Sb Substitution Research Articles

Thermoelectric properties of Fe1.5TiSb1−Sn and Fe1.5Ti1−Y Sb Heusler alloys

Abstract The effects of Sn and Y doping on thermoelectric properties of a Heusler Fe1.5TiSb semiconductor was studied. Samples of Fe1.5TiSb1−xSnx and Fe1.5Ti1−xYxSb solid solutions (x = 0; 0.05; 0.1) were synthesized by arc and induction melting, annealed at 1073 K, and examined by X-ray diffraction and scanning electron microscopy with energy-dispersive X-ray analysis. All alloys of the solid solutions crystallize in the half Heusler structure (space group F43m), and have dominant phase Fe1.33TiSb with a small amount of precipitates. Measurements of the transport properties revealed that all the alloys are p-type semiconductors. In the parent Fe1.5TiSb, substitution of Sb by Sn results in increasing electrical conductivity σ, whereas substitution of Ti Y decreases σ. Measurements of thermal conductivity κ showed that it decreases with substitution Sb for Sn, as well as with substitution of Ti for Y. The highest zT = 0.14 (at 473 K), was found for the composition Fe1.5TiSb.

Spin dynamics in antiferromagnetic oxypnictides and fluoropnictides: LaMnAsO, LaMnSbO, and BaMnAsF

Inelastic neutron scattering (INS) from polycrystalline antiferromagnetic LaMnAsO, LaMnSbO, and BaMnAsF are analyzed using a ${J}_{1}\text{\ensuremath{-}}{J}_{2}\text{\ensuremath{-}}{J}_{c}$ Heisenberg model in the framework of the linear spin-wave theory. All three systems show clear evidence that the nearest- and next-nearest-neighbor interactions within the Mn square lattice layer (${J}_{1}$ and ${J}_{2}$) are both antiferromagnetic (AFM). However, for all compounds studied the competing interactions have a ratio of $2{J}_{2}/{J}_{1}<1$, which favors the square lattice checkerboard AFM structure over the stripe AFM structure. The interplane coupling ${J}_{c}$ in all three systems is on the order of $\ensuremath{\sim}3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}{J}_{1}$, rendering the magnetic properties of these systems with quasi-two-dimensional character. The substitution of Sb for As significantly lowers the in-plane exchange coupling, which is also reflected in the decrease of the N\'eel temperature, ${T}_{\mathrm{N}}$. Although BaMnAsF shares the same MnAs sheets as LaMnAsO, their ${J}_{1}$ and ${J}_{2}$ values are substantially different. Using density functional theory, we calculate exchange parameters ${J}_{ij}$ to rationalize the differences among these systems.

Dielectric loss management by antimony (Sb) incorporation in giant dielectric CaCu3Ti4O12

The partial substitution of Sb5+ on the Ti site for giant dielectric constant material CaCu3Ti4O12 (CCTO) has been done in the present paper, and the effect of Sb substitution on the microstructural, dielectric and electrical property of the material is investigated. The main objective of this paper is to minimize high loss tangent (tan δ) which has restricted the practical applications of CCTO. XRD analysis carried out on the as-synthesized powders confirms formation of single phase material accompanied by dopant-induced lattice constant shrinkage. Scanning electron microscope images demonstrate that the grain size of sintered ceramic samples decreases with the increasing Sb content. The dielectric response of sintered CaCu3Ti4−xSbxO12 samples studied by precision LCR meter suggests that Sb doping is an effective way for maintaining a high dielectric constant and low loss over a broad range in temperature and frequency. Room temperature complex impedance spectroscopy analysis suggests that all compounds are electrically heterogeneous consisting of semiconducting grains and insulating grain boundaries establishing internal barrier layer capacitance model. These results indicate that Sb-doped CCTO ceramics have a favorable prospect to be able to stimulate practical applications.

P-type IGZO by the substitution of antimony with a sol-gel method: Explanation with the aid of defect formation equation

Indium gallium zinc oxide (IGZO) thin films with various antimony (Sb) substitution contents were prepared on the glass substrate by using sol-gel spin coating technique. After calcined at 550 °C for 1 h in air, the structure identity, chemical bonding state, optical, and electrical properties of Sb-IGZO thin films were characterized with X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible spectroscopy (UV–vis), and Hall effect measurement. With the chemical route, the film composition in the form of Sb-x-IGZO with x at 0–0.3 can be well controlled for the purpose of study on the effect of Sb substitution. The results showed that all Sb-IGZO thin films have an amorphous structure and had optical transmittance above 86.5 %, band gap of 3.73–3.81 eV, and an n-to-p semiconducting transition at Sb-0.1-IGZO. The Sb-0.2-IGZO films with 89.2 % optical transmittance had carrier concentration of 1.67 × 1015 cm−3, mobility of 2.35 cm2/V s, and electrical conductivity of 6.3 × 10−4 S/cm. The defect mechanism with equations to support the n-to-p transition by substituting Sb3+ onto Zn2+ site in IGZO has been proposed.

