The temperature dependence of the integrated luminescence intensity of PbWO4 microspheres measured with an
excitation wavelength of 285 nm was shown in the inset of
Figure 13, indicating that the luminescence intensity of PbWO4
microspheres decreases with increasing temperature from 10 K
to room temperature, which is in good agreement with that
reported previously.35
CaWO4 monodisperse microspheres show optical properties
similar to those of PbWO4. Figure 14 shows that the emission
peak at 420 nm (2.95 eV) is in good agreement with the reported
value. The luminescence intensity of CaWO4 microspheres with
an excitation wavelength of 235 nm also decreases with
increasing temperature from 10 to 270 K (Figure 14)