Double Perovskite Structure Research Articles

Ball milling synthesis and optical properties of Na and Bi ions Co-doped double perovskite Cs2AgInCl6

Double perovskite Cs2AgInCl6 is a new direct band gap semiconductor material. Compared with traditional perovskite CsPbX3 (X = Cl, Br, I), double perovskite Cs2AgInCl6 has good stability and wide fluorescence half peak width. This study reports the mechanochemical synthesis, characterization and application of a lead-free double perovskite Cs2AgInCl6 doped with Na and Bi ions. It was found that through a facile room temperature mechanical ball milling process, the double perovskite structure can be obtained within 30 min. Then, Na and Bi ions were used to dope to optimize its luminescence properties. By this synthesis method, the sample with the best doping ratio obtained in the experiment is Cs2Ag0.7Na0.3In0.9Bi0.1Cl6 with the photoluminescence quantum yield (PLQY) of 32.7%. The X-ray diffraction (XRD) and photoluminescence (PL) results show that Na and Bi ions can promote the crystallization and optimize the luminescence properties of Cs2AgInCl6. The theoretical calculation results show that both conduction band minimum (CBM) and valance band maximum (VBM) of Cs2Ag0.7Na0.3In0.9Bi0.1Cl6 are flat, which is favorable for the generation of self-trapped excitons. Packaging Cs2Ag0.7Na0.3In0.9Bi0.1Cl6 sample on an ultraviolet (UV) LED chip, and a warm white LED with good performance can be obtained, which shows a bright potential application in the field of white LED.

A bright orange luminescence with a single ultra-sharp emission peak in a cubic double perovskite

Ba 2+ ions in the cubic double perovskite structure of Ba 2 ZnWO 6 (BZWO) are coordinated with twelve O ions with high symmetry, and a novel orange phosphor Ba 2 ZnWO 6 :Eu 3+ (BZWO:Eu) has been obtained by substituting the partial Ba 2+ with Eu 3+ ions by one-step synthesis. The crystal structure and composition, morphology, optical properties, and temperature resistance of the orange phosphor BZWO:Eu have been studied, respectively. Only a single ultra-sharp emission peaking at 596 nm with full width at half maximum (FWHM) of 1 nm has been detected in the emission spectrum of BZWO:Eu, which is originated from the magnetic dipole transition 5 D 0 → 7 F 1 of Eu 3+ . The photoluminescence (PL) intensity of the phosphor BZWO:Eu has been improved by controlling the experimental condition reaching a PL quantum yield (PLQY) of 53.5%, which is much stronger than that of ZnWO 4 :Eu 3+ . The emission peak of BZWO:Eu keeps without any discernable change when the measurement temperature arises from 77 to 300 K, which indicates its superior temperature resistance. Only a single ultra-sharp emission peak located at 596 nm with full width at half maximum of 1 nm has been observed in the emission spectrum of Ba 2 ZnWO 6 :Eu 3+ , which is originated from the magnetic dipole transition 5 D 0 → 7 F 1 of Eu 3+ .

The optical properties of Mn4+ ions in Ba2CaWO6 with double perovskite structure for optical thermometer application

A series of red-emitting phosphors Ba2CaWO6:xMn4+ were synthesized by solid-state method. The phosphors were characterized by X-ray diffraction (XRD), photo-luminescent excitation spectra (PLE), photo-luminescent emission spectra (PL), decay curves, and quantum efficiency (QE). The concentration-dependent PL spectra were measured to evaluate the optimum Mn4+ ion doping concentration. The energy transfer behavior between Mn4+ ions or Mn4+ ions and tungstate group [WO6] were measured in details. PL emission spectra recorded at different temperatures were introduced to quantify the thermal stability. The temperature dependent emission intensity ratio values were used in temperature sensing applications in the temperature region of 7 to 510 K. The obtained results indicate that the synthesized phosphors have the possibility to be used as an optical thermometer.

