Paramagnetic Resonance of Vanadium in Amorphous and Polycrystalline GeO2

Abstract

The $X$-band electron paramagnetic resonance absorption spectra of vanadium-doped amorphous and polycrystalline tetragonal Ge${\mathrm{O}}_2$ have been observed at room temperature. The spectrum of the amorphous Ge${\mathrm{O}}_2$, attributed to V${\mathrm{O}}^{++}$, can be described by $g_{\mathrm{II}}=1.929\mathrm{}\pm 0.001$, $g_{\perp }=1.976\mathrm{}\pm 0.001$, $\left|A_{\mathrm{II}}\right|=(175.5\mathrm{}\pm 0.1)\times {10}^{-4\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$, and $\left|A_{\perp }\right|=(68.2\mathrm{}\pm 0.1)\times {10}^{-4\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$. In the tetragonal Ge${\mathrm{O}}_2$, the vanadium appears as ${\mathrm{V}}^{4+}$ with spectrum constants $g_z={1.963}_2\pm 0.0003$, $g_x={1.921}_3\pm 0.0006$, $g_y={1.921}_3\pm 0.0001$, $\left|A_z\right|=(134.36\mathrm{}\pm 0.02)\times {10}^{-4\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$, $\left|A_x\right|=(36.69\mathrm{}\pm 0.01)\times {10}^{-4\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$, and $\left|A_y\right|=(37.54\mathrm{}\pm 0.01)\times {10}^{-4\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$. The spectrum of vanadium-doped polycrystalline hexagonal Ge${\mathrm{O}}_2$ was not observable at 300 or at 77°K.