Inhomogeneous broadening of electron-paramagnetic-resonance and optical spectra ofV4+inCaYAlO4

${\mathrm{CaYAlO}}_4$ crystals codoped with ${\mathrm{V}}^{4+}$ and ${\mathrm{Mg}}^{2+}$ ions have been grown in an inert atmosphere. EPR measurements reveal that ${\mathrm{V}}^{4+}$ ions in ${\mathrm{CaYAlO}}_4$ occupy orthorhombic symmetry sites. The optical-absorption spectrum comprises two intense bands with peaks at 330 and 430 nm, together with a weak band around 500 nm. Excitation in the 500-nm band produces a broad luminescence band with a peak at 690 nm. The radiative center associated with these spectra is assigned to ${\mathrm{V}}^{4+}$(3${\mathit{d}}^1$) ions. The peak wavelength of the luminescence band shifts to longer wavelengths with increasing excitation wavelengths in the 500-nm absorption band, an effect associated with the inhomogeneous broadening of the luminescence band caused by random distribution of ${\mathrm{Ca}}^{2+}$ and ${\mathrm{Y}}^{3+}$ ions in the disordered ${\mathrm{CaYAlO}}_4$ lattice.