Setup of high resolution thermal expansion measurements in closed cycle cryostats using capacitive dilatometers

We present high resolution thermal expansion measurement data obtained with high relative sensitivity of ΔL/L = 10-9 and accuracy of ±2% using closed cycle refrigerators employing two different dilatometers. Experimental details of the set-up utilizing the multi-function probe integrated with the cold head of two kinds of closed cycle refrigerators, namely, pulse tube and Gifford-McMahon cryocoolers, has been described in detail. The design consists of decoupling the bottom sample puck and taking connections from the top of the multi-function probe to mitigate the vibrational noise arising from the cold heads, using which smooth and high quality thermal expansion data could be obtained. It was found that dilatometer #2 performs a better noise mitigation than dilatometer #1 due to the constrained movement of the spring in dilatometer #2. This was confirmed by finite element method simulations that were performed for understanding the spring movement in each dilatometer using which the effect of different forces/pressures and vibrations on the displacement of the spring was studied. Linear thermal expansion coefficient α obtained using both dilatometers was evaluated using derivative of a polynomial fit. The resultant α obtained using dilatometer #2 and either of the closed cycle cryostats on standard metals silver and aluminium showed excellent match with published values obtained using wet cryostats. Finally, thermal expansion measurements is reported on single crystals of two high temperature superconductors YBa2Cu3-xAlxO6+δ and Bi2Sr2CaCu2O8+x along the c-axis with very good match found with published data obtained earlier using wet liquid helium based cryostats.

Marble decay: towards a measure of marble degradation based on ultrasonic wave velocities and thermal expansion data

Marble as ornamental and dimensional stones as well as in their natural environments show complex weathering phenomena. Physical, chemical, and biological weathering of marble are well documented. The impact of climate change on monuments and historic buildings in terms of modeling and predicting future scenarios requires new approaches to forecast the ongoing decay in the near and far future. Ultrasonic wave velocities are a powerful and sensitive tool for the damage assessment of marble. For a maximum porosity of up to 1%, ultrasonic wave velocities (P-wave velocities) are ranging between 1 km/s and over 6 km/s. Water saturation has an important influence on the magnitude and directional dependence of ultrasonic wave velocities together with the mineralogical composition and the rock fabrics. Ongoing experimental alteration approaches were used to document the state of deterioration using Vp-systematics. In addition, thermal expansion and the residual strain values after applying thermal impacts were used to introduce a new quantitative measure based on experimental length changes and volume changes. To quantify such volume changes, a so-called decay index was proposed. Marbles are sensitive to weathering and have different volume changes under exposure depending on fabric parameters. The volume extension index of marble, based on thermal expansion measurements under dry and water-saturated conditions, is proposed as a decay index for quantifying sample stability and for defining the directions of maximum and minimal dilatation. Such decay index was implemented to different marble types and it was turned out that marbles with the larger decay indexes are more prone to weathering than with smaller ones. The effect of changing climate and, in consequence, different weathering actions can help to calculate or forecast risk numbers based on the Vp data in combination with the proposed decay index especially for marbles.

Synthesizing long-term sea level rise projections – the MAGICC sea level model v2.0

Sea level rise (SLR) is one of the major impacts of global warming; it will threaten coastal populations, infrastructure, and ecosystems around the globe in coming centuries. Well-constrained sea level projections are needed to estimate future losses from SLR and benefits of climate protection and adaptation. Process-based models that are designed to resolve the underlying physics of individual sea level drivers form the basis for state-of-the-art sea level projections. However, associated computational costs allow for only a small number of simulations based on selected scenarios that often vary for different sea level components. This approach does not sufficiently support sea level impact science and climate policy analysis, which require a sea level projection methodology that is flexible with regard to the climate scenario yet comprehensive and bound by the physical constraints provided by process-based models. To fill this gap, we present a sea level model that emulates global-mean long-term process-based model projections for all major sea level components. Thermal expansion estimates are calculated with the hemispheric upwelling-diffusion ocean component of the simple carbon-cycle climate model MAGICC, which has been updated and calibrated against CMIP5 ocean temperature profiles and thermal expansion data. Global glacier contributions are estimated based on a parameterization constrained by transient and equilibrium process-based projections. Sea level contribution estimates for Greenland and Antarctic ice sheets are derived from surface mass balance and solid ice discharge parameterizations reproducing current output from ice-sheet models. The land water storage component replicates recent hydrological modeling results. For 2100, we project 0.35 to 0.56 m (66 % range) total SLR based on the RCP2.6 scenario, 0.45 to 0.67 m for RCP4.5, 0.46 to 0.71 m for RCP6.0, and 0.65 to 0.97 m for RCP8.5. These projections lie within the range of the latest IPCC SLR estimates. SLR projections for 2300 yield median responses of 1.02 m for RCP2.6, 1.76 m for RCP4.5, 2.38 m for RCP6.0, and 4.73 m for RCP8.5. The MAGICC sea level model provides a flexible and efficient platform for the analysis of major scenario, model, and climate uncertainties underlying long-term SLR projections. It can be used as a tool to directly investigate the SLR implications of different mitigation pathways and may also serve as input for regional SLR assessments via component-wise sea level pattern scaling.

