A new identification and indexing for the phase BaAl2Ti5O14 were accomplished using an X‐ray diffraction technique. The new lattice parameters for the tetragonal lattice structure are: a0=9.990 × 10‐10 m and c0=12.264 × 10‐10 m, with a corresponding volume 1.224 × 10‐27 m3. The data provided by the Joint Committee on Powder Diffraction Standards are inconsistent both in lattice parameter values and Miller indices. The X‐ray powder diffraction pattern of BaAl2Ti5O14 was indexed using the LSUCR (least‐squares unit cell refinement) computer program.
Pb and Th based on t w o X-ray fluorescence (XRF) methods and combined with instrumental neutron activation analysis and infrared combustion analysis was developed to give quantitative analytical information on a large number of ceramic catalyst samples used for the denitration of flue gas from a coal-fired power plant. A special sample preparation method for small amounts (20 mg) of powder was used for XRF analysis. Two types of synthetic calibration standards were prepared: (1) single-element standards with an Fe203 matrix for the minor elements and limited concentration ranges (nine elements) and (2) multi-element standards with simulated matrices for the major elements and large concentration ranges (ten elements). The quantitative evaluation of minor elements was performed with a linear calibration graph. Major elements were determined using the so-called fundamental parameters program.
Thermogravimetry and differential thermal analyses were conducted on the mixture 2CsN03+A1203+2Ti02 up to 1530 K . The resultant phase was identified as orthorhombic Cs2A12Ti208 with lattice parameters ao=0.996, bo=0.898, and co=0.573 nm. Simultaneous TGIDTA was performed to quantify weight loss and volatilization of cesium and to monitor the development and/or stability of the phase as a function of temperature.YNTHETIC minerals, i.e. synroc assemSblages, are considered a potential host matrix for deep geologic disposal of highlevel radioactive waste generated from reprocessing of spent nuclear reactor fuel. '.'Synroc is an assemblage of multimineral phases. Each phase has the ability to retain or incorporate selectively in its crystal lattice structure different radioactive species, depending on ion size, stoichiometry, and the valence state of the ion. Cesium is thought to be incorporated in the Ba hollandite phase, BaAl,Ti,O,,.' Recently, CONTRIBUTING EDITOR-A . A SOLOMON Received November 1, 1983; approved Novemher 17, 1983. 0 10 cn v) 0 -J
25this phase was studied by powder X-ray diffraction (XRD) and found to have the stoichiometry BaA1ZTi,0,4.3 In the present work, cesium fixation in SYNOC and its individual mineral phase, a hollandite-like composition, were investigated to evaluate the volatilization of Cs in synroc during processing and to study the crystal structure of the proposed mineral phase, xCs20-yAlzO,-zTiOz. Attempts to synthesize a Cs hollandite phase by varying the stoichiometry were performed to determine the thermal and chemical stability of the host phase for radioactive cesium in such a complex polyphase multicomponent system.
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