The effect of substitution of Sb with Zn on the optical and physical properties of Se90Sb10-xZnx (x = 0, 2, 4, 6, 10 at. %) thin films

In the present study, the effect of substitution of Sb with Zn on the optical properties of Se90Sb10-xZnx (x = 0, 2, 4, 6, 10 at. %) thin films is discussed. Bulk samples are prepared using a conventional melt-quench technique. Amorphous thin films of the compositions are synthesized using thermal evaporation technique. Normal incidence transmission spectra of films is obtained in the spectral range of 400–1100 nm. The envelope method is applied to calculate the refractive index, followed by Cauchy's extrapolation. Spectral distributions of extinction coefficient, absorption coefficient and dielectric loss factor are obtained. Wemple-Didomenico single oscillator model is employed to study refractive index dispersion. The absorption coefficient is of the order of 104 cm−1, and the band-gap is calculated using Tauc’s extrapolation for the indirect transition. The increase in band gap with Zn addition is explained on the basis of chemical bond approach. Topological studies show that the system is in a rigid region The glass transition temperature, mean bond energy and density of the system is also increasing with the increase in Zn content. An effort is made to discuss all the parameters in terms of change in bond length, bond energy and connectedness of the glassy network.

Charge compensation weakening ionized impurity scattering and assessing the minority carrier contribution to the Seebeck coefficient in Pb-doped Mg3Sb2 compounds.

This work reports the electrical and thermal transport processes in p-type Pb-doped Mg3(1+x)Sb2-yPby (0.02 ≤ x ≤ 0.08; 0 ≤ y ≤ 0.02) compounds. Low-energy electron acceptor defects Mg vacancies are easy to form, which can provide holes and make p-type transport in the Mg3Sb2 matrix. However, with an increase in excess Mg, the transport behavior changes from p type to n type as manifested synergistically by both the Hall coefficient and Seebeck coefficient. This indicates the effective role of Mg in tuning carrier type and concentration for a pristine Mg3Sb2 compound. Upon substitution of Sb by Pb, the hole concentration slightly increases, and mobility is greatly improved by 133% at room temperature. The significant increase in mobility is attributed to the weakening ionized impurity scattering, stemming from the decreasing concentration induced by Pb doping. Thus, the power factor is enhanced with a 146% improvement at room temperature. Consequently, the figure of merit ZT of the Pb-doped sample is 1.8 times larger than the pristine one at around 300 K. Moreover, the non-degenerate transport behavior revealed by electrical properties is simply analyzed regarding the effects of minority carriers on the overall Seebeck coefficient. This study proposes a new strategy of charge compensation for improving mobility and a simple way to guide the prediction about the onset of bipolar conduction for Mg3Sb2-based compounds and other potential thermoelectric materials.

Shape memory behavior of Ni45Mn40Co5Sb10−xBx magnetic shape memory alloys

The transformation temperatures, magnetization behavior, shape memory behavior, and mechanical properties of polycrystalline Ni45Mn40Co5Sb10−xBx (at.%) (x = 0, 1, 2, 3, 4, 5) alloys were systematically investigated. It was revealed that substituting Sb with B drastically increases the transformation temperatures, while it decreases the saturation magnetization due to the alteration of electron concentration of the matrix and formation of Co-rich second phases. With the substitution of Sb with 5% B, martensite start temperature and activation energy were increased from 50 to 316.8 °C, and 185 to 722.6 kJ mol−1, respectively. The thermal cycling under stress, superelasticity, and failure experiments showed that shape memory properties and strength were improved by the substitution of Sb with B. The shape memory effect with maximum recoverable strain of 1.6% was observed with in Ni45Mn40Co5Sb9B1, and perfect superelasticity was exhibited at 220 °C in Ni45Mn40Co5Sb8B2. It was concluded that NiMnCoSb alloys can be used as high-temperature magnetic shape memory alloys as they exhibit transformation temperatures above 100 °C and show promising shape memory and superelasticity behavior, and there is a magnetization difference between their transforming phases.

