Nowadays, for lanthanide fluorescence thermometry, high relative temperature sensitivity (S r) and wide sensing range are urgently required in practical applications. Herein, a Pr3+-doped scandate (Pr3+:CaSc2O4) luminescent thermometer is proposed, and the related crystal-field splitting of Pr3+ ions is systematically discussed. The 4f5d-4f and 4f-4f emissions of Pr3+ ions in CaSc2O4 basically present positive and negative correlation relationships with the increase in temperature, respectively. The different changing tendencies in relation to temperature for the two kinds of transitions are mainly derived from the effects of the thermally activated trap energy levels and the crossover process between 5d and 4f energy states of Pr3+ ions and are beneficial for the enhancement of relevant temperature sensitivities. The obtained experimental results manifest that Pr3+:CaSc2O4 owns a maximum relative temperature sensitivity S r of 2.49%·K–1 (at 390 K) and a low temperature uncertainty (around 0.1 K from 275 to 490 K). Moreover, it is also able to keep a relatively high S r (not lower than 2%·K–1) over a wide temperature sensing range (∼200 K), which is more excellent than those of reported luminescent thermometric materials (∼100 K). Hence, what discussed in this study might provide a useful design perspective for the exploration and development of high-performance luminescent thermometers with a wide applicable temperature range.

The dynamic performance of 4-SPS/CU (spherical joint, prismatic joint, cylindrical joint, and universal joint) parallel mechanism considering spherical joint with clearance is developed, and the three-dimensional (3D) wear property of the socket is based on the Archard's wear model. First, the kinematics model of spherical joint with clearance is established, and the updated procedure pertaining to the contact mechanics and wear state is explained via a flowchart. An improved contact force model was proposed by Flores et al. contact force model through a revised contact stiffness coefficient. The normal and tangential contact forces between ball and socket are calculated using the improved contact force model and a modified Coulomb friction model. Second, the dynamic model of the parallel mechanism considering spherical joint with clearance is formulated based on the multibody equations of motion. In order to obtain the 3D wear property of spherical joint with clearance, the contact force is decomposed into three components in the global coordinate system. The three components of sliding distance are computed based on the 3D revolute property of the parallel mechanism. Finally, the contact pressures in three different directions are calculated by the corresponding contact force and approximate contact area components for the sake of predicting the 3D wear depth of socket based on the Archard's wear model. The simulation results show that the wear depth in different directions along the socket surface is nonuniform, which affects the performance of 4-SPS/CU parallel mechanism.

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