Influence of Rare Earth on the Electrical Properties and Microstructure of Barium Titanate Ceramics

2008 ◽  
Vol 368-372 ◽  
pp. 465-468
Author(s):  
Wen Hu Yang ◽  
Yong Ping Pu ◽  
Shou Tian Chen
Keyword(s):  
Rare Earth ◽  
Critical Concentration ◽  
Rare Earth Ions ◽  
Breakdown Field ◽  
Fine Grained ◽  
Ceramic Samples ◽  
Ptcr Effect ◽  
Fine Grained Structure ◽  
Electronic Compensation ◽  
Titanate Ceramics

The ceramic samples of BaTiO3+½xLn2O3+2mol%TiO2 (0.001≤x≤0.01) were prepared, where Ln is Y, Dy, Ho, Er or Y. The influence of rare earth on the resistivity and microstructure of the samples was investigated by the means of XRD, SEM and electric properties testing. The results showed that the resistivity of La-doped sample decreases when x= 0.003 compared with the undoped sample. However, the range of dopant concentration with Dy, Ho, Er or Y for semiconducting samples is wider, especially for Y-doping. Minimum resistivity at room temperature was observed when x=0.003, which is named after the critical concentration. The experimental results indicated that below the critical concentration of Dy, Ho, Er or Y, the substitution took place in the barium sublattice with electronic compensation, and the rare earth ions began to substitute for titanium gradually above the critical concentration. For Ho-doped BaTiO3 ceramic, the resistivity jump (PTCR effect) near the Curie temperature was the highest in the case of x=0.003. Fine-grained structure of the sample doped with 0.6mol% Dy led to the increase of breakdown field strength and dielectric constant of ceramic samples.

Luminescence properties of barium - gadolinium-titanate ceramics doped with rare-earth ions (Eu3+and Tb3+)

Luminescence ◽  
2014 ◽  
Vol 29 (7) ◽  
pp. 861-867 ◽  
Author(s):  
S. Hemasundara Raju ◽  
B. Muni Sudhakar ◽  
B. Sudhakar Reddy ◽  
S. J. Dhoble ◽  
K. Thyagarajan ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Ions ◽  
Luminescence Properties ◽  
Titanate Ceramics

The Influence of Addition of the Rare Earth Elements on the Structure and Hardness of AlZn12Mg3.5Cu2.5 Alloy

2015 ◽  
Vol 226 ◽  
pp. 39-42
Author(s):  
Rafał Michalik ◽  
Tomasz Mikuszewski
Keyword(s):  
Rare Earth ◽  
Automotive Industry ◽  
Electrical Power ◽  
High Strength ◽  
Hardness Test ◽  
Relative Strength ◽  
Zinc Alloys ◽  
Fine Grained ◽  
Fine Grained Structure ◽  
High Strength Aluminum Alloys

Aluminium alloys are characterized by a number of advantageous properties , which include: low density ,high relative strength , high electrical and thermal conductivity , ease of machining and good dumping features. Particular interesting are high-strength aluminum alloys of zinc, magnesium and copper. These alloys are used mainly in aircraft, building &structure, electrical, electrical power and automotive industry. A significant problem associated with the use of high-strength aluminium-zinc alloys is their insufficient resistance to corrosion. Improvement of corrosion resistance can be obtained by application of alloy micro-additives. The article shows results of examinations related to influence of rare earth additive on the structure and hardness of AlZn12Mg3.5Cu2.5 alloy. The scope of examination included: structure testing using scanning microscope, X – ray microanalysis, hardness test. Examinations have shown higher hardness of samples with rare earth additives. Was found , that rare earth addition influences on more fine –grained structure of the AlZn12Mg3.5Cu2.5 alloy.

Phase Equilibria and Dielectric Properties of Rare Earth Containing BaTiO3 Ceramics

1996 ◽  
Vol 453 ◽  
Author(s):  
D. Kolar
Keyword(s):  
Rare Earth ◽  
Barium Titanate ◽  
Phase Equilibria ◽  
Rare Earth Ions ◽  
Wavelength Dispersive Spectroscopy ◽  
X Ray ◽  
Preparation Conditions ◽  
Titanate Ceramics ◽  
Rare Earth La ◽  
Scanning Electron

AbstractAddition of rare earth oxides affects several properties of barium titanate ceramics such as dielectric constant, Curie temperature and electrical conductivity. Electrical properties depend on the composition, firing conditions and mode of incorporation of rare earth ions into perovskite or perovskite-like lattice.Incorporation of rare earth ions into the BaTiO3 lattice was studied by quantitative wavelength dispersive spectroscopy in combination with scanning electron microscopy and X-ray powder diffraction. Broad solubility regions between rare earth titanates and barium titanate were detected, influencing the properties.In present review, phase equilibria and properties of rare earth (La,Nd,Ce) containing BaTiO3 ceramics are compared with particular emphasis on preparation conditions.

