TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The first material comprises an element selected from titanium, aluminum, hafnium, zirconium, strontium, silicon, tantalum, transition metal (group 3(III B) to 12(II B) except actinide series), germanium, carbon, gallium, arsenic, indium, zinc and/or cadmium (preferably titanium). The second material comprises an element selected from titanium, zinc, aluminum, hafnium, gallium, copper, strontium, zirconium, silicon, indium and/or barium (preferably titanium, strontium titanium, or barium titanium, especially titanium). The first material further comprises an element compensating the valence of a first element selected from carbon, nitrogen, oxygen, phosphorus, arsenic, antimony, selenium, tellurium and/or sulfur (preferably nitrogen). The second material further comprises an element compensating the valence of a first element selected from carbon, nitrogen, phosphorus, arsenic, antimony, oxygen, sulfur, selenium, tellurium, fluorine, chlorine and/or organic group (preferably oxygen). The shell is semiconducting and dielectric. ACTIVITY - Antibacterial. Particle powder (test) comprising TiO2 (96%) and TiN (4%), was tested for antibacterial activity (measured in terms of death ratio of bacteria) against Streptococcus mutans (ATCC 700610), which was incubated in a brain heart infusion (BHI) broth for 8 hours at 37 degrees C. The test powder suspension (50 mg/l) was added into the medium and tested after exposure to halogen lamp. A particle powder without exposure to light was used as a control. The test/control particle powders showed approximately 130/95% death ratio of bacteria at 75 minutes.    MECHANISM OF ACTION - None given.    EXAMPLE - Particle powder comprising (%): TiN core (4) and TiO2 shell (96) was prepared. The powder absorbs the light at less than 550 nm, which was higher than UV light (wavelength ( lambda ) less than 387 nm). The powder decompose acid orange 7 (AO7) after 1 hour of exposure to the halogen lamp, which was exceptionally fast. This phenomenon showed the strong photocatalytic activity of the particle.