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The domain reversal dynamics of rhombohedral and tetragonal PIN–PMN–PT ferroelectric single crystals has been investigated by analyzing the variation of hysteresis loops under various electric fields and frequencies. As the electric field amplitude E0 continuously increases, the hysteresis area ⟨A⟩ clearly reflects three stages of polarization reversal. The complete scaling relations of domain reversal dynamics were determined. For rhombohedral PIN–47PMN–29PT crystals, the dynamic hysteresis area follows the law of ⟨A⟩ ∝ f −0.38816E05.21244 in the first E0-stage and ⟨A⟩ ∝ f 0.03553E00.37126 in the third E0-stage. For tetragonal PIN–37PMN–39PT crystals, the dynamic hysteresis area follows the law of ⟨A⟩ ∝ f −0.09054E02.74854 in the first E0-stage and ⟨A⟩ ∝ f −0.15504E02.06936 in the third E0-stage. The negative α indicates that with the alternating velocity of the increasing periodic electric field, more and more domain reversals fail to follow with the alternating electric field. However, rhombohedral PIN–47PMN–29PT crystals possess a positive α in the third E0-stage, indicating that 71° and 109° domains can keep pace with varying E0 more easily. The positive β indicates that when the electric field frequency is fixed, more and more domains begin to reverse with the intensity of the increasing electric field. In addition, the function of ⟨A⟩ ∝ f αE0β cannot be applied to the second E0-stage, where the non-180° domain rotation starts occurring but 180° domain rotation has not finished yet.

Undesirable pyrochlore phase often appears in Pb(Mg1/3Nb2/3)O3‐PbTiO3 (PMN‐PT)‐based ceramics with high rare‐earth ion (RE3+) doping concentration, which greatly limits their development. In this study, 0–5 mol% Sm3+‐doped Pb(Mg1/3Nb2/3)O3‐29PbTiO3 (PMN‐29PT:0‐5Sm) ceramics were first synthesized using traditional precursor method. In the X‐ray diffraction spectra and scanning electron microscope images of PMN‐29PT:3‐5Sm ceramics, the diffraction peaks of pyrochlore phase and pyrochlore grains with octahedral morphology were observed, respectively. The reason for the appearance of the pyrochlore phase is that Sm3+ doping causes the Nb‐rich regions. To eliminate the pyrochlore phase, PMN‐29PT:3‐5Sm ceramics were resynthesized by an improved precursor method in which an excess of 4 mol% MgO was added to the reactants before pre‐sintering. After adding an excess of 4 mol% MgO, the concentration ratio of Nb5+ and Mg2+ in the pyrochlore grains returned to the value in the perovskite grains, and the pyrochlore phase was transformed into the perovskite phase PMN. The dielectric, ferroelectric, and electromechanical properties were compared before and after eliminating the pyrochlore phase. The results show that the comprehensive performance of the ceramics is improved after eliminating the pyrochlore phase.

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The nanopositioning stage with a piezoelectric driver usually compensates for the nonlinear outer-loop hysteresis characteristic of the piezoelectric effect using the Prandtl–Ishlinskii (PI) model under a single-ring linear voltage, but cannot accurately describe the characteristics of the inner-loop hysteresis under the reciprocating linear voltage. In order to improve the accuracy of the nanopositioning, this study designs a nanopositioning stage with a double-parallel guiding mechanism. On the basis of the classical PI model, the study firstly identifies the hysteresis rate tangent slope mark points, then segments and finally proposes a phenomenological model—the mark-segmented Prandtl–Ishlinskii (MSPI) model. The MSPI model, which is fitted together by each segment, can further improve the fitting accuracy of the outer-loop hysteresis nonlinearity, while describing the inner-loop hysteresis nonlinearity perfectly. The experimental results of the inverse model compensation control show that the MSPI model can achieve 99.6% reciprocating linear voltage inner-loop characteristic accuracy. Compared with the classical PI model, the 81.6% accuracy of the hysteresis loop outer loop is improved.

This paper presents a novel mechanical and thermal activation assisted carbothermal reduction (CR) method for synthesising Ti(C,N) powder at lower temperatures. Nano Ti(C,N) powder with approximately 30 nm grain size was synthesised by mixing powders of titanium, anatase, and carbon black. The starting powders were first milled for 10 to 40 h under N 2 /Ar atmosphere, and then vacuum heat treated for 1 h at 800 to 10508C. Consequently, nano Ti(C,N) powder with approximately 30 nm grain size was synthesised. X-ray diffraction analysis shows that Ti(C,N) is partially formed during mechanical milling, and the remaining reactants react completely below 10508C. However, when the unmilled starting powders are heat treated at 10508C under N 2 for 1 h, large amounts of reactants remain. Thermogravimetry and differential scanning calorimetry analysis shows that the CR reaction of activated TiO 2 occurs at a lower temperature under N 2 than under Ar or vacuum.

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