Second harmonic generation in germanotellurite bulk glass‐ceramics

In this study, we have investigated the use of silver cation as nucleating agent in germanotellurite glass matrix of compositions (100?x) [70TeO₂–10GeO₂–10Nb₂O₅–10K₂O]–xAg₂O (x=0‐6 mol%), in order to promote bulk crystallization. Density measurements, differential scanning calorimetry, X‐ray diffraction, UV‐Vis, and Raman spectroscopies have been performed to study the crystallization process. We have observed bulk crystallization of a unique noncentrosymmetric phase, K[Nb_1/3Te_2/3]₂O_4.8, which has been investigated for its second‐order optical activity. Transparent to translucent glass‐ceramics have been successfully tailored under thermal treatment and second harmonic generation signals were recorded on the glass‐ceramic samples as a function of their synthesis procedure. It is suggested that the second‐order optical properties observed are strongly related to the organization of crystallites within phase‐separated domains.     

Understanding the structure,thermal, and optical properties in Al2O3-incorporated La2O3-TiO2-Nb2O5 glasses

Glasses in the 30La₂O₃-40TiO₂-30Nb₂O₅ system are known to have excellent optical properties such as refractive indices over 2.25 and wide transmittance within the visible to mid-infrared (MIR) region. However, titanoniobate glasses also tend to crystallize easily, significantly limiting their applications in optical glasses due to processing challenges. Therefore, the 30La₂O₃-40TiO₂-(30−x) Nb₂O₅-xAl₂O₃ (LTNA) glass system was successfully synthesized using a aerodynamic containerless technique, which improves glass thermal stability and expands the glass-forming region. The effects of Al₂O₃ on the structure, thermal, and optical properties of base composition glasses were investigated by XRD, DSC, NMR, Raman spectroscopy, and optical measurements. DSC results indicated that as the content of Al₂O₃ increased, the thermal stability of the glasses and glass-forming ability increased, as the 30La₂O₃-40TiO₂-25Nb₂O₅-5Al₂O₃ (Nb-Al-5) glass obtained the highest ΔT value (103.5°C). Structural analysis indicates that the proportion of [AlO₄] units increases gradually and participates in the glass network structure to increase connectivity, promoting more oxygen to become bridging oxygen and form [AlO₄] tetrahedral linkages to [TiO₅] and [NbO₆] groups. The refractive index values of amorphous glasses remained above 2.1 upon Al₂O₃ substitution, and a transmittance exceeding 65% in the visible and mid-infrared range. The crystallization activation energies of 30La₂O₃-40TiO₂-30Nb₂O₅ (Nb-Al-0) and Nb-Al-5 glasses were calculated to be 611.7 and 561.4 kJ/mol, and the Avrami parameters are 5.28 and 4.96, respectively. These results are useful to design new optical glass with good thermal stability, high refractive index and low wavelength dispersion for optical applications such as lenses, endoscopes, mini size lasers, and optical couplers.     

Hierarchical growth of BiOCl on SrO‐Bi2O3‐B2O3 glass‐ceramics for self‐cleaning applications

We have grown hierarchical structure of bismuth oxycloride (BiOCl) on SrO‐Bi₂O₃‐B₂O₃ (SBBO) transparent glass‐ceramic. SBBO glass‐ceramics were fabricated via conventional melt‐quenching technique while BiOCl was grown by etching the glass via HCl. Enhanced visible light driven photocatalytic activity and increasing hydrophobic feature were observed on BiOCl grown SBBO than as‐quenched SBBO glass‐ceramics. Contact angle analysis showed maximum contact angle of 130.7° on the surface of most BiOCl grown SBBO glass‐ceramic. Furthermore, under visible light illumination water contact angle decreased from 130.7° to 30.8°. Such photo‐induced hydrophilicity and catalytic performance in translucent glass‐ceramics lead self‐cleaning applications.     

Optical properties,thermal stability,and forming region of high refractive index La2O3–TiO2–Nb2O5 glasses

The high refractive index La₂O₃–TiO₂–Nb₂O₅ glasses were prepared by containerless processing, and the glass‐forming region was determined. The refractive index showed the range from 2.20 to 2.32, and the values were much higher than those of most optical glasses. The completely miscible 30LaO_3/2–(70?x)TiO₂–xNbO_5/2 (0 ≤ x ≤70) system was fabricated to study the compositional dependence of refractive index and optical transmittance. The crucial determinants of the refractive index of oxide glasses, oxygen molar volume, and electronic polarizability of oxygen ions were calculated. The principle of additivity of glass properties was suitable for the calculation of refractive index between glass and compositional oxides. All the glasses were colorless and transparent in the visible to 6.5 μm middle infrared (MIR) region. These results are useful for designing new optical glasses with high refractive index and low wavelength dispersion in wide optical window.     

