Study on Phase Structure and Electrical Properties of La-Doped (K0.5Na0.5)0.94Li0.06NbO3 Ceramics

2011 ◽  
Vol 328-330 ◽  
pp. 1127-1130 ◽  
Author(s):  
Yong Liu ◽  
Rui Qing Chu ◽  
Zhi Jun Xu ◽  
Qian Chen ◽  
Lin Shao ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Phase Structure ◽  
Room Temperature ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
La Doping ◽  
La Doped ◽  
Lower Loss

Lead-free piezoceramics (K0.5Na0.5)0.94-3xLi0.06LaxNbO3were synthesized by the conventional solid-state reaction process. The effect of La-doping on the phase structure and electrical properties of (K0.5Na0.5)0.94Li0.06NbO3ceramics was investigated. X-ray diffraction analysis showed that the crystal structure of the ceramics changed from coexistence of orthorhombic and tetragonal phases to pseudo-cubic phase with the increase of La-doping level, and the change of phase structure seriously weakened the dielectric, ferroelectric and piezoelectric properties of the ceramics. In addition, it was found that the La-doping improved the density of the ceramics and the ceramics became dense. Meanwhile, the ceramics with La-doping displayed a relative lower loss tangent (tanδ) from room temperature to approximately 350°C.

Effects of La-Doping on Phase Structure and Electrical Properties of Pb(Mg1/3Nb2/3)0.67Ti0.33O3 Ceramic

2012 ◽  
Vol 622-623 ◽  
pp. 767-770
Author(s):  
Yong Liu ◽  
Rui Qing Chu ◽  
Zhi Jun Xu ◽  
Shu Ting Wang ◽  
Qing Bin Chi ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Phase Structure ◽  
Doping Level ◽  
Raw Materials ◽  
Pyrochlore Phase ◽  
X Ray Diffraction ◽  
La Doping ◽  
Low X ◽  
Sintering Method ◽  
La Doped

La-doped Pb(Mg1/3Nb2/3)0.67Ti0.33O3 ceramics were fabricated by a two-stage sintering method from conventional raw materials. The effects of La doping on the phase structure and electrical properties of ceramics were investigated. X-ray diffraction analysis showed that the pyrochlore phase increased with the increase of La-doping level. The effects of La doping on the dielectric, ferroelectric and piezoelectric properties of the ceramics were also investigated. The results showed that La doping seriously weakened the electrical properties of the ceramics. The ceramics possess optimum properties (d33=239pC/N, Pr=10.6μC/cm2, Ec=8.5kV/cm, tanδ=0.029, εr = 2250) when the doping level is low (x = 0.02).

X-ray diffraction study of oxygen-conducting compoundsLn2Mo2O9(Ln= La, Pr)

2014 ◽  
Vol 70 (4) ◽  
pp. 669-675 ◽  
Author(s):  
Alexander M. Antipin ◽  
Olga A. Alekseeva ◽  
Natalia I. Sorokina ◽  
Alexandra N. Kuskova ◽  
Michail Yu. Presniakov ◽  
...  
Keyword(s):  
Room Temperature ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Ion Migration ◽  
Transmission Microscopy ◽  
Coordination Environment ◽  
X Ray ◽  
Oxygen Ions ◽  
Oxygen Ion ◽  
Oxygen Ion Migration

The La2Mo2O9(LM) and Pr2Mo2O9(PM) single crystals are studied using precision X-ray diffraction and high-resolution transmission microscopy at room temperature. The crystal structures are determined in the space groupP213. La and Pr atoms, as well as Mo1 and O1 atoms, are located in the vicinity of the threefold axes rather than on the axes as in the high-temperature cubic phase. In both structures studied, the O2 and O3 positions are partially occupied. The coexistence of different configurations of the Mo coordination environment facilitates the oxygen-ion migration in the structure. Based on the X-ray data, the activation energies of O atoms are calculated and the migration paths of oxygen ions in the structures are analysed. The conductivity of PM crystals is close to that of LM crystals. The O2 and O3 atoms are the main contributors to the ion conductivity of LM and PM.

scholarly journals Cubic InGaN Grown by MOCVD

1999 ◽  
Vol 4 (S1) ◽  
pp. 239-243
Author(s):  
J.B. Li ◽  
Hui Yang ◽  
L.X. Zheng ◽  
D.P. Xu ◽  
Y.T. Wang
Keyword(s):  
Room Temperature ◽  
Emission Peak ◽  
Buffer Layers ◽  
Cubic Phase ◽  
Yellow Luminescence ◽  
X Ray Diffraction ◽  
High Quality ◽  
X Ray ◽  
Cubic Gan ◽  
Pl Emission

We report on the growth of high-quality cubic phase InGaN on GaAs by MOCVD. The cubic InGaN layers are grown on cubic GaN buffer layers on GaAs (001) substrates. The surface morphology of the films are mirror-like. The cubic nature of the InGaN films is obtained by X-ray diffraction (XRD) measurements. The InGaN layers show strong photoluminescence (PL) at room temperature. Neither emission peak from wurtzite GaN nor yellow luminescence is observed in our films. The highest In content as determined by XRD is about 17% with an PL emission wavelength of 450 nm. The FWHM of the cubic InGaN PL peak are 153 meV and 216 meV for 427 nm and 450 nm emissions, respectively. It is found that the In compositions determined from XRD are not in agreement with those estimated from PL measurements. The reasons for this disagreement are discussed.

