High　quality　Cr-,　Fe-　and　Ni-doped　Al2O3　(A:Al2O3)　single　crystals　with　a　diameter　of　6-8　mm　and　a　length　of　60-80　mm　were　successfully　produced　by　the　floating　zone　technique.　The　relationship　between　crystal　quality　and　growth　conditions　was　discussed,　and　the　optimum　preparation　parameter　was　obtained.　The　crystals　growth　direction　was　determined　as　＜　001　＞　by　X-ray　diffraction.　The　X-ray　rocking　curve　of　the　crystal　had　a　FWMH　of　0.089　degrees,　proving　excellent　quality　of　the　crystal.　The　as-grown　crystals　were　characterized　by　polarized　optical　microscope　and　scanning　electron　microscope,　as　well　as　X-ray　diffraction.　The　observed　primary　crystal　defects　were　sub-angle　grain　boundaries,　inclusions　and　solute　trails.　The　absorption　spectra　properties　and　dielectric　constant　measurements　of　A:Al2O3　crystals　and　fluorescence　spectra　for　Cr:Al2O3　crystals　were　investigated.　In　view　of　the　fact　that　grown　A:Al2O3　crystals　show　good　quality,　a　respectively　high　dielectric　constant　epsilon(r)　(12.1-15.7),　low　dielectric　loss　tan　delta　(0.0020-0.0002),　and　favorable　thermal　stability　suggests　their　utilization　as　laser　matrix,　dielectric　material　for　microelectronics　and　substrate　material.