Increased strontium uptake in trabecular bone of ovariectomized calcium‐deficient rats treated with strontium ranelate or strontium chloride

Based on clinical trials showing the efficacy to reduce vertebral and non‐vertebral fractures, strontium ranelate (SrR) has been approved in several countries for the treatment of postmenopausal osteoporosis. Hence, it is of special clinical interest to elucidate how the Sr uptake is influenced by dietary Ca deficiency as well as by the formula of Sr administration, SrR versus strontium chloride (SrCl₂). Three‐month‐old ovariectomized rats were treated for 90 days with doses of 25 mg kg^?1 d^?1 and 150 mg kg^?1 d^?1 of SrR or SrCl₂ at low (0.1% Ca) or normal (1.19% Ca) Ca diet. Vertebral bone tissue was analysed by confocal synchrotron‐radiation‐induced micro X‐ray fluorescence and by backscattered electron imaging. Principal component analysis and k‐means clustering of the acquired elemental maps of Ca and Sr revealed that the newly formed bone exhibited the highest Sr fractions and that low Ca diet increased the Sr uptake by a factor of three to four. Furthermore, Sr uptake in bone of the SrCl₂‐treated animals was generally lower compared with SrR. The study clearly shows that inadequate nutritional calcium intake significantly increases uptake of Sr in serum as well as in trabecular bone matrix. This indicates that nutritional calcium intake as well as serum Ca levels are important regulators of any Sr treatment.     

Freezing of a modulated liquid: The superionic-to-normal transition of strontium chloride

The anionic component in SrCl₂ near melting is treated as a modulated liquid in the periodic potential of the sublattice of cations. With decreasing temperature from the melting point, we find a diffuse disorder—order transition. The calculated behaviours of the order parameter and of thermodynamic properties approximate those observed for SrCl₂ across its superionic transition.     

Self-luminescence of several fluorite-structure halides doped with curium or berkelium

The self-luminescence emission spectra of several fluorite-structure halides doped with 0.1 cation % ²⁴⁴Cm or ²⁴⁹Bk were measured in the range 14 × 10⁵ to 50 × 10⁵ m^-1 (200–700 nm) between 295 and 600 K. The hosts studied included CaF₂, SrF₂, BaF₂, and SrCl₂ (for Cm) and BaF₂ and SrCl₂ (for Bk). The room-temperature spectra of the Cm-doped samples all have relatively sharp peaks at approximately 16.5 × 10⁵ m^-1 and broad, asymmetric bands with maxima near 35 × 10⁵ m^-1 (fluorides) or 28 × 10⁵ m^-1 (SrCl₂). The sharp peaks are attributed to the Cm dopant and are stable to at least 600 K, while the broad bands appear to be associated with host anion centers and disappear on sample heating. The room-temperature spectrum of Bk-doped BaF₂ also displays an anion- related band at 35 × 10⁵ m^-1, while that of Bk-doped SrCl₂ has both an anion band at 28 × 10⁵ m^-1 and a peak at 19 × 10⁵ m^-1 (believed to be an additional host effect). The luminescence intensity of all samples decreased with room-temperature storage, but could be partially restored by annealing.     

Effect of cation mixing on luminescence of Eu in SrCl2

SrCl₂ forms solid solutions of various compositions with BaCl₂ and CaCl₂. Orthorhombic and tetragonal phases are also known to occur in the SrCl₂-CaCl₂ system. Though efficient emission of Eu²⁺ in SrCl₂ and CaCl₂ is known, there are no reports available on Eu²⁺ luminescence in the solid solutions and other phases. Investigations on these lines were carried out and the results are presented in this paper. Very intense emission comparable to that of the commercial lamp phosphors was observed for the solid solutions while the intensities for the orthorhombic and tetragonal phases are an order of magnitude smaller. Emission wavelengths do not vary much while excitation spectra for the solid solutions are much enhanced in the near UV region (350-400 nm). It is suggested that these results will be significant for developing phosphors with near UV excitations needed in applications such as solid state lighting.     

Tetragonally distorted Cr2+ ions in BaF2 and SrCl2 studied by ESEEM spectroscopy

Electron spin echoes on tetragonally distorted non-Kramers Cr²⁺ ions in chromium doped BaF₂ and SrCl₂ single crystals have been observed. The superhyperfine interaction (shf) with the nearest halide ions has been studied using the electron spin echo envelope modulation (ESEEM) signal. For Cr²⁺ in BaF₂ the nearest coordination shell consists of four equivalent fluorine ions in a plane perpendicular to the defect tetragonal axis, the Cr²⁺ ion being off-centre displaced towards the fluorine plane. The Cr²⁺ shf tensor for BaF₂ has been determined. For SrCl₂:Cr ESEEM signals associated to the shf interaction with nearest chloride ions were observed but the measurements did not allow us to give a definitive defect model in this case.     

