The main objective of this thesis is to evaluate the effect of production technology on the properties of forsterite. The theoretical part contains the fundamental parameters and the use of forsterite in the industry together with various possibilities of forsterite production. The main emphasis is placed on the characteristics of the raw materials for production as well as the raw materials possibilities of the Czech Republic. The end of the theoretical part contains a design for the production technology of forsterite, which will be verified in the practical part. The practical part verifies the use of various raw materials for the composition of the raw material mixture. The created test specimens were subjected to the X-ray diffraction analysis, the determination of tensile bending strength, thermal conductivity coefficient, apparent porosity, bulk density, apparent density, water absorption, permanent change in dimension on heating, refractoriness, thermal expansion coefficient, refractoriness under load and the thermal shock resistance. At the end of the practical part is the verification of the design of the production technology of forsterite.

This work deals with the issue of packaging and heat transfer. Especially this work focused on QFN and BGA packages. Nowadays most sophisticated conventional solution. First part deals with analysis of the current status of packages. Next part is analyze the issue of heat transfer in electronic systems. The following section is an experimental dealing with simulation in ANSYS Workbench and validation of these simulations by designed test structures. At the end is evaluated properties and behavior of these packages.

The aim of this master thesis was to measure and evaluate shifts of rail strip and deck of the bridge in the 0,206 km route Zábřeh - Bludov across the river Moravská Sázava. The measurement was performed by classical geodetic methods. The result of the study was evaluation of the three periods of deformation measurements and numerical and graphical documentation. Shifts were caused especially by changes in temperature and operational effects.

In der vorliegenden Arbeit wird die Einkristallzüchtung nach dem Czochralskiverfahren von GdCa4O(BO3)3 (GdCOB) beschrieben. Aus insgesamt 18 Zuchtversuchen, bei denen auch die Ziehgeschwindigkeit zwischen 1 und 3mm/h variiert wurde, wurden erfolgreich nahezu perfekte Einkristalle gewonnen. In einigen Kristallen traten jedoch auch Risse oder Einschlüsse auf. Diese enthielten neben Iridium vom Tiegelmaterial auch andere Phasen des Gd2O3–B2O3–CaO-Systems, sowie P und Yb, deren Herkunft unklar ist. Als Hauptziehrichtung wurde die kristallographische b-Achse gewählt, ergänzt durch einige Experimente in der c-Richtung. In den drei kristallographischen Hauptrichtungen wurden die thermischen Ausdehnungskoeffizienten von GdCOB bestimmt. Diese können in zwei nahezu lineare Bereiche unterteilt werden: von Zimmertemperatur bis etwa 850° C und von 850 bis 1200° C, wobei die Koeffizienten im Hochtemperaturbereich deutlich höher sind (unter 850° C: alpha_a=11.1, alpha_b=8.6, alpha_c=13.3 10^-6/K, oberhalb 850° C: alpha_a=14.1, alpha_b=11.7, alpha_c=17.8 10^-6/K). Daraus ergibt sich, dass ein Phasenübergang höherer Ordnung vorliegen muss. Als mögliche Ursache wurde mittels HT-Raman Spektroskopie ein Ordnungs-Unordnungs-Übergang identifiziert, während dessen die BO3-Gruppen in der Struktur leicht rotieren. Weitere Untersuchungen mittels thermodynamischer Methoden führten zu schwachen, aber eindeutigen Signalen, die diesem Effekt ebenfalls zuzuordnen sind. Obwohl das Material ein vielversprechender Kandidat für piezoelektrische Anwendungen im Hochtemperaturbereich ist, wurde dieser Effekt bisher unzureichend beschrieben. Dieses Verhalten, kombiniert mit den anisotropen thermischen Ausdehnungskoeffizienten, könnte eine der Ursachen für das Vorkommen von Rissen in den Kristallen während der Synthese darstellen. Spektroskopische Untersuchungen ergaben einen großen Transparenzbereich von 340 bis 2500nm (29 400–4000 cm^-1), was für optische Anwendungen von großer Bedeutung ist. / In a series of 18 growth experiments, GdCa4O(BO3)3 (GdCOB) single crystals were successfully grown by the Czochralski method. They have a well-ordered structure, as revealed by single crystal structure analysis. Although the main growth direction was along the crystallographic b-axis, some experiments were conducted using the cdirection. Pulling velocities were varied between 1 and 3mm/h. Except for a few crystals with cracks or elongated "silk-like" inclusions