Thermo-optic coefficients of monoclinic Er3+:(GdY)2SiO5 crystal

Thermo-optic coefficients of the Er3+-doped gadolinium-yttrium oxyorthosilicate crystal Er3+:GdYSO are determined at a wavelength of 632.8 nm for light polarizations E // Np, Nm and Ng. Linear thermal expansion coefficients are estimated for this crystal in the directions of the optical indicatrix axes Nm and Ng

Use of the Laser Beam Deflection Technique for Thermo-Optic Coefficients Study in Gadolinium-Yttrium Oxyorthosilicate Doped with Erbium Ions

Results of use of the laser beam deflection technique for determination of thermo-optic coefficients (TOCs) of the Er3+-doped gadolinium-yttrium oxyorthosilicate crystal (Er3+:(GdY)2SiO5 – Er:GYSO) are presented. A 0.1 at.% Er-doped gadolinium-yttrium oxyorthosilicate crystal was grown by the Czochralski method under nitrogen atmosphere. Raw materials such as Er2O3, Gd2O3, Y2O3, and SiO2 were weighed according to the formula (Er0.001Gd0.8995Y0.0995)2SiO5. Optical properties of the biaxial Er:GYSO crystal are described within the frame of the optical indicatrix with orthogonal principal axes Np , Nm , and Ng . To characterize the anisotropy of the TOCs a sample from the grown Er:GYSO crystal was prepared in a shape of a rectangular parallelepiped with dimensions of 7.0 (Np ) × 8.0 (Nm ) × 8.5 (Ng ) mm3. Each face of the sample is perpendicular to one of the optical indicatrix axes Np , Nm and Ng . For determination of the TOCs the laser beam deflection technique for a material with a linear temperature gradient is used. Measurements are performed at the wavelength of 632.8 nm. The thermal coefficient of the optical path (TCOP) for the Er:GYSO crystal measured at the wavelength of 632.8 nm at different light polarization E and propagation direction k were obtained. The TCOP values are positive for all directions of the light propagation k // Np , Nm , Ng . This means that the sign of the thermal lens which is directly related to the TCOP value will also be positive, and the positive thermal lens is then expected for Np - Nm-, and Ng -cut Er:GYSO. Applying an analysis of the thermal lensing the dn /dT value for Yb:GYSO is estimated to be 6.5×10–6 K–1

Применение метода отклонения лазерного пучка для определения термооптических коэффициентов в кристалле гадолиний-иттриевого ортосиликата, легированного ионами эрбия

Results of use of the laser beam deflection technique for determination of thermo-optic coefficients (TOCs) of the Er3+-doped gadolinium-yttrium oxyorthosilicate crystal (Er3+:(GdY) SiO– Er:GYSO) are presented. A 0.1 at.% Er-doped gadolinium-yttrium oxyorthosilicate crystal was grown by the Czochralski method under nitrogen atmosphere. Raw materials such as Er2O3, Gd2O3, Y2O3, and SiO2 were weighed according to the formula (Er0.001Gd0.8995Y0.0995)2SiO5. Optical properties of the biaxial Er:GYSO crystal are described within the frame of the optical indicatrix with orthogonal principal axes Np , Nm , and Ng . To characterize the anisotropy of the TOCs a sample from the grown Er:GYSO crystal was prepared in a shape of a rectangular parallelepiped with dimensions of 7.0 (Np ) × 8.0 (Nm ) × 8.5 (Ng ) mm3. Each face of the sample is perpendicular to one of the optical indicatrix axes Np , Nm and Ng . For determination of the TOCs the laser beam deflection technique for a material with a linear temperature gradient is used. Measurements are performed at the wavelength of 632.8 nm. The thermal coefficient of the optical path (TCOP) for the Er:GYSO crystal measured at the wavelength of 632.8 nm at different light polarization E and propagation direction k were obtained. The TCOP values are positive for all directions of the light propagation k // Np , Nm , Ng . This means that the sign of the thermal lens which is directly related to the TCOP value will also be positive, and the positive thermal lens is then expected for Np Nm-, and Ng -cut Er:GYSO. Applying an analysis of the thermal lensing the dn /dT value for Yb:GYSO is estimated to be 6.5×10–6 K–1.  В статье представлены результаты использования метода отклонения лазерного пучка для определения величин термооптических коэффициентов (ТОК) в кристалле гадолиний-иттриевого ортосиликата, легированного ионами эрбия Er3+ (Er3+:(GdY)2SiO5– Er:GYSO). Кристалл Er:GYSO, легированный ионами эрбия в количестве 0,1 ат.%, выращен методом Чохральского в атмосфере азота. Шихта состояла из оксидов Er2O3, Gd2O3, Y2O3 и SiO2 в пропорции, соответствующей формуле (Er0.001Gd0.8995Y0.0995)2SiO5. Оптические свойства кристалла Er:GYSO описываются на основе оптической индикатрисы с тремя ортогональными главными осями Np , Nm  и Ng . Для характеризации TOК использовался образец кристалла Er:GYSO в форме прямоугольного параллелепипеда размером 7,0 (Np) × 8,0 (Nm ) × 8,5 (Ng ) мм3. Грани образца перпендикулярны осям оптической индикатрисы Np , Nm  и Ng . Метод отклонения лазерного пучка в результате распространения через исследуемый материал, в котором создан линейный градиент температуры, использован для определения TOК. Измерения проведены на длине волны 632,8 нм. Установлены также термические коэффициенты оптического пути (TКOП) для кристалла Er:GYSO на длине волны 632,8 нм для различных поляризаций света E и волнового вектора k. Величины TКOП являются положительными для всех направлений распространения света k // Np , Nm , Ng . Это означает, что знак термической линзы, которая непосредственно связана с величиной TКOП, будет также положительным и, следовательно, положительная термическая линза будет наблюдаться в кристалле Er:GYSO, вырезанном вдоль направлений Np , Nm  и Ng . Из анализа значений термической линзы величина dn/dT в кристалле Yb:GYSO оценена как 6,5×10–6 K–1

