Artículos de revistas sobre el tema "Upconverting nanomaterials"

Photodynamic therapy (PDT) has been reported as a possible pathway for the treatment of tumors. The exploration for promising PDT systems thus attracts continuous research efforts. This work focused on an ordered core–shell structure encapsulated by mesoporous SiO2 with the upconverting emission property following a surfactant-assisted sol–gel technique. The mesoporous silica shell possessed a high surface area-to-volume ratio and uniform distribution in pore size, favoring photosensitizer (rose bengal) loading. Simultaneously, upconverting nanocrystals were synthesized and used as the core. After modification via hydrophobic silica, the hydrophobic upconverting nanocrystals became hydrophilic ones. Under near-infrared (NIR) light irradiation, the nanomaterials exhibited strong green upconverting luminescence so that rose bengal could be excited to produce singlet oxygen. The photodynamic therapy (PDT) feature was evaluated using a 1O2 fluorescent indicator. It was found that this core–shell structure generates 1O2 efficiently. The novelty of this core–shell structure was the combination of upconverting nanocrystals with a mesoporous SiO2 shell so that photosensitizer rose bengal could be effectively adsorbed in the SiO2 shell and then excited by the upconverting core.

NaYF₄:Yb,Er@NaYF₄ is an efficient and well-known upconverting nanomaterials at 980 nm, also it has strong optical nonlinearity at 532 nm related to energy states of the Yb/Er system which is determined by a unique approach.

Combustion and sol-gel methods were used to prepare the upconverting nanocrystallineZrO2:Yb3+,Er3+phosphors. The crystal structure was studied by X-ray powder diffraction and the crystallite sizes were estimated with the Scherrer formula. Impurities and nanomaterials' thermal degradation were analyzed with FT-IR spectroscopy and thermal analysis, respectively. Upconversion luminescence and luminescence decays were studied with IR-laser excitation at 977 nm. All nanomaterials possessed the cubicZrO2fluorite-type structure except for a small monoclinic impurity obtained with the sol-gel method. The conventionalNO3−andOH−impurities were observed for the combustion synthesis products. TheZrO2:Yb3,Er3+nanomaterials showed red (630–710 nm) and green (510–570 nm) upconversion luminescence due to the4F9/2→4I15/2and(2H11/2,4S3/2)→4I15/2transitions ofEr3+, respectively. The products of the combustion synthesis exhibited the most intense luminescence intensity and showed considerable afterglow. It was concluded that excitation energy is partially trapped in the system and subsequently bleached thermally to the luminescentEr3+center to yield “persistent upconversion”.

Salmonella bacteria is a foodborne pathogen found mainly in food products causing severe symptoms in the individual, such as diarrhea, fever, and abdominal cramps after consuming the infected food, which can be fatal in some severe cases. Rapid and selective methods to detect Salmonella bacteria can prevent outbreaks when ingesting contaminated food. Nanobiosensors are a highly sensitive, simple, faster, and lower cost method for the rapid detection of Salmonella, an alternative to conventional enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) techniques. This study systematically searched and analyzed literature data related to nucleic acid-based nanobiosensors (NABs) with nanomaterials to detect Salmonella in food, retrieved from three databases, published between 2010 and 2021. We extracted data and critically analyzed the effect of nanomaterial functionalized with aptamer or DNA at the limit of detection (LOD). Among the nanomaterials, gold nanoparticles (AuNPs) were the most used nanomaterial in studies due to their unique optical properties of the metal, followed by magnetic nanoparticles (MNPs) of Fe3O4, copper nanoparticles (CuNPs), and also hybrid nanomaterials multiwalled carbon nanotubes (c-MWCNT/AuNP), QD/UCNP-MB (quantum dotes upconverting nanoparticle of magnetic beads), and cadmium telluride quantum dots (CdTe QDs@MNPs) showed excellent LOD values. The transducers used for detection also varied from electrochemical, fluorescent, surface-enhanced Raman spectroscopy (SERS), RAMAN spectroscopy, and mainly colorimetric due to the possibility of visualizing the detection result with the naked eye. Furthermore, we show the magnetic separation system capable of detecting the target amplification of the genetic material. Finally, we present perspectives, future research, and opportunities to use point-of-care (POC) diagnostic devices as a faster and lower cost approach for detecting Salmonella in food as they prove to be viable for resource-constrained environments such as field-based or economically limited conditions.