consisting of multiphase impurities, most of the obtained crystals are of good quality. Those inclusions contain iridium, deriving from the crucible, P and Yb with unclear source, and other phases from the system Gd2O3–B2O3–CaO. Thermal expansion coefficients of GdCOB were determined in the directions of the crystallographic axes and found to be approximately linear in two temperature ranges: from 25° C to around 850° C, and from 850 to 1200° C, with the latter range showing significantly higher coefficients (below 850° C: alpha_a=11.1, alpha_b=8.6, alpha_c=13.3 10^-6/K, and above 850° C: alpha_a=14.1, alpha_b=11.7, alpha_c=17.8 x10^-6/K). This sudden increase of thermal expansion coefficients indicates a phase transition of higher order. An order-disorder transition in form of the rotation of BO3-triangles in the structure was made tentatively responsible for this transition, as revealed by HT-Raman spectroscopy. This transition was also detected by DSC-methods but appeared to result in very weak effects. Although the material is thought to represent a promising candidate for high temperature piezoelectric applications (noncentrosymmetric space group Cm), this effect of change in specification has not been described and it is unknown whether it has influence on the piezoelectric properties. Furthermore, this characteristic behaviour in combination with anisotropic coefficients may be the reason for the development of cracks during cooling of crystals, making the growth difficult. Spectroscopic investigation revealed a wide transparency range from 340 to 2500nm (29 400–4000 cm^-1) of GdCOB, which is a very important property for optical applications.

We characterize the impact of high-energy, 172 nm vacuum ultraviolet photons on the molecular weight and the glass transition temperature of poly(methyl methacrylate). We found that the molecular weight is reduced strongly on the surface of the exposed samples with a continuous transition towards the unexposed bulk material being located below the modified region. The glass transition temperature was found to be significantly lowered in the exposed region to well below 50°C compared to that of the 122°C of the bulk region. We could use this material contrast to selectively reflow the top surface of the exposed samples only. This allowed us to create ultra-smooth micro-optical structures by postprocessing without influencing the overall geometry that is required for the optical functionality.

In the past years, more concerns are focused on the nuclear waste management due to the very long half-lives of various actinides produced in Light Water Reactors (LWRs). Sodium Fast Reactors (SFRs) are thus becoming more attractive since they are known to be very efficient to transmute long-lived radionuclides present in spent fuel. However, the current simulation tools (thermal-hydraulics code with point kinetics) and safety assessment methods are not as mature as for LWR applications and need to be enhanced. This thesis aims at filling the gap in safety analysis of SFR cores to reach a standard similar to LWR applications by applying multi-physics modelling. In contrast to LWRs, the reactivity in SFRs is affected by three main feedback: the Doppler broadening reactivity effect, the sodium density change reactivity effect and the thermal expansion of several mechanical components of the reactor. In this thesis, the thermal-hydraulic system code ATHLET is coupled with the three-dimensional neutron-physics code PARCS for transient analysis. Developed at GRS, ATHLET was recently upgraded for sodium coolant properties. The nodal diffusion codes PARCS, developed at the University of Michigan, can solve the multi-group diffusion equation in hexagonal geometry. While both codes already have the main features to simulate SFRs, the development of models dedicated to the thermal expansion effect of reactivity is necessary. The latter has three main origins i.e. the core axial thermal expansion effect (caused by the fuel and the cladding axial thermal expansion), the core radial thermal expansion effect (caused by the diagrid thermal expansion), the control rod displacement due to the thermal expansion of the Control Rod Drive Lines (CRDLs), the strongback and the reactor vessel. Thus, the three main new developments achieved in the scope of this work are: - Development of a method to generate homogenized multi-energy-group neutron macroscopic cross sections (needed by PARCS) for SFR applications which consider not only the Doppler temperature and sodium density but also