Phosphate-based Glass Ceramics Research Articles

Enhancement of sodium ion conductivity in phosphate-based glass-ceramics by chemical substitution approach

A NASICON-type sodium-ion conducting material was synthesized via the glass-ceramic route by investigating the zinc doped Na2O–Al2O3–TiO2–P2O5 system. The glasses and glass-ceramics corresponding to the formula Na2+xAl1-xZnxTi(PO4)3 (x = 0, 0.2, 0.4, 0.6, 0.8, 1), labeled as (NAZTP-Gx) and (NAZTP-GCx) respectively, were characterized using different techniques. Differential Scanning Calorimetry (DSC) measurements were carried out to identify the characteristic temperatures, the glass transition (Tg) and the crystallization temperature (Tc). X-ray Diffraction (XRD) analysis of the glass-ceramics confirmed the formation of a solid solution Na2+xAl1-xZnxTi(PO4)3 NASICON phase, Theoretical calculations employing the Perdew–Burke–Ernzerhoff generalized gradients approximation (PBE-GGA) model supported the potential substitution of aluminum by zinc in the octahedral site in the NASICON-phase. Further structural insights were obtained through Infrared (IR) and Raman spectroscopies. Scanning electron microscopy (SEM) analysis revealed a distinct flower-like shape of the formed crystallites in the glass-ceramic NAZTP-GC0.2. Electrical characterization using electrochemical impedance spectroscopy (EIS) demonstrated that the NAZTP-GC0.2 sample exhibited the highest ionic conductivity at 300 °C, reaching 4.1 × 10−5 (Ω−1 cm−1) with an activation energy of 0.25 eV. The DC polarization was performed on the NAZTP-GC0.2 glass-ceramic, revealing that the ions are the main charge carriers in the sample. This comprehensive analysis provides valuable insights into the partial zinc doping of NASICON glass-ceramics, offering potential for improved performance as solid electrolytes in various applications.

Optimization of Mn-Zn ferrite doping in phosphate-based glass ceramics for enhanced hyperthermia efficiency and bioactivity

This study investigates the effects of Mn-Zn ferrite (MZF) content and heat treatment temperature on the structural, mechanical, magnetic, and bioactive properties of Na2O-CaO-P2O5 glass ceramics. Various MZF contents (5MZF, 10MZF, 20MZF, and 40MZF) were incorporated into the glass ceramics and subjected to heat treatment at different temperatures (600, 650, 700, and 800 °C). The results demonstrated that increasing the MZF content significantly enhanced the mechanical properties, including Vickers hardness, Knoop hardness, and Young's modulus. For example, the Vickers hardness values increased from 5.6 GPa in 5MZF samples to 7.1 GPa in 40MZF samples. X-ray diffraction analysis revealed the presence of major crystalline phases, such as Ca2P2O7 and Na4Ca(PO3)6, with NaFe3P3O12 and (Zn,Mn)Fe2O4 appearing in samples with higher MZF content. Magnetic measurements indicated that the 40MZF samples treated at 700 °C reached a satisfactory hyperthermia temperature of 43 °C within 16 min. Bioactivity tests showed a decrease in bioactivity with increasing MZF content, whereas cytotoxicity assays confirmed that all MZF-Na2O-CaO-P2O5 bioactive glass ceramics were non-toxic, maintaining over 100 % cell viability after 24 h. These findings suggest that MZF-containing glass ceramics have potential applications in the biomedical field, particularly when enhanced mechanical and magnetic properties are required.

Effects of heat treatment temperature and CeO2 content on the phase composition, structure, and properties of monazite phosphate-based glass-ceramics

The influences of heat treatment temperature and CeO2 content on the phase composition, structure, and properties of the monazite phosphate-based glass-ceramics prepared by a glass melt-quenching process were investigated. The results show that the CeO2 addition promotes the formation of monazite CePO4 phase but restrains the Fe(PO3)3 and Fe4(PO4)2O phases formed. The batches with high CeO2 content should be heat treated at higher temperatures to obtain the glass-ceramics with a single monazite CePO4 phase. Moreover, the mechanisms of the variations are discussed. At the heat treatment temperatures of ≤1200°C, the as-prepared glass-ceramics show good aqueous durability and the main networks of pyrophosphate and orthophosphate groups. The CeO2 loading can be increased up to 16 mol% from ∼9 mol% by forming the glass-ceramics through the melt-quenching process. The conclusions provide researchers with the roles of temperature and CeO2 in preparing monazite phosphate-based glass-ceramics as potential hosts for specific nuclear waste.