Texturization-Induced In-Plane High-Performance Thermoelectrics and Inapplicability of the Debye Model to Out-of-Plane Lattice Thermal Conductivity in Misfit-Layered Chalcogenides.

Texturization tuning is of crucial significance for designing and developing high-performance thermoelectric materials and devices. Here, we report for the first time that a strong texturization effect induces an in-plane high-performance thermoelectric and an out-of-plane low lattice thermal conductivity in Sb-substituted misfit-layered (SnS)1.2(TiS2)2 alloys. In the in-plane direction, the oriented texture promotes a high carrier mobility, contributing to the maximization of the power factor (∼0.90 mW K-2 m-1). Moreover, the in-plane lattice thermal conductivity dramatically reduces deriving from the point defects due to the Sb substitution and weakened transverse sound velocity owing to the softening of bonding, ultimately leading to one of the highest thermoelectric performances ever reported among misfit-layered chalcogenides. In particular, in the out-of-plane direction, the texturization triggers the lowest lattice thermal conductivity (∼0.39 W K-1 m-1), exceeding the theoretical limit of the Debye-Cahill model, which provides a precious opportunity to investigate this real Sb-substituted (SnS)1.2(TiS2)2 material. The present finding in misfit-layered chalcogenides provides a novel strategy for manipulating thermoelectrics via texturization engineering.

Direct atomic insight into the role of dopants in phase-change materials

Doping is indispensable to tailor phase-change materials (PCM) in optical and electronic data storage. Very few experimental studies, however, have provided quantitative information on the distribution of dopants on the atomic-scale. Here, we present atom-resolved images of Ag and In dopants in Sb2Te-based (AIST) PCM using electron microscopy and atom-probe tomography. Combing these with DFT calculations and chemical-bonding analysis, we unambiguously determine the dopants’ role upon recrystallization. Composition profiles corroborate the substitution of Sb by In and Ag, and the segregation of excessive Ag into grain boundaries. While In is bonded covalently to neighboring Te, Ag binds ionically. Moreover, In doping accelerates the crystallization and hence operation while Ag doping limits the random diffusion of In atoms and enhances the thermal stability of the amorphous phase.

Structure and Multifunctional Properties of Co50V33Ga16Sb1 Alloy

Co50V33Ga17−xSbx (x = 0, 1, 2) alloys were prepared by the arc-melting method. The effect of substitution of Sb for Ga on the crystalline structure, martensitic transformation (MT), magnetocaloric effect and shape memory effect of Co50V33Ga17 alloy has been investigated. The experimental results combined with theoretical calculation results indicate that Co50V33Ga17−xSbx (x = 0, 1, 2) series alloys are stabilized in a highly ordered Cu2MnAl (L21)-type structure with a space group $$ {\text{F}}m\bar{3}m $$ (no. 225) and Pearson’s symbol cF16 at 300 K. The temperature dependence of magnetization indicates that both Co50V33Ga16Sb1 and Co50V33Ga15Sb2 alloys experience the MT process; however, only Co50V33Ga16Sb1 possesses metamagnetic MT, which is relatively sensitive to the applied magnetic field. Associated with such a prominent behavior, the isothermal entropy change was obtained, which is about 4.53 J K−1 kg−1, 7.51 J K−1 kg−1 and 10.67 J K−1 kg−1 at about 164 K under the applied field of 1 T, 2 T and 3 T, respectively. Furthermore, a large strain value of 0.33% in Co50V33Ga16Sb1 alloy was obtained under an external magnetic field of 3 T during the MT, which is larger than that of 0.28% induced by temperature. These salient features indicate that the alloy may probably act as a potential candidate for applications in the shape memory alloy, magnetic refrigeration and magnetic sensors.

Charge Density Waves and Magnetism in Topological Semimetal Candidates GdSbxTe2−x−δ

AbstractMany topological semimetals are known to exhibit exceptional electronic properties, which are the fundamental basis for design of novel devices and further applications. Materials containing the structural motif of a square net are known to frequently be topological semimetals. In this work, the synthesis and structural characterization of the square‐net‐based magnetic topological semimetal candidates GdSbxTe2−x−δ (0, δ indicating the vacancy level) are reported. The structural evolution of the series with Sb substitution is studied, finding a transition between a simple tetragonal square‐net structure to complex superstructure formations due to the presence of charge density waves. The structural modulations coincide with a significant modification of the magnetic order. This work thus establishes GdSbxTe2−x−δ as a platform to study the interplay between crystal symmetry, band filling, charge density wave, and magnetism in a topological semimetal candidate.

