Ab-initio DFT calculations and experimental investigations into optoelectronic and structural properties of Ca9Al(PO4)7:Sm3+ orange phosphor

•Ca9Al(PO4)7:Sm3+ nanophosphors have been synthesized via urea-assisted solution-combustion method.•Crystal structure analysis of Ca9Al0.90(PO4)7:0.10Sm3+ nanophosphor has been reported on Rietveld treatment.•Optical properties for Ca9Al(PO4)7 host lattice are calculated from DFT.•Energy band gap for Ca9Al(PO4)7 host is obtained experimentally and theoretically.•These nanophosphors have potential applications in solid state lighting devices.