Color tuning of Bi3+-doped double-perovskite Ba2(Gd1−x,Lux)NbO6 (0 ≤ x ≤ 0.6) solid solution compounds via crystal field modulation for white LEDs
Authors: Jun Zhao
Dingfeng Jin
Xufang Tang
Min Jin
Journal: RSC Advances (2020)
Discipline: CHEMISTRY
Keywords: rare-earth-free; color-tunable; solid solutions; double-perovskite; Ba2(Gd1-x ,Lu x )NbO6:Bi3+
Affiliations: College of Materials and Chemistry, China Jiliang University, Hangzhou 310018, P. R. China, Sichuan College of Architectural Technology, Deyang 618000, Department of Physics, Sichuan University, Chengdu 610041

Abstract:  Nowadays, rare-earth-free color-tunable solid solutions are receiving great attention. Here, we synthesize a type of double-perovskite Ba2(Gd1-x ,Lu x )NbO6:Bi3+ (0 ≤ x ≤ 0.6) solid solution compound using high temperature solid state reaction. The structural phase purity and photoluminescence (PL) properties of the samples are characterized by powder X-ray diffraction (XRD), density functional theory (DFT) calculations, UV-visible diffuse reflectance spectroscopy and PL spectroscopy. Structural analysis shows that all the samples are crystallized in the double-perovskite structure with a cubic space group of Fm3̄m. Moreover, with the increase of Lu3+ content, the XRD positions are gradually shifted toward higher diffraction angles, indicating the shrinkage of the crystal lattice. Our PL results show that the Ba2(Gd1-x ,Lu x )NbO6:Bi3+ solid solutions can show Bi3+ tunable emissions from 462 nm to 493 nm and excitation peaks from 363 nm to 390 nm with the increase of Lu3+ content from 0 to 0.6, owing to the crystal field modulation around the Bi3+ ion. In addition, the blue-shift of the host excitation peaks is also observed, which is ascribed to the increase of bandgap energies (i.e., from 3.01 eV to 4.14 eV based on the DFT calculations). Besides, due to the closer structural rigidity induced by the replacement of larger Gd3+ ions with smaller Lu3+ ions, the Ba2(Gd1-x ,Lu x )NbO6:Bi3+ solid solutions show an increase of Bi3+ emission intensity and QE values followed by a subsequent decrease. As a result, the highest QE value, which corresponds to Ba2Gd0.8Lu0.2NbO6:Bi3+, is 49%. Finally, by coating this optimal blue phosphor and the red CsPb(Br0.4I0.6)3 phosphor on a commercial UV LED chip, a white LED device with a color temperature (CT) of 3633 K, CIE value at (0.381, 0.379), color rendering index (CRI) of 78.4, and luminous efficiency of 48 lm W-1 is achieved. 

Retracted: No

PubPeer comments:
 Some of these references look deep and meaningful until they are examined closely and turn out to be completely irrelevant to the topic.  Lattice dynamical properties and bandgap energies were calculated using the projector-augmented planeu2013wave (PAW) potentials27 with the generalized gradient approximation (GGA) of Perdewu2013Burkeu2013Ernzerh of parameterization.28 - [28] H. L. Fu, M. M. Wang, P. Li, S. Jiang, W. Hu, X. T. Guo and M. Cao, **Tracing Knowledge Development Trajectories of the Internet of Things Domain: A main path analysis**, IEEE Transactions on Industrial Informatics, 2019, 15, 6531u20136540 Some References bear no resemblance to the corresponding in-text citations.  All in all, this work reports a new type of perovskite-typed Bi3+-doped tunable solid solutions, which can have the potential application for the white LEDs,33,34 - [33] C. Duan, Y. Yu, J. Xiao, X. Zhang, L. Li, P. Yang, J. Wu and H. Xi, **Water-based routes for synthesis of metal-organic frameworks: A review**, Sci. China Mater., 2020, 63, 667. - [34] C. Duan, Y. Yu, J. Xiao, Y. Li, P. Yang, F. Hu and H. Xi, Recent advancements in metal-organic frameworks for green applications, Green Energy Environment, 2020, DOI: 10.1016 j.gee.2020.04.006.  and the building lighing.35,36 - [35] L. Jiang, L. Yan, Y. Liu, L. Tang, Z. Chen and D. Hong, Climatic and seasonal suitability of phase change materials coupled with night ventilation for office buildings in Western China, Renew. Energy, 2020, 147(1), 356u2013373. - [36] W. Liu, J. Li, L. Ren, J. Xu, C. Li and S. Li, **Exploring Livelihood Resilience and Its Impact on Livelihood Strategy in Rural China**, Soc. Indicat. Res., 2020, DOI: 10.1007 s11205-020-02347-2. The closing sentence seems to be no more than an excuse to bring up a list of irrelevant topics. I hope it isn t simply a citation plantation.  Furthermore, this work can also give clues to other fields, such as the use of the light to address the environmental problems, such as the degradation of antibiotic materials,37 - [37] D. L. Yuan, C. Zhang, S. F. Tang, M. T. Sun, Y. T. Zhang, Y. D. Rao, Z. B. Wang and J. Ke, Fe3+-sulfite complexation enhanced persulfate Fenton-like process for antibiotic degradation based on response surface optimization, Sci. Total Environ., 2020, 727, 138773.  organic materials,38 - [38] S. F. Tang, Z. T. Wang, D. L. Yuan, C. Zhang, Y. D. Rao, Z. B. Wang and K. Yin, Ferrous ion-tartaric acid chelation promoted calcium peroxide fenton-like reactions for simulated organic wastewater treatment, J. Clean. Prod., 2020, 268, 122253.  and the treatment of wastewater,38 acid water.39 - [39] S. F. Tang, J. C. Tang, D. L. Yuan, Z. T. Wang, Y. T. Zhang and Y. D. Rao, Elimination of humic acid in water: comparison of UV PDS and UV PMS, RSC Adv., 2020, 10, 17627u201317634. ,