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The flame-excited emission (candoluminescence) of the oxides Ta 2 O 5 , Nb 2 O 5 , TiO 2 , ZnO, and SnO 2 have been reexamined. By measuring the emission spectra as a function of temperature in comparison with the optical band gap, also measured as a function of temperature, it is concluded that a portion of the emission, particularly in Ta 2 O 5 and Nb 2 O 5 , is non-thermal. The results support the hypothesis that the excess emission is due to recombination of electron–hole pairs created by de-excitation of neutral radicals on the phosphor surface.

The Th 3 P 4 -structure ternary sulfide compound SrLa 2 S 4 :0.01Mn 2+ is shown to be a photophosphor with a deep crimson emission peaking at 675 nm (1.84 eV) at 300 K. Measurement of the temperature dependence of emission and excitation spectra reveals a systematic shift in band position at 200 K which is interpreted as a second-order transition in the host structure.

New ternary alkaline-earth rare-earth sulfide phases of composition MLn2S7 where M = Ca or Sr and Ln = La, Nd, or Gd have been formed by open-system reactions in flowing H2S. The phases have been characterized by X-ray powder diffraction and electron microprobe analysis. These compounds form as low-melting (Tm approximately 1100°C) products when refractory compounds along the MS-Ln2S3 join are oxidized at high sulfur fugacities.

New ternary alkaline-earth rare-earth sulfide phases of composition MLn2S7 where M = Ca or Sr and Ln = La, Nd, or Gd have been formed by open-system reactions in flowing H2S. The phases have been characterized by X-ray powder diffraction and electron microprobe analysis. These compounds form as low-melting (Tm approximately 1100°C) products when refractory compounds along the MS-Ln2S3 join are oxidized at high sulfur fugacities.

Raman spectra and precision X-ray diffraction patterns have been measured along the solid solution series between SrNd 2 S 4 and γ-Nd 2 S 3 . Breaks in the values of unit cell edge and Raman linewidths are interpreted to indicate different disorder structures in this defect solid solution series.

Raman spectra have been measured on powders of a sequence of compounds ARE 2 S 4 (A = Ca, Sr, RE = larger rare earths) with the Th 3 P 4 structure. All nine theoretically allowed Raman modes were observed only in low temperature spectra. Effects of disorder on the cation sub-lattice appear as increased widths in most of the Raman lines. Specular infrared reflectance was measured on a hot-pressed specimen of SrNd 2 S 4 from which a classical oscillator fit gave the transverse and longitudinal optic modes.