Goldschmidt's concept of ionic Tolerance Factors was recently shown to be a valuable guideline for the preparation of new compounds within the field of organic–inorganic perovskites. Here, we extend this approach and calculate Tolerance Factors for over 2500 amine–metal–anion permutations of the periodic table. The results suggest the potential existence of more than 600 undiscovered hybrid perovskites including alkaline earth metal and lanthanide based materials.

/pdf/an-extended-tolerance-factor-approach-for-organic-inorganic-3vg0eetu4o.pdf

An extended Tolerance Factor approach for organic–inorganic perovskites

The application of ferroelectric materials (i.e. solids that exhibit spontaneous electric polarisation) in solar cells has a long and controversial history. This includes the first observations of the anomalous photovoltaic effect (APE) and the bulk photovoltaic effect (BPE). The recent successful application of inorganic and hybrid perovskite structured materials (e.g. BiFeO3, CsSnI3, CH3NH3PbI3) in solar cells emphasises that polar semiconductors can be used in conventional photovoltaic architectures. We review developments in this field, with a particular emphasis on the materials known to display the APE/BPE (e.g. ZnS, CdTe, SbSI), and the theoretical explanation. Critical analysis is complemented with first-principles calculation of the underlying electronic structure. In addition to discussing the implications of a ferroelectric absorber layer, and the solid state theory of polarisation (Berry phase analysis), design principles and opportunities for high-efficiency ferroelectric photovoltaics are presented.

/pdf/ferroelectric-materials-for-solar-energy-conversion-19ffns6ifj.pdf

Ferroelectric materials for solar energy conversion: photoferroics revisited

Z.L., T.L., R.W., and Y.L. thank the Australian Research Council (ARCDP160104780) for financial support in the form of ARC Discovery Project. Z.L., J.Y., G.W., and X.D. thank the financial support of the National Natural Science Foundation of China (NSFC No. 11774366) and International Partnership Project of Chinese Academy of Science. Z.L. also acknowledges the support of Shanghai Sailing Program (No. 17YF1429700).

Antiferroelectrics for Energy Storage Applications: a Review

Local Structural Heterogeneity and Electromechanical Responses of Ferroelectrics: Learning from Relaxor Ferroelectrics

Owing to growing environmental concerns, the development of lead-free piezoelectrics with comparable performance to the benchmark Pb(Zr,Ti)O3 (PZT) becomes of great urgency. However, a further enhancement of lead-free piezoelectrics based on existing strategies has reached a bottleneck. Here we achieve a slush polar state with multiphase coexistence in lead-free potassium-sodium niobate (KNN) piezoceramics, which shows a novel relaxor behavior, i.e., frequency dispersion at the transition between different ferroelectric phases. It is very different from the conventional relaxor behavior which occurs at the paraelectric-ferroelectric phase transition. We obtain an ultrahigh piezoelectric coefficient (d33) of 650 ± 20 pC/N, the largest value of nontextured KNN-based ceramics, outperforming that of the commercialized PZT-5H. Atomic-resolution polarization mapping by Z-contrast imaging from different orientations reveals the entire material to comprise polar nanoregions with multiphase coexistence, which is again very different from conventional ferroelectric relaxors which have polar domains within a nonpolar matrix. Theoretical simulations validate the significantly decreased energy barrier and polarization anisotropy, which is facilitated by the high-density domain boundaries with easy polarization rotation bridging the multiphase-coexisting nanodomains. This work demonstrates a new strategy for designing lead-free piezoelectrics with further enhanced performance, which should also be applicable to other functional materials requiring a slush (flexible) state with respect to external stimulus.

Ultrahigh Performance in Lead-Free Piezoceramics Utilizing a Relaxor Slush Polar State with Multiphase Coexistence.

