  Increased reflectance from the inclusion of highly scattering particles at
low volume fractions in an insulating dielectric offers a promising way to
reduce radiative thermal losses at high temperatures. Here, we investigate
plasmonic resonance driven enhanced scattering from microinclusions of
low-bandgap semiconductors (InP, Si, Ge, PbS, InAs and Te) in an insulating
composite to tailor its infrared reflectance for minimizing thermal losses from
radiative transfer. To this end, we compute the spectral properties of the
microcomposites using Monte Carlo modeling and compare them with results from
Fresnel equations. The role of particle size-dependent Mie scattering and
absorption efficiencies, and, scattering anisotropy are studied to identify the
optimal microinclusion size and material parameters for maximizing the
reflectance of the thermal radiation. For composites with Si and Ge
microinclusions we obtain reflectance efficiencies of 57 - 65% for the incident
blackbody radiation from sources at temperatures in the range 400 - 1600
{\deg}C. Furthermore, we observe a broadbanding of the reflectance spectra from
the plasmonic resonances due to charge carriers generated from defect states
within the semiconductor bandgap. Our results thus open up the possibility of
developing efficient high-temperature thermal insulators through use of the
low-bandgap semiconductor microinclusions in insulating dielectrics.
