Broadband absorption and photothermal conversion in titanium diboride

Titanium diboride (TiB2) is a well-known ceramic material with high mechanical strength, durability, chemical inertness and high melting point. It has a layered structure comprising of graphenic boron layers alternated by hexagonally close packed titanium layers. In this work, we identify bulk TiB2 as a good light to heat conversion material in the solid-state. The optical response of the material in its powder form was obtained by UV-Diffuse Reflectance Spectroscopy (UV-DRS) and fluorescence spectroscopy. The heat flow from the samples upon irradiation with a broadband UV-vis lightsource (λ~250−450 nm) was measured by using a photo-differential scanning calorimeter (photo DSC). The exothermic heat flow, upon irradiation registered bythe powder sample, was found to be ∼19 W/g at an irradiance of 693 mW/cm2. The magnitude of heat flow registered by TiB2 powder was found to be several times higher as compared to that reported for many bulk materials such as TiO2, ZnO, SnO2 and ZrNCl. The discovery of light-to-heat conversion efficacy of the material is a new perspective in the science of TiB2.