| Abstract: |
Antimony-containing chalcogenide glasses sit at an awkward and productive boundary. They are stable enough to be shaped into films, fibres and waveguides, yet their metastable networks respond strongly to heat. This review examines how thermal treatment modulates the optical properties of Sb-based chalcogenide glasses and thin films, drawing on work published mainly between 1990 and 2025 on Sb–S, Sb–Se, Ge–Sb–Se, Ge–Sb–S and related systems. A structured literature search, explicit inclusion criteria and directional vote-counting were used to combine results that differ in composition, film thickness, annealing atmosphere and measurement technique. The synthesis shows a consistent pattern. Annealing below the glass transition relaxes the network, removes homopolar bonds and usually raises the refractive index while shifting the absorption edge to lower energy. Annealing near or above crystallization onset produces a larger, step-like change in both quantities as nanocrystalline Sb₂S₃ or Sb₂Se₃ domains nucleate, accompanied by scattering losses and a wider Urbach tail. The size of the shift scales with the Sb fraction, the distance of the as-prepared state from equilibrium, and the average coordination number. Reported index contrasts between amorphous and crystalline states reach values useful for phase-change photonics, but the evidence base is uneven. Annealing times, ramp rates and atmospheres are rarely controlled or reported in a comparable way, and band gaps are extracted with differing Tauc conventions. We identify these gaps, propose a minimum reporting standard, and outline directions for composition-aware thermal engineering of optical function. |