Nonstoichiometry, Defect Chemistry and Oxygen Transport in Fe-Doped Layered Double Perovskite Cobaltite PrBaCo2-xFexO6-δ (x = 0-0.6) Membrane Materials.

Mixed conducting cobaltites PrBaCo2-xFexO6-δ (x = 0-0.6) with a double perovskite structure are promising materials for ceramic semi-permeable membranes for oxygen separation and purification due to their fast oxygen exchange and diffusion capability. Here, we report the results of the detailed study of an interplay between the defect chemistry, oxygen nonstoichiometry and oxygen transport in these materials as a function of iron doping. We show that doping leads to a systematic variation of both the thermodynamics of defect formation reactions and oxygen transport properties. Thus, iron doping can be used to optimize the performance of mixed conducting oxygen-permeable double perovskite membrane materials.

Preparation and characterization of highly active and stable NdBaCo0.8Fe0.8Ni0.4O5+δ oxygen electrode for solid oxide fuel cells

In order to develop high active and stable oxygen electrode for intermediate temperature solid oxide fuel cells (IT-SOFCs), NdBaCo0.8Fe0.8Ni0.4O5+δ (NBCFN) oxygen electrode was successfully prepared by sol-gel method. The NBCFN sample formed a double perovskite structure after calcination at 1100 °C for 10 h. The NBCFN electrode and La0.9Sr0.1Ga0.83Mg0.17O3-δ (LSGM) electrolyte has good chemical compatibility below 950 °C. Compared with NdBaCo2O5+δ, the average thermal expansion coefficient (TEC) of NBCFN sample was 17.2 × 10−6 K-1 at 30 °C - 850 °C in air and decreased by 30%. The conductivity of NBCFN sample exhibited p-type semiconductor conduction and reached 441.8 S cm−1 at 800 °C. The polarization impedance (RP) of NBCFN oxygen electrode on LSGM electrolyte reached 0.055 Ω cm2 at 700 °C. The charge transfer process of NBCFN oxygen electrode was mainly rate-limiting step. The RP of NBCFN oxygen electrode exhibited good stability in air during 200 h test. At 800 °C, the NBCFN oxygen electrode on 300μm-thick LSGM electrolyte reached 1042 mWcm−2 at fuel cell mode and current density was 0.9 A cm−2 at 1.3 V under the electrolysis cell mode, respectively. These results primarily indicated that NBCFN oxygen electrode had good electrochemical performance for IT-SOFCs.

Eu3+, Tb3+ doping induced tunable luminescence of Cs2AgInCl6 double perovskite nanocrystals and its mechanism

Incorporation of lanthanide ions (Ln3+) can remarkably enhance the structural stability and optical properties of lead-free perovskite NCs. Herein, we have established the relationship between the intrinsic emission of Cs2AgInCl6 host and the Ln3+ by Eu3+, Tb3+ doping in Cs2AgInCl6 NCs, realizing tunable luminescence of NCs in the visible region. Experimental studies and density functional theory (DFT) calculations analysis show that Eu3+ and Tb3+ occupy the sites of In3+ in Cs2AgInCl6, the defect formation energy for Cs2AgInCl6:Ln3+ is larger than the pristine Cs2AgInCl6, resulting in a more stable cubic double perovskite structure. The optical band gap increases with the increase in Ln3+ doping percentage. Turning excitation from 250 nm to 300 nm, the broad self-trapped excitons (STEs) emission is more remarkable, and the narrow Ln3+ emission is less notable. The emitted color can be adjusted from white to red and to green light by altering the doping concentration of Eu3+ or Tb3+ and excitation wavelength. This work promotes the design and optoelectronic application of desired lead-free perovskites.