Upconverting nanoparticles (UCNPs) compose a class of luminescent materials that utilize the unique wavelength-converting properties of lanthanide (Ln) ions for light-harvesting applications, photonics technologies, and biological imaging and sensing experiments. Recent advances in UCNP design have shed light on the properties of local color centers, both intrinsic and controllably induced, within these materials and their potential influence on UCNP photophysics. In this review, we describe fundamental studies of color centers in Ln-based materials, including research into their origins and their roles in observed photodarkening and photobrightening mechanisms. We place particular focus on the new functionalities that are enabled by harnessing the properties of color centers within Ln-doped nanocrystals, illustrated through applications in afterglow-based bioimaging, X-ray detection, all-inorganic nanocrystal photoswitching, and fully rewritable optical patterning and memory.

Upconversion has attracted much attention for the potential applications of nanomaterials and bulk materials. Upconversion nanoprobes and sensors rely on the non-linear emission of the reporters, which present a low efficiency due to their anti-Stokes nature. For these two reasons, the materials require accurate and contrastable efficiency measurements, typically by measuring the absolute upconversion quantum yield (UCQY). The methodology for such measurements will vary from traditional photoluminescence quantum yield techniques that have been applied for downshifting materials [1]. Effects like the scattering, broadband absorption and reemission, inner-filter effects, thickness, self-absorption, and temperature, have to be considered [2]. This presentation will focus on some of these effects. The scattering has usually been neglected, however systems with scattering can increase the power density and subsequently the UCQY, as demonstrated both experimentally and via simulations [3]. Furthermore, this energy concentration also provides a new method for identifying the refractive index of phosphors, which is useful since some phosphors cannot be produced in macroscopic sizes. Broadband characterisation enables a route for characterisation exploiting the wide energy levels at the near-infrared. However, it introduces new challenges such as reemission [4]. In the case of applications that use a thick upconverted, the thickness is also a key parameter that can be responsible up to 50% of the emission [5]. Finally, one of the applications that is been intensively researched is the use of upconverting and downshifting nanoparticles as temperature reporters. Absolute upconversion photoluminescence quantum yield characterisation for different probes will be presented with a modified integrating sphere that allows in-situ absorption and emission measurements. References: [1] Callum M. S. Jones, Anna Gakamsky & Jose Marques-Hueso (2021) The upconversion quantum yield (UCQY): a review to standardize the measurement methodology, improve comparability, and define efficiency standards, Science and Technology of Advanced Materials, 22:1, 810-848, DOI: 10.1080/14686996.2021.1967698 [2] Callum M. S. Jones, Daniel Biner, Stavros Misopoulos, et al. Optimized photoluminescence quantum yield in upconversion composites considering the scattering, inner-filter effects, thickness, self-absorption, and temperature. Sci Rep 11, 13910 (2021). DOI:10.1038/s41598-021-93400-8 [3] Callum M. S. Jones, Nikita Panov, Artiom Skripka, et al., "Effect of light scattering on upconversion photoluminescence quantum yield in microscale-to-nanoscale materials," Opt. Express 28, 22803-22818 (2020). DOI: 10.1364/OE.398353 [4] Sean K. W. MacDougall, Aruna Ivaturi, Jose Marques-Hueso, et al; “Measurement procedure for absolute broadband infrared up-conversion photoluminescent quantum yields: Correcting for absorption/re-emission”. Rev Sci Instrum, 85 (6), 063109 (2014). DOI:10.1063/1.4881537 [5] Alessandro Boccolini, Jose Marques-Hueso, and Bryce S. Richards, "Self-absorption in upconverter luminescent layers: impact on quantum yield measurements and on designing optimized photovoltaic devices," Opt. Lett. 39, 2904-2907 (2014). DOI: 10.1364/OL.39.002904 Figure 1

Lanthanide-doped upconversion nanoparticles (UCNPs) are inorganic nanomaterials in which the lanthanide cations embedded in the host matrix can convert incident near-infrared light to visible or ultraviolet light. These particles are often used for long-term and real-time imaging because they are extremely stable even when subjected to continuous irradiation for a long time. It is now possible to image their movement at the single particle level with a scale of a few nanometers and track their trajectories as a function of time with a scale of a few microseconds. Such UCNP-based single-particle tracking (SPT) technology provides information about the intracellular structures and dynamics in living cells. Thus far, most imaging techniques have been built on fluorescence microscopic techniques (epifluorescence, total internal reflection, etc.). However, two-dimensional (2D) images obtained using these techniques are limited in only being able to visualize those on the focal planes of the objective lens. On the contrary, if three-dimensional (3D) structures and dynamics are known, deeper insights into the biology of the thick cells and tissues can be obtained. In this review, we introduce the status of the fluorescence imaging techniques, discuss the mathematical description of SPT, and outline the past few studies using UCNPs as imaging probes or biologically functionalized carriers.