the core axial and radial thermal expansion. - Development of a three-dimensional core radial thermal expansion model and its implementation in PARCS. A core axial thermal expansion model has already been developed for PARCS prior to this work. - Development of a module in ATHLET for modelling the control rod displacement as a result of the influence of the reactor structures thermal expansion. The parametrized homogenized multi-energy-group neutron macroscopic cross section libraries for PARCS applications are generated with the Monte Carlo reactor-physics code Serpent. For all materials contained in fuel assemblies, a three-dimensional model is used while the SPH method is applied to materials contained in non-fuel assemblies (e.g. control rods, etc.). The cross section libraries are collapsed into a 12-energy-group structure. Furthermore, a dedicated module was successfully developed and implemented within the core simulator KMACS (developed at GRS). The core radial thermal expansion effect is implemented in PARCS using a coordinate transformation of the diffusion equation from the expanded state to the nominal geometry. The core radial thermal expansion depends on the diagrid temperature. It is calculated by ATHLET and transferred to PARCS by the extended interface between both codes. The modelling of the control rod displacement as a result of the reactor structures thermal expansion is performed by a module linked to ATHLET. The strongback, the reactor vessel and the CRDLs are modelled as heated structures in ATHLET, which calculates their respective temperature. The module can compute the thermal expansion of each structure as well as the total control rod banks displacement. The new techniques are verfied on a selected case study, the ASTRID core design. First, full core criticality simulations are performed with the Monte Carlo reactor-physics code Serpent (considered as reference calculations) and with PARCS. Good agreement between the two codes is achieved in terms of multiplication factors and power distribution. This allows to conclude that the developed method for neutron cross section libraries can be used for SFR applications. The newly implemented core radial expansion model in PARCS is successfully verified on the ASTRID core with the standalone version of PARCS. Then, various transient simulations are performed in order to separately analyse the different contributions to the reactivity by: the Doppler broadening effects, the sodium density change effect, the core radial and axial thermal expansion effect and the control rod displacement effect. It is demonstrated that the core power responses are plausible which allows the conclusion that all the different thermal expansion models are properly implemented. Furthermore, the presented simulations show very different core power responses. It appears that the effect of the sodium density change on reactivity is a parameter that is strongly heterogeneous (depending on the core location). This shows the importance of using a three-dimensional neutron kinetics model rather than a point-kinetic model for transient simulations with thermal-hydraulic codes. Moreover, the time-scale of the various effects are ranging from few seconds to several hundred seconds. While the Doppler broadening, the sodium density change, as well as the core axial and radial thermal expansion effects on reactivity are fast, the thermal expansion of the strongback and the vessel only appears after several hundred seconds. This emphasizes the importance of considering all thermal expansion effects in addition to the usual thermal-hydraulic feedback parameters (e.g. fuel temperature, coolant density etc.) to be able to compute the core behavior realistically.:Contents Abstract II List of Figures VII List of Tables X List of Acronyms XI Acknowledgments XIII 1 Introduction 1.1 Sodium cooled fast reactors 1.1.1 Fast reactor development 1.1.2 Comparison of sodium fast reactor and pressurized water reactor designs 1.1.2.1 Neutron spectrum 1.1.2.2 Breeding 1.1.2.3 Partitioning and Transmutation 1.1.2.4 Control of the reactivity in the core 1.1.2.5 Coolant properties 1.1.2.6 Reactivity feedback 1.1.2.7 Comparison summary 1.2 Objectives and structure of the thesis 1.2.1 Objectives 1.2.2 Structure of the thesis 2 State of the art of Sodium Fast Reactor safety assessment 2.1 Relevant safety events to consider for Sodium Fast Reactors 2.2 Major reactivity feedback mechanisms 2.3 State of the art of safety analysis methods for Sodium Fast Reactor 3 Methods and codes for safety