We　present　a　thorough　study　of　the　nucleation　and　growth　processes　of　the　solution-based　YBa2Cu3O7-Ba2YTaO6　(　YBCO-BYTO)　system,　carried　out　with　a　view　to　controlling　the　characteristics　of　the　BYTO　phase　to　meet　the　requirements　for　specific　power　applications.　Scanning　transmission　electron　microscopy　and　x-ray　diffraction　have　been　used　to　characterize　the　BYTO　nucleation　and　phase　evolution　during　the　YBCO-BYTO　conversion.　At　high　BYTO　loads　(　＞　10　mol%),　the　nanoparticles　tend　to　aggregate,　resulting　in　much　less　efficiency　for　generating　nanostrained　areas　in　the　YBCO　matrix,　and　enhancement　of　the　vortex　pinning.　Our　experiments　show　that　by　modifying　the　nucleation　kinetics　and　thermodynamics　of　the　BYTO,　the　nucleation　mode　(　homogeneous　versus　heterogeneous),　the　particle　size　and　the　particle　orientation　can　be　controlled.　We　demonstrate　that　YBCO-BYTO　nanocomposites　with　high　concentration　of　nanoparticles　can　be　prepared　in　such　a　way　as　to　obtain　small　and　randomly　oriented　nanoparticles　(i.e.　high　incoherent　interface),　generating　highly　strained　nanoareas　in　the　YBCO,　with　enhancement　in　the　vortex　pinning.　We　have　also　observed　that　the　incoherent　interface　is　not　the　only　parameter　controlling　the　nanostrain.　The　Cu-O　intergrowth　characteristics　must　also　be　a　key　factor　for　controlling　the　nanostrain　in　future　tuning　of　YBCO　vortex　pinning.