Lanthanide-doped upconverting nanoparticles (UCNPs) transform near infrared light (NIR) into higher-energy UV and visible light by multiphotonic processes. Owing to such unique feature, UCNPs have found application in optical imaging and have been investigated for the NIR light activation of prodrugs, including transition metal complexes of interest in photochemotherapy. Besides, UCNPs also function as magnetic resonance imaging (MRI) contrast agents and positron emission tomography (PET) probes when labelled with radionuclides such as 18F. In this contribution, we report on a new series of phosphonate-functionalized NaGdF4:Yb,Er UCNPs that show affinity for hydroxyapatite (inorganic constituent of bones), and we discuss their potential as bone targeting multimodal (MRI/PET) imaging agents. In vivo biodistribution studies of 18F-labelled NaGdF4:Yb,Er UCNPs in rats indicate that surface functionalization with phosphonates favours the accumulation of nanoparticles in bones over time. PET results reveal leakage of 18F− for phosphonate-functionalized NaGdF4:Yb,Er and control nanomaterials. However, Gd was detected in the femur for phosphonate-capped UCNPs by ex vivo analysis using ICP-MS, corresponding to 6–7% of the injected dose.

Based on their outstanding optical properties, lanthanide-based compounds have been suggested for a wide range of applications including the fields of biomedicine, optoelectronics, and solar energy conversion. For instance, the capability of lanthanide-based materials to emit visible and near-infrared (NIR) light under NIR excitation is highly sought after when aiming for biomedical applications. This is as NIR light penetrates deeper into biological tissue and is less phototoxic than UV light commonly used for optical bioprobes. Our favorite nanomaterials are lanthanide-based fluorides (MLnF4, M = alkali metal, Ln = lanthanides and Yttrium), and our research addresses challenges in their synthesis as well as the establishment of structure-property relationships. The growing attention toward such optically active materials has prompted the development of novel synthesis methods for a more reliable and efficient access to these systems. In this regard, microwave-assisted approaches provide unique advantages over traditional solvothermal methods reliant on convectional heating: namely, significantly shorter reaction durations, more rigid reaction conditions, and thus a higher degree of reproducibility. The developed approach allows to control the material’s crystalline phase and doping of various Ln3+ ions into core/shell architectures. Additional surface modification with biopolymers renders the nanomaterials dispersible in various solvents and allows for their assembly into multipurpose micro-carriers. The resultant emission color-tunable upconverting nanoparticles are promising candidates for versatile applications, ranging from multiplexed imaging and light-induced therapy to inks for printing of micropatterns for optoelectronic devices.

Functionalized upconverting nanoparticles (UCNPs) are promising theragnostic nanomaterials for simultaneous therapeutic and diagnostic purposes. We present two types of non-toxic eosin Y (EY) nanoconjugates derived from UCNPs as novel nanophotosensitizers (nano-PS) and deep-tissue bioimaging agents employing light at 800 nm. This excitation wavelength ensures minimum cell damage, since the absorption of water is negligible, and increases tissue penetration, enhancing the specificity of the photodynamic treatment (PDT). These UCNPs are uniquely qualified to fulfil three important roles: as nanocarriers, as energy-transfer materials, and as contrast agents. First, the UCNPs enable the transport of EY across the cell membrane of living HeLa cells that would not be possible otherwise. This cellular internalization facilitates the use of such EY-functionalized UCNPs as nano-PS and allows the generation of reactive oxygen species (ROS) under 800 nm light inside the cell. This becomes possible due to the upconversion and energy transfer processes within the UCNPs, circumventing the excitation of EY by green light, which is incompatible with deep tissue applications. Moreover, the functionalized UCNPs present deep tissue NIR-II fluorescence under 808 nm excitation, thus demonstrating their potential as bioimaging agents in the NIR-II biological window.

