Dielectric Properties of Ba1-xLaxTi1-x/4O3 Ceramics with Different La3+ Content

2012 ◽  
Vol 77 ◽  
pp. 35-40 ◽  
Author(s):  
Beata Wodecka-Dus ◽  
Malgorzata Adamczyk ◽  
Katarzyna Osinska ◽  
Malgorzata Plonska ◽  
Dionizy Czekaj
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Dielectric Properties ◽  
Diffraction Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Composition Formula ◽  
Lcr Meter ◽  
Sintering Method ◽  
Agilent E4980a

Subscript textIn the present research n-doped BaTiO3 compositions, with lanthanum contents x=0, 0.1, 0.3 and 0.5mol% were prepared by the free sintering method, at temperature T=1350°C for 2 h. The EDS investigations showed that samples exhibited conservation of stoichiometry according to the chemical composition formula. Morphology of the ceramic material was observed by scanning electron microscopy, whereas the crystalline structure was studied by X-ray diffraction method. Influence of La3+ doping on dielectric properties of Ba1-xLaxTi1-x/4O3 ceramics was studied in temperature range T=20-260°C, and frequency f=100Hz-1000Hz by the Precision LCR meter Agilent E4980A. The results show a decrease of Tm with lanthanum addition. The degree of diffuseness of phase transition is more pronounced for high La content, implying the existence of a composition-induced phase transition of the ceramics. Ceramics showed maximally enhanced dielectric permittivity around phase transitions, which are the phase transitions of the pure BaTiO3.

Structural-phase transition in (Cu2Te)2−x(ZnTe)x at high temperature

2021 ◽  
pp. 2150113
Author(s):  
H. B. Gasimov ◽  
R. M. Rzayev
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
High Temperature ◽  
Single Crystals ◽  
Structural Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Range ◽  
Xrd Study ◽  
Xrd Method

Cu2Te single crystal was grown by the Bridgman method. X-ray diffraction (XRD) study of Cu2Te single crystals in the temperature range of 293–893 K was performed and possible phase transitions in the mentioned range of temperature have been investigated. (Cu2Te)[Formula: see text](ZnTe)[Formula: see text] single crystals also were grown with [Formula: see text], 0.05, 0.10 concentrations and structural properties of the obtained single crystals were investigated by the XRD method in the temperature range 293–893 K. Lattice parameters and possible phase transitions in the mention temperature range were determined for (Cu2Te)[Formula: see text](ZnTe)[Formula: see text] single crystals for [Formula: see text], 0.05, 0.10 concentrations.

X-ray diffraction and Raman study of DL-alanine at high pressure: revision of phase transitions

2012 ◽  
Vol 68 (4) ◽  
pp. 412-423 ◽  
Author(s):  
Nikolay A. Tumanov ◽  
Elena V. Boldyreva
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Structural Phase ◽  
Group Symmetry ◽  
Second Phase ◽  
Structural Phase Transitions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Raman Study

The effect of pressure on DL-alanine has been studied by X-ray powder diffraction (up to 8.3 GPa), single-crystal X-ray diffraction and Raman spectroscopy (up to ∼ 6 GPa). No structural phase transitions have been observed. At ∼ 1.5–2 GPa, cell parameters b and c become accidentally equal to each other, but the space-group symmetry does not change. There is no phase transition between 1.7 and 2.3 GPa, contrary to what has been reported earlier [Belo et al. (2010). Vibr. Spectrosc. 54, 107–111]. The presence of the second phase transition, which was claimed to appear within the pressure range from 6.0 to 7.3 GPa (Belo et al., 2010), is also argued. The changes in the Raman spectra have been shown to be continuous in all the pressure ranges studied.

Preparation and Properties of CCTO-BCTO Ceramics with Ultrahigh Dielectric Constant

2013 ◽  
Vol 760-762 ◽  
pp. 705-708
Author(s):  
La Chen ◽  
Wei Li ◽  
Zhao Xian Xiong ◽  
Chun Xiao Song ◽  
Hong Qiu
Keyword(s):  
Electron Microscopy ◽  
Dielectric Constant ◽  
Dielectric Properties ◽  
X Ray Diffraction ◽  
Optimum Amount ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Impedance Characteristics ◽  
Lcr Meter ◽  
Scanning Electron

Ceramics of (1-x)CaCu3Ti4O12-xBi2/3Cu3Ti4O12, i.e., CCTO-BCTO, with x=0, 0.01, 0.1 and 0.25, respectively, were prepared via the conventional solid-state reaction. The phase structure of the ceramics was identified by X-ray diffraction. The microstructure of the sample was observed with scanning electron microscopy. Dielectric properties and impedance spectroscopy were measured using a LCR Meter, in which 0.9CCTO-0.1BCTO displayed highest dielectric constant (584108) and lowest dielectric loss (0.42) at 1kHz among the four kinds of specimens. Based on series of experimental results, an optimum amount of x was able to improve the dielectric properties of CCTO-BCTO, through adjusting the impedance characteristics of the grain and grain boundary.

