scholarly journals Dielectric, Thermal and FTIR Studies of Cobalt Doped Magnesium Hydrogen Maleate Hexahydrate Single Crystals

2011 ◽  
Vol 8 (1) ◽  
pp. 91-96
Author(s):  
B. Rajagopal ◽  
M. V. Ramana ◽  
A. V. Sarma
Keyword(s):  
Activation Energy ◽  
Dielectric Constant ◽  
Dielectric Properties ◽  
Melting Point ◽  
Transition Metal ◽  
Single Crystals ◽  
Loss Tangent ◽  
Transition Metal Ions ◽  
Ftir Studies ◽  
First Time

Present work reports the dielectric, thermal and FTIR studies of Co2+: MHMH single crystal for the first time. The influence of addition of transition metal ions on the dielectric properties, like dielectric constant, loss tangent,a.c. conductivity and activation energy of these crystals was discussed. FTIR studies confirm the presence of carboxylate ions. The melting point of the sample and final product after decomposition are studied using TG/DTA.

scholarly journals Synthesis and electrical characterization of Ca2Nd4Ti6O20 ceramics

2016 ◽  
Vol 34 (1) ◽  
pp. 164-168
Author(s):  
Raz Muhammad ◽  
Muhammad Uzair ◽  
M. Javid Iqbal ◽  
M. Jawad Khan ◽  
Yaseen Iqbal ◽  
...  
Keyword(s):  
Activation Energy ◽  
Dielectric Constant ◽  
Room Temperature ◽  
Sol Gel ◽  
Electrical Characterization ◽  
Sintered Sample ◽  
First Time ◽  
Alkoxide Precursors ◽  
Room Temperature Dielectric Constant

AbstractCa2Nd4Ti6O20, a layered perov skite structured material was synthesized via a chemical (citrate sol-gel) route for the first time using nitrates and alkoxide precursors. Phase analysis of a sample sintered at 1625 °C revealed the formation of an orthorhombic (Pbn21) symmetry. The microstructure of the sample after sintering comprised rod-shaped grains of a size of 1.5 to 6.5µm. The room temperature dielectric constant of the sintered sample was 38 at 100 kHz. The remnant polarization (Pr) and the coercive field (Ec) were about 400 μC/cm2 and 8.4 kV/cm, respectively. Impedance spectroscopy revealed that the capacitance (13.7 pF) and activation energy (1.39 eV) of the grain boundary was greater than the capacitance (5.7 pF) and activation energy (1.13 eV) of the grain.

The Temperature-Dependent Ideal Shear Strength of Solid Single Crystals

2018 ◽  
Vol 85 (3) ◽  
Author(s):  
Tianbao Cheng ◽  
Daining Fang ◽  
Yazheng Yang
Keyword(s):  
Shear Strength ◽  
Theoretical Model ◽  
Melting Point ◽  
Single Crystals ◽  
Elevated Temperatures ◽  
Absolute Zero ◽  
Temperature Dependent ◽  
Temperature Changes ◽  
First Time ◽  
The Ideal

Knowledge of the ideal shear strength of solid single crystals is of fundamental importance. However, it is very hard to determine this quantity at finite temperatures. In this work, a theoretical model for the temperature-dependent ideal shear strength of solid single crystals is established in the view of energy. To test the drawn model, the ideal shear properties of Al, Cu, and Ni single crystals are calculated and compared with that existing in the literature. The study shows that the ideal shear strength first remains approximately constant and then decreases almost linearly as temperature changes from absolute zero to melting point. As an example of application, the “brittleness parameter” of solids at elevated temperatures is quantitatively characterized for the first time.

Synthesis and Characteristics of MgO Coated BST-Mg2TiO4 Composite Ceramics

2012 ◽  
Vol 512-515 ◽  
pp. 1180-1183
Author(s):  
Qian Qian Jia ◽  
Hui Ming Ji ◽  
Shan Liu ◽  
Xiao Lei Li ◽  
Zheng Guo Jin
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Curie Temperature ◽  
Loss Tangent ◽  
Phase Shifters ◽  
Precipitation Method ◽  
Composite Ceramics ◽  
Low Dielectric ◽  
Dielectric Constant And Loss ◽  
Bst Ceramics

