Dielectric Properties of Barium Titanate Ceramics Modified by CuO in Different Methods

2012 ◽  
Vol 463-464 ◽  
pp. 276-280 ◽  
Author(s):  
Dan Su ◽  
Yu Wang ◽  
Wan Ping Chen ◽  
Helen Lai Wah Chan ◽  
Li Na Bing
Keyword(s):  
Barium Titanate ◽  
Curie Temperature ◽  
Perovskite Phase ◽  
Hexagonal Phase ◽  
Boundary Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pure Perovskite Phase ◽  
The Difference ◽  
Titanate Ceramics

CuO has been doped solely and together with BaO and SiO2 into barium titanate by mixing and calcination. X-ray diffraction showed that the sample doped by CuO-BaO has stable second hexagonal phase while the samples doped by CuO, CuO-SiO2 were of a pure perovskite phase. For CuO-BaO doping, the Curie temperature was decreased accompanied with higher εmax; while for CuO doping and CuO-SiO2 codoping, the Curie temperature was increased with εmax decreased. The difference can be explained considering that Cu2+ ion could not only incorporate into the BaTiO3 lattice, but also assemble in the boundary phase when CuO was doped solely. Besides, the mechanisms of CuO doping and SiO2 doping could happen at one time.

Effects of NaNbO3 Crystals on Electrical Properties of K0.5Na0.5NbO3 Ceramics

2016 ◽  
Vol 690 ◽  
pp. 126-130 ◽  
Author(s):  
Chavalit Suksri ◽  
Piewpan Parjansri ◽  
Sutatip Thonglem ◽  
Uraiwan Intatha ◽  
Sukum Eitssayeam ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Piezoelectric Properties ◽  
Perovskite Phase ◽  
Seed Crystal ◽  
Molten Salt Synthesis ◽  
X Ray Diffraction ◽  
Mixed Powder ◽  
X Ray ◽  
Structure And Morphology ◽  
Pure Perovskite Phase

Lead-free (K0.5Na0.5)NbO3 (KNN) piezoelectric ceramics were studied and synthesized by the seed-induced method. NaNbO3 crystal was used as seed and prepared by molten salt synthesis (MSS). The average particles size of NaNbO3 seed crystal was about 1-3 mm. Then, the NaNbO3 seed was mixed with KNN powder and ball milled for 24 h. The mixed powder was calcined at 700-900 °C and sintered at 1100 °C. The phase structure and morphology of the ceramics were investigated by X-ray diffraction and scanning electron microscope and the electrical properties were studied. The results indicated that all samples showed a pure perovskite phase. The highest density of the ceramic was 93% compared to the theoretical density. The results showed that NaNbO3seed crystal improved piezoelectric properties of KNN ceramics.

Fabrication of Lead Barium Titanate Ceramics via Conventional Solid-State Mixed Oxide Technique

2008 ◽  
Vol 55-57 ◽  
pp. 209-212 ◽  
Author(s):  
Theerachai Bongkarn ◽  
P. Panya
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Mixed Oxide ◽  
Perovskite Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Calcination Temperatures ◽  
Grain Sizes ◽  
Titanate Ceramics ◽  
Scanning Electron

(Pb0.925Ba0.075)TiO3 (PBT) ceramics have been prepared using a mixed oxide technique. The phase formation and morphology were studied in detail via X-ray diffraction (XRD) and scanning electron microscopy (SEM). The pure tetragonal perovskite structure was discovered with calcination temperatures above 800 oC. The percentage of perovskite phase and particle size tends to increase with the increasing of calcination temperatures. The PBT ceramics sintered at various temperatures belonged to a pure tetragonal perovskite phase. The average grain sizes increased from 0.90 to 6.44 µm with the increase of sintering temperatures from 1100 to 1200 oC. The highest density was obtained from the sample that sintered at 1150 and 1200 oC

scholarly journals Effect of Process Parameter Optimization in Reducing Sintering Temperature in the Synthesis and Characterization of Ba(Zn1/3Nb2/3)O3