Local Structure and Influence of Sb Substitution on the Structure-Transport Properties in AgBiSe2.

Owing to their intrinsically low thermal conductivity and chemical diversity, materials within the I-V-VI2 family, and especially AgBiSe2, have recently attracted interest as promising thermoelectric materials. However, further investigations are needed in order to develop a more fundamental understanding of the origin of the low thermal conductivity in AgBiSe2, to evaluate possible stereochemical activity of the 6s2 lone pair of Bi3+, and to further elaborate on chemical design approaches for influencing the occurring phase transitions. In this work, a combination of temperature-dependent X-ray diffraction, Rietveld refinements of laboratory X-ray diffraction data, and pair distribution function analyses of synchrotron X-ray diffraction data is used to tackle the influence of Sb substitution within AgBi1-xSbxSe2 (0 ⩽ x ⩽ 0.15) on the phase transitions, local distortions, and off-centering of the structure. This work shows that, similar to other lone-pair-containing materials, local off-centering and distortions can be found in AgBiSe2. Furthermore, electronic and thermal transport measurements, in combination with the modeling of point-defect scattering, highlight the importance of structural characterizations toward understanding changes induced by elemental substitutions. This work provides new insights into the structure-transport correlations of the thermoelectric AgBiSe2.

High Thermoelectric Properties in Mg2Ge0.25Sn0.75−xSbx Solid Solution

Mg2Sn-based solid solutions Mg2Ge0.25Sn0.75−xSbx (x = 0, 0.03, 0.05, 0.07, 0.10, 0.15) were synthesized by high-frequency melting in a graphite crucible, followed by spark plasma sintering. The effects of Sb substitution on the phase constitution and thermoelectric properties of the solution were investigated. All the samples were face-centered cubic Mg2Ge0.25Sn0.75 solutions without any additional phase arising from Sb in the compounds. The electrical resistivity decreased significantly from 202 μΩ m to 3.66 μΩ m at 300 K as lower Sb content x increased from 0 to 0.03, but increased slightly from 3.66 μΩ m to 11.6 μΩ m at 300 K as Sb content x further increased from 0.03 to 0.15. The Seebeck coefficient showed a similar pattern of change. The thermal conductivity of the solid solution clearly decreased from 3.6 W m−1 K−1 to 1.4 W m−1 K−1 at 300 K as Sb content x increased from 0 to 0.15. The highest power factor of 4010 μW m−1 K−2 was obtained in the sample of Mg2Ge0.25Sn0.72Sb0.03 at 573 K. The lowest thermal conductivity of 1.17 W m−1 K−1 was found in Mg2Ge0.25Sn0.65Sb0.1 at 473 K. The maximum ZT of 1.54 was obtained in Mg2Ge0.25Sn0.68Sb0.07 at 623 K. Compared with the value 0.03 for its parent alloy at the same temperature, this is a dramatic improvement.

Bandgap-tunable double-perovskite thin films by solution processing

In this study, we present a facile solution-processed method on controlled synthesis of the Cs 2 AgSb x Bi 1− x Br 6 thin films with Sb substitution. The Cs 2 AgSb x Bi 1− x Br 6 thin films were successfully prepared. The resulting Cs 2 AgSb x Bi 1− x Br 6 thin films exhibited high purity, crystallinity, and thermostability. Moreover, the Sb substitution effectively reduced the E g of Cs 2 AgSb x Bi 1− x Br 6 from 2.22 to 1.97 eV. The effective bandgap narrowing via facile solution-processed method might facilitate the development of Cs 2 AgSb x Bi 1− x Br 6 thin-film photoabsorber. Narrowing the bandgap of lead-free double-perovskite Cs 2 AgBiBr 6 is required for using this material in future photovoltaics. Herein, we demonstrate a bandgap engineering of Cs 2 AgBiBr 6 by introducing Sb to substitute up to 75% of Bi via a versatile solution-processed method in dimethyl sulfoxide at 180 °C. The resultant Cs 2 AgSb x Bi 1− x Br 6 ( x = 0, 0.25, 0.50, 0.75) thin films possess high crystallinity and good thermostability. Moreover, the Sb substitution enables an obvious bandgap reduction of 0.25 eV. The fabricated solar cell using the Cs 2 AgSb x Bi 1− x Br 6 ( x = 0.25) thin film obtained an increased performance than the reference Cs 2 AgBiBr 6 . The effective bandgap narrowing via a facile solution method might accelerate the development of Cs 2 AgBiBr 6 -based materials for photovoltaic applications.