Effect of SrO and ZnO on Densification and in Vitro Behaviors of P<sub>2</sub>O<sub>5</sub>-CaO-Na<sub>2</sub>O-SiO<sub>2</sub>-TiO<sub>2</sub> Bioactive Glass-Ceramics

Phosphate based-glass ceramics in the system of P2O5-CaO-Na2O-SiO2-TiO2 were obtained by the sintering method. For evaluating the effect of strontium and zinc, different amounts of these elements were doped in the parent glass instead of calcium oxide. Sintering behavior of the glasses was evaluated through the measurement of bulk density, liquid absorption, and open porosity percentages. Based on the results, 600 °C was determined as the optimum sintering temperature. Based on the X-Ray diffractometry, calcium pyrophosphate was precipitated during the sintering process as the main crystallized phase. It is worth noting that changing the parent glass composition led to its phase transformation. Variation in the pH and ion concentration in the simulated body fluid as well as weight loss percentages of the samples were considered to evaluate the dissolution behavior of the samples. The in vitro tests showed that increasing the amount of strontium and zinc intensified the dissolution rate. According to scanning electron micrographs, hydroxyapatite nuclei precipitated on the surfaces of the samples after three days of simulated body fluid (SBF) soaking; but, they were dissolved in the solution after 28 days due to the dissolution of the substrate. Some residues of the grown apatite-like layer were observed on the surface of the composition when 25 and 2.5 molar percent of calcium were substituted for strontium and zinc, respectively.

Ag nanoparticles localised surface plasmon field regulated spectral characteristics of Ho3+-doped phosphate-based glass-ceramic

The holmium ion (Ho3+)- activated phosphate-based glass-ceramics with silver nanoparticles (Ag NPs) inclusion were prepared using the standard melt-quenching. The samples were characterised to evaluate the effects of different Ag NPs contents on their structure, microstructure and optical properties. The XRD pattern of the as-quenched samples revealed their glass-ceramic nature. The FTIR and Raman analyses showed the modification of the glass-ceramics network structure due to the embedment of Ag NPs. The TEM and HRTEM images together with the localized surface plasmon resonance (LSPR) absorption bands of the glass-ceramics confirmed the existence of Ag NPs inside the host matrix. The complex impedance analyses of the glass-ceramics suggested the glassy phase dominance in the host network. The photoluminescence (PL) peak intensities were significantly enhanced due to the influence of Ag NPs enabled LSPR effects. The PL decay curve analysis of the glass-ceramics indicated the effect of Ag NPs mediated amplified local electric field and energy transfer from the Ag NPs to Ho3+, a mechanism responsible for the optical traits improvement. The achieved branching ratio and stimulated emission cross-section of the optimum glass-ceramic for the three PL peaks were 73.88% and 46.68 × 10−21 cm2 (green); 83.97% and 41.12 × 10−21 cm2 (red); and 71.40% and 36.95 × 10−21 cm2 (IR). Based on the obtained findings, a structural-optical correlation was established.

Customized physical and structural features of phosphate-based glass-ceramics: role of Ag nanoparticles and Ho3+ impurities

The effects of silver nanoparticles (Ag NPs) embedment on the physical and structural characteristics of the holmium ions (Ho3+) activated phosphate-based glass-ceramics were assessed. Two series of such glass-ceramics were prepared using the melt-quenching and characterized. In the first series, the Ag NPs were nucleated from the incorporated AgCl via the redox process. In the second series, the pure Ag nanopowder was directly added. The overall properties of these glass-ceramics were strongly sensitive to the cooling procedure and NPs addition strategies, leading to different density and refractive index modifications in the two series. The recorded O1s XPS peaks were exploited to determine the bridging to non-bridging oxygen ratios in the studied glass-ceramics network that enabled to unfold the differences in the observed inferences. A compelling correlation among various attributes in the achieved glass-ceramics was established. Briefly, the overall traits of the proposed glass-ceramics were tailored by regulating the preparation conditions.

Titanium-doped iron phosphate based glass ceramic waste forms containing 50 wt% simulated nuclear waste

50 wt% of the simulated nuclear waste derived from the high level waste (HLW) in China is immobilized by using titanium-doped iron phosphate based glass ceramics. The effect of TiO2 content on the crystalline phases, structure and aqueous dissolution rate of the glass ceramic waste forms was investigated in detail. The results show that the crystalline phases of the obtained waste forms are monazite (Ce, La)PO4 accompanying with a small concentration of zirconium pyrophosphate ZrP2O7. The crystallization of ZrP2O7 phase is suppressed by adding TiO2 in the phosphate baseline glasses. Meanwhile, smaller grain size of the products is obtained. Moreover, the aqueous dissolution rates of the glass ceramic waste forms keep in the order of magnitude of 10−2 g m−2 d−1 after 14 leaching days, indicating their good chemical durability which are comparable to widely used borosilicate glasses and iron phosphate glasses/waste forms. The conclusions suggest that phosphate-based glass ceramics may potentially be an applicable matrix for the disposal of HLWs which are rich in actinide elements.

