https://nova.newcastle.edu.au/vital/access/ /manager/Index en-au 5 https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:50534 Thu 27 Jul 2023 16:48:16 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:39195 0.5Bi_0.5)TiO₃-0.06BaTiO₃ (NBT-6BT) relaxor fer-roelectrics were investigated using the Vickers indentation method and computation of crack tip opening displacement. It was found that an unpoled sample had a fracture toughness of around 1.35 MPa m^1/2. In contrast, an electrically poled sample exhibited anisotropy with a lower fracture toughness perpendicular to the poling direction and a higher value in the parallel direction, as compared to the unpoled sample. Upon cyclic electrical loading (with applied electric field amplitudes between 0.73E_C and 1.4E_C), the indented surface crack was found to propagate. In general, the crack grew rapidly during the initial cycles followed by crack arrest, and the principal driving force for crack growth was proposed to be residual stress around the indentation, as evidenced by the limited field dependence of crack growth. There was also a contribution from the electromechanical strain, which played a role at high cycles (>100 cycles) and high fields (>1.3 E_C). Evidence of a saturation threshold of crack propagation is an advantage for the electromechanical reliability of relaxor ferroelectrics in devices.]]> Thu 26 May 2022 15:54:29 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:7541 Sat 24 Mar 2018 10:46:08 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:7542 Sat 24 Mar 2018 08:37:43 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:9619 Sat 24 Mar 2018 08:35:27 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:1346 Sat 24 Mar 2018 08:32:40 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:1328 Sat 24 Mar 2018 08:32:35 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:20854 Sat 24 Mar 2018 08:02:54 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:5455 Sat 24 Mar 2018 07:48:11 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:27728 n+1AX_n phases Cr₂GeC and Cr₂GaC were synthesized with high phase-purity directly from Cr₂O₃; Ge or Ga; and C using a single-step carbothermal reduction. X-ray diffraction and scanning electron microscope analysis of the materials shows them to be >99 mol% Cr₂GeC and 92 mol% Cr₂GaC, respectively. Extension to non-Cr systems is briefly demonstrated by applying the method to the synthesis of V₂GeC.]]> Sat 24 Mar 2018 07:36:43 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:22842 x. Irradiation at 200°C results in maximum microstrain, a maximum in the c lattice parameter, and the appearance of a ß phase in addition to the normal a phase of Ti₃SiC₂. A minimum in the observed damage level near the surface was seen for irradiation at a sample temperature of 300°C but the damaged phase increases at higher temperatures. Differences between the present work and a previous C irradiation study have been ascribed to the enhanced Si defect transport at low temperatures.]]> Sat 24 Mar 2018 07:16:07 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:32643 n+1AX_n phase elastic constants as previously predicted by density functional theory calculations is confirmed experimentally for Ti₃AlC₂ to be c₄₄=115.3 ± 30.7 GPa. In contrast, Ti₃SiC₂ is confirmed to be shear stiff with c₄₄=402.7 ± 78.3 GPa supporting results obtained by earlier elastic neutron diffraction experiments.]]> Mon 02 Jul 2018 14:47:12 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:46106 2AlC MAX phase thin films prepared by radio-frequency magnetron sputtering were irradiated at room temperature by 100 keV helium ions to a fluence of 1 × 10¹⁷ ions cm⁻². The effects of thermal annealing on the structural and mechanical properties of the helium-irradiated Cr₂AlC films as well as the helium release were investigated by grazing-incidence X-ray diffraction (GIXRD), Raman spectroscopy, and scanning electron microscope (SEM) in combination with nano-indentation and elastic recoil detection (ERD) analysis. The irradiation-induced structural damage in the Cr₂AlC is significantly recovered by thermal annealing at temperatures around 600℃, attributed to high defect diffusivity. After annealing to 750℃, the hardness of irradiated films recovered almost completely, which is ascribes to both defect recombination and reformation of damaged chemical bonds. Substantial helium release occurring at this annealing temperature is closely related to the damage recovery due to helium irradiation.]]> Fri 11 Nov 2022 12:05:10 AEDT ]]>