To date, the increase in reactive oxygen species (ROS) production for effectual photodynamic therapy (PDT) treatment still remains challenging. In this study, a facile and effective approach is utilized to coat mesoporous silica (mSiO2) shell on the ligand-free upconversion nanoparticles (UCNPs) based on the LiYF4 host material. Two kinds of mesoporous silica-coated UCNPs (UCNP@mSiO2) that display green emission (doped with Ho3+) and red emission (doped with Er3+), respectively, were successfully synthesized and well characterized. Three photosensitizers (PSs), merocyanine 540 (MC 540), rose bengal (RB), and chlorin e6 (Ce6), with the function of absorption of green or red emission, were selected and loaded into the mSiO2 shell of both UCNP@mSiO2 nanomaterials. A comprehensive study for the three UCNP@mSiO2/PS donor/acceptor pairs was performed to investigate the efficacy of fluorescence resonance energy transfer (FRET), ROS generation, and in vitro PDT using a MCF-7 cell line. ROS generation detection showed that as compared to the oleate-capped and ligand-free UCNP/PS pairs, the UCNP@mSiO2/PS nanocarrier system demonstrated more pronounced ROS generation due to the UCNP@mSiO2 nanoparticles in close vicinity to PS molecules and a higher loading capacity of the photosensitizer. As a result, the three LiYF4 UCNP@mSiO2/PS nanoplatforms displayed more prominent therapeutic efficacies in PDT by using in vitro cytotoxicity tests.

Upconverting luminescent nanoparticles (UCNPs) are “new generation fluorophores” with an evolving landscape of applications in diverse industries, especially life sciences and healthcare. The anti-Stokes emission accompanied by long luminescence lifetimes, multiple absorptions, emission bands, and good photostability, enables background-free and multiplexed detection in deep tissues for enhanced imaging contrast. Their properties such as high color purity, high resistance to photobleaching, less photodamage to biological samples, attractive physical and chemical stability, and low toxicity are affected by the chemical composition; nanoparticle crystal structure, size, shape and the route; reagents; and procedure used in their synthesis. A wide range of hosts and lanthanide ion (Ln3+) types have been used to control the luminescent properties of nanosystems. By modification of these properties, the performance of UCNPs can be designed for anticipated end-use applications such as photodynamic therapy (PDT), high-resolution displays, bioimaging, biosensors, and drug delivery. The application landscape of inorganic nanomaterials in biological environments can be expanded by bridging the gap between nanoparticles and biomolecules via surface modifications and appropriate functionalization. This review highlights the synthesis, surface modification, and biomedical applications of UCNPs, such as bioimaging and drug delivery, and presents the scope and future perspective on Ln-doped UCNPs in biomedical applications.

