hafnia and titanium-dioxide

Interest in the study of the thermoluminescence of metallic oxides doped with various elements has been steadily increasing due to the characteristics of these materials and their possible applications in the dosimetry of ionizing radiation. Metal oxides such as zirconium oxide (ZrO

Topics: Aluminum Oxide; Beryllium; Hafnium; Humans; Luminescence; Metals; Mexico; Microscopy, Atomic Force; Oxides; Powders; Semiconductors; Thermoluminescent Dosimetry; Titanium; X-Ray Diffraction; Zirconium

Damage tests are carried out at 1064nm to measure the laser resistance of TiO(2)/Al(2)O(3) and HfO(2)/Al(2)O(3) antireflection coatings grown by atomic layer deposition (ALD). The damage results are determined by S-on-1 and R-on-1 tests. Interestingly, the damage performance of ALD coatings is similar to those grown by conventional e-beam evaporation process. A decline law of damage resistance under multiple irradiations is revealed. The influence of growth temperature on damage performance has been investigated. Result shows that the crystallization of TiO(2) layer at higher temperature could lead to numerous absorption defects that reduce the laser-induced damage threshold (LIDT). In addition, it has been found that using inorganic compound instead of organic compound as precursors for ALD process maybe effectively prevent carbon impurities in films and will increase the LIDT obviously.

Topics: Aluminum Oxide; Equipment Failure Analysis; Hafnium; Lasers; Models, Theoretical; Optics and Photonics; Oxides; Surface Properties; Titanium

NiTi shape memory alloy was modified by Hf ion implantation to improve its wear resistance and surface integrity against deformation. The Auger electron spectroscopy and x-ray photoelectron spectroscopy results indicated that the oxide thickness of NiTi alloy was increased by the formation of TiO₂/HfO₂ nanofilm on the surface. The nano-hardness measured by nano-indentation was decreased even at the depth larger than the maximum reach of the implanted Hf ion. The lower coefficient of friction with much longer fretting time indicated the remarkable improvement of wear resistance of Hf implanted NiTi, especially for the sample with a moderate incident dose. The formation of TiO₂/HfO₂ nanofilm with larger thickness and decrease of the nano-hardness played important roles in the improvement of wear resistance. Moreover, Hf implanted NiTi exhibited larger pseudoelastic recovery strain and retained better surface integrity even after being strained to 10% as demonstrated by in situ scanning electron microscope observation.

Topics: Elasticity; Hafnium; Hardness; Joint Prosthesis; Nanostructures; Nanotechnology; Nickel; Oxides; Phase Transition; Stress, Mechanical; Surface Properties; Titanium

A comparative study of laser induced damage of HfO2/SiO2 and TiO2/SiO2 mirrors at 1064 nm has been carried out. One TiO2/SiO2 mirror with absorption of 300 ppm and two HfO2/SiO2 mirrors with absorption of 40 and 4.5 ppm were fabricated using electron beam evaporation method. For r-on-1 test, all HfO2/SiO2 mirrors with low average absorption are above 150 J/cm2 at 10 ns. However, the TiO2/SiO2 mirrors with high average absorption are just 9.5 J/cm2, which are probably due to the rather high absorption and rather low band gap energy. Meanwhile, all the samples were irradiated from front and back side respectively using the raster scan test mode. In case of front side irradiation, it is found that: for TiO2/SiO2 high reflectors, the representative damage morphologies are shallow pits that were probably caused by absorbing centers. However, for HfO2/SiO2 high reflectors, the dominant damage morphologies are micrometer-sized nodules ejected pits and the delamination initiating from the pits. The absorption of HfO2/SiO2 coatings is low enough to have minor influence on the laser damage resistance. In case of backside irradiation, the morphology of TiO2/SiO2 mirrors is mainly center melted pits that are thermal melting induced damage. Meanwhile, HfO2/SiO2 mirrors with isometrical fracture rings damage morphology are thermal induced stress damage.

Topics: Equipment Design; Equipment Failure Analysis; Hafnium; Lasers; Lenses; Light; Oxides; Silicon Dioxide; Titanium

Mass spectrometry (MS)-based phosphoproteomics remains challenging due to the low abundance of phosphoproteins and substoichiometric phosphorylation. This demands better methods to effectively enrich phosphoproteins/peptides prior to MS analysis. We have previously communicated the first use of mesoporous zirconium dioxide (ZrO(2)) nanomaterials for effective phosphopeptide enrichment. Here, we present the full report including the synthesis, characterization, and application of mesoporous titanium dioxide (TiO(2)), ZrO(2), and hafnium dioxide (HfO(2)) in phosphopeptide enrichment and MS analysis. Mesoporous ZrO(2) and HfO(2) are demonstrated to be superior to TiO(2) for phosphopeptide enrichment from a complex mixture with high specificity (>99%), which could almost be considered as a "purification", mainly because of the extremely large active surface area of mesoporous nanomaterials. A single enrichment and Fourier transform MS analysis of phosphopeptides digested from a complex mixture containing 7% of alpha-casein identified 21 out of 22 phosphorylation sites for alpha-casein. Moreover, the mesoporous ZrO(2) and HfO(2) can be reused after a simple solution regeneration procedure with comparable enrichment performance to that of fresh materials. Mesoporous ZrO(2) and HfO(2) nanomaterials hold great promise for applications in MS-based phosphoproteomics.

Topics: Amino Acid Sequence; Caseins; Hafnium; Mass Spectrometry; Metals; Molecular Sequence Data; Nanostructures; Oxides; Phosphopeptides; Porosity; Spectroscopy, Fourier Transform Infrared; Titanium; Trypsin; Zirconium

Hafnium oxide (hafnia) exhibits unique enrichment properties towards phosphorylated peptides that are complementary to those of titanium oxide (titania) and zirconium oxide (zirconia) for use with mass spectrometric analysis in the field of proteomics.

Topics: Animals; Caseins; Cattle; Hafnium; Humans; Oxides; Phosphorylation; Proteomics; Spectrometry, Mass, Electrospray Ionization; Titanium; Zirconium