Abstract: Methods of coating ceramic (e.g., barium titanate-based) particles, as well as articles and compositions formed from the coated particles are provided. The methods involve forming a mixture of barium titanate-based particles and at least two dopant metal solutions. According to some methods, a second solution (e.g., a base) is added to the mixture to cause the dopant metals to sequentially precipitate onto surfaces of the particles. The resulting particles are coated with respective layers having different dopant metal compositions. According to other methods, the mixture of barium titanate-based particles and at least two dopant metal solutions are added to a second solution (e.g., a base) to precipitate the dopant metal or metals to form a coating on surfaces of the barium titanate-based particles. The resulting particles are coated with a homogeneous coating.

Abstract: Methods of heat treating barium titanate-based particles are provided, as well as compositions and devices formed from the particles. The methods involve forming a coating on surfaces of barium titanate-based particles and heating the coated particles, for example, to a temperature of greater than about 400° C. and less than about 1150° C. The heating step may increase the bond strength between the coating and barium titanate-based particles, reduce the average specific surface area of the coated particles, remove water present in the coating, and remove other contaminants from the composition, amongst other advantages. These effects of heat treating can improve the performance of devices (e.g., MLCCs) that include dielectric layers formed from the barium titanate-based particles.

Abstract: The invention provides dielectric compositions and methods of forming the same. The dielectric compositions may be used to form dielectric layers in electronic devices such as multilayer ceramic capacitors (MLCCs) and, in particular, MLCCs which include base metal electrodes. The dielectric compositions include a barium titanate-based material and several dopants. The type and concentration of each dopant is selected to provide the dielectric composition with desirable electrical properties including a stable capacitance over a temperature range, a low dissipation factor, and a high capacitance. Preferably, MLCCs including dielectric layers formed with the composition satisfy X7R and/or X5R requirements.

Abstract: Coated barium titanate-based particles and a process to coat the particles are provided. The coating includes a dopant metal compound that is insoluble in water under alkaline conditions. The dopant metal in the coating is selected from the group of metals which form oxides or hydroxides that are soluble in water under alkaline conditions such as tungsten, molybdenum, vanadium, and chromium. The process involves precipitating the insoluble compound from an aqueous medium as a coating on surfaces of barium titanate-based particles. The coated barium titanate-based particles may be further processed, for example, to form dielectric materials which may be used in many electronic applications such as in MLCCs applications.

Abstract: Methods of forming dispersible dielectric particles, as well as articles and compositions that include the dispersible dielectric particles, are provided. The methods involve forming an aqueous mixture of dielectric (e.g., barium titanate-based) particles and replacing at least a portion of water in the mixture with a non-aqueous solvent (e.g., ethanol). According to one set of methods, the particles are then dried. The limited, or lack, of water present in the mixture during drying reduces capillary forces that otherwise may draw the particles together to cause formation of strong agglomerates. Thus, particle agglomeration during drying may be reduced which increases particle dispersibility. According to another set of methods of the invention, the particles are not dried after non-aqueous solvent replacement, thus, avoiding formation of agglomerates during drying and increasing dispersibility.

Abstract: Dispersible barium titanate-based particles and methods of forming the same are provided. One method involves subjecting the barium titanate-based particles to a heating step which removes hydroxyl groups from particle surfaces. Another method involves attaching a coupling agent to surfaces of the barium titanate-based particles. Both methods reduce the tendency of particles to agglomerate and/or aggregate when subsequently dispersed in a fluid. Thus, the methods enable production of dispersions that have a relatively uniform distribution of particles throughout. Such dispersions may be further processed as desired to form, for example, dielectric layers, polymer/dielectric composites or other structures. The structure may also include a uniform distribution of barium titanate-based particles which can improve properties amongst other advantages.

Abstract: The invention provides dielectric compositions and methods of forming the same. The dielectric compositions may be used to form dielectric layers in electronic devices such as multilayer ceramic capacitors (MLCCs) and, in particular, MLCCs which include base metal electrodes. The dielectric compositions include a barium titanate-based material and several dopants. The type and concentration of each dopant is selected to provide the dielectric composition with desirable electrical properties including a stable capacitance over a temperature range, a low dissipation factor, and a high capacitance. Preferably, MLCCs including dielectric layers formed with the composition satisfy X7R and/or X5R requirements.

Abstract: The present invention is directed to electrode additives, electrode compositions including the additives, capacitor structures formed using the electrode compositions, and methods of forming the electrode additives, the electrode compositions and the capacitor structures. For example, the electrode composition may be used to form electrode layers in electronic devices, such as multi-layer ceramic capacitors (MLCCs). The electrode composition is particularly well-suited for use with MLCCs that have base metal (e.g., nickel) electrodes.

Abstract: Coated barium titanate-based particles and a process to coat the particles are provided. The coating includes a dopant metal compound that is insoluble in water under alkaline conditions. The dopant metal in the coating is selected from the group of metals which form oxides or hydroxides that are soluble in water under alkaline conditions such as tungsten, molybdenum, vanadium, and chromium. The process involves precipitating the insoluble compound from an aqueous medium as a coating on surfaces of barium titanate-based particles. The coated barium titanate-based particles may be further processed, for example, to form dielectric materials which may be used in many electronic applications such as in MLCCs applications.

Abstract: A polymer matrix composite. The composite is made from a mixture of barium titanate-based particles dispersed in a polymeric resin. The mixture includes more than one barium titanate-based component, with each component having a different composition. The different barium titanate-based components are present in the mixture in specific proportions to provide the mixture with a relatively high, temperature-stable dielectric constant. Preferably, the mixture and resulting composite meets the temperature stability requirements to satisfy X7R capacitor specifications. The polymer matrix composite may be used in a number of applications, such as printed circuit boards which include embedded capacitors.

Abstract: Barium titanate-based particles having a coating comprising an oxide, hydrous oxide, hydroxide or organic acid salt of a metal other than barium or titanium, wherein at least 90 percent of said particles have a particle size less than 0.9 micrometer when said particles are dispersed by high shear mixing, useful in the fabrication of thin, fine-grained dielectric layers for multilayer ceramic capacitors with high breakdown voltage.

Abstract: Barium titanate-based particles having a coating comprising an oxide, hydrous oxide, hydroxide or organic acid salt of a metal other than barium or titanium, wherein at least 90 percent of said particles have a particle size less than 0.9 micrometer when said particles are dispersed by high shear mixing, useful in the fabrication of thin, fine-grained dielectric layers for multilayer ceramic capacitors with high breakdown voltage.

Abstract: Barium titanate-based particles having a coating comprising an oxide, hydrous oxide, hydroxide or organic acid salt of a metal other than barium or titanium, wherein at least 90 percent of said particles have a particle size less than 0.9 micrometer when said particles are dispersed by high shear mixing, useful in the fabrication of thin, fine-grained dielectric layers for multilayer ceramic capacitors with high breakdown voltage.

Abstract: A method for producing phase-pure, monodispersed, single crystal alpha-alumina particles of controlled size and shape comprises the steps of providing an aluminum hydrous oxide precursor and a glycol solution, dispersing said precursor in said glycol solution to create a suspension, heating and stirring said suspension in a closed pressure vessel to produce alpha-alumina particles, cooling said suspension, and removing said alpha-alumina particles from said solution. Additionally nucleation seeds may be added to the solution. Control of size is a function of seeding concentration, and control of morphology is a function of stirring rate.