The radiation conversion phenomenon is used for UV sensing applications with rare earth doped phosphors. This paper presents the results of structural and optical measurements of undoped and europium doped LaPO4 phosphors. LaPO4 phosphors with 1% mol, 2% mol, and 5% mol of europium were fabricated by the co-precipitation method. The effect of Eu3+ concentrations on the luminescence characteristics under UV LED excitation was investigated. The maximum quantum efficiency of luminescence (c.a. 82%) was obtained in sampled doped with 5% of europium. Full Text: PDF ReferencesM. Runowski, "Nanotechnologia – nanomateriały, nanocząstki i wielofunkcyjne nanostruktury typu rdzeń/powłoka", Chemik 68, 9, 766-775 (2014). DirectLink J. Zhou, J.L. Leano Jr., Z. Liu, D. Jin, K.-L. Wong, R.S. Liu, et al., "Impact of Lanthanide Nanomaterials on Photonic Devices and Smart Applications", Small 14, 1801882 (2018). CrossRef Z. Li, Y. Zhang, G. Han, "Lanthanide-Doped Upconversion Nanoparticles for Imaging-Guided Drug Delivery and Therapy", Springer Series in Biomater. Sci. Eng. 6, 139-164, (2016). CrossRef M. Lin, Y. Zhao, S. Wang, M. Liu, Z. Duan, Y. Chen, et al., "Recent advances in synthesis and surface modification of lanthanide-doped upconversion nanoparticles for biomedical applications", Biotechnol. Adv. 30, 1551-1561 (2012). CrossRef H. Su, Y. Nie, H. Yang, D. Tang, K. Chen, T. Zhang, "Improving the thermal stability of phosphor in a white light-emitting diode (LED) by glass-ceramics: Effect of Al2O3 dopant", J. Eur. Ceram. Soc. 38, 2005-2009 (2018). CrossRef J. Huang, X. Hu, J. Shen, D. Wu, C. Yin, R. Xiang, et al., "Facile synthesis of a thermally stable Ce3+:Y3Al5O12 phosphor-in-glass for white LEDs", Cryst. Eng. Comm 17, 7079-7085 (2015). CrossRef R. Zhang, H. Lin, Y. Yu, D. Chen, J. Xu, Y. Wang, "A new-generation color converter for high-power white LED: transparent Ce3+:YAG phosphor-in-glass", Laser Photon. Rev. 8, 158-164 (2014). CrossRef B. Zheng, Y. Bai, H. Chen, H. Pan, W. Ji, X. Gong, et al., "Near-Infrared Light-Excited Upconverting Persistent Nanophosphors in Vivo for Imaging-Guided Cell Therapy", ACS Appl. Mater. Interfaces 10, 19514 (2018). CrossRef J. Qiao, G. Zhou, Y. Zhou, Q. Zhang, Z. Xia, "Divalent europium-doped near-infrared-emitting phosphor for light-emitting diodes", Nature Communications 10 (1), 5267 (2019). CrossRef V. Singh, A. Kumar, C. Mehare, H. Jeong, S. Dhoble, "UV/VUV excited photoluminescence of Tb3+ doped LaPO4 green emitting phosphors for PDP applications", Optik 206, 163733 (2020). CrossRef G. Han, Y. Wang, C. Wu, J. Zhang, "Hydrothermal synthesis and vacuum ultraviolet-excited luminescence properties of novel Dy3+-doped LaPO4 white light phosphors", Mat. Res. Bull. 44 (12), 2255-2257 (2009). CrossRef K. S. Gupta, P. S. Ghosh, M. Sahu, K. Bhattacharyya, R. Tewari, V. Natarajan, "Intense red emitting monoclinic LaPO4:Eu3+ nanoparticles: host–dopant energy transfer dynamics and photoluminescence properties", RSC Adv. 5, 58832-58842 (2015). CrossRef

A novel nanomaterial with CuS nanoparticles decorated onto the surface of NaYF₄:Mn/Yb/Er@photosensitizer doped SiO₂ was synthesized for synergistic multidrug-resistant bacteria therapy.

Two key concerns exist in contemporary cancer chemotherapy in clinics: limited therapeutic efficiency and substantial side effects in patients. In recent years, researchers have been investigating revolutionary cancer treatment techniques and photo-thermal therapy (PTT) has been proposed by many scholars. A drug for photothermal cancer treatment was synthesized using the hydrothermal method, which has a high light-to-heat conversion efficiency. It may also be utilized as a clear multi-modality bioimaging platform for photoacoustic imaging (PAI), computed tomography (CT), and magnetic resonance imaging (MRI). When compared to single-modality imaging, multi-modality imaging delivers far more thorough and precise details for cancer diagnosis. Furthermore, gold-doped upconverting nanoparticles (UCNPs) have an exceptionally high target recognition for tumor cells. The gold-doped UCNPs, in particular, are non-toxic to normal tissues, endowing the as-prepared medications with outstanding therapeutic efficacy but exceptionally low side effects. These findings may encourage the creation of fresh effective imaging-guided approaches to meet the goal of photothermal cancer therapy.

Abstract Photodynamic therapy (PDT) is a well-established treatment of cancer that uses the toxic reactive oxygen species, including singlet oxygen (1O2), generated by photosensitiser drugs following irradiation of a specific wavelength to destroy the cancerous cells and tumours. Visible light is commonly used as the excitation source in PDT, which is not ideal for cancer treatment due to its reduced tissue penetration, and thus inefficiency to treat deep-lying tumours. Additionally, these wavelengths exhibit elevated autofluorescence background from the biological tissues which hinders optical biomedical imaging. An alternative to UV-Vis irradiation is the use of near infrared (NIR) excitation for PDT. This can be achieved using upconverting nanoparticles (UCNPs) functionalised with photosensitiser (PS) drugs where UCNPs can be used as an indirect excitation source for the activation of PS drugs yielding to the production of singlet 1O2 following NIR excitation. The use of nanoparticles for PDT is also beneficial due to their tumour targeting capability, either passively via the enhanced permeability and retention (EPR) effect or actively via stimuli-responsive targeting and ligand-mediated targeting (ie. using recognition units that can bind specific receptors only present or overexpressed on tumour cells). Here, we review recent advances in NIR upconverting nanomaterials for PDT of cancer with a clear distinction between those reported nanoparticles that could potentially target the tumour due to accumulation via the EPR effect (passive targeting) and nanoparticle-based systems that contain targeting agents with the aim of actively target the tumour via a molecular recognition process.

