ABSTRACT
Single-phase epitaxial Hf0.5Zr0.5O2 films with non-centrosymmetric orthorhombic structure have been grown directly on electrode-free corundum (α-Al2O3) substrates by pulsed laser deposition. A combination of high-resolution X-ray diffraction and X-ray absorption spectroscopy confirms the epitaxial growth of high-quality films belonging to the Pca21 space group, with [111] out-of-plane orientation. The surface of a 7-nm-thick sample exhibits an atomic step-terrace structure with a corrugation of the order of one atomic layer, as proved by atomic force microscopy. Scanning transmission electron microscopy reveals that it consists of grains with around 10 nm lateral size. The polar nature of this film has been corroborated by pyroelectric measurements. These results shed light on the mechanisms of the epitaxial stabilization of the ferroelectric phase of hafnia.
ABSTRACT
BACKGROUND: The aim of this study was to evaluate obturation depth and volume by means of micro-CT when filling lateral canals. MATERIAL AND METHODS: Thirty single-rooted teeth were used. After instrumentation, three artificial lateral canals were created on each mesial and distal surface (one on each third). The samples were then separated randomly into three groups according to the obturation technique used (n=10): lateral condensation (Group 1), Tagger's hybrid technique (Group 2) and GuttaCore™ (Group 3). Samples were scanned and data was processed with Avizo software. Depth and volume of the infilling were measured in each lateral canal. Values were expressed as percentages and were analyzed using the Kruskal-Wallis test. RESULTS: Mean depth showed statistically significant differences between Group 3 and Groups 1 (p=0.001) and 2 (p=0.003), whereas no significant difference was found between Groups 1 and 2 (p≈1). As for mean volume, significant differences were found between Group 3 and Groups 1 (p=0.01) and 2 (p=0.003) but no differences were found between Groups 1 and 2 (p=1.00). CONCLUSIONS: GuttaCore provided the best lateral canal sealing among the three techniques compared. Key words:Lateral canals, Micro-CT, obturation.
ABSTRACT
El presente documento, es el resultado del trabajo disciplinado y silencioso de un centenar de colegas, miembros de las comisiones, damas auxiliares, estudiantes y personal de soporte, sin cuya contribución este ambicioso programa no habria llegado a su completo desarrollo, el mismo que demandó mucho tiempo y esfuerzo
