Technology: general issues 10 Research & information: general 9 History of engineering and technology 8 Oxygen vacancies 8 oxygen vacancies 4 Calculations 3 Chemistry 3 Density functional theory 3 History of engineering & technology 3 Magnetic fields 3 Nitrogen-vacancy center 3 Quantum optics 3 Semiconductor doping 3 Strontium compounds 3 Titanium dioxide 3 X ray photoelectron spectroscopy 3 Electrochemical performance 2 Electronic structure 2 Energy industries and utilities 2 First principle calculations 2 Gallium compounds 2 Lanthanum compounds 2 Magnetic resonance 2 Nitrogen 2 Nitrogen vacancies 2 Performance 2 Perovskite 2 Physics 2 Quantum information processing 2 Research and information: general 2