Surface defect-induced electronic structures of lead-free Cs2AgBiBr6 double-perovskite for efficiently solar-driven photocatalytic performance

Lead-free Cs2AgBiBr6 double-perovskite has triggered appealing interest in various solar energy-related applications including solar devices and photocatalysis. Nevertheless, further development of the perovskite materials is restricted due to their low redox capacity of the energy band, which is determined by the intrinsic electronic structure. Herein, we demonstrate surface defect-induced electronic structures of the Cs2AgBiBr6 for achieving efficient photocatalytic performance by simply controlling the nucleation and growth processes of the lead-free double-perovskite. During the synthesis process, the strong interaction between the chelating agent EDTA and Cs+ ion leads to the generation of Cs vacancies of Cs2AgBiBr6, which promotes the formation of surface defects to control the electronic structure of double perovskite. The optimized Cs2AgBiBr6 has the strongest reduction capacity with the conduction band potential of −1.53 V (vs NHE at pH = 7) so far, which can greatly promote the production of superoxide radicals (O2–), improving the photocatalytic efficiency of the Cs2AgBiBr6. Under one simulated sunlight irradiation, the photodegradation efficiency of tetracycline (TC) for the as-obtained Cs2AgBiBr6 with surface defect is up to 81.8 % within 90 min. Environmental ImplicationEnvironmental pollution resulting from various factitious and industrial activities is primarily composed of organic compounds such as pesticides, dyes, antibiotic and so on. Antibiotic, difficult to decompose, can only be decomposed slowly by chemical or biological methods owing to their strong stability. Photocatalysis is emerging as a promising technology for environmental remediation because of its strong oxidation ability and fast reaction rate. The eco-friendly Cs2AgBiBr6 perovskite with a suitable bandgap (1.83 eV ∼ 2.19 eV) has recently emerged as a promising photocatalyst for application in pollutant degradation.

Calcium doping in double perovskite SmBa1−xCaxCo2O5+δ to enhance the electrochemical activity of solid oxide cell reversible oxygen electrode

Despite the remarkable reduction of carbon emissions due to COVID-19 pandemic during 2020, a reckless energy demand has compromised the 2050 agenda. In this scenario, reversible Solid Oxide Cells (rSOCs) could play a key-role due to their high fuel flexibility and versatility but there is still room for electrode stability and performance improvement. Lately, double perovskite materials have been widely studied due to their extraordinary fast oxygen diffusion rates and high conductivity mainly related to their layered ordering structure. In this work, the authors present the synthesis route and the electrochemical characterization of the A-site layered double perovskite structure SmBa1−xCaxCo2O5+δ in which calcium co-doping demonstrates a remarkable effect in the oxygen electrode activity. The best calcium doping corresponding to SmBa0.8Ca0.2Co2O5+δ displays a Rp reduction from 0.082 for the undoped material to 0.019 Ω·cm2 at 700 °C. Moreover, under anodic and cathodic operating conditions the electrocatalytic activity was further increased to 0.007 and 0.006 Ω·cm2 at η = ± 0.3 V, respectively. This behaviour demonstrates the suitability of the material to work as reversible oxygen electrode. Finally, the electrode material was subjected to a switching current aging test for over 100 h to prove the electrode stability under operating conditions.

Influence of Sintering Parameters on Spectroscopic Properties of BMW: Eu3+ Ceramic Materials Prepared by HPLT Technique.

In this work, Ba2MgWO6: Eu3+ (BMW: Eu3+) ceramic materials with a double perovskite structure were sintered using the High-Pressure Low-Temperature sintering (HPLT) technique. As part of the research, the influence of pressure (CP), sintering temperature (CT), and sintering time (CTS) on the structure and luminescence of the doped BMW were determined. Structural analysis via XRD and SEM + EDS and spectroscopic analysis via emission and excitation spectra, decay time, and absorption spectra of the obtained ceramics were performed. Dense double perovskite ceramics were obtained with a cubic structure with optimal sintering parameters: T = 500 °C, p = 8 GPa, and t = 1 min. The increase in temperature caused an increased extinction of the luminescence due to the diffusion of carbon into the ceramics. The increase in pressure led to the formation of the amorphous phase, which increased the speed of non-radiative transitions and also led to the extinction of the luminescence. The increase in sintering time from 1 to 3 min enhanced the luminescence output, but when the ceramic was sintered for 5 min, the luminescence was quenched, most likely by increasing the rate of the non-radiative process, as evidenced by reduced decay time.