Charge Disproportionation Triggers Bipolar Doping in FeSb2- xSn xSe4 Ferromagnetic Semiconductors, Enabling a Temperature-Induced Lifshitz Transition.

Ferromagnetic semiconductors (FMSs) featuring a high Curie transition temperature ( Tc) and a strong correlation between itinerant carriers and localized magnetic moments are of tremendous importance for the development of practical spintronic devices. The realization of such materials hinges on the ability to generate and manipulate a high density of itinerant spin-polarized carriers and the understanding of their responses to external stimuli. In this study, we demonstrate the ability to tune magnetic ordering in the p-type FMS FeSb2- xSn xSe4 (0 ≤ x ≤ 0.20) through carrier density engineering. We found that the substitution of Sb by Sn FeSb2- xSn xSe4 increases the ordering of metal atoms within the selenium crystal lattice, leading to a large separation between magnetic centers. This results in a decrease in the Tc from 450 K for samples with x ≤ 0.05 to 325 K for samples with 0.05 < x ≤ 0.2. In addition, charge disproportionation arising from the substitution of Sb3+ by Sn2+ triggers the partial oxidation of Sb3+ to Sb5+, which is accompanied by the generation of both electrons and holes. This leads to a drastic decrease in the electrical resistivity and thermopower simultaneously with a large increase in the magnetic susceptibility and saturation magnetization upon increasing Sn content. The observed bipolar doping induces a very interesting temperature-induced quantum electronic transition (Lifshitz transition), which is manifested by the presence of an anomalous peak in the resistivity curve simultaneously with a reversal of the sign of a majority of the charge carriers from hole-like to electron-like at the temperature of maximum resistivity. This study suggests that while there is a strong correlation between the overall magnetic moment and free carrier spin in FeSb2- xSn xSe4 FMSs, the magnitude of the Curie temperature strongly depends on the spatial separation between localized magnetic centers rather than the concentration of magnetic atoms or the density of itinerant carriers.

Effects of chemical pressure on diluted magnetic semiconductor (Ba,K)(Zn,Mn)2As2**Project supported by the National Key R&D Program of China (Grant No. 2017YFB0405703), the Ministry of Science and Technology of China (Grant Nos. 2018YFA03057001 and 2015CB921000), and the National Natural Science Foundation of China through the Research Projects (Grant Nos. 11534016 and 61504166).

Chemical pressure induced by iso-valent doping has been widely employed to tune physical properties of materials. In this work, we report effects of chemical pressure by substitution of Sb or P into As on a recently discovered diluted magnetic semiconductor (Ba,K)(Zn,Mn)2As2, which has the record of reliable Curie temperature of 230 K due to independent charge and spin doping. Sb and P are substituted into As-site to produce negative and positive chemical pressures, respectively. X-ray diffraction results demonstrate the successful chemical solution of dopants. Magnetic properties of both K-under-doped and K-optimal-doped samples are effectively tuned by Sb- and P-doping. The Hall effect measurements do not show decrease in carrier concentrations upon Sb- and P-doping. Impressively, magnetoresistance is significantly improved from 7% to 27% by only 10% P-doping, successfully extending potential application of (Ba,K)(Zn,Mn)2As2.

Effect of Sb substitution on crystal structure, texture and hard magnetic properties of melt-spun MnBi alloys