assessment of sodium cooled fast reactors 3.1 Neutronics core calculations 3.1.1 Core calculations with the diffusion code PARCS 3.1.2 Generation of nodal few-group cross sections with the Monte Carlo code Serpent 3.1.3 Core simulator KMACS 3.2 Thermal-hydraulics simulations with the system code ATHLET 3.3 Coupled three-dimensional thermal-hydraulics / neutronics calculations 4 Development of three-dimensional thermal expansion models 4.1 General calculation approach proposed for safety assessment 4.2 Thermal expansion in solids 4.3 Model for generating nodal few-energy-group cross sections for deterministic core analysis 4.3.1 Energy group structure 4.3.2 Full-scale three-dimensional fuel assembly models in Serpent 4.3.3 Two-dimensional non-fuel assembly models in Serpent 4.3.4 Super homogenization method for non-multiplying media 4.3.5 Automated creation of Serpent models for parametrized cross section generation with KMACS 4.4 Core radial thermal expansion effect 4.4.1 Description of the core radial thermal expansion phenomenon 4.4.2 Coordinate transformation of the diffusion equation 4.4.3 Implementation of the coordinates transformation in PARCS 4.4.4 Adapted cross section parametrization scheme for the core radial expansion model 4.4.5 Diagrid model in ATHLET and temperature transfer 4.5 Core axial thermal expansion effect 4.5.1 Description of the core axial thermal expansion phenomenon 4.5.2 Implementation of a core axial thermal expansion model in PARCS 4.5.3 Appropriate cross section parametrization scheme 4.6 Control rod displacement due to reactor structures thermal expansion effects 4.6.1 Modelling scheme 4.6.2 Strongback model in ATHLET 4.6.3 Vessel model in ATHLET 4.6.4 Control rods drive lines ATHLET model 5 Verification on a case study 5.1 Description of the ASTRID reactor 5.2 Full core models 5.2.1 Full core Serpent reference models of the ASTRID core 5.2.2 Three-dimensional neutron kinetics model of ASTRID core in PARCS 5.2.3 Generation of appropriate few-group cross sections 5.2.4 Thermal-hydraulic model in ATHLET and ATHLET-PARCS feedback mapping 5.3 Verfications of the radial core expansion model 5.4 Assessment of the Doppler and sodium density effects 5.4.1 Assessment of the Doppler effect 5.4.2 Assessment of the sodium density effect 6 Coupled three-dimensional thermal-hydraulics/neutron-physics transient simulations with ATHLET-PARCS 6.1 Description of the models and transient simulations 6.2 Simulation 1: Doppler effect 6.2.1 Description 6.2.2 Results 6.3 Simulation 2: Sodium density effect 6.3.1 Description 6.3.2 Results 6.4 Simulation 3: Doppler and sodium density effects 6.4.1 Description 6.4.2 Results 6.5 Simulation 4: Core radial thermal expansion effect 6.5.1 Description 6.5.2 Results 6.6 Simulation 5: Doppler, Sodium density and core radial thermal expansion effects 6.6.1 Description 6.6.2 Results 6.7 Simulation 6: Core axial thermal expansion effect 6.7.1 Description 6.7.2 Results 6.8 Simulation 7: Doppler, Sodium density and core axial thermal expansion effects 6.8.1 Description 6.8.2 Results 6.9 Simulation 8: Doppler effect, Sodium density effect, core radial thermal expansion effect and core axial thermal expansion effect 6.9.1 Description 6.9.2 Results 6.10 Simulation 9: Doppler effect, Sodium density effect, core radial thermal expansion effect, core axial thermal expansion effect and control rod displacement due to reactor structures thermal expansion effect 6.10.1 Description 6.10.2 Results 6.11 Preliminary conclusions of the test calculations 7 Conclusion and outlook for future developments 7.1 Summary and conclusions 7.2 Suggestions for future work Appendices A The Boltzmann equation B Macro-group structure Bibliography

L'objectif de la thèse a été d'explorer différentes voies de dispersion de charges graphitiques dans des élastomères de type polyisoprène dans le but d'améliorer les propriétés mécaniques et barrière. Pour augmenter les interactions entre le graphite et l'élastomère et donc diminuer les interactions entre charges, les charges graphitiques ont été modifiées chimiquement. Le graphite a été préalablement oxydé pour obtenir du graphite oxydé (GO) contenant des groupements époxyde, hydroxyle et acide carboxylique, susceptibles de servir comme sites d'ancrage de molécules et de chaînes polymères. Afin d'améliorer la compatibilité du GO avec la matrice polyisoprène, des amines et des alkoxysilanes ainsi que des chaînes polyisoprène ont été greffées sur le GO. Des taux de greffage variant de 4 à 50 % en poids ont été obtenus selon la technique de fonctionnalisation