Borophosphosilicate Glasses Research Articles

Correlations of structural, thermal and electrical properties of sodium doped complex borophosphosilicate glass

Borophosphosilicate glasses with varying sodium ion concentrations were investigated for their, structural, thermal, and electrical properties. All the obtained glasses were transparent except the glass with the highest sodium content, which exhibited translucency due to inhomogeneities. Increasing sodium content led to reduced boron and silicon content while maintaining a constant B/Si ratio, indicating progressive depolymerization of the glass network. Confocal microscopy, scanning electron microscopy, and atomic force microscopy showed homogeneous and granular structure for samples with lower sodium content, but higher sodium content resulted in visible agglomeration/nanocrystallization. X-ray diffractograms showed amorphous nature for most samples, with samples doped with the highest concentrations of Na2O showing several broad reflections suggesting nanoscale crystallinity. Fourier-transform infrared spectroscopy revealed shifts in dominant bands with increasing sodium content, indicating depolymerization of the borate network. An observed decrease in glass transition temperature and thermal stability with increasing sodium content was attributed to depolymerization and formation of non-bridging oxygens. Impedance spectroscopy revealed two relaxation processes associated with the transport of Na+ ions through two different regions. DC conductivity and activation energy predominantly increased with the sodium ion content at high temperatures.

Impact of TiO2 on DTA and Elastic Moduli of Calcium Potassium Borophosphosilicate Glasses in Prelude for Use in Dental and Orthopedic Applications

Impact of TiO2 on DTA and Elastic Moduli of Calcium Potassium Borophosphosilicate Glasses in Prelude for Use in Dental and Orthopedic Applications

Evaluation of the dynamic behavior, elastic properties, and in vitro bioactivity of some borophosphosilicate glasses for orthopedic applications

The present work employed the finite element model (FEM) to predict the influence of successive increases in borate (B2O3) contents, from 0 to 25 mol%, on mechanical properties and dynamic behavior. By feeding the isotropic elasticity characteristics of the phosphosilicate glass to the model, such as Young's modulus, density, and maximum compressive stress of the produced glass samples to fit the aim of their clinical use. The effect of successive addition of B2O3 on the in vitro bioactivity of the examined glasses in addition to examined after being dipped in simulated body fluid (SBF) at different times. Moreover, tracking the formation of hydroxyapatite (HA)-like layers on their surfaces using X-ray diffraction technique (XRD) technique and scanning electron microscopy (SEM). The results obtained indicated that increasing B2O3 content to 25% was responsible for improving the deflect resistance by 39%.On the other hand, neither shear stress nor principles stress was affected by this increase in B2O3 content. Moreover, the gradual increases in B2O3 contents were very helpful in improving the bioactivity of the samples. The prepared glasses can be successfully used in bone replacement applications from these promising results.

Structural Role of Sodium in Borosilicate, Phosphosilicate, and Borophosphosilicate Glasses Unveiled by Solid-State NMR and MD Simulations

We present a comprehensive study of the Na environments in a large ensemble of 32 silicate-based glass compositions from the borosilicate, phosphosilicate, and borophosphosilicate systems, which co...

Medium-Range Structural Organization of Phosphorus-Bearing Borosilicate Glasses Revealed by Advanced Solid-State NMR Experiments and MD Simulations: Consequences of B/Si Substitutions.

The short and intermediate range structures of a large series of bioactive borophosphosilicate (BPS) glasses were probed by solid-state nuclear magnetic resonance (NMR) spectroscopy and atomistic molecular dynamics (MD) simulations. Two BPS glass series were designed by gradually substituting SiO2 by B2O3 in the respective phosphosilicate base compositions 24.1Na2O-23.3CaO-48.6SiO2-4.0P2O5 ("S49") and 24.6Na2O-26.7CaO-46.1SiO2-2.6P2O5 ("S46"), the latter constituting the "45S5 Bioglass" utilized for bone grafting applications. The BPS glass networks are built by interconnected SiO4, BO4, and BO3 moieties, whereas P exists mainly as orthophosphate anions, except for a minor network-associated portion involving P-O-Si and P-O-B[4] motifs, whose populations were estimated by heteronuclear 31P{11B} NMR experimentation. The high Na+/Ca2+ contents give fragmented glass networks with large amounts of nonbridging oxygen (NBO) anions. The MD-generated glass models reveal an increasing propensity for NBO accommodation among the network units according to BO4 < SiO4 < BO3 ≪ PO4. The BO4/BO3 intermixing was examined by double-quantum-single-quantum correlation 11B NMR experiments, which evidenced the presence of all three BO3-BO3, BO3-BO4, and BO4-BO4 connectivities, with B[3]-O-B[4] bridges dominating. Notwithstanding that B[4]-O-B[4] linkages are disfavored, both NMR spectroscopy and MD simulations established their presence in these modifier-rich BPS glasses, along with non-negligible B[4]-NBO contacts, at odds with the conventional structural view of borosilicate glasses. We discuss the relative propensities for intermixing of the Si/B/P network formers. Despite the absence of pronounced preferences for Si-O-Si bond formation, the glass models manifest subtle subnanometer-sized structural inhomogeneities, where SiO4 tetrahedra tend to self-associate into small chain/ring motifs embedded in BO3/BO4-dominated domains.

