Sb Substitution Research Articles

Enhanced thermoelectric performance of n-type Nb-doped PbTe by compensating resonant level and inducing atomic disorder

The inferior thermoelectric performance of n-type PbTe limits the overall conversion efficiency in PbTe-based thermoelectric devices. Here, we introduce Sb and Cu2Te into n-type Nb-doped PbTe for achieving ultra-high thermoelectric performance. The co-doping of Sb and Cu effectively optimizes carrier concentration to compensate for the resonant level in Nb-doped PbTe alloys, and consequently achieves superior electrical performance over a wide temperature range. Meanwhile, by combining extended X-ray absorption fine structure and exhaustive electron microscopy investigations, we found Nb and Sb substitutions at Pb sites induce atomic disorders, such local mass fluctuation and local strain variation, in the lattice, and Cu2Te further results in microsized segregations and nanoprecipitates, which significantly suppress lattice thermal conductivity. Eventually, a peak ZT of ∼1.32 at 823 K and a high average ZTave ∼1.01 in the range from 323 to 823 K are achieved in the Pb0·975Nb0·02Sb0·005Te-0.004Cu2Te. Based on our findings, we innovatively employ comprehensive characterization to reveal the origin of ultrahigh thermoelectric performance in n-type Nb-doped PbTe within a wide temperature range, which should be generalized to other thermoelectric materials.

Manipulation of the ferromagnetic ordering in magnetic semiconductor (La,Ca)(Zn,Mn)AsO by chemical pressure

We investigate the chemical pressure effects on the ferromagnetic ordering in magnetic semiconductor (La0.9Ca0.1)(Zn0.9Mn0.1)AsO by isovalent substitutions of Sb for As and Y for La, respectively. X-ray diffraction measurements indicate that Sb substitution for As expands the lattice and introduces negative chemical pressure into the system. On the other hand, Y substitution for La reduces the unit-cell volume, and improves the Curie temperature by ∼30% at the doping level of 7.5%.

Enhanced Thermoelectric Performance in Ternary Skutterudite Co(Ge0.5Te0.5)3 via Band Engineering.

We report the phase evolution and thermoelectric properties of a series of Co(Ge0.5Te0.5)3-xSbx (x = 0-0.20) compositions synthesized by mechanical alloying. Pristine ternary Co(Ge0.5Te0.5)3 skutterudite crystallizes in the rhombohedral symmetry (R3̅), and Sb doping induces a structural transition to the cubic phase (ideal skutterudite, Im3̅). The Sb substitution increases the carrier concentration while maintaining a high thermopower even at higher doping levels owing to an increased effective mass. The exceptional electronic properties exhibited by Co(Ge0.5Te0.5)3 upon doping are attributed to the carrier transport from both the primary and secondary conduction bands, as shown by theoretical calculations. The enhanced electrical conductivity and high thermopower increase the power factor by more than 20 times. Because the dominant phonon propagation modes in binary skutterudites are associated with the vibrations of pnictogen rings, twisting the latter through the isoelectronic replacement of Sb4 rings with Ge2Te2 ones, as done in this study, can effectively reduce the thermal conductivity. This leads to an increase in the dimensionless figure-of-merit (zT) by a factor of 30, reaching 0.65 at 723 K for Co(Ge0.5Te0.5)2.9Sb0.1.

Suppressing O3−O’3 phase transition in NaCrO2 cathode enabling high rate capability for sodium-ion batteries by Sb substitution

Poor rate capability of cathode materials for sodium-ion batteries (SIBs) is one of the major obstacles hindering practical application of SIBs due to the large ion radius of Na+ and its sluggish kinetics. Improving rate capability for SIBs is a critical issue. Herein, we reveal that introducing small amount of Sb into O3-NaCrO2 can improve the rate capability of NaCrO2 cathode significantly. The occupation of Sb in Cr sites can expand the c/a ratio and the unit cell volume, thus promoting sodium diffusion in the a-b channels. Under a high rate of 5C, the 5% Sb-substituted Na0.9Cr0.95Sb0.05O2 (NCS-0.05) shows a reversible capacity of 114 mAh g−1 with capacity retention of 70.9% after 1000 cycles. Under an ultrahigh current rate of 32C, a reversible capacity of 96.1 mAh g−1 can still be maintained. Synchrotron in situ X-ray diffraction results reveals highly reversible phase transition behavior of NCS-0.05 during cycling even under high rates, and the O3 → O’3 phase transition in NaCrO2 is suppressed effectively by Sb substitution. Density functional theory calculations indicate that Sb substitution can also lower desodiation energy and decrease the bandgap of NaCrO2, leading to improved reaction kinetics and electronic conductivity.

