Influences of copper–potassium ion exchange process on the optical bandgaps and spectroscopic properties of Cr3+/Yb3+ co-doped in lanthanum aluminosilicate glasses
Authors: Dacheng Zhou
Jianbei Qiu
Nguyen Minh Ty
Anh-Luan Phan
Ho Kim Dan
T H Le
Journal: RSC Advances (2021)
Discipline: CHEMISTRY
Keywords: lanthanum aluminosilicate glasses; ion exchange process; luminescence spectra; Cr3+/Yb3+ co-doped; EDS analysis
Affiliations: Department of Physics and Technology, Thai Nguyen University of Sciences, Thai Nguyen, Vietnam, Institute of Fundamental and Applied Sciences, Duy Tan University, Ho Chi Minh City 700000, Faculty of Natural Sciences, Thu Dau Mot University, Thu Dau Mot 590000, Key Laboratory of Advanced Materials of Yunnan Province, School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, China, Ceramics and Biomaterials Research Group, Advanced Institute of Materials Science, Ton Duc Thang University, Ho Chi Minh City

Abstract:  In this study, lanthanum aluminosilicate glasses with compositions of 45SiO2-20Al2O3-12.5LaF3-10BaF2-9K2O-1Cr2O3-2.5Yb2O3 (SALBK) were prepared using the conventional melting method and copper-potassium ion exchange process. Influences of the ion exchange process between copper and potassium on the visible, upconversion, and near-infrared luminescence spectra of Cr3+/Yb3+ co-doped under excitations of 343, 490, and 980 nm LD were investigated. The EDS analysis of SALBK glasses was measured to confirm the presence of atoms in the glasses. The values of direct and indirect bandgaps of Cr3+/Yb3+ co-doped SALBK glasses were calculated and analyzed. Besides, the energy exchange processes between Cu+, Cu2+ ions, and Cr3+, Yb3+ ions were also proposed and discussed. 

Retracted: No

PubPeer comments:
 All curves except the black one in Fig 3 (see attached plot) are surprisingly identical to each other, even the noise. Could the authors please give an explanation for this strange result ? ![file] , 
 Dear Reader, your observation is very interesting. On behalf of all the authors, I can reply to your question as follows: 1. First, the  surprising identicality of the curves (except the black one) is actually an illusion caused by the plotting style of Figure. 3. The measured data for these curves are indeed not the same, however the differences are too insignificant. I attached here another plot of these data, but now we set them to the same  standard axis so that we can see that the curves are obviously distinguished from each other. 2. Now, your question may be why the five curves are very similar, while the black one is totally different. The black curve is for the glass sample without performing the ion exchange process. For all other samples, we performed the ion exchange processes with different concentration ratios of the salts. The peaks (110), (111) and (200) are the evidence for the presence of copper ions, mainly on the surfaces of the samples, not deep into the bulk. When the salt concentration ratio changes, the data of XRD analysis changes a bit too, but not much because of the amorphousness of the glass material. Hope this reply could satisfy you. Thank you again for your question. , 
 XRD https: drive.google.com file d 1G17G1PC6IL4TaA0X_qEaQA-P0Bb3YaJa view?usp=sharing , 
 #2 I would like to add here the new plot that is mentioned in my co-author s reply: ![file] , 
 5 copies of the same XRD pattern, very clear. , 
 #2 *an illusion caused by the plotting style of Figure. 3* So any real differences between the XRD patterns of these materials, and any stochastic experimental noise produced by the equipment, are below the resolution of Fig 3? , 
 The shared XRD data file is not accessible. There is no possible physical mechanism by which the experimental noise from independent measurement on different samples would be identical within that resolution, really. , 
 Upon close inspection there are similar problems with some of the other figures. For one such example, here is an enlargement of a portion of Fig 11(D) (Supporting Information S11d) showing what appears to be identical noise in each of the 6 decays curves depicted. ![file] ,