Enhancement of Electrocatalytic Activity for both Hydrogen and Oxygen Evolution Reactions of a Perovskite Oxide

We have used both experimental and computational methods to show the significant impact of the incorporation of a 4d metal, Mo, into the perovskite oxide Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF), which is known as a benchmark electrocatalyst for the anodic reaction of water-splitting. We demonstrate the enhanced electrocatalytic properties of the resulting catalytic material, Ba0.5Sr0.5Co0.5Mo0.5O3 (BaSrCoMoO6), where the presence of the 4d metal Mo leads to the formation of a double perovskite structure, as opposed to the simple perovskite structure of BSCF. The consequence of this transformation is the enhancement of the electrocatalytic properties of BaSrCoMoO6 over BSCF for both half reactions of water-splitting, i.e., hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Furthermore, BaSrCoMoO6 shows electrocatalytic activity for HER and OER in bulk form without additives, even carbon black, which is commonly added to HER and OER catalysts, including BSCF. Experiments for BaSrCoMoO6 with or without carbon black lead to similar overpotentials. Density functional theory (DFT) calculations reveal the effect of the structural transformation on the shift of the transition metal d bands toward the Fermi level, which correlates with the enhanced electrocatalytic activity.

High-pressure stabilisation of R = Y member of R2CuTiO6 double perovskite series

Double perovskite oxides of the A2B’B″O6 type with Jahn-Teller active Cu2+ as the B′ constituent have gained considerable research interest in recent years. For fundamental studies, the rare earth element (R) based systems such as R2CuTiO6 form an intriguing research platform as they allow systematic chemical-pressure studies by simply controlling the size of the R constituent. However, for the R2CuTiO6 compounds conventional ambient-pressure high-temperature synthesis yields an orthorhombic (Pnma) double perovskite structure for the largest R constituents (La–Gd) only, while the compounds with the smaller R:s adopt a hexagonal structure. Here we demonstrate a hexagonal-to-perovskite structure conversion for the R ​= ​Y compound achieved through a high-pressure (HP) high-temperature treatment at 4 ​GPa and 1000 ​°C. Structural details of the thus stabilized new double perovskite phase of Y2CuTiO6 are addressed through a combined DFT simulation and Rietveld refinement study, revealing signs towards the rare layered-type ordering of the B-site (Cu and Ti) cations. Similar to the previously reported R2CuTiO6 perovskite phases with R ​= ​La, Pr, and Nd, the R ​= ​Y member is found paramagnetic throughout the measured temperature range of 5–300 ​K. From UV–vis absorption measurements the optical bandgap is estimated to be ca 3.4 ​eV.

Synthesis of an Isostructural Series of 12-Coordinate Lanthanide Nitrate Hybrid Double Perovskites with Cubic Symmetry.

In efforts to study the periodic chemical properties of the rare earth elements and their structural chemistry, a hybrid double perovskite phase A2B'BX6 with the formula ((CH3)4N)2KLn(NO3)6 (Ln = La-Lu, Y ex. Pm) was synthesized that crystallizes in the cubic space group, Fm3̅m. This series was obtained via evaporative crystallization from a mixture of Ln(NO3)3, KNO3, and (CH3)4N·NO3 in a 1:1:2 ratio from either H2O or 4.0 M HNO3. In this double perovskite structure, the B site containing the lanthanide ion is coordinated by six bidentate nitrate ligands, with the distal N═O oxygen atoms coordinating the potassium on the B' site in an octahedral six-coordinate environment. The two remaining charge-compensating (CH3)4N+ cations occupy the interstitial voids in the lattice on the A site. This periodic series was characterized via single-crystal X-ray diffraction, powder X-ray diffraction, IR, and Raman spectroscopy. Emission spectra of the Eu complex indicate a phase transition to trigonal symmetry upon cooling. This series is unique as it represents a rare isostructural series spanning the entirety of the rare earth elements excluding promethium with homoleptic 12-coordinate rare earth metal ions.

