Akihito Yoshida

LiNbO3:Pr3+: A Multipiezo Material with Simultaneous Piezoelectricity and Sensitive Piezoluminescence

Red-emitting piezoluminescence (elasticoluminescence) is achieved by doping rare earth Pr3+ into the well-known piezoelectric matrix, LiNbO3 . By precisely tuning the Li/Nb ratio in nonstoichiometric Li x NbO3 :Pr3+ , a material that exhibits an unusually high piezoluminescence intensity, which far exceeds that of any well-known piezoelectric material, is produced. Li x NbO3 :Pr3+ shows excellent strain sensitivity at the lowest strain level, with no threshold for stress sensing. These multipiezo properties of sensitive piezoluminescence in a piezoelectric matrix are ideal for microstress sensing, damage diagnosis, electro-mechano-optical energy conversion, and multifunctional control in optoelectronics.

Tuning the mechano-optical conversion in CaZnOS with Cu ion concentration

This article reports a new class of mechano-optical materials CaZnOS : Cu with a non-centrosymmetric layered structure. The mechano-optical conversion is strongly dependent on the Cu concentration in CaZnOS. The mechano-optical conversion of CaZnOS : Cu changes from initial mechanoluminescence to mechanical quenching (MQ) with increasing Cu concentration, and reaches a maximum MQ intensity at 0.01%. It is proposed that MQ arises from nonradiative recombination, caused by electron transfer from trap levels to nonradiative centers as a result of the mechanical load.