Size- and morphology-dependent structural transformations in anatase TiO2 nanowires under high pressures

2015 ◽  
Vol 93 (2) ◽  
pp. 165-172 ◽  
Author(s):  
Zhaohui Dong ◽  
Yang Song
Keyword(s):  
High Pressure ◽  
Phase Transitions ◽  
High Pressures ◽  
Anatase Phase ◽  
X Ray Diffraction ◽  
Bulk Materials ◽  
Tio2 Nanowires ◽  
X Ray ◽  
Different Dimensions ◽  
Size And Morphology

Titanium dioxide (TiO2) nanowires with two different dimensions (i.e., <100 nm and ∼200 nm in diameter) were synthesized and studied under high pressure up to 37 GPa by Raman spectroscopy and synchrotron X-ray diffraction. Direct anatase to baddeleyite phase transitions were observed in both samples upon compression, but with different onset pressures. The observed phase transitions are in contrast to bulk TiO2, where the anatase phase transforms to α-PbO2 phase and then the baddeleyite phase. Compressibility of the anatase and baddeleyite phases was found different than both nanocrystals and the corresponding bulk materials. Our comparative study demonstrated not only that the morphology of TiO2 nanowire substantially influences the high pressure behaviors, but dimensions play a determining role in terms of transformation pressures, phase stability regions, and compressibility.

High-Pressure Phase Transitions of Cubic Y 2 O 3 under High Pressures by In-situ Synchrotron X-Ray Diffraction

2019 ◽  
Vol 36 (4) ◽  
pp. 046103 ◽  
Author(s):  
Sheng Jiang ◽  
Jing Liu ◽  
Xiao-Dong Li ◽  
Yan-Chun Li ◽  
Shang-Ming He ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Transitions ◽  
High Pressures ◽  
High Pressure Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pressure Phase

High pressure phase transitions in organic solids II: X-ray diffraction study ofp-dichlorobenzene at high pressures

Pramana ◽  
1986 ◽  
Vol 27 (6) ◽  
pp. 835-839 ◽  
Author(s):  
Hema Sankaran ◽  
Surinder M Sharma ◽  
S K Sikka ◽  
R Chidambaram
Keyword(s):  
High Pressure ◽  
Phase Transitions ◽  
Diffraction Study ◽  
High Pressures ◽  
High Pressure Phase ◽  
X Ray Diffraction ◽  
Organic Solids ◽  
X Ray ◽  
Pressure Phase

Monoclinic FeO at high pressures

2008 ◽  
Vol 223 (7/2008) ◽  
Author(s):  
Innokenty Kantor ◽  
Alexander Kurnosov ◽  
Catherine McCammon ◽  
Leonid Dubrovinsky
Keyword(s):  
High Pressure ◽  
Iron Oxide ◽  
Single Crystal ◽  
Diffraction Study ◽  
High Pressures ◽  
X Ray Diffraction ◽  
X Ray

AbstractA high-pressure quasi-single crystal X-ray diffraction study of a synthetic iron oxide Fe

Phase transitions in ReO3studied by high-pressure X-ray diffraction

2000 ◽  
Vol 33 (2) ◽  
pp. 279-284 ◽  
Author(s):  
J.-E. Jørgensen ◽  
J. Staun Olsen ◽  
L. Gerward
Keyword(s):  
High Pressure ◽  
Phase Transitions ◽  
Powder Diffraction ◽  
Ambient Pressure ◽  
Rhombohedral Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxygen Ions ◽  
Pressure Phase ◽  
Related Phase

ReO3has been studied at pressures up to 52 GPa by X-ray powder diffraction. The previously observed cubicIm3¯ high-pressure phase was shown to transform to a monoclinic MnF3-related phase at about 3 GPa. All patterns recorded above 12 GPa could be indexed on rhombohedral cells. The compressibility was observed to decrease abruptly at 38 GPa. It is therefore proposed that the oxygen ions are hexagonally close packed above this pressure, giving rise to two rhombohedral phases labelled I and II. The zero-pressure bulk moduliBoof the observed phases were determined and the rhombohedral phase II was found to have an extremely large value of 617 (10) GPa. It was found that ReO3transforms back to thePm3¯mphase found at ambient pressure.