Growth and optical characterization of Sn0.6Sb0.4Se layer single crystals for optoelectronic applications

SnSe compound is an attractive semiconductor material due to its usage in photovoltaic applications. The substitution of Sb in the SnSe compound presents a remarkable advantage especially in point of tuning optical characteristics. The present paper reports the structural and optical properties of Sn1-xSbxSe (x = 0.4) layered single crystals grown by the vertical Bridgman method. To the best of our knowledge, this work is the first investigation of the Sn0.6Sb0.4Se crystal grown with the vertical Bridgman technique. X-ray diffraction (XRD) pattern of the grown crystal indicated the well crystalline structure of the grown crystals. Lattice strain and interplanar spacing of the crystal structure were determined using the XRD pattern. Scanning electron microscope images allowed to the observation of the layer crystal structure. The layer crystalline structure shows 2D material properties and provides 2D applications. Optical properties were revealed by carrying out Raman, ellipsometry and transmission measurements. Raman modes, refractive index, extinction coefficient, and dielectric spectra, band gap energy of the crystal were presented throughout the paper. The obtained results indicated that Sn1-xSbxSe (x = 0.4) layer single crystals may be an alternative potential for photovoltaic and optoelectronic applications.

Excellent energy storage properties in NaNbO3-based lead-free ceramics by modulating antiferrodistortive of P phase

The adjustment of the antiferroelectricity of a perovskite cell and the reversibility of antiferroelectric (AFE) -ferroelectric (FE) phase transition under electric field is very important for achieving excellent energy storage properties in AFEs. In this work, obvious change of antiferroelectricity was found in novel Na(Nb1−xSbx)O3 lead-free ceramics fabricated via a conventional solid-state reaction method. Repeatable double P-E loops with large EA-F ~28 kV/mm and large EF-A ~10 kV/mm were obtained in the x = 0.1 ceramic with AFE P phase at room temperature, resulting in excellent energy storage properties with Wrec ~3.4 J/cm3, large CD ~366 A/cm2, high PD ~26 MW/cm3 as well as fast discharge rate t0.9 ~75 ns. The multiscale structure analysis results indicate that the increased antiferrodistortive (oxygen octahedral tilting) degree and the decreased off-centering displacements of B-site cations after the substitution of Sb for Nb make the main contributions to the achievement of stable AFE phase and reversible AFE-FE phase transition in this work. The Na(Nb1−xSbx)O3 ceramics with excellent energy storage properties show large potential for the next-generation pulse power capacitor applications, and the mechanism for modulating antiferroelectricity found in this work would provide guidance for designing high-performance AFEs.

High ionic conductivity and stable phase Na11.5Sn2Sb0.5Ti0.5S12 for all-solid-state sodium batteries

The quaternary antimony (Sb)-based sulfide sodium solid electrolyte Na11Sn2SbS12 with good moisture stability is attractive for practical application in all-solid-state sodium batteries. However, the Na11Sn2SbS12 exhibits low room temperature ionic conductivity and it is difficult to obtain pure phase due to the limited solubility of Sb in the Na11Sn2SbS12 crystal structure. Herein, titanium (Ti)-doping Na11+xSn2Sb1-xTixS12 (x = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.8, 1.0) materials are systematically investigated, and the highest room temperature ionic conductivity of 1.01 mS cm−1 is achieved when x = 0.5 (Na11.5Sn2Sb0.5Ti0.5S12), which is 3 times higher than that of pristine Na11Sn2SbS12. X-ray diffraction and alternating current impedance analyses reveal that the substitution of Sb with Ti can prevent the formation of the NaSbS2 impurity, determining high ionic conductivity. Meanwhile, the Na11.5Sn2Sb0.5Ti0.5S12 demonstrates good air stability with limited H2S gas evolution. Besides, the activation energy, electronic conductivity and electrochemistry stability window for Na11.5Sn2Sb0.5Ti0.5S12 are also evaluated. Moreover, a high reversible capacity and stable cyclic performance of TiS2 based all-solid-state sodium battery using Na11.5Sn2Sb0.5Ti0.5S12 are demonstrated, showing an initial discharge capacity of 177.6 mAh g−1 at 0.1C with a capacity retention of 83.5% based on the second discharge capacity after 50 cycles at 25 °C.