In situ crystallization and elastic properties of transparent MgO–Al2O3–SiO2 glass‐ceramic

Glass‐ceramics (GC) generally possess enhanced mechanical properties compared to their parent glasses. The knowledge of how crystallization evolves and affects the mechanical properties with increasing temperature is essential to optimize the design of the crystallization cycle. In this study, we crystallized a glass of the MgO–Al₂O₃–SiO₂ system with nucleating agents TiO₂ and ZrO₂. The crystallization cycle comprised a 48 hour nucleation treatment at the glass‐transition temperature followed by a 10 hour growth step at a higher temperature. During this cycle, the evolution of crystalline phases was followed by high‐temperature X‐ray diffraction (HTXRD), which revealed the presence of karooite (MgO·2TiO₂), spinel (MgO·Al₂O₃), rutile (TiO₂), sillimanite (Al₂O₃·SiO₂), and sapphirine (4MgO·5Al₂O₃·2SiO₂). The same heat treatment was applied for in situ measurement of elastic properties: elastic modulus, E, shear modulus, G, and Poisson's ratio, ν. The evolution of these parameters during the heating path from room temperature to the final crystallization temperature and during the nucleation and the crystallization plateaus is discussed. E and G evolve significantly in the first two hours of the growth step. At the end of the crystallization process, the elastic and shear moduli of the GC were approximately 20% larger than those of the parent glass.     

Structural and emission properties of Eu3+‐doped alkaline earth zinc‐phosphate glasses for white LED applications

Quaternary alkaline earth zinc‐phosphate glasses in molar composition (40 ? x)ZnO – 35P₂O₅ – 20RO – 5TiO₂ – xEu₂O₃ (where x=1 and R=Mg, Ca, Sr, and Ba) were prepared by melt quenching technique. These glasses were studied with respect to their thermal, structural, and photoluminescent properties. The maximum value of the glass transition temperature (T_g) was observed for BaO network modifier mixed glass and minimum was observed for MgO network modifier glass. All the glasses were found to be amorphous in nature. The FT‐IR suggested the glasses to be in pyrophosphate structure, which matches with the theoretical estimation of O/P atomic ratio and the maximum depolymerization was observed for glass mixed with BaO network modifier. The intense emission peak was observed at 613 nm (⁵D₀→⁷F₂) under excitation of 392 nm, which matches well with excitation of commercial n‐UV LED chips. The highest emission intensity and quantum efficiency was observed for the glass mixed with BaO network modifier. Based on these results, another set of glass samples was prepared with molar composition (40 ? x)ZnO – 35P₂O₅ – 20BaO – 5TiO₂ – xEu₂O₃ (x=3, 5, 7, and 9) to investigate the optimized emission intensity in these glasses. The glasses exhibited crystalline features along with amorphous nature and a drastic variation in asymmetric ratio at higher concentration (7 and 9 mol%) of Eu₂O₃. The color of emission also shifted from red to reddish orange with increase in the concentration of Eu₂O₃. These glasses are potential candidates to use as a red photoluminsecent component in the field of solid‐state lighting devices.     

P2O5‐Fe2O3‐CaO‐SiO2 ferromagnetic glass‐ceramics for hyperthermia

Ferromagnetic glass‐ceramics are an important kind of thermoseed material for hyperthermia treatments. In order to investigate the applications of glass‐ceramics in magnetic hyperthermia, P₂O₅‐Fe₂O₃‐CaO‐SiO₂ (PFCS) glass‐ceramics with different compositions were prepared by the sol‐gel method. The crystal phase, magnetic properties, induction heating ability, and cytotoxicity of the as‐prepared glass‐ceramics were investigated. The results show that all the samples exhibit low cytotoxicity and good induction heating ability. Moreover, it was found that the phosphorus content affected the crystal phase component of the sample, and thus influenced the induction heating ability. Results of the magnetic hyperthermia experiments showed that the PFCS glass‐ceramic samples induced significant cell death of the LoVo cancer cells. The highest cell death rate for sample B2P7 was more than 95%, which suggests good application prospects in the field of hyperthermia therapy.     

