Hydrothermal crystal growth of yttrium and rare earth stabilized hafnia

The unoccupied electronic structure characterization of hydrothermally grown ThO2 single crystals

“…The crystal structure was confirmed by XRD and then through the rocking curves, oriented in the (200) direction, as found in other Ref. 9–12. Before analysis, the crystals were cleaned using an organic solution of mixed crown ethers and picric acid.…”

“…Obtaining ThO 2 single crystals by the hydrothermal technique opens a route to resolving questions regarding the electronic structure by enabling spectroscopic measurements of both the occupied and unoccupied band structure. The work of 9, 10 indicates this growth process to be an excellent means of obtaining large single crystals of refractory oxides on the order of several mm. Starting with large single crystals of ThO 2 , on the order of 9 mm 2 per face, the electronic structure in the region of the band gap has been probed.…”

Electronic structure of hydrothermally synthesized single crystal U0.22Th0.78O2

“…The U 0.22 Th 0.78 O 2 single crystal studied in this research was hydrothermally synthesized kinetically in a supercritical 9 M CsF mineralizer as detailed elsewhere . The structure of U 0.22 Th 0.78 O 2 was confirmed as a fluorite crystal lattice through X‐ray diffraction as previously for other refractory oxides grown through by this method, such as ThO 2 and HfO 2 . The previous studies of ThO 2 obtained through this technique indicated that the surface can have near surface regions of impurity deposits resulting from cooling the hydrothermal solution.…”

“…In the present research, a hydrothermal synthesis technique was developed and demonstrated to be suitable for quality ThO 2 crystal growth. This was followed by the synthesis and structural confirmation of U x Th 1– x O 2 single crystal alloys .…”

Фазовый состав, микроструктура и электропроводность твердых электролитов HfO_2-R-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=- (R=Sc, Y, Ho, Er, Tm, Yb, Lu)

“…Недопированный HfO 2 , как и ZrO 2 , имеет моноклинную кристаллическую структуру, претерпевающую превращение в тетрагональную при температуре выше 1600 • C, а затем при температуре около 2700 • C переходит в кубическую структуру типа флюорита [19]. Фазовые переходы сопровождаются возникновением значительных напряжений растяжения-сжатия, которые обычно приводят к растрескиванию образцов [20,21].…”