Structure and magnetism across the Sr2−xBaxNiOsO6 phase diagram: Understanding magnetic superexchange between first and third row transition metal ions

The crystal chemistry and magnetism of compositions in the Sr2−xBaxNiOsO6 phase diagram have been investigated to better understand the superexchange interactions between 3d and 5d transition metal ions. Compositions with x ​< ​1.35 crystallize with the double perovskite structure, while those with x ​> ​1.83 crystallize in a trigonal structure that is a cation ordered variant of the 6H hexagonal perovskite structure. The Sr-rich double perovskites undergo a cubic to tetragonal distortion upon cooling that is driven by out-of-phase octahedral tilting. The tetragonal distortion occurs upon cooling below 650 ​K in Sr2NiOsO6. The temperature of this transition decreases as the barium content increases and is completely suppressed for x ​≥ ​1.2. All compositions in the double perovskite region become spin glasses below Tg ​≈ ​40 ​K, due to the competition between ferromagnetic Ni–Os and antiferromagnetic Ni–Ni and Os–Os superexchange interactions. The double perovskite compositions that are rich in barium, like Sr0.8Ba1.2NiOsO6 show some signs of magnetic ordering in small clusters, but the presence of Ba/Sr disorder inhibits long-range magnetic order. Trigonal Ba2NiOsO6 orders ferrimagnetically below TC ​= ​108 ​K. The magnetic structure of this compound contains ferromagnetic ∼180° Ni–O–Os interactions and antiferromagnetic ∼90° Ni–O–Os interactions, both in agreement with the Goodenough-Kanamori rules.

Luminescence from Self‐Trapped Excitons and Energy Transfers in Vacancy‐Ordered Hexagonal Halide Perovskite Cs2HfF6 Doped with Rare Earths for Radiation Detection (Advanced Optical Materials 19/2022)

Cs2HfX6 halides show a vacancy-ordered cubic double perovskite structure when X = Cl, Br, and I. As to the first member of the halide family, Zhiping Luo and co-workers (article number 2201374) identify Cs2HfF6 as a new type of vacancy-ordered hexagonal perovskite. It is composed of single layers of building blocks. Tunable emission is obtained based on self-trapped exciton emissions from the host and energy transfers in the rare-earth-doped material. From energy-dependent cathodoluminescence and time-resolved X-ray radioluminescence, the co-doped material is found to be more sensitive to radiation energy than the singly-doped or pristine host.

Nanostructured double perovskite magnetic thin films by PLD

Semi-metallic ferromagnetic oxides, having a double perovskite structure, exhibit a variety of strange magneto transport and magnetic characteristics for spintronics applications. The double perovskites Sr2FeMoO6 (SFMO) and Sr2FeWO6 (SFWO) are known as potential magneto resistive materials that exhibit appreciable tunnel-type intrinsic magnetoresistance (TMR) at room temperature. Current research is focused on the deposition and characterization of nanocrystalline thin layers of SFMO and SFWO materials on LaAlO3 substrate with a temperature of 825 °C and pressure of 0.03 mTorr using the pulsed laser deposition (PLD) method. Films are nearly single-crystalline with a predominant c-axis orientation. A smaller peak corresponding to the plane (101) at 2θ = 19.6° was also found, indicating the arrangement of Fe, and Mo ions at B and B' locations in samples. Atomic Force Microscope (AFM) studies reflect uniform grain growth with surface roughness and average grain size of approximately 8 nm and 52.6 nm; 6 nm and 28.2 nm, respectively for SFMO and SFWO thin films. Magnetization measurement at 5 K shows that SFMO is ferromagnetic and SFWO is antiferromagnetic with a significant difference in their magnetic moments. M−T curve of the SFWO film shows a peak at 36.7 K, resembling the Neel temperature. While the M−T graph of SFMO thin films reveals that ferromagnetic transition temperature (Tc) is higher than 320 K.

