Preparation and Properties of BaBiBO4-SiO2 Glasses

Glasses in the new system (100-x) BaBiBO4–xSiO2 where x = 10–50 (mol%) were prepared by the melt-quench technique. The density of the glasses increases with an increase in BaBiBO4 content because of its higher molecular mass. Tg, Td,and Ts decrease while coefficient of thermal expansion increases with the increase in BaBiBO4 content. Vis-NIR spectra reveal that with increasing melting temperature transmission of the glasses decreases due to auto thermal reduction of Bi31 to Bi0 as confirmed by transmission electron microscopy and selected area electron diffraction analyses. Fourier transform infrared reflection spectroscopic spectra of the glasses indicate the formation of BiO6, BO3, and BO4 structural units. Ferroelectric BaBiBO4 crystalline phase is obtained from these glasses by controlled heat treatment at 5801C. X-ray diffraction analysis reveals its 45–66nm crystallite size range. Whereas, the field-emission scanning electron microscopy images show the formation of polycrystalline spherical grains of 89–194nm along with single-crystalline microrods of average diameter of 0.5–1.5 mm. Dielectric constant of the glasses increases with increase in BaBiBO4 content, which is attributed to the combined effects of high polarization and ionic refraction of both Bi31 and Ba21 ions. It is shown here that BaBiBO4–SiO2 is a promising glass system for the synthesis of glass–ceramics of novel BaBiBO4 nonlinear optical crystal

Effects of Nano-LiTaO(3) Crystallization on the Dielectric and Optical Properties in Er(3+)-Doped Li(2)O-Ta(2)O(5)-SiO(2)-Al(2)O(3) Glasses

The precursor glass of LiTaO(3) nanocrystals was prepared in a new Er(3+)-doped Li(2)O-Ta(2)O(5)-SiO(2)-Al(2)O(3) system by the melt-quench technique. They were isothermally crystallized at 680 degrees C for 3-100 h to obtain nanostructured glass-ceramics. The X-ray diffraction and transmission electron microscopy confirm the nanocrystallization of LiTaO(3) (16-34 nm) yielding transparent glass-ceramics. A steep rise in the dielectric constant with the heat-treatment time is attributed to ferroelectric LiTaO(3) crystallization. Photoluminescence spectra exhibit the (4)I(13/2) -> (4)I(15/2) emission transition of Er(3+) ions at 1570 nm when excited at 984 nm. Its intensity and lifetime decrease with an increase in heat-treatment time due to concentration quenching effect

Structure and dielectric properties of potassium niobate nano glass-ceramics

Glasses in the composition of 25K(2)O-25Nb(2)O(5)-50SiO(2) (mol %) have been prepared by melt quenching technique and isothermally heat-treated at 800 A degrees C for different duration (0-200 h). The formed nanocrystalline KNbO(3) phase, crystallite size and morphology are examined by X-ray diffraction, Fourier transform infrared reflection spectroscopy, field emission scanning and transmission electron microscopes. The frequency and temperature dependent dielectric constant and loss tangent are measured in the frequency and temperature ranges 0.1-1000 kHz and 200-500 A degrees C respectively. The dielectric constant and loss tangent are found to decrease with increasing frequency and increase with increasing temperature. The dielectric constant and loss tangent versus temperature curve at different frequency revealed the phase transition of KNbO(3) from paraelectric cubic to ferroelectric tetragonal around 425 and 397 A degrees C (Curie temperature) for nano glass-ceramics obtained after 1 and 200 h heat-treatment respectively

Optical and dielectric properties of isothermally crystallized nano-KNbO(3) in Er(3+)-doped K(2)O-Nb(2)O(5)-SiO(2) glasses

Precursor glass of composition 25K(2)O-25Nb(2)O(5)-50SiO(2) (mol%) doped with Er(2)O(3) (0.5wt% in excess) was isothermally crystallized at 800 degrees C for 0-100h to obtain transparent KNbO(3) nanostructured glass-ceramics. XRD, FESEM, TEM, FTIRRS, dielectric constant, refractive index, absorption and fluorescence measurements were carried out to analyze the morphology, dielectric, structure and optical properties of the glass-ceramics. The crystallite size of KNbO(3) estimated from XRD and TEM is found to vary in the range 7-23 nm. A steep rise in the dielectric constant of glass-ceramics with heat-treatment time reveals the formation of ferroelectric nanocrystalline KNbO(3) phase. The measured visible photoluminescence spectra have exhibited green emission transitions of (2)H(11/2). (4)S(3/2) -> (4)I(15/2) upon ;excitation at 377 nm ((4)[(15/2) -> (4)G(11/2)) absorption band of Er(3+) ions. The near infrared (NIR) emission transition (4)[(13/2) -> 4[(15/2) is detected around 1550 nm on excitation at 980 mn ((4)[(15/2) -> 4 [(11/2)) of absorption bands of Er(3+) ions. It is observed that photoluminescent intensity at 526 nm ((2)H(11/2) -> (4)I(15/2)), 550nm (4S(3/2) -> (4)I(15/2)) and 1550nm ((4)I(13/2) -> (4)I(15/2)) initially decrease and then gradually increase with increase in heat-treatment time.'rhe measured lifetime (tau(f)) of the (4)I(13/2) -> (4)I(15/2) transition also possesses a similar trend. The measured absorption and fluorescence spectra reveal that the Er(3+) ions gradually enter into the KNbO(3) nanocrystals. (C) 2009 Elsevier B.V. All rights reserved

Structure, dielectric and optical properties of transparent Nd(3+):KNbO(3) nanocrystalline glass-ceramics