The (Ba, Sr)TiO3 (hereafter BST) ceramics are promising candidate for applying in tunable devices. MgO coated BST-Mg2TiO4 (BSTM-MT) composite ceramics were prepared to obtain the low dielectric constant, low dielectric loss, good dielectric constant temperature stability, and high tunability of BST ceramics. The Ba0.55Sr0.40Ca0.05TiO3 nanoparticles were coated with MgO using the precipitation method and then mixed with Mg2TiO4 powders to fabricate BSTM-MT composite ceramics. The morphologies, phases, elements, and dielectric properties of the sintered ceramics were investigated. The core-shell structure of BST powder wrapped with MgO was clearly observed from the TEM image. After sintered at 1100 °C for 2 h, the composite ceramics expressed dense microstructures from SEM images and two main phases BST and Mg2TiO4 were detected in the XRD patterns. The dielectric constant and loss tangent were both reduced after the coating. The reduced dielectric constant and loss tangent of BSTM-MT were 190, 0.0011 (2MHz), respectively. The ceramics exhibited the diffuse phase transition near the Curie temperature and the Curie temperature shifted from 10 °C to 5 °C after the coating. Since the continuous Ti-O bonds were disconnected with the MgO coating, the tunability was reduced to 15.14 % under a DC bias field of 1.1 kV/mm. The optimistic dielectric properties made it useful for the application of tunable capacitors and phase shifters.

Single Crystals of Ice Grown from KCl Solution and Their Dielectric Properties

1973 ◽  
Vol 51 (10) ◽  
pp. 1045-1052 ◽  
Author(s):  
Norikazu Maeno
Keyword(s):  
Activation Energy ◽  
Dielectric Properties ◽  
Crystal Lattice ◽  
Single Crystals ◽  
Low Frequency ◽  
Distribution Coefficients ◽  
Square Root ◽  
Dielectric Polarization ◽  
Kcal Mole ◽  
Upper Limit

Single crystals of ice were grown from KCl solution and their dielectric properties were investigated as functions of concentration, frequency, and temperature. It was found that a limited amount of chlorine was incorporated into the crystal lattice of ice but no trace of potassium. The upper limit of the substitutional incorporation of chlorine was approximately 1 × 10−4M(g moles/1). The distribution coefficients of the solutes were obtained as functions of the KCl concentration of the mother solution.The static dielectric constant of the single crystals of ice decreased due to the chlorine incorporation and the activation energy of its dielectric relaxation was reduced to 5.8 kcal/mole. The low-frequency conductivity increased with the square root dependence upon the chlorine concentration, and its activation energy was 6.1 kcal/mole. The mechanism of the dielectric polarization and conduction was discussed in relation to the defects introduced by chlorine built in the crystal lattice.

Growth and characterization of divalent transition metal ions doped zinc hydrogen phosphate single crystals

2018 ◽  
Author(s):  
Delma D’Souza ◽  
N. Jagannatha ◽  
K. P. Nagaraja ◽  
P. S. Rohith ◽  
K. V. Pradeepkumar
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Single Crystals ◽  
Transition Metal Ions ◽  
Hydrogen Phosphate

EFFECT OF IMPURITIES ON THE DIELECTRIC PROPERTIES OF OLEIC ACID

2012 ◽  
Vol 02 (03) ◽  
pp. 1250014
Author(s):  
F. F. DE SOUSA ◽  
P. T. C. FREIRE ◽  
J. MENDES FILHO ◽  
A. C. OLIVEIRA ◽  
E. LONGHINOTTI ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dipole Moment ◽  
Oleic Acid ◽  
Dielectric Properties ◽  
Melting Point ◽  
Temperature Dependence ◽  
Effect Of Impurities ◽  
Correlation Parameters

Temperature dependence of the dielectric constant of oleic acid with different degrees of purity was measured in the 233–313 K range. It was observed that the presence of impurities (palmitic and linolenic acids) strongly influences the dielectric constant, melting point and dipole moment of the oleic acid. The values of apparent dipole moment and the Kirkwood correlation parameters were evaluated using the Kirkwood's model and were estimated to be about 1.20, 1.61 and 2.27 D, respectively for 60, 90 and 97 wt% oleic acid.