Temperature Dependence on Dielectric Response of La0.7Ba0.3Mn0.4Ti0.6O3 Ceramic

2015 ◽  
Vol 1107 ◽  
pp. 45-52
Author(s):  
Aaliyawani Ezzerin Sinin ◽  
Walter Charles Primus ◽  
Abdul Halim Shaari ◽  
Zainal Abidin Talib ◽  
Sinin Hamdan
Keyword(s):  
Dielectric Properties ◽  
Temperature Dependence ◽  
Low Frequency ◽  
Sintered Sample ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
Low Frequencies ◽  
X Ray ◽  
Lcr Meter

Ceramic sample of La0.70Ba0.30Mn0.40Ti0.60O3 oxide has been prepared by the conventional solid-state reaction method. The sintered sample was characterized by using x-ray diffraction (XRD) and low frequency LCR meter. XRD result shows that the sample has a cubic structure with the existence of impurity phase. The dielectric properties of La0.70Ba0.30Mn0.40Ti0.60O3 measured from room temperature to 200°C shows that the dielectric permittivity is temperature dependence with strong dispersion at low frequencies. A circuit model based on the universal capacitor response function is also being used to represent the dielectric properties of the sample.

Structures and phase transitions in a new ferroelectric – pyridinium chlorochromate – studied by X-ray diffraction, DSC and dielectric methods

2012 ◽  
Vol 68 (2) ◽  
pp. 128-136 ◽  
Author(s):  
Hanna Małuszyńska ◽  
Piotr Czarnecki ◽  
Anna Czarnecka ◽  
Zdzisław Pająk
Keyword(s):  
Phase Transitions ◽  
Pyridinium Salt ◽  
Diffraction Method ◽  
Phase Iii ◽  
Pyridinium Chlorochromate ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Intermediate Phases ◽  
Ferroelectric Hysteresis

Pyridinium chlorochromate, [C5H5NH]+[ClCrO3]− (hereafter referred to as PyClCrO3), was studied by X-ray diffraction, differential scanning calorimetry (DSC) and dielectric methods. Studies reveal three reversible phase transitions at 346, 316 and 170 K with the following phase sequence: R\bar 3m (I) → R3m (II) → Cm (III) → Cc (IV), c′ = 2c. PyClCrO3 is the first pyridinium salt in which all four phases have been successfully characterized by a single-crystal X-ray diffraction method. Structural results together with dielectric and calorimetric studies allow the classification of the two intermediate phases (II) and (III) as ferroelectric with the Curie point at 346 K, and the lowest phase (IV) as most probably ferroelectric. The ferroelectric hysteresis loop was observed only in phase (III). The high ionic conductivity hindered its observation in phase (II).

Investigation of Phase Transitions in Stacked GeTe/SnTe and Ge2Se3/SnTe Chalcogenide Films

2011 ◽  
Vol 687 ◽  
pp. 677-683 ◽  
Author(s):  
Fei Ming Bai ◽  
Huai Wu Zhang ◽  
Surendra Gupta ◽  
Santosh Kurinec
Keyword(s):  
Phase Transition ◽  
Solid Solution ◽  
Phase Transitions ◽  
Phase Change Memory ◽  
Thin Layers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Area Detector ◽  
Memory Applications ◽  
Change Memory

Phase transitions in stacked GeTe/SnTe and Ge2Se3/SnTe thin layers for potential phase-change memory applications have been investigated by X-ray diffraction using an area detector system and by scanning electron microscopy. The as-deposited underlying GeTe or Ge2Se3 layer is amorphous, whereas the top SnTe layer is crystalline. In GeTe/SnTe stack, the crystallization of GeTe phase occurs near 170°C, and upon further heating, GeTe phase disappears, followed by the formation of rocksalt-structured GexSn1-xTe solid solution. In Ge2Se3/SnTe stack, the phase transition starts with the separation of SnSe phase due to the migration of Sn ions into the Ge2Se3 layer. The migration of Sn ions and the formation of SnSe are believed to facilitate the crystallization of Ge2Se3 solid solution at ~360°C, which is much lower than the crystallization temperature of Ge2Se3, therefore consuming less power during the phase transition.