Effects of Nd Content on Structure and Chemical Durability of Zirconolite–Barium Borosilicate Glass‐Ceramics

The effects of Nd₂O₃ content (0–12 wt %) on crystalline phases, microstructure, and chemical durability of barium borosilicate glass‐ceramics belonging to SiO₂–B₂O₃–Na₂O–BaO–CaO–TiO₂–ZrO₂–Nd₂O₃ system were studied. The results show that the glass‐ceramics with 2–6 wt% of Nd₂O₃ possess mainly zirconolite and titanite phases along with a small amount baddeleyite phase in the bulk. Calcium titanate appears when the Nd₂O₃ content increases to 8 wt%, and the amount of quadrate calcium titanate crystals increases with further increasing content of Nd₂O₃. For the glass‐ceramics with 6 wt% Nd₂O₃ (Nd‐6), Nd elements homogeneously distribute in zirconolite, titanite, and residual glass phases. There is a strong enrichment of Nd in calcium titanate crystals for the sample with 10 wt% Nd₂O₃. The viscosity of Nd‐6 glass is about 49 dPa·s at 1150°C. Moreover, Nd‐6 glass‐ceramics show the lower normalized leaching rates of B (LR_B), Ca (LR_Ca), and Nd (LR_Nd) when compared to that of the sample with 8 wt% Nd₂O₃. After 42 days, LR_B, LR_Ca, and LR_Nd of the Nd‐6 glass‐ceramics are about 6.8 × 10^?3, 1.6 × 10^?3, and 4.4 × 10^?6 g·m^?2·d^?1, respectively.     

Crystallization Kinetics of Superionic Conductive Al(B,La)‐ Incorporated LiTi2(PO4)3 Glass‐Ceramics

For the purpose of developing high‐performance glass‐ceramic superionic conductor, the controllable precipitation of LiTi₂(PO₄)₃‐like superionic conducting phase in the Li₂O–TiO₂–P₂O₅ glass system was studied. Al with B or La co‐incorporated LiTi₂(PO₄)₃‐based glass‐ceramics were prepared by the crystallization of the corresponding original glasses. Compared with the sole Al‐incorporated LiTi₂(PO₄)₃‐based glass‐ceramics, the ionic conductivity shows an increase for the boron co‐incorporated one and a decrease for the lanthanum co‐incorporated one. Through the further in‐depth analysis based on the methods of DSC and X‐ray diffractive technique, this opposite change in ion conductivity was ascribed to the alterations of crystallization mechanism together with quantity of crystal phases within the glass‐ceramics.. The boron addition promoted the precipitation of LiTi₂(PO₄)₃ phase and restrained the precipitation of second phase. The highest ionic conductivity 1.3 × 10^?3 S/cm at 25°C was obtained through the heat treatment of B and Al co‐incorporated glassy samples at 900°C for 12 h. These inorganic solid electrolytes have a potential application in lithium batteries or other electrochemical ionic devices.     

Rare‐earth‐doped SiO2‐CaF2 glass ceramic nano‐particle with upconversion properties

Rare‐earth‐doped upconversion nano‐phosphor shows new possibilities in the field of bioimaging because of its unique properties like higher penetration depth, low signal to noise ratio (SNR), good photo stability, and zero auto fluorescence. The oxyfluoride glass system is the combination of both fluoride and oxide where fluoride host offers high optical transparency due to low phonon energy and oxide network offers high physical stability. Thus, in the present work, an attempt has been made to synthesize 1 mol% Er³⁺ doped SiO₂‐CaF₂ glass ceramic nano‐particles through sol‐gel route. The synthesized glass ceramic particles were heat treated at 4 different temperatures starting from 600°C to 900°C.The X‐ray diffraction (XRD) analysis and Transmission electron microscopy (TEM) analysis confirmed the formation of CaF₂ nano‐crystals in the matrix which is 20‐30 nm in size. The vibrational spectroscopic analysis of the glass ceramics sample has been investigated by Fourier transform infrared (FTIR) spectroscopy. The UV‐Visible‐NIR spectroscopy analysis was carried out to analyze the absorption intensity in the near infrared region. Upon 980 nm excitation, the sample shows red emission corresponds to ⁴F_9/2→⁴I_15/2 energy level transition. The prepared nano‐particles showed excellent biocompatibility when tasted on MG‐63 osteoblast cells.     

