Synthesis, characterization and testing of Cr(III)‐doped aluminum oxide/molybdate nanocomposites as luminescent probes for scanning thermal microscopy

Abstract

AbstractThe conditions of synthesis and luminescence characteristics of composites Al2O3:Cr3+/NaAl(MoO4)2:Cr3+obtained from molybdate high‐temperature solutions have been studied. The composite formation has been achieved by rapid cooling of a Na‐Al‐Cr‐Mo‐O molten solution in the range of 1173‐820 K. The sizes of the alumina inclusions in the molybdate host range from sub‐microns to tenth of microns. The composite material is transparent for light in the visible spectral region, it allows effective excitation of the Cr3+ luminescence in Cr3+‐ related absorption bands in both NaAl(MoO4)2hosts and Al2O3inclusions. At liquid helium temperature, the Al2O3:Cr3+/NaAl(MoO4)2:Cr3+composite materials simultaneously reveal luminescence of Cr3+ ions in NaAl(MoO4)2(the R‐line near 741 nm) and in Al2O3(the R1 line near 693 nm). At room temperature, the Al2O3:Cr3+ inclusions reveal Cr3+‐related R1 and R2 lines at 694.2 and 692.8 nm, respectively, whereas the luminescence of Cr3+ ions in the molybdate host is quenched. Testing of Al2O3:Cr3+ fluorescent particles in a scanning thermal microscope reveals potential of using the Cr‐doped Al2O3:Cr/NaAl(MoO4)2 nanocomposites for high‐resolution mapping of the surface temperature in 300‐380 K temperature range. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)