This specification discloses methods of enhancing the stability and performance of Eu.sup.2+ doped narrow band red emitting phosphors. In one embodiment the resulting phosphor compositions are characterized by crystallizing in ordered structure variants of the UCr.sub.4C.sub.4 crystal structure type and having a composition of AE.sub.1−xLi.sub.3−2yAl.sub.1+y−zSi.sub.zO.sub.4−4y−zN.sub.4y+z:Eu.sub.x (AE=Ca, Sr, Ba, or a combination thereof, 0<x<0.04, 0≤y<1, 0<z<0.05, y+z≤1). It is believed that the formal substitution (Al,O).sup.+ by (Si,N).sup.+ reduces the concentration of unwanted Eu.sup.3+ and thus enhances properties of the phosphor such as stability and conversion efficiency.

Provided a method of producing a β-sialon fluorescent material having excellent emission intensity. The method includes providing a first composition containing aluminum, an oxygen atom, and a europium-containing silicon nitride, heat treating the first composition, contacting the heat-treated composition and a basic substance to obtain a second composition, and contacting the second composition resulting from contacting the heat-treated composition with the basic substance and an acidic liquid medium containing an acidic substance.

Provided a method of producing a β-sialon fluorescent material having excellent emission intensity. The method includes providing a first composition containing aluminum, an oxygen atom, and a europium-containing silicon nitride, heat treating the first composition, contacting the heat-treated composition and a basic substance to obtain a second composition, and contacting the second composition resulting from contacting the heat-treated composition with the basic substance and an acidic liquid medium containing an acidic substance.

A method of forming an alkali metal-doped calcium-SiAlON material is provided. The method includes mixing calcium-SiAlON powder and an alkali metal hydroxide to form a reaction mixture. The mixture further includes spark plasma sintering (SPS) the reaction mixture at 800 to 940 degrees Celsius (° C.) to form the alkali metal-doped calcium-SiAlON material. The alkali metal hydroxide is present in an amount of 0.1 to 10 weight percentage (wt. %), based on a total weight of the reaction mixture.

A method of making a β-SiAlON is described in involves mixing nanoparticles of AlN, Al.sub.2O.sub.3, and SiO.sub.2 with particles of Si.sub.3N.sub.4 and spark plasma sintering the mixture. The sintering may be at a temperature of 1450-1600° C. or about 1500° C. The particles of Si.sub.3N.sub.4 may be nanoparticles comprising amorphous Si.sub.3N.sub.4, or 25-55 μm diameter microparticles comprising β-Si.sub.3N.sub.4.

Electrode for an energy storage device which comprises a powder of particles (26) comprising amorphous, micro- or nano-crystalline coated or uncoated silicon oxynitride having a chemical formula SiN.sub.xO.sub.y, where 0.03≤x+y<1.3, whereby nitrogen makes up 10-99% of said x+y value with the balance being oxygen.

Provided is a method for producing a phosphor, using a nitride raw material, that gives a high-reliability (Sr,Ca)AlSiN.sub.3-based nitride phosphor at a productivity higher than before. The method comprises a mixing step of mixing raw materials and a calcining step of calcining the mixture obtained in the mixing step and, in producing the phosphor having a crystalline structure substantially identical with that of (Sr,Ca)AlSiN.sub.3 crystal as the host crystal, a strontium nitride containing SrN, Sr.sub.2N, or the mixture thereof as the main crystalline phase, as determined by crystalline phase analysis by powder X-ray diffractometry, and having a nitrogen content of 5 to 12 mass % is used as part of the raw materials.

A ceramic material includes of β-sialon (Si.sub.(6-z)Al.sub.zO.sub.zN.sub.(8-z)), polytype 15R, an intergranular phase, and yttrium. The polytype 15R includes twin grains.

An α-sialon phosphor particle containing Eu. At least one minute recess is formed on a surface of the α-sialon phosphor particle. The α-sialon phosphor particle is preferably produced by undergoing a raw material mixing step, a heating step, a pulverizing step, and an acid treatment step.

This specification discloses a method of enhancing the stability and performance of Eu.sup.2+ doped narrow band red emitting phosphors. The resulting phosphor compositions are characterized by crystallizing in ordered structure variants of the UCr.sub.4C.sub.4 crystal structure type and having a composition of AE.sub.1−xLi.sub.3−2yAl.sub.1+2y−zSi.sub.zO.sub.4−4y−zN.sub.4y+z:EU.sub.x(AE=Ca, Sr, Ba; 0<x<0.04, 0≤y<1, 0<z<0.05, y+z≤1). It is believed that the formal substitution (Al,O).sup.+ by (Si,N).sup.+ reduces the concentration of unwanted Eu.sup.3+ and thus enhances properties of the phosphor such as stability and conversion efficiency.