Two　new　substrate　crystals,　Ca2.90Li0.30Nb1.93Ga2.76O12　(CLNGG)　and　La0.57Ca2.38Li0.72Nb2.01Ga2.26O12　(LCLNGG),　were　successfully　grown　by　the　Czochralski　method.　Compared　with　Gd3Ga5O12　crystal,　CLNGG　and　LCLNGG　crystals　possess　the　lattice　constants　better　matched　with　those　of　highly　Bi-　or　Ce-doped　YIG　films　that　have　been　widely　used　in　the　magneto-optical　devices.　The　high　quality　and　performance　films　are　expected　to　be　obtained　by　using　CLNGG　or　LCLNGG　as　substrate　material.　In　this　paper,　the　structures　of　CLNGG　and　LCLNGG　are　refined　by　the　Rietveld　method,　and　the　influences　of　doping　on　the　crystal　structure,　transmittance,　electrical　conductivity,　thermal　expansion　coefficient　are　discussed.　Then,　the　causes　of　crystal　defects　are　analyzed　in　detail.　The　results　show　that　the　lattice-matched　seed　and　the　atmosphere　containing　suitable　oxygen　partial　pressure　are　crucial　to　obtain　high-quality　CLNGG　crystal　without　crack　and　inclusion　defects.　Since　the　oxygen-vacancy　defects　are　effectively　reduced　by　doping　Li+,　Nb5+,　and　La3+　ions,　LCLNGG　crystal　has　a　more　perfect　crystal　structure,　fewer　vacancy　defects　and　dislocation　defects　than　CLNGG　crystal.　(C)　2015　Elsevier　B.V.　All　rights　reserved.