Structural and luminescent properties of water-quenched Eu3+-doped HfW2O8 with negative thermal expansion

초록

This study represents the first attempt to correlate the photoluminescence properties of Eu3+-doped HfW2O8 (Hf1-xEuxW2O8) with their novel thermal structural changes, i.e., negative thermal expansion (NTE). We synthesized Hf1-xEuxW2O8 (x = 0, 0.01, 0.03, 0.05, 0.07, 0.09, 0.12, and 0.15) via a fast solid state reaction method with water quenching. Temperature dependent X-ray diffraction patterns exhibited the phase transition from alpha-phase ( P2 1 3 , cubic) to n-phase ( Pa-3 , cubic) as the temperature increased from room temperature to 200 degrees C, along with highly linear contraction of lattice constants. The thermal expansion coefficient and the volume thermal expansion coefficient were determined as approximately-1.1 x 10-5 and-3.4 x 10-5, respectively. In the temperature dependent photoluminescence measurement, together with the thermal quenching behavior, we found that the asymmetric ratios decreased in accord with the structural change to higher symmetry. These findings reveal that the luminescent properties of Eu3+ are closely related to the structural properties in NTE HfW2O8.

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