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| Author | : Sudhir R. Kulkarni |
| Publisher | : |
| Total Pages | : 444 |
| Release | : 1986 |
| Genre | : Barium titanate |
| ISBN | : |
| Author | : Jeffrey Duncan Keck |
| Publisher | : |
| Total Pages | : 0 |
| Release | : 1976 |
| Genre | : |
| ISBN | : |
"The stability of BaTiO3-type insulators to DC fields has long been recognized as one of the important factors in determining the quality of a capacitor which uses such a material as its dielectric. The slow increase of the electrical conductivity of an insulator which is stressed by DC fields at levels below the breakdown strength is normally termed degradation. Since degradation is a very common malady to the ceramic capacitor manufacturers, many studies have been conducted over the past two decades in efforts to learn how to remedy the problem. The results of previous studies have shown that certain dopants (present both as intentional additives and as impurities), the Ba:Ti ratio, and hydroxyl content greatly influence the degradation process. Since all of the studies have been carried out on ill-defined commercial materials, no correlation between defect structure and degradation has been possible. It was the intent of this present investigation to study degradation in well-defined BaTiO3 (both high purity and intentionally doped) with the intent of developing a defect model which can be used to explain the influence of dopants and Ba:Ti ratio upon degradation. High purity BaTiO3 powder was prepared by a chemical preparation technique which allows the ratio of cations and dopant levels to be precisely controlled. The DC current-voltage characteristics of sintered discs were measured as a function of both time and temperature. Undoped BaTiO3 with a Ba:Ti ratio less than unity had the greatest tendency to degrade. Undoped and acceptor doped material with a Ba:Ti ratio greater than unity had a high resistance to degradation. Donor and acceptor doping with a Ba:Ti ratio less than unity improved the degradation resistance while donor doping with a Ba:Ti ratio greater than one increased the degradation. To explain the observed behavior, a model is presented that includes the effect of acceptors, donors, and the Ba:Ti ratio on the degradation process"--Abstract, leaves ii-iii
| Author | : |
| Publisher | : |
| Total Pages | : 684 |
| Release | : 1987 |
| Genre | : Dissertations, Academic |
| ISBN | : |
| Author | : |
| Publisher | : |
| Total Pages | : 606 |
| Release | : 1986 |
| Genre | : Dissertations, Academic |
| ISBN | : |
| Author | : M. Hasan |
| Publisher | : |
| Total Pages | : 9 |
| Release | : 2013 |
| Genre | : Barium titanate |
| ISBN | : |
The effects of zinc oxide addition and sintering parameters on the structure and dielectric properties of barium titanate are observed. Different percentage of ZnO ranging from 0.30 to 1 wt. % is doped in barium titanate. Both the doped and undoped samples are sintered at temperatures ranging from 1250°C to 1325°C at different soaking times. The amount of densification of the doped and undoped samples is measured in terms of percentage theoretical density. Grain size and microstructural analysis is performed by a scanning electron microscope (SEM). Lattice parameters and tetragonality of doped and undoped barium titanate are calculated from x-ray diffraction pattern obtained from x-ray diffractometer (XRD) test. Dielectric properties of the samples are measured by an impedance analyzer. It is found that all the doped samples obtain their maximum percentage theoretical density at a lower sintering temperature compared to the undoped sample. SEM study reveals that the doped samples always show smaller grains compared to the undoped sample. Significant grain growth is observed in all of the samples at sintering temperatures above 1300°C. The evidence of surface melting is observed in 1 wt. % ZnO-doped sample soaked at 1325°C for 2 h. The presence of liquid at that sintering condition is explained by the doping mechanism of Zn2+ in BaTiO3. Correlation among the grain size, tetragonality, and dielectric properties of the doped and undoped samples are also discussed.
| Author | : Wayne Huebner |
| Publisher | : |
| Total Pages | : 353 |
| Release | : 1987 |
| Genre | : |
| ISBN | : |
| Author | : |
| Publisher | : |
| Total Pages | : 1116 |
| Release | : 1989 |
| Genre | : Dissertations, Academic |
| ISBN | : |
| Author | : |
| Publisher | : |
| Total Pages | : 524 |
| Release | : 1987 |
| Genre | : Materials at high temperatures |
| ISBN | : |
| Author | : Adil Alshoaibi |
| Publisher | : |
| Total Pages | : |
| Release | : 2017 |
| Genre | : |
| ISBN | : |
| Author | : R. Saravanan |
| Publisher | : Materials Research Forum LLC |
| Total Pages | : 167 |
| Release | : 2018-02-25 |
| Genre | : Technology & Engineering |
| ISBN | : 1945291559 |
Barium titanate is one of the most important electronic materials; due to its high permittivity, low dielectric loss and high tunability. The environment friendly material is suitable for microphones and microwave device applications such as tunable capacitors, delay lines, filters, resonators and phase shifters. Doped titanates are extensively used for various electronic devices, such as transducers, piezoelectric actuators, passive memory storage devices, dynamic random access memory (DRAM), multilayer ceramic capacitors (MLCCs), positive temperature coefficient resistors (PTCR), optoelectronic devices and infrared sensors. The book presents research results concerning the electron density distribution in a number of doped barium titanate ceramic materials using experimental X-ray diffraction data, UV-visible spectrophotometry (UV-vis), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The analysis of interatomic bonding and electron density distribution is important for predicting the properties of potentially important materials and has previously been lacking for the materials studied. Barium Titanate, Barium Titanate Doping, Dielectric Ceramics, Permittivity, Tunability, Transducers, Piezoelectric Actuators, Memory Storage Devices, Multilayer Ceramic Capacitors, Optoelectronic Devices, X-Ray Diffraction Data, UV-Visible Spectrophotometry, Energy Dispersive X-Ray Spectroscopy, Interatomic Bonding, Electron Density Distribution, Ceramic Property Predictions.