Effect of La doping on the structural and electrical properties of SrBi2Ta2O9

2004 ◽  
Vol 811 ◽  
Author(s):  
Ortega Nora ◽  
S. Bhattacharyya ◽  
P. Bhattacharya ◽  
R.R. Das ◽  
R.S. Katiyar
Keyword(s):  
Electrical Properties ◽  
Structural Evolution ◽  
Phase Segregation ◽  
X Ray Diffraction ◽  
Lanthanum Doping ◽  
X Ray ◽  
La Doping ◽  
Structural And Electrical Properties ◽  
Vibrational Characteristics ◽  
La Substitution

ABSTRACTThe effect of anthanum substitution (0-20%) on phase formation, structural evolution and electrical properties of SrBi2Ta2O9 (SBT) ceramics were investigated. X-ray diffraction studies revealed that phase pure SBT bulk samples can be synthesized with lanthanum doping without any phase segregation. Raman spectroscopy was used to understand the lattice vibrational characteristics of La substituted SBT compound. The ferroelectric soft mode at 27 cm−1 was shifted towards the lower frequencies at room temperature with increase in La concentrations. The octahedral stretching mode (O-Ta-O) did not influenced by La substitution in SBT. The x-ray photoemission spectroscopy measurements showed the decrease of binding energy of Bi 4f core levels (5/2 and 7/2) upon La substitution in SBT. The dielectric constant was increased from 120 to 190 up to 10% La doping and decreased with further increase in La concentration.

Development of CNT-Silicon Nitrides with Improved Mechanical and Electrical Properties

2006 ◽  
Vol 45 ◽  
pp. 1723-1728 ◽  
Author(s):  
Csaba Balázsi ◽  
Ferenc Wéber ◽  
Péter Arató ◽  
Balazs Fényi ◽  
Norbert Hegman ◽  
...  
Keyword(s):  
Silicon Nitride ◽  
Electrical Properties ◽  
Room Temperature ◽  
Hot Isostatic Pressing ◽  
Ceramic Composites ◽  
X Ray Diffraction ◽  
Nano Structure ◽  
X Ray ◽  
Mechanical And Electrical Properties ◽  
Gas Pressure Sintering

This work is focusing on exploring preparing processes to tailor the microstructure of carbon nanotube (CNT) reinforced silicon nitride-based ceramic composites. Samples with different porosity’s and different amount (1, 3 or 5 wt%) of carbon nanotubes have been prepared by using gas pressure sintering or hot isostatic pressing. In comparison, composites with 1wt%, 5wt% or 10wt% carbon black and graphite have been manufactured. We measured the room temperature mechanical and electrical properties, examined the micro and nano structure by X-ray diffraction and electron microscopy. It was found that it is possible to develop CNT-silicon nitride composite for applications where a decent electric conductivity and good mechanical properties are required.

Low-temperature crystal structure of RS-thiocamphor

2004 ◽  
Vol 219 (9) ◽  
Author(s):  
E. Louise R. Robins ◽  
Michela Brunelli ◽  
Asiloé J. Mora ◽  
Andrew N. Fitch
Keyword(s):  
Crystal Structure ◽  
Phase Transitions ◽  
Low Temperature ◽  
Room Temperature ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Two Phase ◽  
X Ray ◽  
Low Temperature Crystal Structure

AbstractDSC and high-resolution powder X-ray diffraction measurements in the range 295 K–100 K show that RS-thiocamphor undergoes two phase transitions. The first, at around 260 K on cooling, is from the room-temperature body-centred-cubic phase to a short-lived intermediate. At 258 K the low-temperature form starts to appear. The crystal structure of the latter is orthorhombic, space group

Phase Diagram and Cation Dynamics of Mixed MA1-xFAxPbBr3 Hybrid Perovskites

2021 ◽  
Author(s):  
Mantas Simenas ◽  
Sergejus Balčiūnas ◽  
Sarunas Svirskas ◽  
Martynas Kinka ◽  
Maciej Ptak ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Room Temperature ◽  
Structural Phase ◽  
Cubic Phase ◽  
Structural Phase Transitions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dielectric Relaxations ◽  
Broadband Dielectric Spectroscopy ◽  
Molecular Cation