Effect of Platinum Substitution on the Microstructures and Dielectric Relaxation of CaCu3Ti4O12 Ceramics

2013 ◽  
Vol 802 ◽  
pp. 134-138 ◽  
Author(s):  
Worawut Makcharoen
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Loss Tangent ◽  
Room Temperature ◽  
High Dielectric Constant ◽  
Ferroelectric Materials ◽  
X Ray Diffraction ◽  
High Loss ◽  
Internal Barrier Layer Capacitor ◽  
High Dielectric

The CaCu3Ti4O12(CCTO) has the advantage for the various applications especially for capacitive elements in microelectronic devices over the ferroelectric materials including BaTiO3. CCTO is a ceramic compound with a high dielectric constant but it has a high loss tangent at room temperature. In this work, the Influences of PtO2doping on the dielectric properties of CaCu3Ti4O12(CCTO) ceramics were investigate. The ceramics CCTO and PtO2doping CCTO were studied by X- ray diffraction, scanning electron microscopy. The dielectric properties have been measured as a function of temperature and frequency range 0.1 - 500 kHz. The XRD shows the CCTO structure does not changes after doping with platinum. The results show that PtO2doped can reduce the mean grain sizes of CCTO, but the dielectric constant still remained a height. The samples of 2.0 mol% Pt-doped have exhibited high dielectric constant of about 22,000 and the loss tangent about 0.7 at room temperature and frequency at 10 kHz. The reduced of the loss tangent could be interpreted with the internal barrier layer capacitor model (IBLC)

scholarly journals Dielectric properties of zinc sulfide concentrate during the roasting at microwave frequencies

2017 ◽  
Author(s):  
Guangjun He ◽  
Shiwei Li ◽  
Kun Yang ◽  
Jian Liu ◽  
Peng Liu ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Zinc Sulfide ◽  
Apparent Density ◽  
Loss Tangent ◽  
Loss Factor ◽  
Microwave Energy ◽  
Dielectric Loss Factor ◽  
Sulfide Concentrate

Microwave technology has a potential application in the extraction of zinc from sulphide ores, knowledge of the dielectric properties of these ores plays a major role in the microwave design and simulation for any process. The dielectric properties of zinc sulfide concentrate for two different apparent densities—1.54 and 1.63 g/cm3—have been measured by using the resonance cavity perturbation technique at 915 and 2450 MHz during the roasting process for the temperature ranging from room temperature to 850 °C. The variations of dielectric constant, the dielectric loss factor, the dielectric loss tangent and the penetration depth with the temperature, frequency and apparent density have been investigated numerically. The results indicate that the dielectric constant increases as the temperature increases and temperature has a pivotal effect on the dielectric constant, while the dielectric loss factor has a complicated change and all of the temperature, frequency and apparent density have a significant impact to dielectric loss factor. Zinc sulfide concentrate is high loss material from 450 to 800 °C on the basis of theoretical analyses of dielectric loss tangent and penetration depth, its ability of absorbing microwave energy would be enhanced by increasing the apparent density as well. The experimental results also have proved that zinc sulfide concentrate is easy to be heated by microwave energy from 450 to 800 °C. In addition, the experimental date of dielectric constant and loss factor can be fitted perfectly by Boltzmann model and Gauss model, respectively.

Behavior of Implanted α-Al2O3 in an Oxidizing Annealing Environment

1983 ◽  
Vol 27 ◽  
Author(s):  
G. C. Farlow ◽  
C. W. White ◽  
C. J. Mchargue ◽  
B. R. Appleton
Keyword(s):  
Transition Metal ◽  
Single Crystals ◽  
Bulk Diffusion ◽  
Transition Metal Ions ◽  
Divalent Ions ◽  
Oxygen Sublattice ◽  
Group Iii ◽  
Random Direction ◽  
Α Al2o3 ◽  
Flowing Oxygen

ABSTRACTThe transition metal ions Fe, Mn, Ni, Ti, and Cr as well as the group III-A ion Ga were implanted in a random direction close to the c-axis of α-Al2O3 single crystals. These were subsequently annealed in flowing oxygen at temperatures between 600 and 1500°C. The impurity and damage distributions were determined by He backscattering and channeling techniques. The normally trivalent ions, Fe, Ga, and Cr show strong tendency to become incorporated into substitutional sites, whereas the normally divalent ions, Cu and Mn show no such tendency, even at high temperatures. Most of the impurities tend to move toward the surface with only Fe, Ga, and Cr showing tendency towards bulk diffusion. In all cases the Al sublattice recovers at lower temperatures than the oxygen sublattice.

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