$\beta \text{‐}{\mathrm{Ga}}_2{\mathrm{O}}_3$ nano- and microwires with diameters ranging from tens of nanometers to about one micron and lengths of up to tens of microns, have been obtained by sintering ${\mathrm{Ga}}_2{\mathrm{O}}_3$ powder under argon flow. The structures have been investigated by cathodoluminescence in the scanning electron microscope. The samples showed the violet-blue emission characteristic of ${\mathrm{Ga}}_2{\mathrm{O}}_3$ and a red emission at 1.73 eV dominant in the nanowires and other nano- and microstructures formed during the sintering treatment. At temperatures below 210 K, this band exhibits sharp peaks separated by 20 meV. This observation suggests the exchange of phonons in the recombination process.

Red luminescence emission from chromium doped $\beta \text{‐}{\mathrm{Ga}}_2{\mathrm{O}}_3$ nanowires has been studied by means of photoluminescence (PL) techniques. PL excitation shows several bands in the ultraviolet-visible region. Time decay values, obtained by time resolved PL, at different temperatures fit a three level model with thermal population of the upper level from the middle one. From the results, the origin of the emission is assigned to ${\mathrm{Cr}}^{3+}$ ions in the $\beta \text{‐}{\mathrm{Ga}}_2{\mathrm{O}}_3$ host, and values for the energy level separation and Huang-Rhys factor of the broad ${}^{4}T_2\text{‐}{}^{4}A_2$ emission are estimated.

Er and Cr doped $\beta \text{-}{\mathrm{Ga}}_2{\mathrm{O}}_3$ nano- and microwires have been grown by thermal treatments of ${\mathrm{Ga}}_2{\mathrm{O}}_3$ powder containing a fraction of ${\mathrm{Er}}_2{\mathrm{O}}_3$ powder or in the presence of ${\mathrm{Cr}}_2{\mathrm{O}}_3$ powder, respectively. Doping gives rise to the characteristic red photoluminescence (PL) of ${\mathrm{Cr}}^{3+}$ ions at about $700\mathrm{nm}$ and to green emission of ${\mathrm{Er}}^{3+}$ at about $555\mathrm{nm}$ . Waveguiding of the ion related PL light excited in the wires has been studied for wires with different sizes. Waveguide behavior for incident visible light of different wavelengths was demonstrated.