Various embodiments disclosed relate to an optical window including an infrared light transmissive optical material. The optical material includes a first ceramic phase including a first ceramic material and a first dopant distributed therein. The optical material further includes a second ceramic phase homogenously intermixed with the first ceramic phase and comprising a second ceramic material and a second dopant distributed therein. The first dopant increases the refractive index of the first ceramic material and the second dopant decreases the refractive index of the second ceramic material. The first dopant and the second dopant are present in an amount such that a difference in a refractive index of the first ceramic phase and of the second ceramic phase is in a range of from about 0.001 to about 0.2.

A zirconia ceramic material for use in dental applications is provided comprising an yttria-stabilized zirconia material stabilized with 5 mol % yttria to 8 mol % yttria, and methods for making a sintered body from the ceramic material. The zirconia ceramic materials exhibit both enhanced translucency and a flexural strength of at least 300 MPa, or at least 500 MPa, when fully sintered.

A preparation method for a ceramic composite material, a ceramic composite material, and a wavelength converter. The preparation method comprises: preparing an aluminium salt solution and a fluorescent powder; dispersing the fluorescent powder into a buffer solution having a pH 4.5-5.5 to obtain a suspension; titrating the suspension with the aluminium salt solution to obtain a fluorescent powder coated with Al.sub.2O.sub.3 hydrate film; calcining the fluorescent powder coated with Al.sub.2O.sub.3 hydrate film to obtain a Al.sub.2O.sub.3-coated fluorescent powder; mixing aluminium oxide powder with a particle size of 0.1 μm-1 μm and aluminium oxide powder with a particle size of 1 μm-10 μm to obtain mixed aluminium oxide powder; mixing the Al.sub.2O.sub.3-coated fluorescent powder and the mixed aluminium oxide powder to obtain mixed powder, the Al.sub.2O.sub.3-coated fluorescent powder being present in 40%-90% by weight of the mixed powder; and pre-pressing and sintering the mixed powder to obtain the ceramic composite material.

A process for preparing roofing granules includes forming kaolin clay into green granules and sintering the green granules at a temperature of at least 900 degrees Celsius to cure the green granules until the crystalline content of the sintered granules is at least ten percent as determined by x-ray diffraction.

In one aspect of the present disclosure, there is provided an optical wavelength conversion member including a polycrystalline ceramic sintered body containing, as main components, Al.sub.2O.sub.3 crystal grains and crystal grains represented by formula X.sub.3Al.sub.5O.sub.12:Ce. In the optical wavelength conversion member 9, atoms of element X are present also in an Al.sub.2O.sub.3 crystal grain adjacent to the interface between the Al.sub.2O.sub.3 crystal grain and an X.sub.3Al.sub.5O.sub.12:Ce crystal grain.

Provided are a method for producing a ceramic composite material that has a high light emission intensity, a ceramic composite material, and a light emitting device. The method for producing a ceramic composite material, includes: preparing a green body containing a nitride fluorescent material having a composition represented by the following chemical formula (I) and aluminum oxide particles mixed with each other; and performing primary sintering the green body at a temperature in a range of 1,250° C. or more and 1,600° C. or less to provide a first sintered body:
M.sub.wLn.sup.1.sub.xA.sub.yN.sub.z  (I)
wherein in the chemical formula (I), M represents at least one element selected from the group consisting of Ce and Pr; Ln.sup.1 represents at least one element selected from the group consisting of Sc, Y, La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; A represents at least one element selected from the group consisting of Si and B; and w, x, y, and z each satisfy 0<w≤1.0, 2.5≤x≤3.5, 5.5≤y≤6.5, and 10≤z≤12.

Solar reflective roofing granules include a binder and inert mineral particles, with solar reflective particles dispersed in the binder. An agglomeration process preferentially disposes the solar reflective particles at a desired depth within or beneath the surface of the granules.

Provided are a transparent fluorescent sialon ceramic having fluorescence and optical transparency; and a method of producing the same. Such a transparent fluorescent sialon ceramic includes a sialon phosphor which contains a matrix formed of a silicon nitride compound represented by the formula M.sub.x(Si,Al).sub.y(N,O).sub.z (here, M represents at least one selected from the group consisting of Li, alkaline earth metals, and rare earth metals, 0≤x/z<3, and 0<y/z<1) and a luminescent center element.

A garnet-structure complex oxide powder having formula (1) is prepared by adding an aqueous solution containing (a) Tb ion, an aqueous solution containing (b) Al ion, and an aqueous solution containing (c) Sc ion to a co-precipitating aqueous solution, to induce a co-precipitate of components (a), (b) and (c), filtering, heat drying and firing the co-precipitate.
(R.sub.1-xSc.sub.x).sub.3(A.sub.1-ySc.sub.y).sub.5O.sub.12  (1)
R is yttrium or a lanthanoid element, typically Tb, A is a Group 13 element, typically Al, x and y are 0<x<0.08 and 0.004<y<0.16.

The light shielding member of the present disclosure includes an aluminum oxide ceramics including an oxide of titanium whose composition formula is shown as TiO.sub.2-x (1≤x<2), and a total content of Fe, Ni, Co, Mn and Cr is 260 mass ppm or less.