Synthesizing long-term sea level rise projections – the MAGICC sea level model

Sea level rise is one of the major impacts of global warming; it will threaten coastal populations, infrastructure, and ecosystems around the globe in coming centuries. Well-constrained sea level projections are needed to estimate future losses from Sea Level Rise (SLR) and benefits of climate protection and adaptation. Process-based models that are designed to resolve the underlying physics of individual sea level drivers form the basis for state-of-the-art sea level projections. However, associated computational costs allow for only a small number of simulations based on selected scenarios that often vary for different sea level components. This approach does not sufficiently support sea level impact science and climate policy advice, which require a sea level projection methodology that is flexible with regard to the climate scenario yet comprehensive and bound to the physical constraints provided by process-based models. To fill this gap, we present a sea level model that emulates global mean long-term process-based model projections for all major sea level components. Thermal expansion estimates are calculated with the hemispheric upwelling-diffusion ocean component of the simple carbon cycle-climate model MAGICC, which has been updated and calibrated against CMIP5 ocean temperature profiles and thermal expansion data. Global glacier contributions are estimated based on a parameterization constrained by transient and equilibrium process-based projections. Sea level contribution estimates for Greenland and Antarctic ice sheets are derived from surface mass balance and solid ice discharge parameterizations reproducing current output from ice-sheet models. The land water storage component replicates the latest hydrological modeling results. For 2100, we project 0.38 m to 0.59 m (66 % range) total SLR based on the RCP2.6 scenario, 0.48 m to 0.68 m for RCP4.5, 0.48 m to 0.72 m for RCP6.0, and 0.67 m to 0.97 m for RCP8.5. These projections lie within the range of the latest IPCC SLR estimates. SLR projections for 2300 yield median responses of 0.97 m for RCP2.6, 1.66 m for RCP4.5, 2.32 m for RCP6.0, and 5.12 m for RCP8.5. The MAGICC sea level model provides a powerful and efficient platform for probabilistic uncertainty analyses of long-term SLR projections. It can be used as a tool to directly investigate the SLR implications of different mitigation pathways and may also serve as input for regional SLR assessments via component-wise sea level pattern scaling.

Thermal expansion behaviour of orthopyroxenes: the role of the Fe-Mn substitution

Two Pbca orthopyroxene samples, donpeacorite (DP N.1) and enstatite (B22 N.60) with chemical formulae Mn0.54Ca0.03Mg1.43Si2O6 (XMn = 0.27) and Fe0.54Ca0.03Mg1.43Si2O6 (XFe = 0.27), respectively, were investigated by single-crystal X-ray diffraction at high-temperature conditions.The nearly identical XFe and XMn make the two samples the perfect candidates to investigate the effect of the compositional change at the M2 site (i.e. Fe-Mn substitution) on the thermal expansion behaviour of orthopyroxenes.Therefore, the unit-cell parameter thermal expansion behaviour of both samples has been investigated in the temperature range between room T and 1073 K. No evidence for phase transitions was found over that range. The two samples have been previously disordered with an ex situ annealing at ∼1273 K.The unit-cell parameters and volume thermal expansion data, collected on the disordered samples, have been fitted to a Fei Equation of State (EoS) and the following coefficients obtained: V0 = 853.35(4) Å3, αV,303K = 2.31(24) × 10–5 K–1 and V0 = 845.40(6) Å3, αV,303K = 2.51(25) × 10–5 K–1 for DP N.1 and B22 N.60, respectively.While there is no difference in the volume thermal expansion coefficient as a function of composition and the expansion along the b direction is nearly identical for both samples, slight differences have been found along a and c lattice directions. The thermal expansion along the a direction is counterbalanced by that along c being responsible for the changes in lattice expansion scheme from αb > αc > αa at room T, to αc > αb > αa at high T. Therefore, as a result of the different behaviour along a and c, the unit-cell volume thermal expansion for both samples is identical within estimated standard deviations. The negligible effect of the Fe-Mn substitution on the bulk thermal expansion can be applied when dealing with geothermobarometry based on the elastic host-inclusion approach (e.g. Nestola et al., 2011; Howell et al., 2010; Angel et al., 2014 a, b, 2015). In fact, though the compressibility effect is still not known, the nearly identical thermal expansion coefficients will not affect the entrapment pressure (Pe).

