A composite oxide contains oxides of aluminum, strontium, cerium, lanthanum, and manganese. A light emitting aspect of the composite oxide when the composite oxide is irradiated with a first electromagnetic wave having a wavelength not longer than 300 nm is different from a light emitting aspect of the composite oxide when the composite oxide is irradiated with a second electromagnetic wave having a wavelength longer than 300 nm.

Provided is a reddish light emitting phosphorescent phosphor, that is efficiently excited with visible light and is chemically stable. The phosphorescent phosphor comprises a compound represented by MSi.sub.2O.sub.2N.sub.2:Yb,R, wherein M is at least one metal element selected from strontium, calcium, barium, and magnesium, and R is at least one element selected front erbium, holmium, gadolinium, praseodymium, terbium, dysprosium, neodymium, bismuth, scandium, and chromium. The phosphorescent phosphor is an excellent phosphorescent phosphor having a reddish afterglow.

The present invention relates to a crystalline material comprising a basic crystal based on at least one host element (We), which basic crystal is doped with at least one element of the rare earths (Do), the crystalline material having the formula:

We1.sub.(a)We2.sub.(b)Ta.sub.(c)Do1.sub.(d)Do2.sub.(e)Hal.sub.(w)O.sub.(x)Te.sub.(y)Se.sub.(z)

A coating including a plurality of indicator oxide nanoparticles, a binder, and a wetting agent. A sulfidation corrosion mitigation coating including: a sulfidation corrosion mitigation material, a binder, and a plurality of indicator oxide nanoparticles. An article including a metal alloy substrate having the sulfidation corrosion mitigation coating thereon is also provided. The sulfidation corrosion mitigation coating can include a first indicator layer containing indicator oxide nanoparticles disposed on the surface of the metal alloy substrate. Methods for inspection of an article having a coating containing a plurality of indicator oxide nanoparticles is also provided.

A coating including a plurality of indicator oxide nanoparticles, a binder, and a wetting agent. A sulfidation corrosion mitigation coating including: a sulfidation corrosion mitigation material, a binder, and a plurality of indicator oxide nanoparticles. An article including a metal alloy substrate having the sulfidation corrosion mitigation coating thereon is also provided. The sulfidation corrosion mitigation coating can include a first indicator layer containing indicator oxide nanoparticles disposed on the surface of the metal alloy substrate. Methods for inspection of an article having a coating containing a plurality of indicator oxide nanoparticles is also provided.