scholarly journals Synthesis, Microstructure and the Crystalline Structure of the Barium Titanate Ceramics Doped with Lanthanum

2013 ◽  
Vol 58 (4) ◽  
pp. 1305-1308 ◽  
Author(s):  
B. Wodecka-Duś ◽  
M. Plońska ◽  
D. Czekaj
Keyword(s):  
Thermal Analysis ◽  
Crystalline Structure ◽  
Diffraction Method ◽  
Simultaneous Thermal Analysis ◽  
Tetragonal Symmetry ◽  
X Ray Diffraction ◽  
Ceramic Powders ◽  
X Ray ◽  
Composition Formula ◽  
Titanate Ceramics

Abstract In the present study BaTiO3 and Ba1-xLaxTiO3 (0.1-0.4mol.% La) ceramic powders were synthesized by the conventional mixed oxide method (MOM). The characterization of the ceramic powders was carried out using a simultaneous thermal analysis (STA), with a combined DTA/TG/DTG system (Netzsch STA409). The results of thermal analysis allowed to determine the optimal temperature of synthesis. Microstructure was investigated by scanning electron microscopy (SEM), crystalline structure was studied by X-ray diffraction method (XRD). The EDS investigations showed that samples exhibited conservation of stoichiometry according to the chemical composition formula. The X-ray diffraction analysis confirmed formation of the desired crystalline structure both pure and La3+-doped BaTiO3 ceramics exhibiting a perovskite-type structure ABO3 with tetragonal symmetry P4 mm.

scholarly journals Effect of Fe Substitution on the Structural, Electrical and Dielectric Properties of La0.70Ca0.30MnO3 Cathode for SOFCs

2019 ◽  
Vol 9 (1) ◽  
pp. 324-328
Keyword(s):  
Dielectric Properties ◽  
Single Phase ◽  
Diffraction Method ◽  
X Ray Diffraction ◽  
Reaction Route ◽  
X Ray ◽  
Suitable Material ◽  
Density Values ◽  
Electrical And Dielectric Properties ◽  
Fe Substitution

Perovskite solid solutions (La0.70Ca0.30)(FexMn1-x)O3 where x = 0.01, 0.20, 0.30 and 0.40 ceramics were synthesized by solid state reaction route. The structural studies were carried by X-Ray diffraction method and the observed results have indicated that all the prepared samples were crystallized into single phase. The surface morphology was studied by Scanning Electron Microscopy and the images have revealed that grain size has increased with the increasing concentration of Fe. Archimedes principle was used to calculate the density of all the sintered samples and the density values were observed to be in increasing order. The impedance and dielectric properties have been characterized at different ranges of temperature and frequency. The value of electrical conductivity were found to be more than 100 S cm-1 , which indicate that the synthesized material is suitable material for cathode of Solid Oxide Fuel Cell.

Single Crystal X-Ray Diffraction Study of the Phase Transitions in Graphite-Bromine Intercalation Compounds

1982 ◽  
Vol 20 ◽  
Author(s):  
D. Ghosh ◽  
D.D.L. Chung
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Diffraction Study ◽  
Structure Characteristic ◽  
Q Value ◽  
X Ray Diffraction ◽  
X Ray ◽  
Stage 4 ◽  
Commensurate Phase ◽  
Bromine Vapor

ABSTRACTReported here is the first observation of an incommensurate-commensurate phase transition at 316 ± 1 K upon heating stage-2 graphite-bromine prepared in bromine liquid. The transition during heating involved the movement of the 300 reflection toward a lower q value and the sharpening of the 010 reflection, thereby resulting in the commensurate structure characteristic of stage-2 prepared in bromine vapor. The transition was reversible. The previously reported comtmensurate-incommensurate transition occurred at 326, 329, 332, 338 and 348 K for stage 2 (in bromine liquid), stage 2 (in bromine vapor), stage 3, stage 4, and desorbed material, respectively. Disordering was observed upon completion of this transition.

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