Ab initio study of elastic properties of orthorhombic cadmium stannate as a substrate for the manufacture of MEMS devices

International audienceThe elastic properties of the orthorhombic cadmium stannate (Cd2SnO4) were investigated using density functional theory, applying both energy-strain relationship (which is found in the literature) and stress-strain relationship (which we have developed in this study), both in the generalized gradient approximation and local density approximation (LDA) as implemented in the Quantum Espresso code. The results from both methods were found to be in good agreement with each other. However, the values for the stress-strain calculation were found to be relatively higher than those of the energy-strain and also, were those obtained from the LDA. The study found out that Cd2SnO4 possesses desirable elastic properties that are comparable to those of silicon, the dominant substrate material used in the manufacture of Microelectromechanical Systems. The bulk modulus was found to be nearly twice (more than 1.5 times) that of Si. Moreover, the material was found to be ductile, which when combined with the transparent nature that has been studied earlier and is available in the literature, can form a better substrate for the manufacture of transparent and flexible MEMS such as cardiopulmonary sensors, microbolometers, temperature and pressure sensors

Thermal properties and pressure-dependent elastic constants of cadmium stannate as a substrate for MEMS: An ab initio study

International audienceSilicon carbide (SiC) has become a suitable replacement to silicon as a substrate for manufacture of microelectromechanical systems (MEMS) that operate in harsh environmental conditions, owing to its better mechanical properties such as excellent wear resistance. However, just like silicon, SiC is also brittle, a property that limits its application as a substrate for manufacture of flexible MEMS. In this study, we explored the thermal properties as well as the pressure-dependent elastic constants of cadmium stannate (Cd2SnO4) for the first time within the quantum espresso code. The result showed that the elastic constants of SiC are much higher than those of Cd2SnO4. The properties of SiC were found to be more sensitive to the applied pressure compared those of Cd2SnO4, implying that it is less mechanically and thermally stable with the applied pressure compared to Cd2SnO4, and therefore, less appealing compared to Cd2SnO4 for the manufacture of most MEMS

Accurate Ab-initio calculation of elastic constants of anisotropic binary alloys: A case of Fe–Al

International audienc

Microstructural and Elastic Properties of Stable Aluminium-rich TiAl and TiAl2 Formed Phase Intermetallics

International audienceWe studied aluminium-rich Ti-Al (Ti32Al68 and Ti40Al60) binary alloys that were composed of TiAl and TiAl2 lamellar microstructures. The law of mixtures was employed in calculating the theoretical Young’s moduli. The lattice parameters of the alloys showed that both were tetragonal crystals. In the computational study, we made use of our modified method for the stress–strain calculation of elastic constants. The alloys at the respective chemical compositions were modelled by creating titanium (Ti) supercells, which were then doped by replacing some of the Ti atoms with aluminium atoms. The values of elastic moduli were verified by the ab initio calculation in this work, which showed a perfect agreement. The Pugh’s ratio showed that both the alloys are ductile

Temperature-Dependent Elastic Constants of Substrates for Manufacture of Mems Devices

International audienceWe present a comparative computational study of temperature-dependent elastic constants of silicon (Si), silicon carbide (SiC) and diamond as substrates that are commonly used in the manufacture of Micro-Electromechanical Systems (MEMS) devices. Also mentioned is Cd 2 SnO 4 , whose ground-state elastic constants were determined just recently for the first time. Si is the dominant substrate used in the manufacture of MEMS devices, owing to its desirable electrical, electronic, thermal and mechanical properties. However, its low hardness, brittleness and inability to work under harsh environment such as hightemperature environment, has limited its use in the manufacture of MEMS like mechanical sensors and bioMEMS. Mechanical sensors are fabricated on SiC and diamond due to their high Young's moduli as well as high fracture strength, while the bioMEMS are fabricated on polymers. The effect of temperature on the elastic constants of these substrates will help in giving insight into how their performance vary with temperature

Thermal properties and pressure-dependent elastic constants of cadmium stannate as a substrate for MEMS: An ab initio study

Silicon carbide (SiC) has become a suitable replacement to silicon as a substrate for manufacture of microelectromechanical systems (MEMS) that operate in harsh environmental conditions, owing to its better mechanical properties such as excellent wear resistance. However, just like silicon, SiC is also brittle, a property that limits its application as a substrate for manufacture of flexible MEMS. In this study, we explored the thermal properties as well as the pressure-dependent elastic constants of cadmium stannate (Cd2SnO4) for the first time within the quantum espresso code. The result showed that the elastic constants of SiC are much higher than those of Cd2SnO4. The properties of SiC were found to be more sensitive to the applied pressure compared those of Cd2SnO4, implying that it is less mechanically and thermally stable with the applied pressure compared to Cd2SnO4, and therefore, less appealing compared to Cd2SnO4 for manufacture of most MEM

Structural and Mechanical Properties of theTi32Al68 and Ti40Al60 Binary Alloys: Experimental and computational Studies

International audienc

Corrigendum on “Microstructural and elastic properties of stable aluminium-rich TiAl and TiAl2 formed phase intermetallics” [Mater. Lett. 287 (2021) 129295]

International audienc