scholarly journals Preparation and Dielectric Properties of Co Contained Unfilled Tungsten Bronze Ceramics Ba4RCo0.5Nb9.5O30

2021 ◽  
Author(s):  
Xiaoying Guo ◽  
Weifeng Zhang ◽  
Shan Wu ◽  
Chaozhong Sun ◽  
Changzheng Hu ◽  
...  
Keyword(s):  
Phase Transition ◽  
Rare Earth ◽  
Dielectric Properties ◽  
Tungsten Bronze ◽  
Frequency Dispersion ◽  
Rare Earth Ions ◽  
Ionic Radii ◽  
Tetragonal Tungsten Bronze ◽  
Ceramic Samples ◽  
Full Profile

Abstract In this study, Ba4RCo0.5Nb9.5O30 (R = La, Nd, Sm, Eu) (BRCN) ceramics were synthesized using a high-temperature solid-state reaction. The effects of rare-earth ions with different ionic radii at A sites on the phase structure, microstructure, and dielectric properties of ceramics have been systematically studied. The full profile refinement XRD results show that all ceramic samples are tetragonal tungsten bronze (TTB). As the radius of the rare-earth ions decreases, the relaxation ferroelectric phase transition transforms into the dispersed phase transition, and the frequency dispersion of the ceramic samples gradually decreases. The high-frequency shift of Raman peak indicates that lattice distortion is severe. P-E loops under maximum applied electric field showed that BRCN ceramics can be used for energy storage.

High-temperature Creep Resistance in Rare-earth-doped, Fine-grained Al2O3

1998 ◽  
Vol 13 (9) ◽  
pp. 2597-2601 ◽  
Author(s):  
H. Yoshida ◽  
Y. Ikuhara ◽  
T. Sakuma
Keyword(s):  
Rare Earth ◽  
High Temperature ◽  
Grain Boundaries ◽  
Creep Resistance ◽  
Rare Earth Oxide ◽  
Rare Earth Ions ◽  
Second Phase ◽  
High Temperature Creep ◽  
Fine Grained ◽  
Temperature Creep

High-temperature creep in undoped Al2O3 and La2O3- or Y2O3- or Lu2O3-doped Al2O3 with a grain size of about 1 µm is examined in uniaxial compression testing at temperatures between 1150 and 1350 °C. The high-temperature creep resistance in Al2O3 is highly improved by the rare-earth oxide doping in the level of 0.045 mol %, and the creep rate is suppressed in the order La2O3 <Y2O3 <Lu2O3. Rare-earth ions in each doped Al2O3 are found to segregate in Al2O3 grain boundaries without forming amorphous phase or second-phase particles. The activation energy for creep in undoped Al2O3 is estimated to be 410 kJ/mol, while it is about 800 kJ/mol in the three rare-earth oxide-doped Al2O3. The grain boundary diffusivity must be highly reduced by the segregation of the dopant cation in Al2O3 grain boundaries.

Characterization of Rare-Earth Fluoride Anti-Stokes Phosphors by Scanning arid Transmission Electron Microscopy

1971 ◽  
Vol 29 ◽  
pp. 142-143
Author(s):  
N. M. P. Low ◽  
L. E. Brosselard
Keyword(s):  
Electron Microscopy ◽  
Rare Earth ◽  
Elevated Temperatures ◽  
Stoichiometric Composition ◽  
Rare Earth Ions ◽  
Crystalline Solid ◽  
Precipitation Process ◽  
Rare Earth Fluoride ◽  
Earth Fluoride ◽  
Rare Earth Fluorides

There has been considerable interest over the past several years in materials capable of converting infrared radiation to visible light by means of sequential excitation in two or more steps. Several rare-earth trifluorides (LaF3, YF3, GdF3, and LuF3) containing a small amount of other trivalent rare-earth ions (Yb3+ and Er3+, or Ho3+, or Tm3+) have been found to exhibit such phenomenon. The methods of preparation of these rare-earth fluorides in the crystalline solid form generally involve a co-precipitation process and a subsequent solid state reaction at elevated temperatures. This investigation was undertaken to examine the morphological features of both the precipitated and the thermally treated fluoride powders by both transmission and scanning electron microscopy.Rare-earth oxides of stoichiometric composition were dissolved in nitric acid and the mixed rare-earth fluoride was then coprecipitated out as fine granules by the addition of excess hydrofluoric acid. The precipitated rare-earth fluorides were washed with water, separated from the aqueous solution, and oven-dried.

