Characterization of paramagnetic KHo(WO4)2 nanocrystals: Synthesized by polymeric mixed-metal precursor sol–gel method

Nanocrystalline KHo(WO4)2 (KHW) particles were successfully synthesized via conventional Pechini sol–gel method. Prepared precursor gel was calcined at 250, 550, 600, 650 and 700 °C, and the resulting samples were analyzed with TG–DTA, powder X-ray diffraction, FT-IR, Raman, FESEM, TEM, UV–Vis-NIR (diffuse reflectance spectrum (DRS)), fluorescence and vibrating sample magnetometer (VSM). Thermal degradation of derived gel was observed up to 400 °C and phase formation starts from 550 °C. The product phase formation at higher annealing temperature was investigated by means of powder XRD. Organic liberation in the samples with respect to temperature was analyzed using FT-IR spectrum. Raman spectrum reveals the formation of tungsten ribbons as well as the quality of the samples while increasing the calcination temperature. The nano size of the synthesized particles was confirmed with FESEM and TEM micrographs. Reflectance and emission studies reveal the corresponding absorption and emission properties of trivalent state holmium ion. Paramagnetic behavior of the derived KHW was confirmed with VSM results.

► Nano crystallites of KHW were successfully synthesized using Pechini polymeric complex sol–gel method. ► Raman spectrum for samples calcined at 250–700 °C reveals that W–O tungsten oxide double bridge was formed at 600 °C. ► The TEM and FESEM analysis reveals that the individual nano particles were formed at 650 °C with well aligned particles. ► The absorption and emission studies indicate the applicability of the derived material for laser devices.