OPTICAL  TRANSPARENCY

Light passage or transmission through a material does not necessarily imply the ability to see through it. In generic terms, a transparent material, has components with a uniform index of refraction while  a translucent material on the other hand, is made up of components with different indices of refraction. The latter system allows the passage of light but doesn't facilitate visibility through it. Materials that do not enable the transmission of light, are referred to as opaque.

Optical transparency refers to the passage of light through a material, without appreciable scattering. It is one of the most crucial functional properties of transparent ceramics. This determines for example, how well a solar cell works when the glass window covering it scatters less light, and enables better light harvesting or even how well a microscope, camera lens or laser works. 

Achieving  true optical transparency however, is not a task for conventional granular or microscopic materials.

THE  DESIGN  CHALLENGE

Optical transparency in polycrystalline materials (e.g. metals, ceramics), is limited by the amount of light scattered by their structural features such as pores and grain boundaries. Light scattering depends on the wavelength of the light. Limits to spatial scales of visibility are hence expected to arise, depending on the light wavelength as well as the physical dimension of the scattering centre (e.g. grain boundary or pore), within a glass or ceramic. Microscopic pores in sintered ceramics, situated at junctions of microcrystalline junctions grains of conventional ceramic materials, cause light to scatter and prevent the achievement of true transparency.

The size of a scattering centre is in great part determined by the size of the crystalline particles present in the raw material, during the development or formation of the glass or ceramic object. It goes then without saying, that reducing the raw material particle size well below the wavelength of visible light (~ 0.5 μm or 500 nm), eliminates a substantial amount of light scattering.  

A reduction of  the ceramic nanoparticle size well below dimensions of about 1/15 of the light wavelength being used, roughly results in a ceramic or glass  material that is  translucent or  even where desired, transparent. This implies for white light,  the particle grain size should be well below 40 nanometres (nm). Research shows that the total volume fraction of nanoscale pores (both inter- and intra-granular) within the ceramic must be less than 1% in order to achieve high-quality optical transmission. Hence particle uniformity and ultrafine nanoscale particles (well below 40 nm or 0.04 μm)  become strong determining factors, for the development of glass and or ceramic systems with superior opto-mechanical properties.  

OUR  SOLUTION

Quant-Ceramic nanomaterials have dimensions on average in the sub 20 nanometre range. They offer what is needed to achieve transparent ceramic systems.  

IMPLEMENTATION

Transparent ceramics can be achieved using low temperature sintering processes of our high purity atomically-architectured nanopowders.

 A client is at liberty to either use only our quant-ceramics OR, utilise them as "fillers" in order to minimise pore density within their existing systems, prior to sintering. The former approach however, is necessary for more effective design.

OTHER  APPLICATIONS

With our atomically-architectured ultrafine nanopowders, we enable the development of high-performance transparent ceramics, which offer lighter weight, mechanical reinforcement, enhanced thermal transport for energy conservation, stain-resistance, antimicrobial and anti-fungal protection without requiring photo-activation, for durability as well as aesthetic preservation. Be the target application a set of solid-state laser components, smartphone or portable device screens, optical fibres, lenses for microscopes and cameras, waveguides or technically-demanding glass walls and solar panel windows.