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1. The dual role of bismuth in Li 2 O–Bi 2 O 3 –B 2 O 3 glasses along the orthoborate join

   https://doi.org/10.1111/jace.18699  

   Topper, Brian ; Tsekrekas, Elizabeth M. ; Greiner, Lucas ; Youngman, Randall E. ; Kamitsos, Efstratios I. ; Möncke, Doris ( August 2022 , Journal of the American Ceramic Society)

   The structures of glasses in the lithium–bismuth orthoborate composition range deviate significantly from the short‐range order structure of the two crystalline end‐members. Although binary Li₃BO₃and BiBO₃are solely of comprised trigonal orthoborate anions, all glasses formed by their combination contain four‐coordinated borate tetrahedra. We analyze the structure of (75−1.5x)Li₂O–xBi₂O₃–(25+0.5x)B₂O₃glasses in increments ofx = 5, with¹¹B magic‐angle spinning nuclear magnetic resonance (NMR), infrared (IR), and Raman spectroscopy. For the full series, the oxygen‐to‐boron ratio remains constant at O/B = 3:1. NMR quantifies an increase in the fraction of tetrahedral boron with increasing bismuth oxide content. Evolution of the mid‐IR profile suggests multiple types of tetrahedral boron sites. Raman spectroscopy reveals that Bi₂O₃tends to cluster within the lithium borate matrix when initially introduced and that this behavior transforms into a bismuthate network with increasing bismuth oxide content. In all cases, mixed Bi–O–B linkages are observed. The dual role of bismuth as network modifier and network former is likewise observed in the far IR. The glass transition temperature continuously increases with bismuth oxide content; however, the glass stability displays a maximum in the multicomponent glass ofx = 40.

    

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2. Characterization of 20Na 2 O·30((1− x )CaO· x SrO)·50P 2 O 5 glasses for a resorbable optical fiber application

   https://doi.org/10.1111/ijag.13106  

   Freudenberger, Parker T. ; Saitoh, Akira ; Ikeda, Hikaru ; Adnan, Md Shihab ; Takebe, Hiromichi ; Nakane, Shingo ; Kim, Chang‐Soo ; Brow, Richard K. ( March 2019 , International Journal of Applied Glass Science)

   Resorbable glasses with nominal molar compositions of 20Na₂O·30[(1−x)CaO·xSrO]∙50P₂O₅, wherex = 0, 0.25, 0.50, 0.75, and 1, were prepared and characterized. With the replacement of CaO by SrO, the molar volume, refractive index, and coefficient of thermal expansion increased, and the glass transition temperature, crystallization temperature, and viscosity decreased. The replacement of CaO by SrO decreased the dissolution rate in 37°C water by nearly an order of magnitude. Resorbable glass fibers drawn from melts of the 20Na₂O·30CaO·50P₂O₅glass exhibited decreasing transmission of laser light (632 nm) in a predictable way as the fiber dissolved in a phosphate buffer solution. This demonstrated that these glasses could be used to produce resorbable fibers for temporary biosensing or therapeutic applications.

    

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3. Structure‐mechanical properties correlation in bulk LiPON glass produced by nitridation of metaphosphate melts

   https://doi.org/10.1111/jace.19327  

   Torres, III, Victor M. ; Kalnaus, Sergiy ; Martin, Steve W. ; Duggan, Caitlin ; Westover, Andrew S. ( July 2023 , Journal of the American Ceramic Society)

   The glassy solid electrolyte Lithium phosphorous oxynitride (LiPON) has been widely researched in thin film solid state battery format due to its outstanding stability when cycled against lithium. In addition, recent reports show thin film LiPON having interesting mechanical behaviors, especially its ability to resist micro‐scale cracking via densification and shear flow. In the present study, we have produced bulk LiPON glasses with varying nitrogen contents by ammonolysis of LiPO₃melts. The resulting compositions were determined to be LiPO_3‐3z/2N_z, where 0 ≤ z ≤ 0.75, and the z value of 0.75 is among the highest ever reported for this series of LiPON glasses. The short‐range order structures of the different resulting compositions were characterized by infrared, Raman,³¹P magic angle spinning nuclear magnetic resonance, and X‐ray photoelectron spectroscopies. Instrumented nano‐indentation was used to measure mechanical properties. It was observed that similar to previous studies, both trigonally coordinated (N_t) and doubly bonded (N_d) N co‐exist in the glasses in about the same amounts forz ≤ 0.36, the limit of N content in most previous studies. For glasses withz > 0.36, it was found that the fraction of the N_tincreased significantly while the fraction of N_dcorrespondingly decreased. The incorporation of nitrogen increased both the elastic modulus and hardness of the glass by approximately a factor of 1.5 when N/P ratio reaches 0.75. At the same time, an apparent embrittlement of the glass was observed due to nitridation, which was revealed by nanoindentation with an extra sharp nanoindenter tip.

