Ultrafine chromium particles for photothermal conversion of solar energy
Individually isolated chromium particles were prepared by evaporation onto KBr plates in a mixture of argon and air. Such coatings were taken as a model substance simulating the properties of electrodeposited chromium black: a well-known material for efficient photothermal conversion of solar energy. Median diameters of the particles were 5--13 nm; their shapes were spherical or cubelike. Optical transmittance at normal incidence was recorded by spectrophotometry in the interval 0.3--25 ..mu..m. Excellent spectral selectivity was documented with high absorptance over the wavelength range for solar radiation and high transmittance further out in the infrared. The optical data were interpreted within the Maxwell Garnett theory, which was generalized so as to encompass dipole-dipole coupling among aggregated spheres, cubelike shapes, and oxide pellicles. Agreement between theory and experiments was achieved by considering aggregation of spherical particles into linear chains. The effects of having cubic particles, as well as oxide-coated spherical ones, were calculated and found to be rather unimportant for understanding the spectral selectivity.
- Research Organization:
- Physics Department, Chalmers University of Technology, Fack, S-402 20 Gothenburg, Sweden
- OSTI ID:
- 6972624
- Journal Information:
- J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 49:6; ISSN JAPIA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
140500* -- Solar Energy Conversion
ABSORPTION SPECTRA
ALKALI METAL COMPOUNDS
BROMIDES
BROMINE COMPOUNDS
CHROMIUM
CONVERSION
DEPOSITION
ELECTRODEPOSITION
ELECTROLYSIS
ELECTROMAGNETIC RADIATION
ELEMENTS
ENERGY CONVERSION
EVAPORATION
FREQUENCY SELECTION
HALIDES
HALOGEN COMPOUNDS
INFRARED RADIATION
LIGHT TRANSMISSION
LYSIS
METALS
PARTICLES
PHASE TRANSFORMATIONS
POTASSIUM BROMIDES
POTASSIUM COMPOUNDS
RADIATIONS
SIMULATION
SOLAR ABSORBERS
SOLAR ENERGY CONVERSION
SPECTRA
SPECTROPHOTOMETRY
SURFACE COATING
TRANSITION ELEMENTS