There is herein described a method of making a single crystal wavelength conversion element from a polycrystalline wavelength conversion element, a single crystal wavelength conversion element, and a light source containing same. By making the single crystal wavelength conversion element from a polycrystalline wavelength conversion element, the method provides greater flexibility in creating single crystal wavelength conversion elements as compared to melt grown methods for forming single crystals. Advantages may include higher activator contents, forming more complex shapes without machining, providing a wider range of possible activator gradients and higher growth rates at lower temperatures.

A heater tube for molten metal immersion 1 has a cylindrical heater housing part 4 equipped with a closed end 2 and an open end 3, wherein the heater housing part 4 comprises silicon nitride, a compound comprising yttrium, and a compound comprising magnesium. The heater housing part 4 has a surface roughness Ra of an outer circumferential surface of the heater housing part 4 is between 0.5 m and 10 m, inclusive.

A silicon nitride substrate including silicon nitride crystal grains and a grain boundary phase and having a thermal conductivity of 50 W/m.Math.K or more, wherein, in a sectional structure of the silicon nitride substrate, a ratio (T2/T1) of a total length T2 of the grain boundary phase in a thickness direction with respect to a thickness T1 of the silicon nitride substrate is 0.01 to 0.30, and a variation from a dielectric strength mean value when measured by a four-terminal method in which electrodes are brought into contact with a front and a rear surfaces of the substrate is 20% or less. The dielectric strength mean value of the silicon nitride substrate can be 15 kV/mm or more. According to above structure, there can be obtained a silicon nitride substrate and a silicon nitride circuit board using the substrate in which variation in the dielectric strength is decreased.

A silicon nitride substrate including silicon nitride crystal grains and a grain boundary phase and having a thermal conductivity of 50 W/m.Math.K or more, wherein, in a sectional structure of the silicon nitride substrate, a ratio (T2/T1) of a total length T2 of the grain boundary phase in a thickness direction with respect to a thickness T1 of the silicon nitride substrate is 0.01 to 0.30, and a variation from a dielectric strength mean value when measured by a four-terminal method in which electrodes are brought into contact with a front and a rear surfaces of the substrate is 20% or less. The dielectric strength mean value of the silicon nitride substrate can be 15 kV/mm or more. According to above structure, there can be obtained a silicon nitride substrate and a silicon nitride circuit board using the substrate in which variation in the dielectric strength is decreased.

Ceramic particles for use in a solar power tower and methods for making and using the ceramic particles are disclosed. The ceramic particle can include a sintered ceramic material formed from a mixture of a ceramic raw material and a darkening component comprising MnO as Mn.sup.2+. The ceramic particle can have a size from about 8 mesh to about 170 mesh and a density of less than 4 g/cc.

Ceramic particles for use in a solar power tower and methods for making and using the ceramic particles are disclosed. The ceramic particle can include a sintered ceramic material formed from a mixture of a ceramic raw material and a darkening component comprising MnO as Mn.sup.2+. The ceramic particle can have a size from about 8 mesh to about 170 mesh and a density of less than 4 g/cc.

According to an example, a green body may include from about 1 wt. % to about 20 wt. % of a metal nanoparticle binder and a build material powder, wherein the metal nanoparticle binder is selectively located within an area of the green body to impart a strength greater than about 3 MPa.

A silicon nitride substrate including silicon nitride crystal grains and a grain boundary phase and having a thermal conductivity of 50 W/m.Math.K or more, wherein, in a sectional structure of the silicon nitride substrate, a ratio (T2/T1) of a total length T2 of the grain boundary phase in a thickness direction with respect to a thickness T1 of the silicon nitride substrate is 0.01 to 0.30, and a variation from a dielectric strength mean value when measured by a four-terminal method in which electrodes are brought into contact with a front and a rear surfaces of the substrate is 20% or less. The dielectric strength mean value of the silicon nitride substrate can be 15 kV/rum or more. According to above structure, there can be obtained a silicon nitride substrate and a silicon nitride circuit board using the substrate in which variation in the dielectric strength is decreased.

A silicon nitride substrate including silicon nitride crystal grains and a grain boundary phase and having a thermal conductivity of 50 W/m.Math.K or more, wherein, in a sectional structure of the silicon nitride substrate, a ratio (T2/T1) of a total length T2 of the grain boundary phase in a thickness direction with respect to a thickness T1 of the silicon nitride substrate is 0.01 to 0.30, and a variation from a dielectric strength mean value when measured by a four-terminal method in which electrodes are brought into contact with a front and a rear surfaces of the substrate is 20% or less. The dielectric strength mean value of the silicon nitride substrate can be 15 kV/rum or more. According to above structure, there can be obtained a silicon nitride substrate and a silicon nitride circuit board using the substrate in which variation in the dielectric strength is decreased.

Porous structures are made from compositions that include hollow glass bodies and an inorganic powder. The inorganic powder may act as a rigid frame member, a crystallization agent, or both, which reduces the shrinkage of the porous structures during firing. The porous structures made therefrom have an open porosity of greater than 70% and reduced shrinkage of less than 10% compared to the green structures prior to firing. Methods for firing the green structures made from the compositions are also disclosed, the firing methods including reducing a temperature ramping rate of the green structures during a crystallization temperature range of the glass of the hollow bodies.