Structure–composition relationships of bioactive borophosphosilicate glasses probed by multinuclear11B,29Si, and31P solid state NMR

By combining11B,29Si, and31P nuclear magnetic resonance (NMR) experimental results, we present the first comprehensive structural investigation of 15 borophosphosilicate (BPS) glasses of the Na2O–CaO–B2O3–SiO2–P2O5system.

Growth of novel boron-rich nanocrystals from oxygen-deficient borophosphosilicate glasses for boron neutron capture therapy

We develop a new type of boron-rich nanocrystals, which are dispersible in water and exhibit photoluminescence in the biological window, can be a multifunctional biomaterial used for imaging, diagnosis and boron neutron capture therapy.

Effects of SrO/ZnO on structure and properties of UV-transmitting borophosphosilicate glass

UV-transmitting borophosphosilicate glasses series, 2Al 2O 3− xSrO–(18− x)ZnO-33.3P 2O 5–16.7B 2O 3–30SiO 2 glasses with x=0–18 mol% were prepared and studied. The substitution of SrO for ZnO increases the density and the thermal expansion coefficient ( α), but decreases the molar volume ( V m ). The glass transition temperatures ( T g ) and softening points ( T d ) vary within a small range. The relative chemical durability was determined by measuring the weight loss of a polished glass sample after immersion in deionized water at 50 °C for 24 h, the chemical durability of the glasses increases when x≤9, and drops when x>9. With the increasing SrO content, the UV transmittance of the glasses decreases mildly. The compositional dependence of E opt shows a decrease trend with increasing SrO content. The structural changes with the glass compositions were examined by FT-IR and Raman spectra.

Stability of Luminescent Trivalent Cerium in Silica Host Glasses Modified by Boron and Phosphorus

Ce-doped borosilicate (BSG), phosphosilicate (PSG), and borophosphosilicate (BPSG) glasses (B:P:Si molar ratios 8:0:92, 0:8:92, and 8:8:84; Ce:Si molar ratio 1 x 10(-)(4) to 1 x 10(-)(2)) were prepared by the sol-gel method. High-resolution transmission electron microscopy (HRTEM), (31)P, (29)Si, and (11)B magic angle spinning nuclear magnetic resonance (MAS NMR), electron paramagnetic resonance (EPR), and UV-vis absorption investigations demonstrated that, in PSG and BPSG, Ce(3+) ions interact with phosphoryl, [O=PO(3/2)], metaphosphate, [O=PO(2/ 2)O](-), and pyrophosphate, [O=PO(1/2)O(2)](2)(-), groups, linked to a silica network. This inhibits both CeO(2) segregation and oxidation of isolated Ce(3+) ions to Ce(4+), up to Ce:Si = 5 x 10(-)(3). In BSG, neither trigonal [BO(3/2)] nor tetrahedral [BO(4/2)](-) boron units coordinate cerium; thus, Ce(3+) oxidation occurs even at Ce:Si = 1 x 10(-)(4), as in pure silica glass (SG). The homogeneous rare-earth dispersion in the host matrix and the stabilization of the Ce(3+) oxidation state enhanced the intensity of the photoluminescence emission in PSG and BPSG with respect to BSG and SG. The energy of the Ce(3+) emission band in PSG and BPSG matrixes agrees with the phosphate environment of the rare earth.

On the structure of the BOHC in the borosilicate and borophosphosilicate glasses

This work gives the electronic structures and spectroscopic parameters of two defects proposed in literature that may account for the BOHC in borosilicate and borophosphosilicate glasses. The calculations of this study discard the early model, B–O –Si , for the BOHC identified first in the B 2O 3 · 3SiO 3 glass. The present calculations suggest the structure: B–O for the BOHC. This model agrees with up to date pulsed electron paramagnetic resonance (EPR) studies.