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
P. K. Bajpai ◽  
K. N. Singh
Keyword(s):  
Perovskite Phase ◽  
Impedance Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lattice Constants ◽  
Microwave Dielectric ◽  
Pure Perovskite Phase ◽  
Higher Temperature ◽  
Ac Conduction

Controlling the cooling rate during calcination and sintering, phase pure perovskite Ba(Zn1/3Nb2/3)O3 has been prepared by simple solid state reaction route with density >93% at relatively low sintering of 1175°C making it compatible for microwave dielectric applications. The samples are characterized by X-ray diffraction analysis and scanning electron microscopy. The X-ray diffraction shows pure perovskite phase with cubic structure. The lattice constants were obtained a = 4.1032 Å. Detailed studies of ε′ and ε′′ show that the compound exhibits dielectric anomaly at 430°C. Material shows distributed relaxation at higher temperature. Impedance analysis revealed that the impedance is mainly due to the grains. AC conduction activation energies are estimated from Arrhenius plots, and conduction mechanism is discussed.

Synthesis of Modified K0.5Na0.5NbO3 Powder by Molten-Salt Technique

2017 ◽  
Vol 728 ◽  
pp. 160-165
Author(s):  
Thanatep Phatungthane ◽  
Buagun Samran ◽  
Gobwute Rujijanagul
Keyword(s):  
Molten Salt ◽  
Calcination Temperature ◽  
Perovskite Phase ◽  
Orthorhombic Symmetry ◽  
Molten Salt Method ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Fine Grain ◽  
Pure Perovskite Phase

In the present work, the molten-salt method was applied to synthesize 0.948K0.5Na0.5NbO3–0.052LiSbO3 powder for the first time. Characteristics of the powder were investigated. Based on X-ray diffraction technique, pure perovskite phase was observed at a calcination temperature of 700 oC which is lower than that required by the conventional solid-state reaction technique for ∼200 oC. Raman spectroscopy technique showed that the powder had an orthorhombic symmetry which consistent with the X-ray diffraction results. The powder exhibited very fine grain with narrow size distribution. Particle size of the obtained powders increased with increasing calcination temperature. Therefore, the molten-salt method is a simple and effective method to synthesize 0.948K0.5Na0.5NbO3 – 0.052LiSbO3 powder.

Microstructures and Photoluminescence in Nanocrystalline Barium Titanate

1998 ◽  
Vol 520 ◽  
Author(s):  
M. S. Zhang ◽  
J. Yu ◽  
W. F. Zhang ◽  
Z. Yin ◽  
W. C. Chen
Keyword(s):  
Barium Titanate ◽  
Ultrafine Particles ◽  
Critical Size ◽  
Hexagonal Phase ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
Central Frequency ◽  
X Ray ◽  
Parameter Ratio ◽  
Tetragonal Phase Transition

ABSTRACTBarium titanate ultrafine particles are prepared by hydrothermal method at low temperature. Their phase structures and photoluminescence (PL) properties are examined by X-ray diffraction and Raman spectroscopy. The critical size of the cubic-tetragonal phase transition is about 48 nm and the lattice parameter ratio c/a equals 1.003. Strong photoluminescence is observed with central frequency located at 695 nm. The spectral behaviors at different annealing times and temperatures are studied. We attribute them to the semiconducting hexagonal phase embeded in the nanophase cubic BaTiO3to form trap centers and cause PL process.

scholarly journals X-ray diffraction study of crystalline barium titanate ceramics

2014 ◽  
Author(s):  
Nurazila Mat Zali ◽  
Che Seman Mahmood ◽  
Siti Mariam Mohamad ◽  
Choo Thye Foo ◽  
Julie Adrianny Murshidi
Keyword(s):  
Barium Titanate ◽  
Diffraction Study ◽  
X Ray Diffraction ◽  
X Ray ◽  
Titanate Ceramics
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