Thermal Expansion and Polarization Behavior in Lead Titanate/Zinc Oxide Nanocomposite Ceramics

Nanosized zinc oxide/lead titanate (ZnO/PT) ceramic matrix nanocomposites have been studied. Under an appropriate sintering condition, ZnO/PT ceramic nanocomposites were successfully fabricated by a pressureless sintering technique. Thermal expansion and polatization behaviors were determined by using the dilatometer. This technique measures the temperature-dependent of the strain, and the magnitude of polarization can be deduced from the sets of the thermal expansion data. The calculated electric polarization values on the ZnO/PT nanocomposite ceramics show the simple approach to determine the temperature dependence of the polarization below and around the transition temperature. Various aspects on understanding the polarization behavior and other effects in the ferroelectric are discussed.

Thermal expansion of andalusite and sillimanite at ambient pressure: a powder X-ray diffraction study up to 1000°C

The unit-cell parameters of andalusite and sillimanite have been measured by high-T powder X-ray diffraction up to 1000°C at ambient pressure. Within the temperature range investigated, all the unit-cell parameters varied smoothly, indicating no phase transition. The volume-temperature data were fitted with a polynomial expression for the thermal expansion coefficient (αT = a0 + a1T + a2T-2). yielding a0 = 2.55(2) × 10–5K–1, al = 0 and a2 = 0 for andalusite, and a0 = 1.40(4) × 10–5K–1a1 = 7.1(8) × 10–9K–2 and a2 = 0 for sillimanite. Using the new thermal expansion data determined in the present study and compressional data from the literature, the P-T phase relations of the kyanite-andalusite-sillimanite system were calculated thermodynamically, with the invariant point located at ∼523°C and 3.93 kbar.

On the Thermoelectric Potential of Inverse Clathrates

In the context of a general survey on the thermoelectric potential of cationic clathrates, formation, crystal chemistry and physical properties were investigated for novel inverse clathrates deriving from Sn19.3Cu4.7P22I8. Substitution of Cu by Zn and Sn by Ni was attempted to bring down electrical resistivity and lower thermal conductivity. Materials were synthesized by mechanical alloying using a ball mill and hot pressing. Structural investigations for all specimens confirm isotypism with the cubic primitive clathrate type I structure (lattice parameters a = ˜1.1 nm and space group type Pm-3n). Studies of transport properties evidence holes as the majority charge carriers. Thermal expansion data, measured in a capacitance dilatometer from 4 to 300 K on Sn19.3Cu1.7Zn3P19.92.1I8, compare well with literature data available for Sn24P19.62.4Br8 and for an anionic type I clathrate Ba8Zn8Ge38. From the rather complex crystal structure including split atom sites and lattice defects thermal conductivity in inverse clathrates is generally low. Following Zintl rules rather closely inverse clathrates tend to be semiconductors with attractive Seebeck coefficients. Thus for thermoelectric applications the main activity will have to focus on achieving low electrical resistivity in a compromise with still sufficiently high Seebeck coefficients.

Structure and intermolecular interactions of glipizide from laboratory X-ray powder diffraction

The crystal structure of glipizide, used as a major treatment of type-2 diabetes, has been determined ab initio using variable-temperature laboratory X-ray powder diffraction combined with a direct-space Monte Carlo/simulated annealing methodology. The strengths of the intermolecular interactions (van der Waals, π–π stacking, hydrogen bonding and steric interlock) were quantitatively estimated using the thermal expansion data, which were collected in the same set of experiments as those used to determine the structure.