Microwave dielectric properties of SnO‐SnF2‐P2O5 glass and its composite with alumina for ULTCC applications

Ultralow‐temperature sinterable alumina‐45SnF₂:25SnO:30P₂O₅ glass (Al₂O₃‐SSP glass) composite has been developed for microelectronic applications. The 45SnF₂:25SnO:30P₂O₅ glass prepared by melt quenching from 450°C has a low T_g of about 93°C. The SSP glass has ε_r and tanδ of 20 and 0.007, respectively, at 1 MHz. In the microwave frequency range, it has ε_r=16 and Q_u × f=990 GHz with τ_f=?290 ppm/°C at 6.2 GHz with coefficient of thermal expansion (CTE) value of 17.8 ppm/°C. A 30 wt.% Al₂O₃ ‐ 70 wt.% SSP composite was prepared by sintering at different temperatures from 150°C to 400°C. The crystalline phases and dielectric properties vary with sintering temperature. The alumina‐SSP composite sintered at 200°C has ε_r=5.41 with a tanδ of 0.01 (1 MHz) and at microwave frequencies it has ε_r=5.20 at 11 GHz with Q_u × f=5500 GHz with temperature coefficient of resonant frequency (τ_f)=?18 ppm/°C. The CTE and room‐temperature thermal conductivity of the composite sintered at 200°C are 8.7 ppm/°C and 0.47 W/m/K, respectively. The new composite has a low sintering temperature and is a possible candidate for ultralow‐temperature cofired ceramics applications.     

High lithium ionic conductivity in the garnet‐type oxide Li7−2xLa3Zr2−xMoxO12 (x=0‐0.3) ceramics by sol‐gel method

Lithium garnet‐type oxides Li_7?2xLa₃Zr_2?xMo_xO₁₂ (x=0, 0.1, 0.2, 0.3) ceramics were prepared by a sol‐gel method. The influence of molybdenum on the structure, microstructure and conductivity of Li₇La₃Zr₂O₁₂ were investigated by X‐ray diffraction, scanning electron microscopy, and impedance spectroscopy. The cubic phase Li₇La₃Zr₂O₁₂ has been stabilized by partial substitution of Mo for Zr at low temperature. The introduction of Mo (x≥0.1) can accelerate densification. Li_6.6La₃Zr_1.8Mo_0.2O₁₂ sintered at lower temperature 1100°C for 3 hours exhibits highest total ionic conductivity of 5.09 × 10^?4 S/cm. Results indicate that the Mo doping LLZO synthesized by sol‐gel method effectively lowers its sintering temperature and improves the ionic conductivity.     

Glass Formation and Characterization Studies in the TeO2–WO3–Na2O System

Glass formation behavior of the TeO₂–WO₃–Na₂O system was studied by using conventional melt‐quenching technique. A wide glass formation range was determined for the first time in the literature and thermal, physical, and structural characterization of sodium‐tungsten‐tellurite glasses were realized using differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy techniques. Glass transition (T_g) and crystallization (T_c/T_p) temperatures, glass stability (?T), density (ρ), molar volume (V_M), oxygen molar volume (V_O), and oxygen packing density (OPD) values and structural transformations in the glass network were investigated according to the equimolar substitution of TeO₂ by Na₂O+WO₃ and changing Na₂O or WO₃ at constant TeO₂.     

High niobium oxide content in germanate glasses: Thermal,structural, and optical properties

Niobium alkali germanate glasses were synthesized by the melt‐quenching technique. The ternary system (90‐x)GeO₂–xNb₂O₅–10K₂O forms homogeneous glasses with x ranging from 0 to 20 mol%. Samples were investigated by DSC and XRD analysis, FTIR and Raman spectroscopy, and optical absorption. Structural and physical features are discussed in terms of Nb₂O₅ content. The niobium content increase in the glass network strongly modifies the thermal, structural and optical properties of alkali germanate glasses. DSC, Raman and FTIR analysis suggest niobium addition promotes NbO₆ groups insertion close to GeO₄ units of the glass network. XRD analysis also pointed out that samples containing high niobium oxide contents exhibit preferential niobium oxide‐rich phase after crystallization after heat treatment, which is similar to orthorhombic Nb₂O₅. Absorption spectra revealed high transmission range between 400 nm to 6.2 μm, added to a considerably decreased hydroxyl group content as the addition of niobium in the alkali germanate network. The niobium oxide‐rich phase crystallization process was studied and activation energy was determined, as well as nucleation and crystal growth temperatures and time for obtaining transparent glass‐ceramics.     