Utilization of a dilute solid electrolyte in an oxygen gauge

An electrochemical cell involving a SrCl₂-based solid electrolyte either doped or undoped with SrO was investigated. The measuring electrode was of graphite or vitreous carbon and the reference electrode was formed by dissolving Ag⁺ ions and embedding a silver wire. A simple fabrication technique is described. The reported results indicate that an electrode reaction involving dissolved oxide ions: O₂(gas)+4e⁻=2O²⁻ (SrCl₂) can take place and be utilized in an oxygen gauge down to 200°C. The same cell also functions as a chlorinesensor. At least down to 10⁻³ atm, interference with oxygen is negligible.     

Effect of post-deformation ageing on the recrystallization of KCl-SrCl2 crystals

Room-temperature recrystallization of KCl single crystals, both pure and doped with 0.02 and 0.06 wt % Sr, deformed preliminarily at 250°C is studied. It is found that annealing of the original single crystals at 650°C results in the precipitation of the SrCl₂ phase from the solid solution. X-ray diffraction studies reveal that the deformed crystals undergo ageing at room temperature, which is accompanied by a change in the phase composition. In the first place, particles of the KSr₂Cl₅ phase are formed instead of the phase SrCl₂ observed in the original and deformed crystals. These particles, which are located at the boundaries of growing recrystallized grains (twins of the original single crystal) occupying not more than 8% of the volume, impede the motion of grain boundaries and hamper further recrystallization. Second, it is shown that post-deformation ageing occurring in the remaining 92% of the deformed crystal region that has not undergone recrystallization lends stability to the strain-hardened state of alkali halide crystals over a period of at least two years at room temperature.     

Luminescence of SrX 2 microcrystals (X = Cl,I) activated with Eu2+ ions and dispersed in a NaI matrix

Luminescence spectroscopy has been used to determine the parameters of NaI-SrI₂-Eu, NaI-SrCl₂-Eu, and NaI-BaI₂-Eu compounds in the energy range of 3.7–18 eV at 10 and 295 K and investigate the phase formation in these crystalline systems. The NaI-SrI₂(1 mol %)-Eu(0.02 mol %) crystalline system has revealed formation of SrI₂ microcrystals activated with europium ions and dispersed in the NaI matrix. Formation of SrCl₂-Eu²⁺ microcrystals dispersed in a NaI matrix is observed for NaI-SrCl₂(1 mol %)-Eu(0.02 mol %) crystalline system. The mechanisms of aggregation of impurity ions and specific features of luminescence excitation for europium ions in dispersed microcrystals are discussed.     

Preparation and photoluminescence properties of the Sr1.56Ba0.4SiO4:0.04Eu2+ phosphor

The Sr_1.56Ba_0.4SiO₄:0.04Eu²⁺ phosphors were prepared via a combustion reaction and following the calcination method at low temperature. The influences of the amount of the uncommonly used SrCl₂ flux, different calcination temperatures and time on the structure and the photoluminescence (PL) properties of the phosphors were investigated. Under the excitation of 450 nm blue light, the phosphor shows the intense broad emission band from 490 nm to 650 nm, and the emission peak is centered at 553 nm. The luminescence intensity of Sr_1.56Ba_0.4SiO₄:0.04Eu²⁺ was very sensitive to the crystallinity and morphology characteristics of the phosphor. The phosphor calcined at 950 °C for 3 h in 20%H₂/80%Ar atmosphere exhibits improved PL properties due to its high crystallinity and excellent morphology characteristics. The use of the SrCl₂ flux provides a novel way to improve the crystallinity of the silicates phosphors at low preparation temperature.     

Electron paramagnetic resonance of the Eu2+ ion in SrCl2 at high pressure

This paper reports an EPR study of the effect of hydrostatic pressure (up to 10 kbar) and temperature (300, 77, and 4.2 K) on the spin Hamiltonian parameters of the Eu²⁺ ion in a SrCl₂ cubic crystal. It is found that the b ₄ parameter is related by a power law to the distance from the Cl^?1 ligand (b ₄ ～ R ^?13.5). The pressure and temperature are shown not to be equivalent thermodynamic parameters. Lattice vibrations contribute noticeably to the initial S-ion splitting.     

TiO2 treatment using ultrasonication for bubble cavitation generation and efficiency assessment of a dye-sensitized solar cell