Unveiling the multilevel structure of midgap states in Sb-doped MoX2 (X=S, Se, Te) monolayers

In this study, we use first-principles calculations to investigate the electronic and structural properties of $\text{Mo}{X}_{2}$ $(X=\text{S}, \mathrm{Se}, \mathrm{Te})$ monolayers doped with substitutional Sb atoms, with a central focus on the Sb(Mo) substitution. In ${\mathrm{MoS}}_{2}$, we observe that this substitution is energetically favored under S-rich conditions, where the ${\mathrm{S}}_{2}$ gaseous phase is likely to be present. This result is compatible with a recent experimental observation in Sb-doped ${\mathrm{MoS}}_{2}$ nanosheets grown by chemical vapor deposition. A similar behavior is found in ${\mathrm{MoSe}}_{2}$, but in ${\mathrm{MoTe}}_{2}$ the Sb(Mo) substitution is less likely to occur due to the possible absence of gaseous Te phases in experimental setups. In all cases, several impurity-induced states are found inside the band gap, with energies that span the entire gap. The Fermi energy is pinned a few tenths of eV above the top of the valence band, suggesting a predominant $p$-type behavior, and gap energies are slightly increased in comparison to the pristine systems. The orbital nature of these states is further investigated with projected and local density of states calculations, which reveal similarities to defect states induced by single Mo vacancies as well as their rehybridization with the $5s$ orbital from Sb. Additionally, we find that the band gap of the doped systems is increased in comparison with the pristine materials, in contrast with a previous calculation in Sb-doped ${\mathrm{MoS}}_{2}$ that predicts a gap reduction with a different assignment of valence band and impurity levels. We discuss the similarities, discrepancies, and the limitations of both calculations. We also speculate possible reasons for the experimentally observed redshifts of the $A$ and $B$ excitons in the presence of the Sb dopants in ${\mathrm{MoS}}_{2}$. We hope that these results spark future investigations on other aspects of the problem, particularly those concerning the effects of disorder and electron-hole interaction, and continue to reveal the potential of doped transition-metal dichalcogenides for applications in optoelectronic devices.

Synthesis, structure, and nonlinear optical property of Bi0.33Sb0.67SI

The phase transition of SbSI from non-centrosymmetry to centrosymmetry occurs at 292K, which is too low for its practical applications such as ferroelectricity and nonlinear optics. Here, the substitution of Sb by Bi atoms is proposed to improve its phase transition temperature. A new chalcohalide, Bi0.33Sb0.67SI, has been successfully synthesized by self-flux method. It crystallizes in the non-centrosymmetric space group Pmc21 (No. 26) with a ​= ​4.1190 (9) Å, b ​= ​10.225 (2) Å, c ​= ​8.5318 (18) Å. Different from the crystal structure of SbSI, Bi0.33Sb0.67SI is composed of two kinds of edge-sharing distorted square pyramid [MS3I2]5- (M ​= ​Bi or Sb), which form [∞1M2S4I2]4- chains along a axis. The compound exhibits a moderate powder second harmonic generation signal at 2.09 ​μm, which was consistent with its non-centrosymmetric structure.

Coexistence of ferromagnetism and topology by charge carrier engineering in the intrinsic magnetic topological insulator MnBi4Te7

Intrinsic magnetic topological insulators (MTIs) $\mathrm{Mn}{\mathrm{Bi}}_{2}{\mathrm{Te}}_{4}$ and $\mathrm{Mn}{\mathrm{Bi}}_{2}{\mathrm{Te}}_{4}/{({\mathrm{Bi}}_{2}{\mathrm{Te}}_{3})}_{n}$ are expected to realize the high-temperature quantum anomalous Hall effect and dissipationless electrical transport. However, there is still a lack of ideal MTI candidates with magnetic ordering of the ferromagnetic (FM) ground state. Here, we show a MTI sample of $\mathrm{Mn}{({\mathrm{Bi}}_{0.7}{\mathrm{Sb}}_{0.3})}_{4}{\mathrm{Te}}_{7}$ which holds the coexistence of a FM behavior state and topological nontriviality. The dramatic modulation of the magnetism is induced by a charge carrier engineering process via the Sb substitution in the $\mathrm{Mn}{\mathrm{Bi}}_{4}{\mathrm{Te}}_{7}$ matrix with antiferromagnetic ordering. The evolution of magnetism in $\mathrm{Mn}{({\mathrm{Bi}}_{1\ensuremath{-}x}{\mathrm{Sb}}_{x})}_{4}{\mathrm{Te}}_{7}$ is systematically investigated by our magnetic measurements and theoretical calculations. The clear topological surface states of the FM sample of $\mathrm{Mn}{({\mathrm{Bi}}_{0.7}{\mathrm{Sb}}_{0.3})}_{4}{\mathrm{Te}}_{7}$ are further verified by angle-resolved photoemission spectroscopy. The demonstration of the intrinsic FM-MTI of $\mathrm{Mn}{({\mathrm{Bi}}_{0.7}{\mathrm{Sb}}_{0.3})}_{4}{\mathrm{Te}}_{7}$ in this paper sheds light on further material optimization of intrinsic MTIs and paves the way for further studies to clarify the relationships between topology, magnetism, and charge carriers in topological materials.

