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The arsenic (As) to selenium (Se) ratio in As_xSe_1-x glasses ranging from x = 0.2 to 0.5 was varied in order to examine the effect of chemical and topological ordering on the glass' thermal transport behavior. The fundamental thermal properties of glass transition temperature (T_g), thermal conductivity (k), and heat capacity (c_p) were experimentally measured using differential scanning calorimetry, transient plane source method, and ultrasonic testing. Based on topological constraint theory, inflections in T_g and k were found at the structural coordination number $$\langle$$r$$\rangle$$ of 2.4, whereas a slight increase in heat capacity (c_p) with increasing $$\langle$$r$$\rangle$$ was observed. Amore » maximum in total thermal conductivity of 0.232 W/m·K was measured for the composition with x = 0.4, which corresponds to the stoichiometric As₂Se₃. Gas kinetic theory was used to derive an expression for the photon (k_p) portion of thermal conductivity, which was calculated by measurements of the glass' absorption coefficient (α) and refractive index (n). Models based on Debye theory were then used to derive expressions for specific heat (c_v) and the lattice (k_l) portion of thermal conductivity. The maximum value for k_p was 0.173 W/m·K for the composition with x = 0.2, and a minimum value of 0.144 W/m·K was measured for the composition with x = 0.4. Photonic conduction was found to be the dominant carrier mechanisms in all compositions, comprising 60% to 95% of the measured total thermal conductivity.« less