Synthesis and characterization of phosphate-based glass-ceramics for nuclear waste immobilization: Structure, thermal behavior, and chemical stability

Phosphate-based glass-ceramics were prepared by a traditional glass melt-quenching method in a high-temperature furnace. The effects of the ZrO2 substituted for Na2O on the crystal phase, thermal behavior, structure, and chemical stability of the prepared glass-ceramics were investigated in detail. X-ray diffraction (XRD) analysis showed that NaZr2(PO4)3 is the main crystalline phase of all the studied samples. ZrP2O7 and FePO4 respectively appeared when the ZrO2 substituted for Na2O reached or exceeded 8 mol% and 12 mol%. FTIR and Raman spectra showed that the network structure of the studied glass-ceramics consisted mainly of orthophosphate units, pyrophosphate units, and a small amount of metaphosphate units and [BO4] units. For the samples containing 10 mol% ZrO2 or less, the normalized leaching rates of Zr (LRZr), Fe (LRFe), Na (LRNa), and P (LRP) remained low (2.5 × 10−6 g m−2 d−1, 3.3 × 10−6 g m−2 d−1, 2.5 × 10−3 g m−2 d−1, and 6.2 × 10−4 g m−2 d−1, respectively) after immersion in deionized water at 90 °C for 28 days. The obtained results suggest that the traditional glass making process may potentially be applicable to the synthesis of some phosphate-based glass-ceramics for immobilizing nuclear waste.

Effect of the glass melting condition on the processing of phosphate-based glass–ceramics with persistent luminescence properties

In this paper, we discuss the impact of the temperature and the duration of the melting on the persistent luminescence properties of phosphate glasses within the P2O5–Na2O–CaO and P2O5–Na2O–SrO systems prepared using a standard melting process in normal atmosphere by adding Sr4Al14O25:Eu2+,Dy3+ microparticles in the glass batch before melting. Glasses with persistent luminescence properties can be successfully prepared if the melting conditions are carefully controlled.

Phase Evolution and Microstructure Characteristics of Calcium Phosphate Based Glass Ceramics Prepared by Sol-Gel Technique

Calcium phosphate based glasses and glass-ceramics in the system of 54CaO-36P2O5- (10-x)Na2O-xSrO were fabricated by sol-gel method. The structures of the glasses were investigated by Fourier transform infrared spectroscopy and X-ray diffraction has been used to determine the crystallize phase from glass matrix. The synthesized glass matrix shows a metaphosphate-like structure which consists of a chain and /or ring structure. After sintered at 1150 °C, the crystalline phase -Ca2P2O7 and a small quantity of amorphous glass were observed clearly. With 1.0 mol% addition of SrO, the average grain size of -Ca2P2O7 was obviously decreased and some of them were covered with amorphous glass. When the content of strontium reached to 5.0 mol%, only a little crystalline phase -Ca2P2O7 can be found in the glass matrix, while the grain size has no significant change, compared with that of the sample containing 1.0 mol% SrO. The results showed that SrO addition to 54CaO-36P2O5-10Na2O system can inhibit the crystallization of -Ca2P2O7 and decrease the grain size, and then adjust the degradation rate in body fluid by controlling the ratio of -Ca2P2O7 to amorphous glass.

Microstructural characteristics and crystallization of CaO–P2O5–Na2O–ZnO glass ceramics prepared by sol–gel method

Porous phosphate-based glass ceramics prepared by the sol–gel method were characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and differential thermal analysis (DSC). The 48CaO–45P2O5–2ZnO–5Na2O glassy system can remain fully amorphous up to 550 °C. After heat treated at 650 °C, the obtained porous bodies consisted of dense struts and macropores where β-Ca2P2O7 and Na2CaP2O7 phases crystallized from the glass matrix. When treated at 750 °C, Ca4P6O19 and NaZn(PO3)3 precipitated homogeneously as new phases among the residual glass matrix. The material was assessed by soaking samples in phosphate-based buffer solution (PBS) solution to determine the solubility and observe apatite formation.

Crystallization and microstructure analysis of calcium phosphate-based glass ceramics for biomedical applications

Calcium phosphate glasses and glass ceramics (CaO/P 2O 5=1.25 in molar ratio) modified by small amounts of additives such as Na 2O, MgO, TiO 2 and ZrO 2 were prepared after appropriate heat treatment for nucleation and crystallization. Based upon differential thermal analysis (DTA) results, a two-step heat treatment was used for crystal nucleation and growth. X-ray diffraction (XRD) analysis demonstrated that bioresorbable β-Ca 2P 2O 7 (β-DCP), β-Na 2CaP 2O 7, Na 2Mg(PO 3) 4 phases were formed in the glass matrix depending upon the relative contents of the additives. By adding higher contents of Na 2O and TiO 2 and using CaO/P 2O 5=1.5–2.0, crystallization of β-DCP and Ca 3(PO 4) 2 (β-TCP), and the formation of a dense structure in the glass ceramics were obtained. The precipitation of these crystals could be well distinguished at a magnification of 4000× and phases were dispersed in areas of micron size. A porous structure may be easily formed after the soluble phases are dissolved in physiological media. These glass ceramics with high CaO/P 2O 5 ratio, modified by the above mentioned additives are expected to find use as implants for bone replacement/regeneration and drug delivery carriers synergistically, because the soluble phases may act as drug delivery carriers and the porous structure will allow for bone ingrowth.