Refined Orientation of the Optical Axes as a Function of Wavelength in Monoclinic Double Tungstates

We measured the rotation of the dielectric frame and determined the orientation of the optical axes in KRE(WO4)2 (RE = Gd, Y, Lu) crystals, as a function of wavelength in the 0.4-1.6 μm range

Reading tea leaves worldwide: Decoupled drivers of initial litter decomposition mass‐loss rate and stabilization

The breakdown of plant material fuels soil functioning and biodiversity. Currently, process understanding of global decomposition patterns and the drivers of such patterns are hampered by the lack of coherent large-scale datasets. We buried 36,000 individual litterbags (tea bags) worldwide and found an overall negative correlation between initial mass-loss rates and stabilization factors of plant-derived carbon, using the Tea Bag Index (TBI). The stabilization factor quantifies the degree to which easy-to-degrade components accumulate during early-stage decomposition (e.g. by environmental limitations). However, agriculture and an interaction between moisture and temperature led to a decoupling between initial mass-loss rates and stabilization, notably in colder locations. Using TBI improved mass-loss estimates of natural litter compared to models that ignored stabilization. Ignoring the transformation of dead plant material to more recalcitrant substances during early-stage decomposition, and the environmental control of this transformation, could overestimate carbon losses during early decomposition in carbon cycle models

Reading tea leaves worldwide: decoupled drivers of initial litter decomposition mass-loss rate and stabilisation

The breakdown of plant material fuels soil functioning and biodiversity. Currently, process understanding of global decomposition patterns and the drivers of such patterns are hampered by the lack of coherent large-scale datasets. We buried 36,000 individual litterbags (tea bags) worldwide and found an overall negative correlation between initial mass-loss rates and stabilization factors of plant-derived carbon, using the Tea Bag Index (TBI). The stabilization factor quantifies the degree to which easy-to-degrade components accumulate during early-stage decomposition (e.g. by environmental limitations). However, agriculture and an interaction between moisture and temperature led to a decoupling between initial mass-loss rates and stabilization, notably in colder locations. Using TBI improved mass-loss estimates of natural litter compared to models that ignored stabilization. Ignoring the transformation of dead plant material to more recalcitrant substances during early-stage decomposition, and the environmental control of this transformation, could overestimate carbon losses during early decomposition in carbon cycle models

Reading tea leaves worldwide: decoupled drivers of initial litter decomposition mass‐loss rate and stabilization

The breakdown of plant material fuels soil functioning and biodiversity. Currently, process understanding of global decomposition patterns and the drivers of such patterns are hampered by the lack of coherent large‐scale datasets. We buried 36,000 individual litterbags (tea bags) worldwide and found an overall negative correlation between initial mass‐loss rates and stabilization factors of plant‐derived carbon, using the Tea Bag Index (TBI). The stabilization factor quantifies the degree to which easy‐to‐degrade components accumulate during early‐stage decomposition (e.g. by environmental limitations). However, agriculture and an interaction between moisture and temperature led to a decoupling between initial mass‐loss rates and stabilization, notably in colder locations. Using TBI improved mass‐loss estimates of natural litter compared to models that ignored stabilization. Ignoring the transformation of dead plant material to more recalcitrant substances during early‐stage decomposition, and the environmental control of this transformation, could overestimate carbon losses during early decomposition in carbon cycle models

Thermo-optic properties of orthorhombic BeAl6O10 crystal

Thermo-optic coefficients dn/dT were determined for orthorhombic BeAl6O10 crystal for light polarizations E || Np, Nm and Ng in the wavelength range of 0.4–1.1 m. Thermo-optic dispersion formulas for principal thermo-optic coefficients of BeAl6O10 are presented for this spectral range. The principal dn/dT are positive and show a polarization-anisotropy: dnp/dT = 6.4, dnm/dT = 5.0, dng/dT = 5.6 (10−6 K−1) at wavelength of 0.83 μm. Thermo-optic dispersion data are modeled in accordance with theory taking into account the contributions from the change of the electronic band gap with temperature and from the volumetric thermal expansion coefficient. Key words: orthorhombic crystal, thermo-optic coefficient, BeAl6O10 crystal, thermo-optic dispersion

Phase composition of high strength binding material based on fine microspherical highcalcium fly ash material based on fine microspherical highcalcium fly ash

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.The combination of factors was established for using high-calcium fly ash (HCFA) as a binder material of high early and long-term strength: (1) high dispersity of microspherical HCFA, 90% <10μm; (2) the positive effect of polycarboxylate superplasticizer, that allowed to use water / binder=0.25; (3) formation of finely mixed hydrate phases such as portlandite, ettringite, calcium carboaluminate hydrates and cryptocrystalline calcium hydrosilicates. X-ray powder diffraction quantitative phase analysis of initial HCFA and hydration products in high-strength specimens was performed, which contributes to understanding phase transformations of HCFA during hydration and to improving the properties of the binder