Structural and Magnetic Properties of Some Vacancy-Ordered Osmium Halide Perovskites.

The structures and magnetic properties of the Os4+ (5d4) halides K2OsCl6, K2OsBr6, Na2OsBr6, and Na2OsBr6·6H2O are described. K2OsCl6 and K2OsBr6 have a cubic vacancy-ordered double perovskite structure but undergo different symmetry-lowering structural phase transitions upon cooling associated with a combination of the relative size of the ions and differences in their chemical bonding. The structure of Na2OsBr6·6H2O has been determined for the first time and the thermal stability of this has been established using a combination of in situ diffraction and TGA. Na2OsBr6·6H2O and Na2OsBr6 are isostructural with the analogous iridium chlorides, Na2IrCl6·6H2O and Na2IrCl6, and dehydration proceeds via different intermediate phases. The magnetic moments of four compounds display a Kotani-like behavior consistent with a Jeff = 0 ground state; however, the magnetic susceptibility measurements reveal unusual low temperature properties indicative of a weak magnetic ground state.

New Strategy and Excellent Fluorescence Property of Unique Core–Shell Structure Based on Liquid Metals/Metal Halides

The further applications of liquid metals (LMs) are limited by their common shortcoming of silver-white physical appearance, which deviates from the impose stringent requirements for color and aesthetics. Herein, a concept is proposed for constructing fluorescent core-shell structures based on the components and properties of LMs, and metal halides. The metal halides endow LMs with polychromatic and stable fluorescence characteristics. As a proof-of-concept, LMs-Al obtained by mixing of LMs with aluminum (Al) is reported. The surface of LMs-Al is transformed directly from Al to a multi-phase metal halide of K3 AlCl6 with double perovskites structure, via redox reactions with KCl + HCl solution in a natural environment. The formation of core-shell structure from the K3 AlCl6 and LMs is achieved, and the shell with different phases can emit a cyan light by the superimposition of the polychromatic spectrum. Furthermore, the LMs can be directly converted into a fluorescent shell without affecting their original features. In particular, the luminescence properties of shells can be regulated by the components in LMs. This study provides a new direction for research in spontaneous interfacial modification and fluorescent functionalization of LMs and promises potential applications, such as lighting and displays, anti-counterfeiting measures, sensing, and chameleon robots.

Systemic development of Mn4+-activated double perovskite red phosphors for plant growth applications

Developing efficient and stable red phosphor has always been considered as important academic research of LED plant-growth lamps. In this study, Mn4+-activated double perovskite red phosphors, A2BB’O6:Mn4+ (A = Sr, Ba; B = Lu, Gd; B’ = Nb, Ta), were successfully synthesized by solid-phase method. To elucidate the structure-activity relationship between the double perovskite structure and the luminescence of Mn4+, the crystal structure, electronic structure and luminescence properties of Sr2LuNbO6:Mn4+ were first studied in detail using X-ray powder diffraction data, density functional theory calculations and spectroscopy data. The coordination environment of Mn4+ was analyzed by investigating the crystal-field parameters, Racah parameters and nephelauxetic parameter. Then, the effect of structural evolution on the luminescence of Mn4+ was investigated by regulating the local coordination environment of Mn4+ through cationic modification. The results demonstrate that Mn4+ enters the octahedral lattice site with a strong crystal field and covalent environment, which can be excited by a near-ultraviolet LED chip to emit narrow-band far-red light in the double perovskite oxides. Moreover, the Mn–O bond length, octahedral distortion and crystal-system type all affect the luminescence of Mn4+. This systemic development provides some guidance for the exploration of novel Mn4+-activated double perovskite red phosphors.