Crystallization,mechanical, and optical properties of transparent,nanocrystalline gahnite glass‐ceramics

This paper describes the preparation of a transparent glass‐ceramic from the SiO₂‐K₂O‐ZnO‐Al₂O₃‐TiO₂ system containing a single crystalline phase, gahnite (ZnAl₂O₄). TiO₂ was used as a nucleating agent for the heat‐induced precipitation of gahnite crystals of 5‐10 nm. The evolution of the ZnAl₂O₄ spinel structure through the gradual formation of Al‐O bonds was examined by infrared spectroscopy. The dark brown color of the transparent precursor glass and glass‐ceramic was eliminated using CeO₂. The increase in transparency of the CeO₂‐doped glass and glass‐ceramics was demonstrated by UV‐visible absorption spectroscopy. EPR measurements confirmed the presence of Ce³⁺ ions, indicating that CeO₂ was effective in eliminating the brown color introduced by Ti³⁺ ions via oxidation to Ti⁺⁴. The hardness of the glass‐ceramic was 30% higher than that of the as‐prepared glasses. This work offers key guidelines to produce hard, transparent glass‐ceramics which may be potential candidates for a variety of technological applications, such as armor and display panels.     

Synthesis and characterization of a titanium phosphate-tellurite glass for Faraday rotators

This work is focused on investigation of thermal, structural, optical, magnetic, and magneto-optical properties of novel titanium phosphate-tellurite glass applied as Faraday rotators. The glass belonging to the system 35Li₂O–10Al₂O₃–5TiO₂–45P₂O₅–5TeO₂ was prepared by a nonconventional wet route of raw materials processing, followed by melting-quenching-annealing steps. Some important physical properties of the investigated glass have been measured and calculated, providing knowledge related to glass compactness, electronic structure, glass forming capability, etc. XRD analysis evidenced an amorphous network structure of the investigated glass. The optical absorption in the Vis domain is mainly due to Ti³⁺ ions and Te₂ clusters formed during the glass melting process. A relatively low optical absorption is noticed over 600 nm that activates a significant Faraday magneto-optical effect. Photoluminescence bands in the blue, red, and infrared domains are observed, caused by Te₂ clusters formed during the glass melting process. The magnetization in dependency on applied magnetic field reveals a complex behavior of the glass, depending on temperature. Thus, it is found a ferromagnetic behavior up to 2000 Oe, a paramagnetic component up to 40 000 Oe, followed by a diamagnetic one over 40 000 Oe. Faraday rotation angle and Verdet constant values in the visible domain are correlated with the reduced TeO₂ content of the glass.     

Temperature stability and electrical properties in La‐doped KNN‐based ceramics

To improve the temperature stability and electrical properties of KNN‐based ceramics, we simultaneously consider the phase boundary and the addition of rare earth element (La), 0.96K_0.5Na_0.5Nb_0.96Sb_0.04O₃‐0.04(Bi_1‐xLa_x)_0.5Na_0.5ZrO₃ (0 ≤ x ≤ 1.0) ceramics. More specifically, we investigate how the phase boundary and the addition of La³⁺ affect the phase structure, electrical properties, and temperature stability of the ceramic. We show that increasing the La³⁺ content leads to a change in phase structure, from a rhombohedral‐tetragonal (R‐T) phase coexistence to a cubic phase. More importantly, we show that the appropriate addition of La³⁺ (x = 0.2) can simultaneously improve the unipolar strain (from 0.127% to 0.147%) and the temperature stability (i.e., the unipolar strain of 0.147% remains unchanged when T is increased from 25 to 80°C). In addition, we find that the ceramics with x = 0.2 exhibit a large piezoelectric constant (d₃₃) of ~430 pC/N, a high Curie temperature (T_C) of ~240°C and a fatigue‐free behavior (after 10⁶ electric cycles). The enhanced electrical properties mostly originate from the easy domain switching, whereas the improved temperature stability can be attributed to the R‐T phase boundary and the appropriate addition of La³⁺.     

