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The dctails of the luminescence spectra of Bi3+ in MgO and CaO havc bcen examined over a wide range of temperature. It is found that emission from both 3P0 and 3P, excited states to the 'So ground state occurs, the former forbidden t,ransition dominating a t low temperatnres and the latter a t high temperatures. The bands can be resolved from one another, thus permitting the intensities and lifetimes of each transition to bc followed. These measurcmcnts show t,hat over a substantial ternperaturc rangc the two excited stat,cs arc in thermal equilibrium, and the decay characteristics are examined with the aid of a model developed in the Appendix. The radiativc lifetimes of the 3P, and 3P0 states are found to be 4 X lo-* and 2.9 x and 3.8 X s in CaO. With the aid of the discovery of the true zero-phonon line for the 3P0 + ISo transition in CaO: Hi a t 383.98 nm, the form of the vibronic series for this transition can bc interpreted. The forbidden transition is made slightly allowed by a combination of a static pcrt.urbation and coupling to a vibrational mode which mixes t.he 3P,, and 3P1 states. This interpretation is consistent. with the rcsults of magnetic-field cnhaneement of the zerophoiion line intensity reported by Itunciman e t a1.Die Lumineszenzspcktren von Bi3+ in MgO und CaO werdenin einem breitcn Temperaturbereich untcrsucht. Dabei wird gefunden, daB Emission sowohl vom als auch vom 3P,-Anregnngszustand znm IS,-Grundzustand stattfindct, wobei dcr erstgenannte, vcrbotene Ubcrgang bei nicdrigeren und der zweite bci hoheren Temperaturen iibcrwiegt. Die Banden lasscn sich voneinandcr trennen, wodurch die Intensitiit und Lebensdauer beider tJbergilnge verfolgt werderi kiinnen. Solche Messungcii zeigeri, daO die beiden Anregungszustiinde in einem erhchlichen Tcmperaturbereieh in thcrmischem Gleiehgewicht stehen. l h b e i werden die Zerfallscharakteristika mittcls cines im Anhang hcrgcleitcten Modclls untersucht. Die Strahlungslcbcnsdauer dcr bzw. 3P,-Zustande ergeben sich zu 4 X lo-" bzw.

The current understanding of radiation damage mechanisms in alumina produced by bombardment with energetic electrons, ions, or neutrons is reviewed with particular emphasis on the relative effects of displacement damage on the aluminum and oxygen sublattices. The displacement damage equations are presented and it is shown that a temperature dependence of damage efficiency should be introduced into displacement damage calculations. The evolution of the damage microstructure is discussed for three broad temperature ranges followed by the effects of point and aggregate defects on physical properties. These include dimensional stability, thermal conductivity, electrical conductivity, and dielectric properties. The review concludes with the effects of neutron irradiation on mechanical properties.

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