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An iron-containing yttria-stabilized zirconia (YSZ) or Fe-YSZ was found to be a promising working redox material for the thermochemical two-step water-splitting cycle. The Fe-YSZ was formed by a high-temperature reaction between YSZ doped with more than 8 mol % [Y.sub.2][O.sub.3] and [Fe.sub.3][O.sub.4] supported on the YSZ at 1400[degrees]C in an inert atmosphere. The formed Fe-YSZ reacted with steam to generate hydrogen at 1000 [degrees] C. The oxidized Fe-YSZ was reactivated by a thermal reduction at 1400[degrees]C in an inert atmosphere. The alternative [O.sub.2] and [H.sub.2] generations in the repeated two-step reactions and the X-ray diffraction and chemical analysis studies on the solid materials indicated that the two-step water splitting was associated with a redox transition between [Fe.sup.2+]-[Fe.sup.3+] ions in the cubic YSZ lattice. [DOI: 10.1115/1.2807197] Keywords: solar chemistry, concentrated solar heat, solar hydrogen, thermochemical water splitting, redox metal oxide

Yttrium-90 used for therapy should be of very high radionuclidic (RN) purity (>99.998%) as the most probable contaminant, strontium-90, is a bone seeker with a maximum permissible body burden of 74 kBq (2 [micro]Ci) only. None of the current known methods of RN purity estimations is adequate to reliably measure the [sup.90]Sr RN impurity at such low levels. Our aim was to develop a reliable technique to accurately determine the amount of [sup.90]Sr in [sup.90]y used for therapy. This new technique combines chelate-based extraction with paper chromatography using paper impregnated with 2-ethylhexyl, 2-ethylhexylphosphonic acid (KSM-17), which is a [sup.90]y-specific chelator. A PC strip impregnated with KSM-17 at the point of spotting is used for chromatography. Upon development with normal saline, [sup.90]Sr moves to the solvent front leaving [sup.90]y completely chelated and retained at the point of spotting. The activity at the solvent front ([sup.90]Sr) is quantified by liquid scintillation counting, and the data are compared with the total applied activity to provide the RN purity of the test solution. The method has a sensitivity of [greater than or equal to] 74 kBq (2 [micro]Ci) of [sup.90]Sr per 37 GBq (1 Ci) of [sup.90]Y. This novel, innovative, and simple technique offers a reliable solution to the unanswered problem of estimation of [sup.90]Sr content in [sup.90]Y used for cancer therapy.

Free-ion selective radiotracer extraction (FISRE) using no-carrier-added [sup.90]Y has been applied to assess the dissociation kinetics of yttrium(III)--1,4,7,10-tetraazacyclododecane-1,4, 7,10-tetraacetic acid (Y--DOTA), a radiopharmaceutical precursor with a remarkable kinetic stability. In order to extend the operationally defined detection window, a complemental FISRE-based experiment has been successfully developed. Within a time frame of approximately 10 half-times of [sup.90]y ([t.sub.1/2] = 61.4 h), the complex Y--DOTA has been observed to form two kinetically distinguishable species with significantly different kinetic properties. The time-dependent speciation was measured to be sensitive to pH variations even in the neutral pH range (4.5-7.4) whereas the impact of ionic strength changes is negligible.

The growth and characterization of ceramic red-green-blue (RGB) films based on yttria and gadolinia hosts both doped by rare-earth oxides are presented. The doped [Y.sub.2][O.sub.3] films allow a more intense luminescence with respect to the doped [Gd.sub.2][O.sub.3] films as they are physically more stable and their deposition and growth do not require special experimental conditions.

Polycrystalline (0002)-textured yttrium (Y) films of 50-500 nm thickness on sapphire substrates were loaded electrolytically with hydrogen (H). The stresses that build up in these films were measured in situ using curvature measurements.

A study was conducted, using Rutherford backscattering spectroscopy, x-ray diffraction, and atomic force microscopy, to investigate the structural and morphological features of crystalline rare-earth-doped yttrium oxide thin films grown by pulsed-laser deposition (PLD) on SiO2/Si substrates. The result confirms that the PLD of rare-earth-doped yttria at high temperature and low pressure leads to the growth of good quality thin films with a polycrystalline structure and a low-surface roughness.