Probing disorder in high-pressure cubic tin (IV) oxide: a combined X-ray diffraction and absorption study

2019 ◽  
Vol 26 (4) ◽  
pp. 1245-1252 ◽  
Author(s):  
Daniel Sneed ◽  
John S. C. Kearney ◽  
Dean Smith ◽  
Jesse S. Smith ◽  
Changyong Park ◽  
...  
Keyword(s):  
High Pressure ◽  
Laser Heating ◽  
High Pressures ◽  
Transparent Conducting Oxide ◽  
Large Degree ◽  
X Ray Diffraction ◽  
Quality Of Data ◽  
X Ray ◽  
Direct Laser ◽  
Gap Opening

The transparent conducting oxide, SnO2, is a promising optoelectronic material with predicted tailorable properties via pressure-mediated band gap opening. While such electronic properties are typically modeled assuming perfect crystallinity, disordering of the O sublattice under pressure is qualitatively known. Here a quantitative approach is thus employed, combining extended X-ray absorption fine-structure (EXAFS) spectroscopy with X-ray diffraction, to probe the extent of Sn—O bond anharmonicities in the high-pressure cubic (Pa\bar{3}) SnO2 – formed as a single phase and annealed by CO2 laser heating to 2648 ± 41 K at 44.5 GPa. This combinational study reveals and quantifies a large degree of disordering in the O sublattice, while the Sn lattice remains ordered. Moreover, this study describes implementation of direct laser heating of non-metallic samples by CO2 laser alongside EXAFS, and the high quality of data which may be achieved at high pressures in a diamond anvil cell when appropriate thermal annealing is applied.

Formation of two crystal modifications of Fe7C3−x at 5.5 GPa

2019 ◽  
Vol 52 (6) ◽  
pp. 1378-1384
Author(s):  
Sergey Gromilov ◽  
Anatoly Chepurov ◽  
Valeri Sonin ◽  
Egor Zhimulev ◽  
Aleksandr Sukhikh ◽  
...  
Keyword(s):  
High Pressure ◽  
High Pressures ◽  
Experimental Studies ◽  
X Ray Diffraction ◽  
High Iron Content ◽  
X Ray ◽  
High Pressure High Temperature ◽  
Micro Analysis ◽  
Crystal Modifications ◽  
High Pressure Apparatus

The Fe–C system, which is widely used to grow commercial high-pressure–high-temperature diamond monocrystals, is rather complicated due to the formation of carbides. The carbide Fe3C is a normal run product, but the pressure at which Fe7C3 carbide becomes stable is a subject of discussion. This paper demonstrates the synthesis of Fe7C3 carbide and its detailed study using single-crystal and powder X-ray diffraction, as well as electron probe micro-analysis and scanning electron microscopy. The experiments were performed using a multiple-anvil high-pressure apparatus of `split-sphere' (BARS) type at a pressure of 5.5 GPa and a temperature of 1623 K. Our results show that in the Fe–C system, in addition to diamond, a phase that corresponds to the Fe7C3 carbide was synthesized. This means that both carbides (Fe7C3 and Fe3C) are stable at 5.5 GPa. Two crystal phases are described, Fe14C6 and Fe28C12−x . Fe14C6 is based on the well known rhombic structure of Fe7C3, while Fe28C12−x has a different packing order of Fe6C polyhedrons. The results obtained in this study should be taken into account when synthesizing and growing diamond at high pressures and temperatures in metal–carbon systems with a high iron content, as well as when conducting experimental studies on the synthesis of diamond directly from carbide.

X-ray diffraction and theoretical studies of the high-pressure structures and phase transitions in magnesium fluoride

2001 ◽  
Vol 64 (13) ◽  
Author(s):  
J. Haines ◽  
J. M. Léger ◽  
F. Gorelli ◽  
D. D. Klug ◽  
J. S. Tse ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Transitions ◽  
Magnesium Fluoride ◽  
Theoretical Studies ◽  
X Ray Diffraction ◽  
X Ray
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