Polyamides obtained by direct polycondesation of 4‐[4‐[9‐[4‐(4‐aminophenoxy)‐3‐methyl‐phenyl] fluoren‐9‐YL]‐2‐methyl‐phenoxy]aniline with dicarboxylic acids based on a diphenyl‐silane moiety

Polyamides (PAs) containing fluorene, oxyether, and diphenyl‐silane moieties in the repeating unit were synthesized in > 85% yield by direct polycondesation between a diamine and four dicarboxylic acids. Alternatively, one PA was synthesized from an acid dichloride. The diamine 4‐[4‐[9‐[4‐(4‐aminophenoxy)‐3‐methyl‐phenyl]fluoren‐9‐yl]‐2‐methyl‐phenoxy]aniline ( 3 ) was obtained from the corresponding dinitro compound, which was synthesized by nucleophilic aromatic halogen displacement from p‐chloronitrobenzene and 9,9‐bis (4‐hydroxy‐3‐methyl‐phenyl)fluorene ( 1 ). Monomers and polymers were characterized by FTIR and ¹H, ¹³C, and ²⁹Si‐NMR spectroscopy and the results were in agreement with the proposed structures. PAs showed inherent viscosity values between 0.14 and 0.43 dL/g, indicative of low molecular weight species, probably of oligomeric nature. The glass transition temperature (T_g) values were observed in the 188–211°C range by DSC analysis. Thermal decomposition temperature (TDT_10%) values were above 400°C due to the presence of the aromatic rings in the diamine. All PAs showed good transparency in the visible region (>88% at 400 nm) due to the incorporation of the fluorene moiety. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Understanding the structural origin of crystalline phase transformations in nepheline (NaAlSiO4)‐based glass‐ceramics

Nepheline (Na₆K₂Al₈Si₈O₃₂) is a rock‐forming tectosilicate mineral which is by far the most abundant of the feldspathoids. The crystallization in nepheline‐based glass‐ceramics proceeds through several polymorphic transformations — mainly orthorhombic, hexagonal, cubic — depending on their thermochemistry. However, the fundamental science governing these transformations is poorly understood. In this article, an attempt has been made to elucidate the structural drivers controlling these polymorphic transformations in nepheline‐based glass‐ceramics. Accordingly, two different sets of glasses (meta‐aluminous and per‐alkaline) have been designed in the system Na₂O–CaO–Al₂O₃–SiO₂ in the crystallization field of nepheline and synthesized by the melt‐quench technique. The detailed structural analysis of glasses has been performed by ²⁹Si, ²⁷Al, and ²³Na magic‐angle spinning — nuclear magnetic resonance (MAS NMR), and multiple‐quantum MAS NMR spectroscopy, while the crystalline phase transformations in these glasses have been studied under isothermal and non‐isothermal conditions using differential scanning calorimetry (DSC), X‐ray diffraction (XRD), and MQMAS NMR. Results indicate that the sequence of polymorphic phase transformations in these glass‐ceramics is dictated by the compositional chemistry of the parent glasses and the local environments of different species in the glass structure; for example, the sodium environment in glasses became highly ordered with decreasing Na₂O/CaO ratio, thus favoring the formation of hexagonal nepheline, while the cubic polymorph was the stable phase in SiO₂–poor glass‐ceramics with (Na₂O+CaO)/Al₂O₃ > 1. The structural origins of these crystalline phase transformations have been discussed in the paper.     

New calcium‐free Na2O–Al2O3–P2O5 bioactive glasses with potential applications in bone tissue engineering

Sodium aluminophosphate glasses were evaluated for their bone repair ability. The glasses belonging to the system 45Na₂O–xAl₂O₃‐(55‐x)P₂O₅, with x = (3, 5, 7, 10 mol%) were prepared by a melt‐quenching method. We assessed the effect of Al₂O₃ content on the properties of Na₂O–Al₂O₃–P₂O₅ (NAP) glasses, which were characterized by density measurements, DSC analyses, solubility, bioactivity in simulated body fluid and cytocompatibility with MG‐63 cells. To the best of our knowledge, this is the first investigation of calcium‐free Na₂O–Al₂O₃–P₂O₅ system glasses as bioactive materials for bone tissue engineering.