Evolution of magnetic interactions in Sb-substituted MnBi2Te4

The Mn(Bi$_{1-x}$Sb$_x$)$_2$Te$_4$ series is purported to span from antiferromagnetic (AF) topological insulator at x = 0 to a trivial AF insulator at x = 1. Here we report on neutron diffraction and inelastic neutron scattering studies of the magnetic interactions across this series. All compounds measured possess ferromagnetic (FM) triangular layers and we find a crossover from AF to FM interlayer coupling near x = 1 for our samples. The large spin gap at x = 0 closes rapidly and the average FM exchange interactions within the triangular layer increase with Sb substitution. Similar to a previous study of MnBi$_2$Te$_4$, we find severe spectral broadening which increases dramatically across the compositional series. In addition to broadening, we observe an additional sharp magnetic excitation in MnSb$_2$Te$_4$ that may indicate the development of local magnetic modes based on recent reports of antisite disorder between Mn and Sb sublattices. The results suggest that both substitutional and antisite disorder contribute substantially to the magnetism in Mn(Bi$_{1-x}$Sb$_x$)$_2$Te$_4$.

Antimonate Controls Manganese(II)-Induced Transformation of Birnessite at a Circumneutral pH.

Manganese (Mn) oxides, such as birnessite (δ-MnO2), are ubiquitous mineral phases in soils and sediments that can interact strongly with antimony (Sb). The reaction between birnessite and aqueous Mn(II) can induce the formation of secondary Mn oxides. Here, we studied to what extent different loadings of antimonate (herein termed Sb(V)) sorbed to birnessite determine the products formed during Mn(II)-induced transformation (at pH 7.5) and corresponding changes in Sb behavior. In the presence of 10 mM Mn(II)aq, low Sb(V)aq (10 μmol L-1) triggered the transformation of birnessite to a feitknechtite (β-Mn(III)OOH) intermediary phase within 1 day, which further transformed into manganite (γ-Mn(III)OOH) over 30 days. Medium and high concentrations of Sb(V)aq (200 and 600 μmol L-1, respectively) led to the formation of manganite, hausmannite (Mn(II)Mn(III)2O4), and groutite (αMn(III)OOH). The reaction of Mn(II) with birnessite enhanced Sb(V)aq removal compared to Mn(II)-free treatments. Antimony K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy revealed that heterovalent substitution of Sb(V) for Mn(III) occurred within the secondary Mn oxides, which formed via the Mn(II)-induced transformation of Sb(V)-sorbed birnessite. Overall, Sb(V) strongly influenced the products of the Mn(II)-induced transformation of birnessite, which in turn attenuated Sb mobility via incorporation of Sb(V) within the secondary Mn oxide phases.

Enhanced thermoelectric performance in polymorphic heavily Co-doped Cu2SnS3 through carrier compensation by Sb substitution

ABSTRACT Heavily acceptor-doped Cu2SnS3 (CTS) shows promisingly large power factor (PF) due to its rather high electrical conductivity (σ) which causes a modest ZT with a high electronic thermal conductivity (κe ). In the present work, a strategy of carrier compensation through Sb-doping at the Sn site in Cu2Sn0.8Co0.2S3 was investigated, aiming at tailoring electrical and phonon transport properties simultaneously. Rietveld analysis suggested a complex polymorphic microstructure in which the cation-(semi)ordered tetragonal phase becomes dominant over the coherently bonded cation-disordered cubic phase, as is preliminarily revealed using TEM observation, upon Sb-doping and Sb would substitute Sn preferentially in the tetragonal structure. With increasing content of Sb, the σ was lowered and the Seebeck coefficient (S) was enhanced effectively, which gave rise to high PFs maintained at ~10.4 μWcm−1K−2 at 773 K together with an optimal reduction in κe by 60–70% in the whole temperature range. The lattice thermal conductivity was effectively suppressed from 1.75 Wm−1K−1 to ~1.2 Wm−1K−1 at 323 K while maintained very low at 0.3–0.4 Wm−1K−1 at 773 K. As a result, a peak ZT of ~0.88 at 773 K has been achieved for Cu2Sn0.74Sb0.06Co0.2S3, which stands among the tops so far of the CTS-based diamond-like ternary sulfides. These findings demonstrate that polymorphic microstructures with cation-disordered interfaces as an approach to achieve effective phonon-blocking and low lattice thermal conductivity, of which further crystal chemistry, microstructural and electrical tailoring are possible by appropriate doping.

