FIELD: optical materials. SUBSTANCE: invention relates to the class of optical materials based on silver halides, specifically to silver halide radiation-resistant in the temperature range from -190 to 200°C nanoceramics of the AgCl0.25Br0.75 - AgI system, which can be used for the manufacture of light guides, since it is transparent without absorption windows from the visible to the far infrared range from 0.48 to 55.0 mcm, non-toxic, plastic, insoluble in water. Silver halide nanoceramics is made on the basis of two solid solutions: a hexagonal phase of the wurtzite P63mc structural type with composition AgI0.96Br0.03Cl0.01 and a cubic phase of the NaCl Fm3m structural type with composition AgCl0.21Br0.63I0.16 with the following ratio of components, mol.%: AgI0.96Br0.03Cl0.01 96.0-16.0, AgCl0.21Br0.63I0.16 4.0-84.0. Manufacturing IR light guides with a defective side surface from nanoceramics makes it possible to increase the sensitivity of IR fibre probes by 2 times when determining the composition of chemical substances compared to the smooth surface of IR light guides obtained from single crystals. EFFECT: nanoceramics are transparent in the range of 0.48-55.0 mcm, which makes it possible to detect the spectra of chemical compounds in a wider spectral range and ensures its wide application. 1 cl, 2 dwg, 3 ex.