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Phase transformations of β-LiGaO2 (Pna21) under different pressure conditions are studied using first principles calculations. Under specific conditions, LGO can exist in various structures some of which have not been previously reported (oP16 and P41212). Under sufficiently strong hydrostatic pressure, LGO can transform into a rocksalt-like structure. Under strong uniaxial stress LGO can transform into a tetragonal structure or an orthorhombic structure depending on the orientation of the applied stress. The stability of different crystal structures under different applied stresses and the phase transformation processes are studied by calculating the enthalpy surfaces and transformation barriers under different stresses.

Photoelectric hot carrier generation in metal-semiconductor junctions can enable optical-to-electrical energy conversion at photon energies below the bandgap of the semiconductor. Here, we present the simulated and experimental results of our wafer-scale Au/TiO2 metallic-semiconductor photonic crystal (MSPhC). We demonstrate a broadband sub-bandgap photoresponse with a FWHM of 235 nm centered at 590 nm due to surface plasmon absorption, and we also show a photoresponse enhancement factor of 4.5 at 639 nm compared to a flat chip. Photoresponse is also shown to increase with decreasing metal thickness down to 13 nm. Applications of our results could lead to low-cost and robust photoelectrochemical and thermo-photovoltaic devices.