Structural, optical, and physical properties of glasses prepared by melt reduction in the mixed Sr−Mn metaphosphate system xMnO−(1 − x)SrO−P2O5, 0 ≤ x ≤ 1, have been investigated by vibrational, optical, EPR, and thermal techniques. Mn ions were found mostly in the +2 oxidation state and in sites of octahedral symmetry. Such sites are formed by neighboring Mn−oxygen polyhedra, where the covalent character of Mn−O bonding increases with cation mixing. The phosphate structure was found to consist predominantly of metaphosphate tetrahedral species (Q2) with a minority of pyrophosphate (Q1) and neutral (Q3) phosphate tetrahedra, whose relative abundance changes nonlinearly with MnO content. The symmetric stretching vibration of terminal PO2 − units in Q2 species was employed to probe the influence of mixed Sr/Mn environments on phosphate structure, and the results suggested a deviation from the homogeneous distribution of metal cations. This was attributed to the coordination numbers of Sr and Mn ions (i.e., 8 and 6, respectively) which exceed the available number of terminal oxygen atoms per metal ion, M (i.e., 4), and thus require the formation of neighboring M−oxygen polyhedra which are connected by P−O−M−O−M−O−P linkages. Nevertheless, each metal ion was found to form its own M−O site and to retain the identity of its site in both single and mixed cation glasses. While density and molar volume follow a linear decrease with MnO content, glass transition temperature T g, thermal expansion coefficient, refractive index, and optical dispersion exhibit clear deviations from additivity. The increasing trend of T g with cation mixing was attributed to a combination of the different cross-linking abilities by P−O−M−O−M−O−P bridges of the Sr and Mn ions with the relative proportion of metaphosphate Q2 units. The composition dependence of optical dispersion, as expressed by the Abbe number, was correlated with the average electronic band gap obtained from refractive-index dispersion data using the Wemple−DiDomenico single oscillator model. While all glasses in the Sr−Mn system were found to exhibit low optical dispersion, cation mixing was shown to increase dispersion because of increased covalency in Mn−O bonding.

Ionic conducting glasses in thin film forms are promising candidates for applications in microelectronics devices such as microbatteries and microsupercapacitors. In recent years, it was shown that physicochemical properties of thin films may differ substantially from those of the target bulk materials. Thus, it remains a challenge in science and thin film technology to control the properties of thin films in terms of chemical composition and conditions of manufacturing. This work presents a structural investigation of lithium−borate thin film electrolytes prepared by rf sputtering of Li−diborate targets. Chemically stable thin films ca. 1 μm thick were deposited on Si and gold-covered Si substrates under argon and their infrared spectra were measured in a broad spectral range (30−5000 cm-1). The spectra of thin films were modeled on the basis of rigorous expressions for reflectance and transmittance of the film/substrate bilayer system. The experimental results for thin films were compared with those simulated by using the optical response functions of bulk glasses xLi2O−(1−x)B2O3 (x = 0.33, 0.30, 0.275, 0.25), which were prepared by the conventional melt quenching technique. The comparison of experimental and simulated spectra showed that rf sputtering of Li−diborate targets (x = 0.33) leads to Li−borate thin films with lithium oxide content lower than that of the target material. Best agreement between experimental and simulated thin film spectra was obtained for x = 0.275, after proper annealing of thin films to remove differences in thermal history between thin film and bulk glass states.

Superionic glasses xCuI–(l – x)[Cu2MoO4–CuPO3] were prepared and studied by infrared reflectance spectroscopy to investigate the structure of the oxyanion matrix and the type of sites occupied by copper ions. The study was complemented by the consideration of glasses 0.67CuI–0.33[Cu2MoO4–Cu3PO4] and xCuI–(l – x)[Cu2O-nP2O5] with n = 0.33, 0.50, 1.0. The oxyanion structure of glasses xCuI–(l – x)[Cu2MoO4–CuPO3] was found to involve discrete PO4 3‑, P2O7 4‑ and MoO4 2‑ units, where P and Mo are 4-fold coordinated to oxygen, and molybdate octahedral species which have the MoO3 stoichiometry and are linked by Mo–O–Mo bridging bonds. Despite the nominal metaphosphate composition (CuPO3) of these glasses the spectra gave no signature for metaphosphate structures based on the PO3 – unit. Also, increasing amounts of CuI were found to favor the creation of PO4 3‑ and MoO3 species at the expense of P2O7 4‑ and MoO4 2‑. These findings were explained by the acidity order P2O5 > MoO3 and the need to accommodate the bulky CuI in the glassy matrix, a process facilitated by condensed MoO3 octahedral species. Cu ions were found to be present as monovalent cations and to occupy oxide and iodide sites. The latter sites organize into CuI-like pseudophases at high CuI contents, in agreement with the conduction pathway model for superionic glasses.

In this work, methods are presented for obtaining the real, n, and imaginary, k, parts of the complex refractive index of materials considered as semi-infinite and finite from infrared reflectance, R( ν), and/or transmittance, T( ν), spectra. In semi-infinite samples, with negligible T( ν), only R( ν) is measured, and n and k can derive from the Kramers–Kronig (K–K) transformation or the modeling of the dielectric function of the material. In finite samples, the interference fringes due to multiple internal reflections can significantly alter the measured spectra. It was demonstrated that whenever the period of the fringes is on the order of a few cm−1, n and k can be equivalently obtained by the extended K–K analysis for T( ν) spectra, the modeling of the dielectric function, and the inversion of low-resolution R( ν) and T( ν) spectra, as well as the acquisition of a single high-resolution R( ν) or T( ν) spectrum. Otherwise, n and k can be calculated by modeling the dielectric function of the material once the optical effects are carefully removed. These methods were applied in infrared measurements of crystalline Si wafer and of glassy 0.20AgI·0.80[Ag2O·2B2O3].