The influence of defects on first-order structural phase transitions

1997 ◽  
Vol 9 (25) ◽  
pp. 5313-5320 ◽  
Author(s):  
A P Levanyuk ◽  
S A Minyukov ◽  
M Vallade
Keyword(s):  
Phase Transitions ◽  
Structural Phase ◽  
Structural Phase Transitions ◽  
First Order

scholarly journals First-order magnetic and structural phase transitions inFe1+ySexTe1−x

2009 ◽  
Vol 79 (5) ◽  
Author(s):  
Shiliang Li ◽  
Clarina de la Cruz ◽  
Q. Huang ◽  
Y. Chen ◽  
J. W. Lynn ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Structural Phase ◽  
Structural Phase Transitions ◽  
First Order

Phase and Structural Behaviour in the NdAlO3-EuAlO3 System

2013 ◽  
Vol 200 ◽  
pp. 93-99 ◽  
Author(s):  
Natalia Ohon ◽  
Leonid Vasylechko ◽  
Yurii Prots ◽  
Marcus Schmidt ◽  
Caroline Curfs
Keyword(s):  
Phase Diagram ◽  
Phase Transitions ◽  
Binary System ◽  
Solid Solutions ◽  
Room Temperature ◽  
Structural Phase ◽  
Structural Phase Transitions ◽  
Structural Behaviour ◽  
First Order

Phase and structural behaviour in the NdAlO3–EuAlO3 system has been studied in the whole concentration range. Depending on x two kinds of solid solutions Nd1‑xEuxAlO3 exist at room temperature: one with rhombohedral (x < 0.15) and one with orthorhombic (x≈ 0.15–0.20, where the co-existence of both phases was observed. First-order structural phase transitions Pbnm↔Rc has been detected in Nd1-xEuxAlO3 with x = 0.3, 0.4, 0.6 at 520 K, 627 K and 988 K, respectively. Based on the experimental and literature data, the phase diagram of the pseudo-binary system NdAlO3–EuAlO3 has been constructed.

scholarly journals Structures, Phase Transitions and Tricritical Behavior of the Hybrid Perovskite Methyl Ammonium Lead Iodide

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
P. S. Whitfield ◽  
N. Herron ◽  
W. E. Guise ◽  
K. Page ◽  
Y. Q. Cheng ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Structural Phase ◽  
Photovoltaic Performance ◽  
Orthorhombic Phase ◽  
Structural Phase Transitions ◽  
Lead Iodide ◽  
First Order ◽  
Hybrid Perovskite ◽  
The Impact

Abstract We have examined the crystal structures and structural phase transitions of the deuterated, partially deuterated and hydrogenous organic-inorganic hybrid perovskite methyl ammonium lead iodide (MAPbI3) using time-of-flight neutron and synchrotron X-ray powder diffraction. Near 330 K the high temperature cubic phases transformed to a body-centered tetragonal phase. The variation of the order parameter Q for this transition scaled with temperature T as Q ∼ (Tc−T)β, where Tc is the critical temperature and the exponent β was close to ¼, as predicted for a tricritical phase transition. However, we also observed coexistence of the cubic and tetragonal phases over a range of temperature in all cases, demonstrating that the phase transition was in fact first-order, although still very close to tricritical. Upon cooling further, all the tetragonal phases transformed into a low temperature orthorhombic phase around 160 K, again via a first-order phase transition. Based upon these results, we discuss the impact of the structural phase transitions upon photovoltaic performance of MAPbI3 based solar cells.

Specific Features of Jahn-Teller Structure Phase Transitions in Nanocrystalline Materials

2009 ◽  
Vol 283-286 ◽  
pp. 53-58 ◽  
Author(s):  
Anatoly Yakovlevich Fishman ◽  
M.A. Ivanov ◽  
S.A. Petrova ◽  
Nickolai Tkachev ◽  
Vladimir Borisovich Vykhodets ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Nanocrystalline Materials ◽  
Phase State ◽  
Structural Phase ◽  
Structural Phase Transitions ◽  
First Order ◽  
Structure Phase ◽  
Jahn Teller ◽  
Multi Phase ◽  
Nanosized Crystals

Specific features of the structural phase transitions of the first order were investigated in nanosized crystals with Jahn-Teller ions. As an example the phase transitions of martensite type with changes in symmetry from a cubic to a tetragonal one have been considered. The Kanamori model was used to take into account the size of nanocrystallites and the distribution of cations over non-equivalent crystallographic sublattices in such systems. It was shown the temperature and the latent heat of the transition decrease significantly for the nanoscaled grains. A possibility of multi-phase state for nanocrystalline materials was considered.

Investigation of the structural phase transitions near 190 K in 4,4′-dichlorobenzophenone

1999 ◽  
Vol 55 (5) ◽  
pp. 799-806 ◽  
Author(s):  
V. V. Mitkevich ◽  
V. G. Lirtsman ◽  
M. A. Strzhemechny ◽  
A. A. Avdeenko ◽  
V. V. Eremenko
Keyword(s):  
Phase Transitions ◽  
Intermediate State ◽  
Structural Phase ◽  
Structural Phase Transitions ◽  
Warm Up ◽  
X Ray ◽  
Cell Parameters ◽  
First Order ◽  
Ordered Phases ◽  
First Order Phase

X-ray structure studies have been carried out on single crystals of 4,4′-dichlorobenzophenone at temperatures from 164 to 295 K. The structure determined at 164 K is monoclinic I2/c. Crystal data: T = 164 K; a = 24.527 (6), b = 6.064 (1), c = 7.457 (4) Å; β = 100.10 (2)°; V = 1091.9 (6) Å3; Z = 4; d_{c} = 1.528 g cm^{-3}; \lambda(Mo K{\alpha}) = 0.71073 \AA; \mu = 0.565 mm^{-1}; F(000) = 512; R = 0.04. The temperature dependence of the unit-cell parameters and of the intensities of some symmetry-sensitive reflections has been measured over the range 164–293 K, both in warm-up and cool-down experiments. It has been established that the phase transformation between the C2/c and I2/c structures occurs as a sequence of two closely spaced first-order phase transitions. In between these phase transitions the crystal is in an intermediate state whose structure is different from both C2/c and I2/c. The experimental data give us ground to suppose that the intermediate state is disordered, having a primitive cell half as large as in the two ordered phases. Within the temperature interval where the said intermediate state exists the thermal expansivity along axis c is negative.

Lattice Instabilities, Anharmonicity and Phase Transitions in PbTiO3 and PbZrO3

1995 ◽  
Vol 408 ◽  
Author(s):  
K. M. Rabe ◽  
U. V. Waghmare
Keyword(s):  
Phase Transitions ◽  
Low Temperature ◽  
Structural Phase ◽  
Orthorhombic Phase ◽  
Cubic Phase ◽  
Temperature Phase ◽  
Structural Phase Transitions ◽  
Phonon Modes ◽  
First Order ◽  
Low Temperature Phase

AbstractMost perovskite structure oxides exhibit structural phase transitions from a hightemperature cubic phase to a distorted low-temperature phase which can be described by the freezing-in of one or more phonon modes of the cubic structure [1]. The first-order cubic-tetragonal ferroelectric transition in PbTiO3 at Tc = 763 K involves the freezing-in of a single F15 polar mode. In PbZrO3 , the structure of the antiferroelectric low-temperature orthorhombic phase is far more complicated, with forty atoms per unit cell and the freezing-in of R25 and Σ3 modes, perhaps accompanied by other modes as well [2][3].

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