March 1987Thus, on gradual addition of silica sol to A13' sol during gelation and the subsequent heating, Si-A1 spinel will form with association of amorphous aluminosilicate phase. The composition and amount of the amorphous phase will be expected to change with such additions. As a result, the observed 0.139-nm peak area (Table 11) is found to decrease with increasing percent of SiOz instead of remaining more or less constant and equal to the area of the standard y-Alz03. Therefore, any attempt to prepare pure Si-A1 spinel would be a mixture of Si-A1 spinel and an amorphous ahminosilicate phase. As a result, the XRD intensity would be less than that of pure y-A1203.The sodium titanates Na4Ti04, a-, /3, and y-NaJi03, Na8Ti50,,, Na2Ti307, and NazTi60,s, all of which can be synthesized in the temperature range 800" to 12OO0C, have been characterized by X-ray diffraction (XRD) and Raman spectroscopy. The existing XRD data have been critically reviewed and several inconsistencies and errors have been identified.

The majority of the potassium titanates described in the literature were synthesized, and their Raman spectra recorded. The identity of the compounds K2TiO3, K2Ti2O5, K2Ti4O9, K2Ti6O13, and K2Ti8O17 was confirmed by x-ray diffraction. Raman spectroscopy was then used to study the hydrolysis, under different conditions, of K2Ti2O5 and of K2Ti4O9. On drying of the hydrolysis products, the following species were found to form: K2(H2O)0.66 Ti8O16(OH)2, K1.33(H2O)0.33Ti4O8.33(OH)0.67, and H2Ti8O17. On ignition at temperatures of 500–600°C these species converted, respectively, to K2Ti8O17, K2Ti6O13, and TiO2(B). Raman spectroscopy was used to establish that (1) K6Ti4O11 consists of a mixture of K2TiO3 and a new compound K4Ti3O8; (2) K2Ti3O7 consists of a mixture of K2Ti2O5 and K2Ti4O9, and (3) K2Ti5O11 consists of a mixture of K2Ti4O9 and K2Ti6O13. The temperature of decomposition and the identity of the products of the thermal decomposition of K2Ti8Ol7, K2Ti4O9, K2Ti2O5, and K4Ti3O8 were determined by Raman spectroscopy. The XRD data of the newly identified compounds are reported.

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The compounds SrPu2Ti4O12, Pu2Ti3O8.79, and Pu2Ti2O7, where plutonium is in the (III) oxidation state, were prepared and identified via X‐ray diffraction (XRD). The solid solubility limit of Pu2Ti2O7 in Ln2Ti2O7 (Ln = Gd, Er, or Lu) was also studied via XRD; it was determined that the solubility of Pu2Ti2O7 increased as the radius of the lanthanide ion in the host compound decreased. Attempts to synthesize Sr2Pu2 Ti5O16 and Sr2Ce2–yPuyTi5O16 solid solutions, where plutonium is in the (IV) oxidation state, were unsuccessful.

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The ternary system SrO-CeO,-TiO, was investigated using X-ray diffractometry. The formation of a new compound, Sr,Ce,Ti,O,,, was established, and its compatibilities with SrO, SrCeO,, and SrTiO, were studied. The results revealed the existence of a series of compounds Sr,-,,Ce,Ti,O,, and solid solutions Sr,+,Ce,Ti,+,O,,+,, (n I 6).