AbstractThe continuously growing importance of information storage, transmission, and authentication impose many new demands and challenges for modern nano-photonic materials and information storage technologies, both in security and storage capacity. Recently, luminescent lanthanide-doped nanomaterials have drawn much attention in this field because of their photostability, multimodal/multicolor/narrowband emissions, and long luminescence lifetime. Here, we report a multimodal nanocomposite composed of lanthanide-doped upconverting nanoparticle and EuSe semiconductor, which was constructed by utilizing a cation exchange strategy. The nanocomposite can emit blue and white light under 365 and 394 nm excitation, respectively. Meanwhile, the nanocomposites show different colors under 980 nm laser excitation when the content of Tb3+ ions is changed in the upconversion nanoparticles. Moreover, the time-gating technology is used to filter the upconversion emission of a long lifetime from Tb3+ or Eu3+, and the possibilities for modulating the emission color of the nanocomposites are further expanded. Based on the advantage of multiple tunable luminescence, the nanocomposites are designed as optical modules to load optical information. This work enables multi-dimensional storage of information and provides new insights into the design and fabrication of next-generation storage materials.

Rare earth photonic nanomaterials are increasingly prominently applied in various fields of biomedicine. Currently, there is greater focus on the investigation to control the size and shape of nanomaterials, including the nanospherical form, which allows for precise labeling by only one nanoparticle. This paper demonstrates, for the first time, the construction of a biological nanospherical probe (BNSP) Gd2O3: Yb3+, Er3+/Silica/NH/mAb^CD133 for diagnostic labeling of cancer stem cells (CSCs) NTERA-2. The BNSP was constructed using highly monodisperse spheres with around 200nm uniform size of Gd2O3: 7.6% Yb3+, 1.6% Er3+. They were functionalized by an amine group-contained shell coating and conjugated with CD133 monoclonal antibody. The functionalized nanosphere Gd2O3: Yb, Er/silica/NH2 showed strong upconversion luminescence in red color upon laser excitation in the near-infrared region at 975 nm. The Gd2O3: Yb3+, Er3+/silica/NH2 was carefully implemented to conjugate mAb^CD133 via a linker, glutaraldehyde, to obtain the predictable probe Gd2O3: Yb3+, Er3+/Silica/NH/mAb^CD133. Then, this BNSP was tested in vitro for its capacity to label NTERA-2 cancer stem cells. The efficient labeling based on the fluorescent immunoassay method was detected by incorporating a nanophotometer, Field Energy Scan Electron Microscopy (FESEM), and precisely determined by fluorescent microscopy. The study shows that the BNSP is highly efficient with targeting capacity and specificity in the labeling of cancer stem cells. These advanced results open up promising avenues for the development of precise imaging diagnostics in cancer cellular biomedicine, and beyond.

Исследование посвящено созданию люминофора на основе фторида кальция, легированного редкоземельными элементами: 5% Yb, 1% Er, с использованием методики синтеза из раствора в расплаве. В качестве растворителя использован нитрат натрия NaNO3, в качестве фторирующего агента – фторид натрия NaF. Полученные образцы охарактеризованы методами рентгенофазового анализа, рентгеноспектрального микроанализа, растровой электронной микроскопии и люминесцентной спектроскопии.В ходе работы исследовано влияние параметров синтеза на фазовый состав и морфологию частиц. Было установлено, что для формирования однофазных образцов – твёрдых растворов на основе фторида кальция – необходимо проводить синтез при температуре не ниже 400 °C, оптимальное время выдержки составило 3 ч. Установлен состав полученных образцов, он отличается от номинального и может быть записан как Ca0.88(Yb, Er)0.06Na0.06F2. 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