Quantum oscillations in the field-induced ferromagnetic state of MnBi2−xSbxTe4

The intrinsic antiferromagnetic topological insulator MnBi$_{2}$Te$_{4}$ undergoes a metamagnetic transition in a c-axis magnetic field. It has been predicted that ferromagnetic MnBi$_{2}$Te$_{4}$ is an ideal Weyl semimetal with a single pair of Weyl nodes. Here we report measurements of quantum oscillations detected in the field-induced ferromagnetic phase of MnBi$_{2-x}$Sb$_{x}$Te$_{4}$, where Sb substitution tunes the majority carriers from electrons to holes. Single frequency Shubnikov-de Haas oscillations were observed in a wide range of Sb concentrations (0.54 $\leq$ x $\leq$ 1.21). The evolution of the oscillation frequency and the effective mass shows reasonable agreement with the Weyl semimetal band-structure of ferromagnetic MnBi$_{2}$Te$_{4}$ predicted by density functional calculations. Intriguingly, the quantum oscillation frequency shows a strong temperature dependence, indicating that the electronic structure sensitively depends on magnetism.

Epitaxial growth and properties study of p-type doped ZnO:Sb by PLD

Abstract Undoped and antimony (Sb) doped ZnO films were synthesized on sapphire (0001) substrates using Pulsed Laser Deposition (PLD) method. Structural and morphological studies proved the good crystallinity of the ZnO films with c-axis (0002) orientation growth. The substitution of Sb in ZnO lattice was proved from the analysis of XPS data. Interestingly, it was important that the presence of Sb5+ ions opened the way for the apparition of the complex acceptor (SbZn–2VZn) level with high stability. The decrease in the value of the band gap Eg with Sb doping evidenced the creation of energy levels related to such complex acceptor. From the study of photoluminescence (PL) at low temperatures, it was shown the dominant emission is related to free electron transition from neutral acceptor (e, A0), indicating the conductivity conversion from n to p with Sb doping. The reproducibility and stability of p-type conduction from the ZnO:Sb3% films were evaluated by Hall measurements. As application, ZnO homojunction device was carefully made and shows rectifying current-voltage (I–V) characteristics, typical to perfect diode. Thus, the prepared ZnO–Sb films are promising for application in optoelectronic field.

Mechanisms of antimony ageing in soils: An XAS study

Antimony (Sb) retention in soils increases in the long term, resulting in lower soluble Sb concentrations and thus a decreased environmental risk of Sb. However, the mechanisms responsible for Sb ageing in soils are not clear, although this is necessary to understand, describe and predict Sb ageing processes in soils. To do so, the long-term retention of added Sb(V) to nine soil samples with contrasting soil properties and to a model iron (Fe; hydrous ferric oxide or HFO) and aluminium (Al; hydrous aluminium oxide or HAO) hydroxide under aerobic conditions was studied with X-ray absorption spectroscopy (XAS). The solid-liquid distribution coefficients (KD) of the soils increased by a factor of 2–4 between 2 weeks and 6 months. In addition, ageing of Sb was more pronounced in the Sb(V)-spiked HFO than in the soils, while no ageing of Sb(V) in the HAO was noted. The added Sb(V) did not change redox speciation throughout six months of aerobic incubation and no indications of antimonate precipitates with Fe or calcium (Ca) were found. Conversely, it was found that with time, Sb(V) was increasingly retained by the HFO and by the soils, likely through micropore diffusion and/or through substitution of Sb(V) into surface Fe octahedra in ferrihydrite. In addition, in the soils, the Sb(V) surface speciation on Fe hydroxides changed with time leading to higher proportion of edge-sharing bidentate Sb⋯Fe complexes. These results suggest that Sb(V) ageing in soils is controlled by different mechanisms simultaneously, i.e., by slow micropore diffusion and/or substitution processes that remove Sb(V) from the reactive surface of the Fe hydroxides and by slow surface processes, with slow sorption reactions more prevalent for edge-sharing bidentate Sb(V) than for corner-sharing bidentate Sb(V) surface complexes.