Structural, Morphological and Magnetic Characterization of Sm-substituted Ni-Zn Ferrite

2020 ◽  
Vol 10 (2) ◽  
pp. 152-156 ◽  
Author(s):  
Muhammad Hanif bin Zahari ◽  
Beh Hoe Guan ◽  
Lee Kean Chuan ◽  
Afiq Azri bin Zainudin
Keyword(s):  
Magnetic Properties ◽  
Rare Earth ◽  
Saturation Magnetization ◽  
Sol Gel ◽  
Magnetic Behavior ◽  
Rare Earth Ions ◽  
Ion Concentration ◽  
Zn Ferrite ◽  
Auto Combustion ◽  
Combustion Technique

Background: Rare earth materials are known for its salient electrical insulation properties with high values of electrical resistivity. It is expected that the substitution of rare earth ions into spinel ferrites could significantly alter its magnetic properties. In this work, the effect of the addition of Samarium ions on the structural, morphological and magnetic properties of Ni0.5Zn0.5SmxFe2-xO4 (x=0.00, 0.02, 0.04, 0.06, 0.08, 0.10) synthesized using sol-gel auto combustion technique was investigated. Methods: A series of Samarium-substituted Ni-Zn ferrite nanoparticles (Ni0.5Zn0.5SmxFe2-xO4 where x=0.00, 0.02, 0.04, 0.06, 0.08, 0.10) were synthesized by sol-gel auto-combustion technique. Structural, morphological and magnetic properties of the samples were examined through X-Ray Diffraction (XRD), Field-Emission Scanning Electron Microscope (FESEM) and Vibrating Sample Magnetometer (VSM) measurements. Results: XRD patterns revealed single-phased samples with spinel cubic structure up to x= 0.04. The average crystallite size of the samples varied in the range of 41.8 – 85.6 nm. The prepared samples exhibited agglomerated particles with larger grain size observed in Sm-substituted Ni-Zn ferrite as compared to the unsubstituted sample. The prepared samples exhibited typical soft magnetic behavior as evidenced by the small coercivity field. The magnetic saturation, Ms values decreased as the Sm3+ concentration increases. Conclusion: The substituted Ni-Zn ferrites form agglomerated particles inching towards more uniform microstructure with each increase in Sm3+ substitution. The saturation magnetization of substituted samples decreases with the increase of samarium ion concentration. The decrease in saturation magnetization can be explained based on weak super exchange interaction between A and B sites. The difference in magnetic properties between the samples despite the slight difference in Sm3+ concentrations suggests that the properties of the NiZnFe2O4 can be ‘tuned’, depending on the present need, through the substitution of Fe3+ with rare earth ions.

scholarly journals Structure, Luminescence, and Magnetic Properties of Crystalline Manganese Tungstate Doped with Rare Earth Ion

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3717
Author(s):  
Jae-Young Jung ◽  
Soung-Soo Yi ◽  
Dong-Hyun Hwang ◽  
Chang-Sik Son
Keyword(s):  
Magnetic Field ◽  
Rare Earth ◽  
Sintering Temperature ◽  
Luminescent Properties ◽  
Concentration Quenching ◽  
Rare Earth Ions ◽  
Precipitation Method ◽  
Rare Earth Ion ◽  
Co Precipitation ◽  
Quenching Phenomenon

The precursor prepared by co-precipitation method was sintered at various temperatures to synthesize crystalline manganese tungstate (MnWO4). Sintered MnWO4 showed the best crystallinity at a sintering temperature of 800 °C. Rare earth ion (Dysprosium; Dy3+) was added when preparing the precursor to enhance the magnetic and luminescent properties of crystalline MnWO4 based on these sintering temperature conditions. As the amount of rare earth ions was changed, the magnetic and luminescent characteristics were enhanced; however, after 0.1 mol.%, the luminescent characteristics decreased due to the concentration quenching phenomenon. In addition, a composite was prepared by mixing MnWO4 powder, with enhanced magnetism and luminescence properties due to the addition of dysprosium, with epoxy. To one of the two prepared composites a magnetic field was applied to induce alignment of the MnWO4 particles. Aligned particles showed stronger luminescence than the composite sample prepared with unsorted particles. As a result of this, it was suggested that it can be used as phosphor and a photosensitizer by utilizing the magnetic and luminescent properties of the synthesized MnWO4 powder with the addition of rare earth ions.

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