Two possible approaches to spectroscopic measurements of the internal temperature of Y2O2S: Eu are discussed. Methods based on relative Eu3+ fluorescence line intensities are found either to be insufficiently sensitive or to suffer from unavoidable experimental difficulties. The method which is adopted exploits the quadratic shift of the Eu3+5D0→7F0 transition energy with temperature. Controlled-temperature UV- and CR-excited fluorescence measurements establish the temperature calibration, which is then used to obtain the operating temperature of phosphor screens in a demountable CR excitation apparatus and in a tricolor CRT.

Thin-film CaS:Ce3+, Cl- has been successfully employed for the first time as the active layer of an a.c. thin-film electroluminescent device. In order to compare the performance of a device using this material with that of devices employing the usual ZnS:Mn2+ material, MISM (metal-insulator-semiconductor-metal), ISM, and MSM devices were fabricated. Of these three devices, the singly-insulated device had the highest brightness, of 100 cd/m2, at a frequency of 5 kHz and a pulse height of 200 V. The brightness of this device is still lower than that of devices employing the usual ZnS:Mn2+. This is attributed to the smaller number of internal carriers and the smaller amount of carrier accumulation in the vicinity of the interface between the active luminescent layer and the insulating layer.

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