PbZr(1-x)Ti(x)O3 (PZT) is one of the most important and widely used piezoelectric materials. The study of its local and average structures is of fundamental importance in understanding the origin of its high-performance piezoelectricity. Pair distribution function analysis and Rietveld refinement have been carried out to study both the short- and long-range order in the Zr-rich rhombohedral region of the PZT phase diagram. The nature of the monoclinic phase across the Zr-rich and morphotropic phase boundary area of PZT is clarified. Evidence is found that long-range average rhombohedral and both long- and short-range monoclinic regions coexist at all compositions. In addition, a boundary between a monoclinic (M(A)) structure and another monoclinic (M(B)) structure has been found. The general advantage of a particular monoclinic distortion (M(A)) for high piezoactivity is discussed from a spatial structural model of susceptibility to stress and electric field, which is applicable across the wide field of perovskite materials science.

/pdf/the-missing-boundary-in-the-phase-diagram-of-pbzr1-xtixo3-2k0gc026nq.pdf

The missing boundary in the phase diagram of PbZr1−xTixO3

Mn-doped 0.08Pb(In1/2Nb1/2)O3-0.60Pb(Mg1/3Nb2/3)O3-0.32PbTiO3 (PIN-PMN-PT) ceramics with a composition within the morphotropic phase boundary region have been prepared by solid state reaction method, with Mn-doping levels varying from 0 to 4%. The Curie temperature (TC) for the ferroelectric (FE) to paraelectric (PE) phase transition decreases with increasing Mn-doping rate, from 176°C (0% Mn) to 152°C (4% Mn), and the FE-PE phase transition becomes more diffuse. The temperature for the ferroelectric rhombohedral to ferroelectric tetragonal phase transition (TRT) also decreases with the increasing Mn-doping level, from 87°C (0% Mn) to 65°C (4% Mn). The density of the ceramics is significantly enhanced with Mn-doping.

Effects of Mn-Doping on PIN-PMN-PT Ceramics with MPB Composition

A new solid solution of complex perovksite structure, (1-x)PbZrO3-xPb(Mn1/2W1/2)O3 (PZ-xPMnW, with x = 0–0.1), is prepared by solid state reaction method. Its crystal structure, dielectric properties, and antiferroelectricity are investigated. It is found that the crystal structure of the solid solution remains in the orthorhombic Pbam symmetry with x ≤ 0.1. The induced ferroelectric polarization (PInd) is enhanced, whereas the critical field (ECr) is decreased, with increasing PMnW concentration, indicating the softening of antiferroelectricity in PZ. The Curie temperature (TC) is also decreased with the substitution of PMnW for PZ. The grain size is significantly enlarged, which could be attributed to the presence of a transient liquid phase during the sintering process. Measurements of the magnetization by means of SQUID confirm that the Mn ion exists in a high spin state with a 2+ oxidation state. The softening of antiferroelectric order and the improvement in induced polarization make the PZ-PMnW ceramics an interesting material system for such applications as energy storage devices.

Softening of antiferroelectricity in PbZrO3-Pb(Mn1/2W1/2)O3 complex perovskite solid solution

Catalytic effect of ethylene thiourea on the leaching of chalcopyrite

This application pertains to methods of recovering metals from metal sulfides that involve contacting the metal sulfide with an acidic sulfate solution containing ferric sulfate and a reagent that has a thiocarbonyl functional group, wherein the concentration of reagent in the acidic sulfate solution is sufficient to increase the rate of metal ion extraction relative to an acidic sulfate solution that does not contain the reagent, to produce a pregnant solution containing the metal ions.

Zihe Ren

Papers

The missing boundary in the phase diagram of PbZr1−xTixO3

Effects of Mn-Doping on PIN-PMN-PT Ceramics with MPB Composition

Softening of antiferroelectricity in PbZrO3-Pb(Mn1/2W1/2)O3 complex perovskite solid solution

Catalytic effect of ethylene thiourea on the leaching of chalcopyrite

Process for Leaching Metal Sulfides with Reagents Having Thiocarbonyl Functional Groups