Room temperature ferromagnetism in Sb doped ZnO

Using first-principle calculations, the magnetic properties of the monovacancies and the Sb-related defects including VZn, VO, SbZn, SbO, SbZn-VZn and SbZn-2VZn are studied. It is found that the isolated VZn with the charge state of 0 and −1 can contribute to ferromagnetism in ZnO material. The substitution of Sb on O sites (SbO0) also results in magnetic property. Moreover, the SbZn-2VZn complex is another defect having non-zero magnetic moment and energetically favors for the ferromagnetic state. The resultant density of states (DOS) and spin density distribution clearly show that the ferromagnetic interaction is majorly due to the O-p Zn-d and Sb-p states. To check this calculation, Sb-doped ZnO samples were grown by pulsed laser deposition with different Sb composition under P(O2) = 1.3 Pa. SQUID study showed that all of these samples are ferromagnetic at room temperature. The variation of the saturation magnetization against the Sb composition is discussed.

Tuning Sodium Occupancy Sites in P2‐Layered Cathode Material for Enhancing Electrochemical Performance

AbstractDifferent sodium occupancy sites in P2‐layered cathode materials can reorganize Na‐ion distribution and modify the Na+/vacancy superstructure, which have a vital impact on the Na‐ion transport and Na storage behavior during charge and discharge processes, but have not been investigated specifically and are not yet well understood. Herein, the occupancy ratio of two different Na sites (sites below transition metal ions and sites below oxygen ions along the c direction) in P2‐Na0.67[Mn0.66Ni0.33]O2 cathode is tuned successfully by inducing Sb5+ ions with strong repulsion toward Na sites right below transition metals. It is found that the decrease of Na occupancy right below transition metal ions is beneficial to the electrochemical performance of P2‐layered cathode materials, regarding cycle stability and rate capability. In situ X‐ray absorption spectroscopy reveals that the reversible Mn3.3+/Mn4+ and Ni2+/Ni3+ redox couples provide charge compensation in different voltage regions of 1.8–2.3 and 2.3–4.2 V, respectively. The transmission X‐ray microscopy confirms the uniform redox reaction over the whole electrode particle. In addition, Sb substitution can suppress the “P2‐O2” phase transition in high voltage region by preventing oxygen gliding in a–b planes, thus ensuring robust structure stability during cycling.

Influence of Sb2O3 doping on the sintering and polarization characteristics of PbTiO3 ceramic materials

In this paper, the effect of Sb2O3 doping on the sintering and polarization stability of PbTiO3 ceramics was investigated. The Sb2O3-doped PbTiO3 ceramic materials were prepared viaa conventional piezoelectric ceramic processing. The results showed that the as-prepared PbTiO3 ceramics exhibit a good sintering stability without cracking during sintering because of reducing spontaneous strain stemmed from decrease the tetragonal degree of PbTiO3 by Sb2O3 doping. Furthermore, the polarization stability of Sb2O3-doped PbTiO3 ceramics was considerably enhanced by the relaxation of strain and stress concentration during poling stemmed from the formation of good microstructure with fine grain and high density, and by decreasing the loss stemmed from reduction of oxygen vacancy concentration due to the substitution of Sb[Formula: see text] ions for Ti[Formula: see text] ions under a polarization condition with temperature of 130–150[Formula: see text]C and applied electric field of 4.5–5.5 kV/mm, and its yield of polarization is achieved ca. 80%.

Influence of Sb self-doping on thermoelectric performance of Cu12Sb4S13

Substitution of Sb for Cu and the secondary phases (chalcostible and skinnerite) are introduced by Sb self-doping. The thermoelectric (TE) performance is mainly affected by substitution of Sb for Cu (Cu12-xSb4+xS13, x < 0.3). When x reaches 0.3 or higher, the proportion of the secondary phases increases continuously, and the two effects work together. The κ can be significantly reduced and shows a downward trend with the increase of temperature. The κ is decreased to 0.63 Wm−1 K−1 at 700 K, about 50% of that for the pristine tetrahedrite. Eventually, a maximum zT of 0.8 is achieved in Cu11.8Sb4.2S13 at 700 K, which is about 26% higher than the pristine tetrahedrite.