In this study, the impacts of different ultrasonic treatments on TiO₂ particles were determined and they were used to manufacture the photoelectrodes of a dye-sensitized solar cell (DSSC). Two methods were used to prepare TiO₂ particles directly sonicated by an ultrasonic horn, and TiO₂ treated indirectly by an ultrasonic cleaner. TEM, XPS analysis was confirmed that cavitation bubbles generated during ultrasonication resulted in defects on the surface of TiO₂ particles, and the defect induced surface activation. To understand the effect of TiO₂ surface activation on energy conversion efficiency of DSSC, ultrasonic horn DSSC and ultrasonic cleaner DSSC were prepared. The UV–vis analysis exhibited that the ultrasonic horn DSSC possessed higher dye adsorption when compared to the ultrasonic cleaner DSSC, and the EIS analysis confirmed that the electron mobility was greatly increased in the ultrasonic horn DSSC. The energy conversion efficiency of the ultrasonic horn DSSC was measured to be 3.35%, which is about 45% increase in comparison to that of the non-ultrasonic treated DSSC (2.35%). In addition to this regard, recombination resistance of ultrasonic horn DSSC was calculated to be 450 Ω·cm², increasing more than two times compared to the non-ultrasonic treated DSSC (200 Ω·cm²). Taken together, these ultrasonic treatments significantly improved the energy conversion efficiency of DSSC, which was not tried in DSSC-related research, and might lead us to develop more efficient practical route in the manufacturing of DSSC.     

Line scattering images on admixtures in alkali-halides

Different types of line scattering images in cubic crystals are discussed and a method for finding the distribution of rods in the basic substance by means of the scattering image is demonstrated on NaCl:SrCl₂. It is shown that the rods in NaCl:SrCl₂ are distributed in all equivalent 141 directions with the same probability.     

Inelastic light scattering in strontium borate glasses in the systemxSrO.(1−x)B2O3 and (SrCl2) y .[xSrO.(1−y−x)B2O3]1−y

Raman spectra of strontium borate binary glasses in the systemxSrO.(1-x)B₂O₃ forx=0.20, 0.25, 0.30, 0.35, 0.40, and 0.50 and ternary glasses in the system (SrCl₂) _y .[xSrO.(1−y−x)B₂O₃]_1−y fory=0.10, 0.20, 0.30 and 0.40 andx=0.20 and 0.35, are reported. Raman spectra of the glasses show experimental evidence of glass network modifying nature of SrO in borate matrix. SrO causes a change of boron atom coordination number from 3 to 4 resulting in the complex structural groupings comprising of BO₄ and BO₃ units. Strontium cations are not easily accommodated in the glass structure and tend to break up the network at high concentration (x) of SrO, causing non-bridging oxygens. The effect of temperature variation of binary glasses has also been studied. The introduction of SrCl₂ to the binary stronium borate glass causes a large change in intensity of low frequency Raman scattering whereas there is no change in the vibrational dynamics in the high frequency region. The temperature reduced Raman spectra represents true vibrational density of states. Martin-Brenig model developed for the low frequency region has been discussed to obtain the structural correlation range in the glass.     

Fluorescence of Eu-activated alkaline earth halosilicates

Three luminescent materials, each with a distinct and novel crystalline structure have been found in the alkaline earth halosilicate series. Their emission is in the blue/green part of the spectrum, the peaks falling at 500 nm for the Sr/Cl compound, 442 nm for the Ca/Cl compound and 514 nm for the Ca/Br compound. The strontium chlorsilicate, Sr₂Si₃O₈ 2SrCl₂, is of particular interest showing good temperature dependence characteristics (365 nm excitation) and also exhibiting an acicular crystal habit. Other alkaline earth/halide combinations and the binary alkaline earth systems were examined.     

SrCl2:Co++EPR谱电场效应的理论解释

本文从理论上研究了[111]方向电场对SrCl₂:Co⁺⁺的EPR谱的影响。结果表明:外电场使晶格发生畸变而偏离原来的O_h对称,成为C_3v。由此圆满地从理论上解释了零场分裂因子D随电场强度E线性变化的实验规律,并从理论上预言了晶格在平行电场方向的变化率为α=—8×10^-5α₀mm/kV,在垂直电场方向的变化率β=1.66×10^-4α₀关键词：     

Neutron quasielastic scattering from dynamic disorder in PbF2 and BaF2

Coherent neutron quasielastic scattering has been observed from powder samples of PbF₂, and BaF₂, at temperatures above their transition to fast-ion conduction. The scattering is found to be similar to that previously observed in SrCl₂ and CaF₂, suggesting that it stems from a mechanism common to these fluorites in their fast-ion phase.     

Mobility of cation vacancies in the f.c.c. phase of cesium chloride

Electrical conductivity of CsCl pure and doped by SrCl₂ is measured between 460°C and fusion. The expression of the mobility of cation vacancies is reduced from this. The influence of crystalline transformation on ionic disorder and on mobility is examined.     

The entropy change in fast-ion transitions

The recent prediction that the entropy change in fast ion transitions comprises a volume dependent component and a fundamental component σR 1n 2 arising from localisation of shear modes is confirmed in the case of SrCl₂ and CaF₂. Here R is the molar gas constant and σ the stoichiometric number of disordering ions.     

Long wavelength dynamics of SrClF and BaClF

The long wavelength phonons in SrClF and BaClF are calculated using the shell model of lattice dynamics. The parameters of the model are obtained by the transfer of corresponding parameters from the crystal data of SrF₂, SrCl₂ and BaF₂. The calculated phonon frequencies agree fairly well with the observed results from Raman scattering and infrared absorption experiments.