Improved thermal stability of the red-emitting Gd3+ - Modulated La2LiSbO6:Eu3+ phosphors for WLED

Red-emitting phosphors play an important role in the warm white light emitting diodes (LEDs). However, the development of red phosphors with high luminous efficiency and high thermal stability still faces severe challenges. A series of novel red emitting Eu3+ doped La2LiSbO6 phosphors have been synthesized by the conventional solid-state reaction route. The effects of sintering temperatures as well as co-doped Gd3+ ions were discussed. X - ray diffraction (XRD), photoluminescence excitation (PLE) and emission (PL) spectra, temperature-dependent photoluminescence spectra, and CIE chromaticity coordinates were used to analyze these phosphors. The optimum sintering temperature for La2LiSbO6: Eu3+ phosphors was 1200 °C. The emission intensity reached the maximum when Eu3+ ion concentration was 18 mol%, and the dipole-dipole interaction may be responsible for the concentration quenching mechanism of Eu3+ in the La2LiSbO6:Eu3+ phosphors. Furthermore, the emission intensity could be increased by Gd3+ ions doping and the sample reached the best emission intensity when both dopant contents of Gd3+ and Eu3+ ion concentration were 10 mol%. However, due to the destabilization of the double perovskite structure caused by the doping of Gd3+ ions, the emission intensity of (La0.80Gd0.10Eu0.10)2LiSbO6 (LGLSO: Eu3+) sample was weaker than that of (La0.82Eu0.18)2LiSbO6 (LLSO: Eu3+). Impressively, LGLSO: Eu3+ phosphor exhibited good thermal stability and the luminous intensity at 423 K maintained 84% compared with its initial value at room temperature, which was higher than that of LLSO: Eu3+ (68%). The thermal quenching phenomenon and the enhancement mechanism of thermal stability were analyzed by the configuration coordinate diagram of Eu3+ ion. In addition, both chromaticity coordinates of samples located in red region, demonstrating their potential applications in white LEDs.

A novel Ba2SrWO6:Mn4+/Dy3+ red phosphors for warm WLED applications

A novel non-rare-earth red-emitting phosphor of Ba2SrWO6:Mn4+ with a double-perovskite structure was synthesized via a solid-state reaction method at high temperatures, and the mechanism of structural formation was systematically investigated. Moreover, Dy3+co-dopant ions were exploited to develop a white-light phosphor of Ba2SrWO6:Mn4+/Dy3+. Excitation spectra of Ba2SrWO6:Mn4+ and Ba2SrWO6:Mn4+/Dy3+ were both in a wavelength range of 250–550 nm. Under 325 nm excitation, the Ba2SrWO6:Mn4+ phosphors showed a red emission with a peak at 693 nm because of the 2E → 4A2 transition of Mn4+ ions. The Mn4+ ion concentration in the Ba2SrWO6:Mn4+ phosphors was optimized at 0.6 mol%, and the corresponding CIE (Commission International de I’Edairage) chromaticity coordinate was determined at about (0.7238, 0.2762), locating in the deep-red-light region. Meanwhile, the white-light Ba2SrWO6:Mn4+/Dy3+ phosphors displayed a wide emission band, including a blue emission at 492 nm (attributed to 4F9/2 → 6H15/2), a yellow emission at 582 nm (owing to 4F9/2 → 6H13/2), and the red emission at 693 nm. By varying the Dy3+ ion concentration, the emission color of the co-doped phosphors can be tuned from white light (0.3365, 0.3493) to warm white-light (0.4263, 0.3778), qualifying the phosphorous materials as a potential candidate for white-light- or warm white-light-emitting diode applications.