Metallization improvement on fabrication of interdigitated backside and double sided buried contact solar cells

Metallization based on electroless metal plating of nickel and copper is a simple, cost-effective process used in the fabrication of Buried Contact silicon solar cells. Whereas the electroless Ni–Cu metallization scheme works well for metal deposition on early Buried Contact solar cells, in which deposition was required only on phosphorus diffused contact regions, more care is required for advanced Buried Contact solar cell designs that require simultaneous deposition on to both phosphorus and boron diffused contact regions. In this paper, we examine two key issues related to the metallization in these solar cells. Firstly we demonstrate an improved buffered hydrofluoric acid etch process for simultaneous removal of borosilicate and borophosphosilicate glasses from the contact regions prior to electroless deposition of nickel with good etch selectivity against silicon dioxide masking films. Secondly, we demonstrate an improved process for nucleation of the nickel layer on both phosphorus and boron diffused contact areas based on immersion palladium chloride activation of the plating surfaces. N-type double-sided buried contact solar cells metallized by processing introduced in this study show improvement on absolute efficiency of more than 3%.

Composition/Structure Relationships in Monolithic Borophosphosilicate Glasses Obtained by the Sol−Gel Route

Monolithic borophosphosilicate glasses were prepared by the sol−gel route through xerogel densification. Tetramethoxysilane (Si(OCH3)4), trimethylborate (B(OCH3)3), and trimethyl phosphite (P(OCH3)3) were used as source compounds for Si, B, and P, respectively. After drying, samples underwent thermal treatment up to 700 °C with alternating flowing oxygen and reduced pressure steps, resulting in transparent, monolithic glasses. The sample chemical composition was analyzed by X-ray photoelectron spectroscopy (XPS). Densification was investigated by vibrational spectroscopies (FT-IR, micro-Raman). The boron oxygen hole centers (BOHC) and phosphorus oxygen hole centers (POHC) paramagnetic defects generated by X-ray irradiation of glasses were studied by electron paramagnetic resonance (EPR) spectroscopy. The results obtained on borophosphosilicate glasses showed that paramagnetic defects are not created by independent processes, as expected for randomly distributed noninteracting B and P doping elements. Diamagnetic precursors of BOHC and POHC are thus proposed to be spatially close together in the glasses.

Boron and Phosphorus Quantification in Sol-Gel BPSG Glasses by XPS

Monolithic borophosphosilicate glasses (BPSG) were prepared by the sol-gel route through xerogel densification. Tetramethoxysilane (Si(OCH3)4), trimethylborate (B(OCH3)3), and trimethylphosphite (P(OCH3)3) were used as source compounds for Si, B, and P, respectively. After gel drying, samples underwent thermal treatment up to 700 °C, resulting in transparent and crack-free monolithic glasses. In this work, x-ray photoelectron spectra of a representative glass specimen are presented and discussed. Beside the wide scan spectrum, a detailed analysis of Si 2p, O ls, P 2p, B 1s + P 2s is performed. Moreover, a quantification procedure aimed at resolving problems arising from the overlap between B 1s and P 2s photopeaks in oxide-based systems is proposed.

Coordination of boron and phosphorous in borophosphosilicate glasses

We report boron K-edge x-ray absorption near-edge structure measurements on borophosphosilicate glasses and density functional theory calculations aimed at determining the most stable local geometries for boron and phosphorous. We demonstrate that phosphorous induces a modification in the local structure of boron, from a trigonal to a tetrahedral geometry. The microscopic mechanisms involved are discussed.

Low polarization and low temperature reflow of inorganic borophosphosilicate glasses formed from organic sources

It has been markedly epoch-making that we should form inorganic borophosphosilicate glasses for use in ULSIs from organic sources. Reversible glass forming reactions are proposed, and low electronic polarizable and low temperature reflow glasses are newly found. They showed good dielectric planarizing and low delay time capability as required for the step coverage of multilevel interconnections in ULSIs. A possible device planarization and C– V (capacitance and voltage) properties in MOS capacitors are briefly discussed.

