
(NH
4
)
2
PdCl
6
,
(ND
4
)
2
PdCl
6
,
4
2
6
)
2
4
)
2
from 5 K to 350 K, J. Chem. Thermodyn. 34 (2002) 133e153,
https://doi.org/10.1006/jcht.2001.0910.
[
23] C. Prescher, V.B. Prakapenka, DIOPTAS: a program for reduction of two-
dimensional X-ray diffraction data and data exploration, High Press. Res. 35
[40] S.A. Gromilov, S.P. Khranenko, I.A. Baidina, A.V. Belyaev, Synthesis and crystal
structure refinement of
1354e1359.
3 2 2
b-trans-[Pd(NH ) Cl ], Russ. J. Inorg. Chem. 45 (2000)
(
2015) 223e230. https://doi.org/10.1080/08957959.2015.1059835.
[
24] V. Petricheck, M. Duscheck, L. Palatinus, The Crystallographic Computing
System, eInstitute of Physics, e Praha, Czech Republic, Jana 2006, 2006,
http://www-xray.fzu.cz/jana/jana.html.
[41] D.Yu Naumov, S.P. Khranenko, N.V. Kuratieva, A.V. Panchenko, S.A. Gromilov,
New data on the structure of -trans-[Pd(NH Cl ], J. Struct. Chem. 57 (2016)
1600e1605. https://doi.org/10.1134/S0022476616080163.
[42] J. Nyl eꢀ n, T. Sato, E. Soignard, J.A. Yarger, E. Stoyanov, U. H a€ ussermann, Thermal
decomposition of ammonia borane at high pressures, J. Chem. Phys. 131
(2009), 104506, https://doi.org/10.1063/1.3230973.
[43] C.-S. Zha, H. Liu, J.S. Tse, R.J. Hemley, Melting and high PdT transitions of
hydrogen up to 300 GPa, Phys. Rev. Lett. 119 (2017), 075302. https://doi.org/
10.1103/PhysRevLett.119.075302.
[44] V. Diatschenko, C.W. Chu, D.H. Liebenberg, D.A. Young, M. Ross, R.L. Mills,
Melting curves of molecular hydrogen and molecular deuterium under high
pressures between 20 and 373 K, Phys. Rev. B 32 (1985) 381, https://doi.org/
10.1103/physrevb.32.381.
a
3
)
2
2
[
[
25] L.I. Voronova, V.P. Polyakova, E.M. Savitskii, Alloys of the system PtdOs, Izv.
Akad. Nauk. SSSR, Met. 5 (1984) 191e193.
26] R.S. Rudman, Lattice parameters of some h.c.p. binary alloys of rhenium and
osmium: Re-W, Re-Ir, Re-Pt; Os-Ir, Os-Pt, J. Less Common. Met. 12 (1) (1967)
79e81, https://doi.org/10.1016/0022-5088(67)90075-6.
[
[
27] Powder Diffraction File, Alphabetical Index. Inorganic Phases, JCPDS, Inter-
national Centre for Diffraction Data, Pennsylvania, USA, 1983, 1023.
28] A.I. Gubanov, A.I. Double Complex Salts with Tetraammine Cations as Pre-
cursors for Metallic Powders, PhD Thesis, Nikolaev Int. Inorg. Chem. Novosib.
Russ. Fed., 2003, 21 pp. (in Russian:
G
в
убанов А.И. Двойные к
о
м
п
лексы с
тетраамм нным катионам ред ест
и
и
и
e
п
ш
енн металл ческ
и
ки
и
и
х
по ош ов
р
к .