    

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4. Comparing Pr 3+ and Nd 3+ for deactivating the Er 3+ :  4 I 13/2 level in lanthanum titanate glass

   https://doi.org/10.1364/OME.517790  

   Topper, Brian ; Neumann, Alexander ; Wilke, Stephen K. ; Youngman, Randall E. ; Alrubkhi, Abdulrahman ; Weber, Richard ( April 2024 , Optical Materials Express)

   Erbium lanthanum titanate glasses were prepared by levitation melting for the spectroscopic study of ways to promote the mid-infrared fluorescence. Two series of heavily erbium doped glasses (15 wt%) were prepared with the addition of either Pr³⁺or Nd³⁺in amounts relative to Er³⁺of 0.05, 0.1, and 0.2. Both ions quench the lower Er³⁺laser level with the Pr³⁺doing so more rapidly. Although high co-dopant concentrations result in higher energy transfer, as clearly evidenced in upconversion and downconversion fluorescence measurements, the mid-infrared lifetime also suffers a reduction and, therefore, a balance must be struck in the co-dopant concentration. Lifetime and spectral measurements indicate that, at a fixed relative co-dopant amount, Pr³⁺is more effective than Nd³⁺at removing the bottleneck of the Er^3+ 4I_13/2level. Moreover, consideration of the lifetimes alongside the absorption data of the individual ions indicates that despite the large absorption cross-section of Nd³⁺at 808 nm, the concentration needed to yield more absorbed power than utilizing direct 976 nm excitation of Er³⁺results in unfavorable lifetimes of the mid-infrared transition. In the end, Pr³⁺prevails as the superior co-dopant in terms of the effects on fluorescence lifetimes as well as potential laser system design considerations. In a unique self-doping approach, a reducing melt atmosphere of Ar instead of O₂creates a small fraction of Ti³⁺. In 5Er₂O₃-12La₂O₃-83TiO₂glass, the presence of Ti³⁺quenches the⁴I_13/2emission about 2.6 times more than the⁴I_11/2when lifetimes are compared to an O₂melt environment. As an additional means of increasing the mid-infrared emission, the effect of temperature on the mid- and near- infrared lifetimes of a lightly doped lanthanum titanate composition is investigated between 77-300 K. The mid-infrared lifetime increases by ∼30% while the near-infrared lifetime increases by ∼10%, which suggests in addition to co-doping, active cooling of the gain media will further enhance performance.

    

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5. New minerals in type A inclusions from Allende and clues to processes in the early solar system: Paqueite, Ca 3 TiSi 2 (Al,Ti,Si) 3 O 14 , and burnettite, CaVAlSiO 6

   https://doi.org/10.1111/maps.13826  

   Ma, Chi ; Beckett, John R. ; Tissot, François L. H. ; Rossman, George R. ( May 2022 , Meteoritics & Planetary Science)

   Paqueite (Ca₃TiSi₂[Al,Ti,Si]₃O₁₄; IMA 2013‐053) and burnettite (CaVAlSiO₆; IMA 2013‐054) are new refractory minerals, occurring as euhedral to subhedral crystals within aluminous melilite in A‐WP1, a type A Ca‐Al‐rich inclusion, andCGft‐12, a compact type A (CTA) from the Allende CV3 carbonaceous chondrite. Type paqueite from A‐WP1 has an empirical formula of (Ca_2.91Na_0.11)Ti⁴⁺Si₂(Al_1.64Ti⁴⁺_0.90Si_0.24V³⁺_0.12Sc_0.07Mg_0.03)O₁₄, with a trigonal structure in space groupP321 and cell parametersa = 7.943 Å,c = 4.930 Å, V = 269.37 ų, andZ = 1. Paqueite’s general formula is Ca₃TiSi₂(Al,Ti,Si)₃O₁₄and the endmember formula is Ca₃TiSi₂(Al₂Ti)O₁₄. Type burnettite fromCGft‐12has an empirical formula of Ca_1.01(V³⁺_0.56Al_0.25Mg_0.18)(Si_1.19Al_0.81)O₆. It assumes a diopside‐typeC2/cstructure witha = 9.80 Å,b = 8.85 Å,c = 5.36 Å, β = 105.6°,V = 447.7 ų, andZ = 4. Burnettite’s general formula is Ca(V,Al,Mg)AlSiO₆and the endmember formula is CaVAlSiO₆. Paqueite and burnettite likely originated as condensates, but the observed grains may have crystallized from local V‐rich melts produced during a later thermal event. ForCGft‐12, the compositions of paqueite, clinopyroxene, and perovskite suggest that type As drew from two distinct populations of grains. Hibonite grains drew from multiple populations, but these were well mixed and not equilibrated prior to incorporation into type A host melilite.

    

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