Microwave-assist hydrothermal synthesis and luminescence of NaGd(WO4):Tb3+ phosphors: A case study for the energy saving in the synthesis of phosphors

• Microwave-assisted hydrothermal synthesis of NaGd(WO4):Tb3+ phosphors.
• The case study for the energy saving in the synthesis of phosphors.
• The uniform dimensions, good dispersity, good crystallinity and pure phase of samples.

NaGd(WO4):Tb3+ phosphors are synthesized successfully by the microwave-assist hydrothermal process. The TEM (Transmission electron microscopy) images show that the addition of PVP (polyvinylpyrrolidone) has an obvious influence on the morphology of samples. NaGd(WO4):Tb3+ samples are of microspindles and microcuboids when 0.45 g and 1.00 g of PVP are added in the synthesis. The XRD patterns and Raman shifts indicate that the samples with pure tetragonal phase can be obtained under the current synthesis condition. The excitation and emission spectra of NaGd(WO4):Tb3+ microcrystals show that there exist energy transfers between the WO42− groups and Tb3+ ions. Under the excitation at 261 nm, NaGd(WO4):Tb3+ samples show dominant green emission originating from the 5D4 → 7F5 transition of Tb3+. The decay lifetimes of samples are fitted well with the second-order exponential decay curve. The emission intensity decreases gradually with the increase of temperature. Also, there are blue shifts for the location of green emission peak with the increase of temperature.