The spectroscopic studies of glasses in the BPO 4(GaPO 4)–SiO 2 system

FTIR spectroscopic structural studies of gel-derived glasses in BPO 4–SiO 2 and BPO 4(GaPO 4)–SiO 2 systems are presented. 10B isotope substitution, spectra subtraction procedure and B 3+→Ga 3+ substitution were applied to distinguish the bands, originating from B–O, P–O and Si–O bond vibrations. The spectra of borophosphosilicate glasses containing 10B isotope have also been presented. Changes in the band positions helped to assign bands due to the different B–O bonds vibrations. The spectra subtraction procedure, due to the lowering of intensity of bands assigned to Si–O bonds vibrations, enabled to observe bands at 966 and 1225 cm −1, due to broken Si–O − bridges and (PO 2) − terminal groups, respectively.

Effect of low-energy N2+ ion beam bombardment on silicate glass thin films studied by x-ray photoelectron spectroscopy

Thin film borophosphosilicate glasses, SiOxByPz, have been obtained by chemical vapor deposition on (100) Si substrates. The interaction of low-energy N2+ ions with these films has been studied by x-ray photoelectron spectroscopy (XPS) and infrared spectroscopy. Determination of the chemical composition of the borophosphosilicate glasses was done by qualitative and quantitative XPS analysis. The differences in composition between the films before and after the bombardment have been explained in terms of the relative thermodynamic stability of the compounds present in the sample.

Investigation of borophosphosilicate glasses synthesized by the sol-gel method

The synthesis of vitreous borophosphosilicate materials by the sol-gel method is investigated. The differential thermal analysis and IR spectroscopic studies of xerogels and vitreous materials prepared are carried out. The permittivity of the vitreous material at a frequency of 1 MHz, the dielectric loss tangent, and the linear thermal expansion coefficient in the temperature range 20–500°C are determined. The vitreous dielectric synthesized can be used for the interlayer insulation of silicon integrated circuits and the creation of “siliconon-insulator” structures.

Process-dependent thin-film thermal conductivities for thermal CMOS MEMS

The thermal conductivities /spl kappa/ of the dielectric and conducting thin films of three commercial CMOS processes were determined in the temperature range from 120 to 400 K. The measurements were performed using micromachined heatable test structures containing the layers to be characterized. The /spl kappa/ values of thermally grown silicon oxides are reduced from bulk fused silica by roughly 20%. The /spl kappa/ of phosphosilicate and borophosphosilicate glasses are 0.94/spl plusmn/0.08 W m/sup -1/ K/sup -1/ and 1.18/spl plusmn/0.06 W m/sup -1/ K/sup -1/, respectively, at 300 K. A plasma-enhanced chemical-vapor-deposition silicon-nitride layer has a thermal conductivity of 2.23/spl plusmn/0.12 W m/sup -1/ K/sup -1/ at 300 K. This value is between published data for atmospheric-pressure CVD and low-pressure CVD nitrides. For the metal layers, we found thermal conductivities between 167 W m/sup -1/ K/sup -1/ and 206 W m/sup -1/ K/sup -1/, respectively, at 300 K, to be compared with 238 W m/sup -1/ K/sup -1/ of bulk aluminum. The temperature-dependent product /spl kappa//spl rho/ of /spl kappa/ with the electrical resistivity /spl rho/ agrees better than 8.2% between 180-400 K with that of pure bulk aluminum. The /spl kappa/ values of the polysilicon layers are between 22.4 W m/sup -1/ K/sup -1/ and 37.3 W m/sup -1/ K/sup -1/ at 300 K. They are reduced from similarly doped bulk silicon by factors of between 2.0-1.3. The observed discrepancies between thin film and bulk data demonstrate the importance of determining the process-dependent thermal conductivities of CMOS thin films.

RELATIONSHIP BETWEEN ELECTRONIC MOLAR POLARIZABILITY AND SUPER LOW DIELECTRIC CONSTANT IN B 2O 3-BeF 2-C GLASS SYSTEMS

Low polarizability B 2O 3-BeF 2-C glass-systems were investigated in regard to the super low dielectric constant and dielectric loss. The experimental data showed that the low dielectric properties of these glasses are due to the low electronic molar polarizability calculated from Clausius–Mosotti's equation. They showed the super low dielectric constants ϵ ∞ 2.5 to 3.4, the dielectric loss tanδ 0.002–0.007 from 100 Hz to 1 GHz, the molar polarizability α m 43.5×10 −25 cm 3 to 64.2×10 −21 cm 3 and flow points T f 570–605°C. These glasses have the potential to reflow at lower temperature than borophosphosilicate glasses without crystallization during the process of device planarization. They are compatible with aluminum multilevel interconnection.