Introduction　As　a　high-quality　light　source,　the　performance　of　phosphor-converted　white　light　emitting　diodes　(pc-WLEDs)　is　closely　related　to　the　performance　of　the　selected　luminescent　materials.　The　traditional　method　of　combining　blue　LED　chips　and　yellow　phosphors　to　generate　white　light　has　problems　of　low　color　rendering　index　and　high　color　temperature.　To　address　the　pressing　requirements　of　lighting　and　display　technologies,　the　development　of　novel　red　phosphors　with　high　efficiency　and　excellent　thermal　stability　is　urgent.　Perovskite　tellurites　have　attracted　extensive　attention　due　to　their　elemental　diversity　and　structural　tunability.　Based　on　the　double　perovskite　Ca3TeO6,　a　series　of　NaLaCaTeO6:xEu3+　phosphors　that　can　be　effectively　excited　by　near-ultraviolet　light　have　been　designed　and　synthesized　by　elemental　design.　Through　a　co-substitution　strategy　of　[Na+–La3+]　substitution　of　[Ca2+–Ca2+]　ion　pair,　the　problem　of　low　Eu3+　doping　concentration　in　Ca3TeO6:Eu3+　is　effectively　improved　by　regulating　the　matrix　structure.　Meanwhile,　the　luminous　intensity　and　thermal　stability　of　the　sample　were　also　significantly　improved.　Methods　Series　of　NLCT:xEu3+　(0.05　≤　x　≤　1.0)　samples　were　successfully　synthesized　by　a　high-temperature　solid-state　reaction.　The　stoichiometric　amounts　of　raw　materials,　including　Na2CO3　(105.99　g/mol,　99.9%),　CaCO3　(100.09　g/mol,　99.9%),　TeO2　(159.6　g/mol,　99.99%),　La2O3　(325.84　g/mol,　99.99%)　and　Eu2O3　(351.93　g/mol,　99.99%)　purchased　from　Shanghai　Aladdin　Biochemical　Technology　Co.,　Ltd.,　were　weighed　and　grounded　into　homogeneous　powder　for　30　min.　Afterward,　the　obtained　powder　was　put　into　crucibles　and　heated　at　1473　K　for　12　h　in　a　muffle　furnace.　Eventually,　the　target　substances　were　obtained　after　cooling　down　and　grinding　again.　A　red　LED　device　was　assembled　using　the　NLCT:0.6Eu3+　phosphor　with　a　395　nm　chip.　The　WLED　device　was　fabricated　by　connecting　tricolor　phosphors　including　BaMgAl10O17:Eu2+　(BAM:Eu2+,　blue),　(Ba,　Sr)2SiO4:Eu2+　(BSS:Eu2+,　green),　along　with　the　prepared　NLCT:0.6Eu3+　(red)　with　a　395　nm　chip.　Results　and　discussion　The　results　of　XRD　patterns　showed　that　[Na+–La3+]　substituted　the　[Ca2+–Ca2+]　ion　pair,　which　did　not　affect　the　structure　of　the　sample.　The　diffraction　peaks　of　the　samples　with　x　=　0.1–0.6　did　not　show　obvious　impurity　peaks,　indicating　that　the　synthesized　samples　were　pure　phases.　Eu3+　ions　tended　to　occupy　the　site　of　La　in　the　matrix　rather　than　Te.　DRS　results　also　confirmed　that　Eu3+　ions　were　successfully　introduced　into　the　NLCT　matrix.　The　dominant　absorption　peak　at　395　nm　matches　well　with　InGaN-based　LED,　and　the　emission　intensity　reaches　the　maximum　at　x　=　0.6.　The　primary　mechanism　among　Eu3+　ions　in　NLCT:xEu3+　samples　was　proved　to　the　dipole-dipole　interaction.　The　luminous　intensity　of　the　prepared　NLCT:0.6Eu3+　red　phosphor　is　about　1.98　and　3.97　times　than　that　of　CT:0.2Eu3+　and　Y2O3:Eu3+,　confirming　the　feasibility　of　the　co-substitution　strategy.　The　internal　quantum　yield　and　color　purity　of　NLCT:0.6Eu3+　are　67.6%　and　99.87%,　respectively.　The　CIE　color　coordinates　of　this　sample　(0.658　1,　0.341　0)　are　closer　to　the　ideal　red　point　(0.670,　0.330)　than　that　of　the　purchased　commercial　red　phosphor　Y2O3:Eu3+.　Compared　with　CT:0.2Eu3+　(about　77.5%),　the　thermal　stability　of　NLCT:0.6Eu3+　is　significantly　improved.　When　the　temperature　rises　to　420　K,　the　emission　intensity　at　616　nm　remains　91.7%　of　that　at　300　K.　Furthermore,　the　sample　exhibits　excellent　color　stability　by　the　CIE　coordinates　shifting　only　slightly　from　(0.658　2,0.340　8)　to　(0.646　6,0.351　9)　with　increasing　temperature.　The　CCT　and　Ra　of　the　prepared　WLED　device　are　6215　K　and　80.6,　respectively,　and　the　CIE　coordinates　(0.317　6,　0.334　0)　are　located　in　the　white　light　region.　Conclusions　A　series　of　innovative　NaLaCaTeO6:xEu3+　phosphors　were　synthesized　using　a　high　temperature　solid-state　reaction　method.　Under　395　nm　excitation,　the　NaLaCaTeO6:Eu3+　samples　exhibit　a　strong　red　emission　at　616　nm　(5D0→7F2)　of　Eu3+　ions.　Through　a　co-substitution　strategy　where　[Na+–La3+]　replaced　the　[Ca2+–Ca2+]　ion　pair,　the　optimized　doping　concentration　of　the　NaLaCaTeO6:xEu3+　is　elevated　to　60%　(molar　fractior),　leading　to　exceptional　color　purity　and　high　internal　quantum　efficiency　reaching　99.87%　and　67.60%,　respectively.　Furthermore,　compared　to　the　Ca3TeO6:0.2Eu3+　sample　pre-substitution,　the　luminous　intensity　and　thermal　stability　of　NaLaCaTeO6:0.6Eu3+　phosphor　witness　a　notable　increase.　Even　at　420　K,　the　emission　intensity　remains　at　91.7%　compared　to　300　K.　The　resultant　WLED　displays　a　color　rendering　index　Ra　of　80.6　and　CIE　chromaticity　coordinates　of　(0.317　6,　0.334　0),　underscoring　the　broad　application　potential　of　NaLaCaTeO6:0.6Eu3+　in　solid-state　lighting.　©　2025　Chinese　Ceramic　Society.　All　rights　reserved.