Studies on Local Structural Inhomogeneity and Origin of Ferroelectricity in Yttrium chromite Ceramics

MRS Advances ◽  
2016 ◽  
Vol 1 (9) ◽  
pp. 609-614 ◽  
Author(s):  
Venkateswara rao Mannepalli ◽  
Ranjith Ramadurai
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Structural Phase Transition ◽  
Structural Phase ◽  
Structural Inhomogeneity ◽  
Raman Mode ◽  
Structural Distortions ◽  
Mode Softening ◽  
Yttrium Chromite ◽  
Tilt Mode

ABSTRACTYCrO3 (YCO) is known to be a multiferroic with orthorhombic, Pnma, structure with center of inversion. However, the local structural inhomogeneity in this compound is believed to give rise to ferroelectric behavior. In this study we explore high temperature Raman investigations of YCO and observed that one of its Raman mode B3g (3) (CrO6 Octahedral tilt mode) softens around the structural phase transition which could be the origin of ferroelectric nature in YCO. In addition, we substitute bismuth (Bi) in YCO to understand the structural distortions that lead to local structural inhomogeneity. Besides B3g (3) mode softening with composition and high temperature studies in Y1-xBixCrO3 the study reveals the structural distortions and the structural tunability Bi offers in such systems.

A high temperature structural phase transition in crocoite (PbCrO4) at 1068 K: crystal structure refinement at 1073 K and thermal expansion tensor determination at 1000 K

2000 ◽  
Vol 64 (2) ◽  
pp. 291-300 ◽  
Author(s):  
K. S. Knight
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Thermal Expansion ◽  
High Temperature ◽  
Structural Phase Transition ◽  
Structural Phase ◽  
Structure Type ◽  
Temperature Phase ◽  
Thermal Expansion Tensor ◽  
Principal Axes

AbstractHigh-resolution, neutron time-of-flight, powder diffraction data have been collected on natural crocoite between 873 and 1073 K. Thermal analysis carried out in the 1920s had suggested that chemically pure PbCrO4 exhibited two structural phase transitions, at 964 K, to the β phase, and at 1056 K, to the γ phase. In this study, no evidence was found for the α-β structural phase transition, however a high-temperature phase transition was found at ∼1068 K from the ambient-temperature monazite structure type to the baryte structure type. The phase transition, close to the temperatures reported for the β to γ phase modifications, is first order and is accompanied by a change in volume of −1.6%. The crystal structure of this phase has been refined using the Rietveld method to agreement factors of Rp = 0.018, Rwp = 0.019, Rp = 0.011. No evidence for premonitory behaviour was found in the temperature dependence of the monoclinic lattice constants rom 873 K to 1063 K and these have been used to determine the thermal expansion tensor of crocoite just below the phase transition. At 1000 K the magnitudes of the tensor coefficients are α11, 2.66(1) × 10−5 K−1; α22, 2.04(1) × 10−5 K−1; α33, 4.67(4) × 10−5 K−1; and α13, −1.80(2) × 10−5 K−1 using the IRE convention for the orientation of the tensor basis. The orientation of the principal axes of the thermal expansion tensor are very close to those reported previously for the temperature range 50–300 K.

Holmium induced enhanced functionality at room temperature and structural phase transition at high temperature in bismuth ferrite nanoparticles

2016 ◽  
Vol 4 (4) ◽  
pp. 780-792 ◽  
Author(s):  
Smita Chaturvedi ◽  
Rabindranath Bag ◽  
Vasant Sathe ◽  
Sulabha Kulkarni ◽  
Surjeet Singh
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
High Temperatures ◽  
Structural Phase Transition ◽  
Room Temperature ◽  
Bismuth Ferrite ◽  
Structural Phase ◽  
Ferrite Nanoparticles ◽  
High Coercivity ◽  
Remnant Magnetization

Ho-doped sample simultaneously exhibits high-coercivity and enhanced remnant magnetization with a polar R3c symmetry at room temperature. The onset of R3c to Pnma phase transition is observed at high temperatures in the Ho-doped samples.

An optoelectronic duple bistable phosphate with ultrahigh thermal stability

2018 ◽  
Vol 6 (2) ◽  
pp. 388-392 ◽  
Author(s):  
Yaoguo Shen ◽  
Sangen Zhao ◽  
Chenxi Wang ◽  
Zujian Wang ◽  
Jianghe Feng ◽  
...  
Keyword(s):  
Phase Transition ◽  
Thermal Stability ◽  
High Temperature ◽  
Structural Phase Transition ◽  
Nonlinear Optical ◽  
Structural Phase

A new inorganic CsCdPO4 shows quadratic nonlinear optical and dielectric duple bistability, resulting from a high-temperature order–disorder structural phase transition.

scholarly journals Epitaxially induced high temperature (>900K) cubic-tetragonal structural phase transition in BaTiO3 thin films

2004 ◽  
Vol 85 (18) ◽  
pp. 4109-4111 ◽  
Author(s):  
Feiming Bai ◽  
Haimei Zheng ◽  
Hu Cao ◽  
L. E. Cross ◽  
R. Ramesh ◽  
...  
Keyword(s):  
Thin Films ◽  
Phase Transition ◽  
High Temperature ◽  
Structural Phase Transition ◽  
Structural Phase

Structural phase transition in YBa2Cu3O7−δ: the role of dimensionality for high temperature superconductivity

1987 ◽  
Vol 63 (5) ◽  
pp. 385-388 ◽  
Author(s):  
Ivan K. Schuller ◽  
D.G. Hinks ◽  
M.A. Beno ◽  
D.W. Capone ◽  
L. Soderholm ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Structural Phase Transition ◽  
High Temperature Superconductivity ◽  
Structural Phase
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