Effect of Yb concentration on upconversion luminescence and optical thermometry sensitivity of LaMoO: Yb, Er phosphors.

:, upconversion (UC) micro-crystals with a tetragonal structure were fabricated through a modified sol-gel method. The samples are found to be spherical in shape with a diameter of about 300 nm. Upon excitation of 980 nm light, the UC emission spectra of the phosphors exhibit green and red bands corresponding to the characteristic transitions of ions. As concentration rises, the green emission intensity increases and reaches the maximum at 2.0% content, while the ratio of green/red emission intensities (/) declines monotonically. Temperature sensing capability was studied employing the fluorescent intensity ratio technique from the thermally coupled levels and of in temperature range of 293∼533 K. It is interesting to find that concentration has influence on the absolute sensitivity , while the relative sensitivity is almost independent of content. Furthermore, excellent thermal stability and high temperature sensitivity is also demonstrated in the 2.0% -doped sample with the obtained maximum and as high as 0.008 and 1.093, respectively. The experimental results indicate that / co-doped phosphors can be excellent candidates for temperature sensing applications.