Here, glass in the composition of 25K2O–25Nb2O5–50SiO2 (mol%) doped with Nd2O3 (0.5 wt.% in excess)was isothermally crystallized at 800 C for 1–100 h. Their structures, dielectric and optical properties were analyzed with the progress of nanocrystallization of Nd3+: KNbO3 by XRD, FESEM, TEM, FTIRRS, DC, optical absorption and fluorescence measurements. Crystallization of KNbO3 is confirmed from XRD and the appearance of 749 cm-1 band in the FTIRRS spectra. The crystallite size estimated from XRD and TEM is found to vary in the range 7–11 nm. The formation of ferroelectric nano-crystalline KNbO3 phase is also attributed by a steep rise in the dielectric constant (e) of glass–ceramics with heat-treatment time. The measured photoluminescence spectra have exhibited emission transitions of 4F3/2?4IJ (J = 9/2, 11/2 and 13/2) from Nd3+ ions upon excitation at 817 nm. It is observed that the photoluminescent intensity and excited state lifetime of Nd3+ ions initially decrease and then gradually increase with increase in heat-treatment time. The absorption spectra and fluorescence measurements disclose that the Nd3+ ions gradually enter into the KNbO3 nanocrystals

Structure, dielectric and optical properties of Nd(3+)-doped LiTaO(3) transparent ferroelectric glass-ceramic nanocomposites

Here, we present the structural, dielectric and optical properties of neodymium ion (Nd(3+)) doped novel transparent glass-ceramics containing LiTaO(3) narrocrystals in the Li(2)O-Ta(2)O(5)-SiO(2)-Al(2)O(3) (LTSA) glass system prepared by the melt-quenching technique. The precursor glasses were isothermally crystallized at 680 degrees C for 3-100 h. following the differential thermal analysis (DTA) data, to obtain narrostructured glass-ceramics. They were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), Fourier transform infrared reflection spectra (FTIRRS), optical absorption and luminescence spectroscopy along with dielectric constant measurements. XRD, FESEM, TEM and FTIRRS confirm the nanocrystallization of LiTaO(3) (14-36 nm) in the LTSA glass matrix. A steep increase in dielectric constant (epsilon(r)) of glass-ceramics with heat-treatment time is observed due to high dielectric constant ferroelectric LiTaO(3) formation. The measured NIR photoluminescence spectra have exhibited emission transitions of (4)F(3/2) -> (4)I(J) (J = 9/2, 11/2 and 13/2) from Nd(3+) ions upon excitation at 809 nm. it is observed that the photoluminescent intensity and excited state ((4)F(3/2)) lifetime of Nd(3+) ions decrease with increase in heat-treatment time due to concentration quenching effect. The absorption spectra and fluorescence measurements reveal that the incorporation of Nd(3+) ions in the LiTaO(3) crystal lattice in the oxide glassy matrix is important for obtaining desirable fluorescence performance of the material. (C) 2009 Elsevier B.V. All rights reserved

Second harmonic generation in ferroelectric LiTaO3 and KNbO3 containing bulk nano glass-ceramics

The precursor glasses in (mol%) 25.53Li2O-21.53Ta2O5- 35.29SiO2-17.65Al2O3 (LTSA) and 25K2O-25Nb2O5-50SiO2 (KNS) glass systems were prepared by the melt-quench technique. Ferroelectric LiTaO3 (LT) and KNbO3 (KN) crystallites containing bulk nano glass-ceramics have been prepared by controlled crystallization of these precursor glasses respectively. Second harmonic generations (SHG) at 532 nm in both the glass-ceramics have been realized under fundamental beam of Nd3+:YAG laser source (1064 nm). The SHG power output has been found to increase up to 14 and 62.4 nJ with variation of rotation angle for LT and KN bulk nano glassceramics respectively due to orientation of ferroelectric domains under applied field

A systematic review of non-invasive modalities used to identify women with anal incontinence symptoms after childbirth

© 2018, The International Urogynecological Association. Introduction and hypothesis: Anal incontinence following childbirth is prevalent and has a significant impact upon quality of life (QoL). Currently, there is no standard assessment for women after childbirth to identify these symptoms. This systematic review aimed to identify non-invasive modalities used to identify women with anal incontinence following childbirth and assess response and reporting rates of anal incontinence for these modalities. Methods: Ovid Medline, Allied and Complementary Medicine Database (AMED), Cumulative Index of Nursing and Allied Health Literature (CINAHL), Cochrane Collaboration, EMBASE and Web of Science databases were searched for studies using non-invasive modalities published from January 1966 to May 2018 to identify women with anal incontinence following childbirth. Study data including type of modality, response rates and reported prevalence of anal incontinence were extracted and critically appraised. Results: One hundred and nine studies were included from 1602 screened articles. Three types of non-invasive modalities were identified: validated questionnaires/symptom scales (n = 36 studies using 15 different instruments), non-validated questionnaires (n = 50 studies) and patient interviews (n = 23 studies). Mean response rates were 92% up to 6 weeks after childbirth. Non-personalised assessment modalities (validated and non-validated questionnaires) were associated with reporting of higher rates of anal incontinence compared with patient interview at all periods of follow-up after childbirth, which was statistically significant between 6 weeks and 1 year after childbirth (p < 0.05). Conclusions: This systematic review confirms that questionnaires can be used effectively after childbirth to identify women with anal incontinence. Given the methodological limitations associated with non-validated questionnaires, assessing all women following childbirth for pelvic-floor symptomatology, including anal incontinence, using validated questionnaires should be considered