Melt-spun Mn50Bi50-xSbx alloys with x ≤ 5 were prepared at different solidification rates and characterized both in the as-spun state and after annealing. In the as-spun alloys, the Sb substitution leads to the formation of a metastable phase, similar to the binary “quenched high-temperature phase” but without the superstructure of the latter and exhibiting a different – increasing – temperature dependence of coercivity. The new nanocrystalline metastable phase is not only itself characterized by a high room-temperature coercivity (in excess of 20 kOe), but upon annealing it transforms into a high-coercivity (up to 13.5 kOe) “low-temperature” α phase. However, the advantage of obtaining a high coercivity without the otherwise required milling made possible by the Sb substitution is undermined by the absence of a local crystallographic texture in the melt-spun alloys. The best combination of the isotropic hard magnetic properties realized for the Mn55Bi43.5Sb1.5 composition is a remanence of 35.5 emu/g and a coercivity of 8.1 kOe. The annealed Sb-free Mn50Bi50 alloys did possess a local crystallographic alignment and, for high solidification rates, a moderate coercivity up to 5.6 kOe; however, they had an inadequate “rectangularity” in the demagnetization curve. The orthorhombic compound known as MnBi0.9Sb0.1 and described earlier as antiferromagnetic was obtained in the annealed ribbons with x ≈ 5. The compound was found to order ferromagnetically between 200 K and ≈250 K and to exhibit a significant coercivity, 14.3 kOe at 50 K. It is suggested that the MnBi0.9Sb0.1 may actually be a Sb-stabilized “new phase” observed earlier as metastable in the Bi–MnBi eutectic alloys.

Transformation of hardening to softening behaviors induced by Sb substitution in CuO-doped KNN-based piezoceramics

Pb-free piezoceramics of K0.5Na0.5Nb1-xSbxO3 + 1 mol% CuO are synthesized via a solid-state reaction. Furthermore, the transformation of hardening to softening behaviors induced by Sb substitution is exhibited and the corresponding microscopic mechanism is proposed. The CuO-doped K0.5Na0.5NbO3 ceramic without adding Sb exhibits extremely hardening characteristics (i.e., ultrahigh Qm of ∼2426, low tanδ of 0.32%, and pinched ferroelectric hysteresis loop) due to the formation of defect combinations ((CuNb'''−Vo••)' and (Vo••−CuNb'''−Vo••)•). Whereas, the addition of Sb dramatically reduces the levels of defect combinations, leading to obviously softening properties (d33 > 210 pC N−1, kp > 40%, low Qm, and normal single P-E hysteresis loop). Our results indicate that the decrease of defect combinations with Sb addition should be responsible for the hardening-softening transformation of piezoelectricity and ferroelectricity in CuO-doped K0.5Na0.5Nb1-xSbxO3 piezoceramics.

Structural and electrical properties of SbxW1−xSe2 (0, 0.5) ternary alloys

In present article, we demonstrated for the first time the synthesis and properties of SbXW1−xSe2 (0, 0.5) ternary alloys. The crystals of SbXW1−xSe2 (0, 0.5) ternary alloys were grown by direct vapour transport technique. The XRD results confirm the 2H-hexagonal lattice structure with P63/mmc space group and grown crystals are highly crystallographic c-axis oriented. The screw dislocation mechanism is predominating in the growth process of Sb0.5W0.5Se2 crystals. The results of electrical characterization show n-type semiconducting nature. The Raman spectra exhibit peaks corresponding to out of plane A1g, in-plane E2g and 2LA modes of vibration which is attributing the 2H-polymorph of grown SbXW1−xSe2 (0, 0.5) ternary alloys. The results shows substitution of Sb (+5) on W (+4) lattice site due to similar ionic size. The band gap tailoring from 0.93 to 1.40 eV is achieved, suggesting the effective way to tune the material characteristics for high performance devices.

Magnetic States and Bandgaps of B-Site Substituted Double-Perovskite Ba2Pr(Bi, Sb)O6

We demonstrated crystal structures, magnetic, and optical properties of the B-site substituted double-perovskite Ba <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Pr(Bi <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-x</sub> Sb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> ) O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> (x = 0, 0.1, 0.2, 0.25, 0.3, 0.4, 0.5, and 1.0). The single-phase polycrystalline samples with the light Sb substitution are formed in a monoclinic structure (C <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /m). The heavily Sb-substituted samples crystallize in the rhombohedral system accompanied by B-site disorder. Magnetization measurements show that the effective magnetic moments are located around 3.2 μ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</sub> for the lightly Sb-substituted samples, indicating the valence mixing between Pr <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> and Pr <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4+</sup> . The magnetic moments with the heavy Sb substitution are close to the valence of Pr <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> . The magnitudes of bandgap energy for the two end-member samples were estimated from the optical measurements to be E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> = 0.977 eV at x = 0 and 2.395 eV at x = 1.0. The effect of the bandgap opening due to Sb substitution is examined by using the density functional theory. The lightly and heavily Sb-doped compounds show typical absorption edges in indirect and direct semiconductors, respectively. These findings are qualitatively consistent with the calculated results.