<p>We use a multi-technique approach to determine the phase diagram and molecular cation dynamics of mixed methylammonium-formamidinium MA1-xFAxPbBr3 (0 ≤ x ≤ 1) hybrid perovskites. The calorimetric, ultrasonic and X-ray diffraction experiments show a substantial suppression of the structural phase transitions and stabilization of the cubic phase upon mixing. We use the broadband dielectric and Raman spectroscopies to study the MA and FA cations dynamics in these compounds. The broadband dielectric spectroscopy indicates absence of the MA cation ordering and a gradual increase of the rotation barrier upon mixing. The room-temperature dielectric permittivity substantially decreases as the fraction of the FA cations is increased. No significant changes of the permittivity are detected at temperatures where the dielectric relaxations are absent. We also observe weak signatures of a dipolar glass phase for the highest mixing level (x = 0.5). The Raman spectroscopy supports the dielectric results and reveals additional subtle information about the FA cation dynamics.</p><br>

Synthesis and Luminescence Properties of Alumina Encapsulated InN Nanorods

2008 ◽  
Vol 8 (12) ◽  
pp. 6290-6296
Author(s):  
Ajay Kumar Mann ◽  
Deepak Varandani ◽  
Bodh Raj Mehta ◽  
Lalit Kumar Malhotra ◽  
G. Mangamma ◽  
...  
Keyword(s):  
Room Temperature ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Alumina Membrane ◽  
Temperature Plasma ◽  
Cross Sectional ◽  
Scanning Electron Microscope Study ◽  
X Ray ◽  
Step Procedure ◽  
Plasma Annealing

The present study reports a two-step procedure to synthesize InN nanorods inside the pores of an anodic alumina membrane. In the first step, pores of the membrane are filled with indium via electrodeposition. The second step involves nitridation of the as-deposited nanorods by room temperature plasma annealing. X-ray diffraction studies reveal that as-deposited nanorods consist of In, In2O3 and In(OH)3 phases which get converted to mixed hexagonal and cubic phase InN on plasma annealing. Cross sectional scanning electron microscope study reveals nanorod diameter and length to be 150 nm and 1 μm respectively. X-ray mapping results establish that uniform distribution of nitrogen throughout the length of nanorod has been achieved as a result of plasma annealing. Observation of photoluminescence peaks at 1.4 and 1.6 eV corresponding, to the absorption edges of cubic and hexagonal phases of InN show that room temperature photoemission is due to band to band recombination. The use of alumina as a template for nanorod growth prevents postdeposition agglomeration and provides mechanical strength. Possibility of total internal reflection at the InN-Al2O3 interface makes these structures ideally suitable to reduce the emitted light intensity losses.

Preparation and Photocatalytic Properties of the Chrome Doped Nano-TiO2 Emulsion

2014 ◽  
Vol 675-677 ◽  
pp. 154-157
Author(s):  
Ling Li ◽  
Hua Yan Zhang ◽  
Xiao Wei Li ◽  
Wen Ming Zhang
Keyword(s):  
Photocatalytic Activity ◽  
Phase Structure ◽  
Room Temperature ◽  
Degradation Rate ◽  
Photocatalytic Properties ◽  
X Ray Diffraction ◽  
Absorbance Spectrum ◽  
X Ray ◽  
Hydrolysis Method ◽  
Controlled Hydrolysis

Chrome doped nanoTiO2transparent hydrosol was synthesized by a complexation-controlled hydrolysis method at room temperature. The absorbance spectrum and phase structure of samples were characterized by UV-Vis spectrophotometer, and X-ray diffraction, respectively. The photocatalytic activity by degradating acid red 3R dye was studied, and the results indicated that when nanoparticle doped with 0.5% Cr, the degradation rate exceeded 96% for 60 min under the sunlight.

scholarly journals Study of electrical properties of a reduced graphene-oxadiazole-2-thiol (rGS) PVA polymer composite

2018 ◽  
Vol 27 (1) ◽  
pp. 11-19 ◽  
Author(s):  
Emaad T Bakir Al-Tikrity ◽  
Ibrahim F Waheed ◽  
Sabah M Ali
Keyword(s):  
Electrical Properties ◽  
Room Temperature ◽  
Composite Films ◽  
Low Frequency ◽  
Covalent Bonding ◽  
Poly Vinyl Alcohol ◽  
X Ray Diffraction ◽  
X Ray ◽  
Reduced Graphene ◽  
Tan Δ

This work reports the synthesis and characterisation of reduced graphene-1,3,4-oxadiazole-2-thiol (rGS) as a novel nanocompound derivative for graphene. The preparation was performed through a series of reactions starting from graphene oxide, followed by incorporation of different proportions of this nanocompound with poly(vinyl alcohol) (PVA), via non-covalent bonding, to afford the rGS/PVA polymer composites. The pure rGS compound, rGS/PVA composite films and pure PVA film were characterised by different techniques including infrared (Fourier transform infrared) spectroscopy, scanning electron microscopy and powder x-ray diffraction. The electrical properties of the composite films, involving dielectric constant, permittivity ( ε′), imaginary permittivity ( ε″), conductivity (σAC) and loss factor tan δ, were investigated. The measurements were performed at frequencies of (5kHz to 0.5 MHz) at room temperature. At low frequency, the dielectric permittivity ( ε′) and imaginary permittivity ( ε″) attained higher values in all cases, although with increasing frequency these values diminished rapidly. It was also found that the alternating current conductivity of the composites increased with increasing frequency.

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