utilisée. Une expansion thermique du GO a aussi été étudiée et a conduit à la formation d'une structure graphitique poreuse. Des composites polyisoprène contenant 15 pce de ces charges graphitiques modifiées ont ensuite été préparés et ont montré une diminution de la perméabilité à l'air (-70 % pour les composites graphite traité thermiquement, par rapport à ceux chargés uniquement en noir de carbone) ainsi qu'une amélioration des propriétés mécaniques. Enfin, l'utilisation de liquides ioniques comme agents dispersants a été étudiée. Des composites caoutchouc-graphite avec 1 % en poids de liquides ioniques ont montré un renforcement plus élevé (+ 25 % pour la contrainte à 300 % d'élongation) tout en conservant un allongement à la rupture similaire par rapport à des composites contenant uniquement du noir de carbone / The aim of this study was the investigation of various dispersion methods for graphite-based fillers in elastomers such as polyisoprene, to enhance mechanical and barrier properties. To increase graphite-rubber interactions and so decrease filler-filler aggregation, graphite-based fillers have been chemically modified. Graphite was previously oxidized into graphite oxide (GO), bearing epoxide, hydroxyl and carboxylic acid groups, which could further act as anchor sites for molecules and polymer chains. To increase the compatibility between GO and the polymeric matrix, amines and alkoxysilanes, as well as polymer chains, were grafted on GO. Grafting contents between 4-50 wt% were obtained, depending on the functionalization technique which was used. A thermal modification path of GO was also investigated and led to the formation of porous graphite structure. Polyisoprene composites containing 15 phr of these graphite-based fillers were prepared and showed decreased air permeability (-70 % for composites containing thermally-treated graphite filler, as compared to those containing carbon black only) as well as enhanced tensile properties. Finally, the use of ionic liquids as dispersing agents was investigated. Natural rubber – graphite composites with 1 wt% of ionic liquid displayed enhanced reinforcement (+ 25 % for the stress at 300 % strain) while maintaining similar strain at break to composites containing carbon black only

[pt] Cerâmicas termomióticas vem despertando interesse devido a sua propriedade de apresentar, sob aquecimento, uma expansão térmica baixa, próxima a zero ou negativa. Essa propriedade é proveniente de uma vibração transversal do ânion, que resulta numa aproximação de átomos em determinadas direções. A família A2M3O12 (A = um cátion trivalente e M = Mo6 positivo ou W6 positivo) apresenta uma transição de fase de monoclínica para ortorrômbica, sendo somente a fase ortorrômbica que apresenta o comportamento termomiótico. Essa família, especificamente, vem sendo bastante pesquisada, pois possui a vantagem de permitir uma vasta flexibilidade química, sem mudar de estrutura cristalina e por consequência, permitir ajustes no coeficiente de expansão térmica de acordo com a aplicação a qual o material se destina. A expansão térmica próxima à zero pode levar a uma promissora alta resistência ao choque térmico. Esse trabalho teve como objetivo, estudar as propriedades térmicas e mecânicas do Al2W3O12 que possui baixa expansão térmica positiva com o objetivo de determinar sua resistência ao choque térmico pela figura de mérito de Hasselman. Para isso, todas as suas propriedades térmicas (expansão térmica e condutividade) e mecânicas (módulo de elasticidade e resistência mecânica) foram obtidas experimentalmente apresentando um valor promissor de 120K (comparável ao da safira) para resistência ao choque térmico pela figura de mérito de Hasselman sob condições severas de aquecimento. A partir desse resultado foi desenvolvido uma segunda pesquisa com o objetivo de refinar a microestrutura e aumentar a densidade relativa da cerâmica maciça do Al2W3O12 e assim incrementar suas propriedades mecânicas. Uma síntese por co-precipitação, seguida de uma prensagem isostática e uma sinterização desenvolvida em três etapas foram implementadas, obtendo-se um aumento de 91 porcento para 96 porcento na densidade relativa, com aumento de 19 porcento no módulo de elasticidade e de 35 porcento na dureza vickers se comparados aos resultados obtidos pela amostra sinterizada anteriormente pelo método convencional de sinterização em uma etapa. No terceiro estágio desta tese foi estudada a expansão térmica de uma novo material (In0,5(ZrMg)0,75Mo3O12) com promissora expansão térmica próxima a zero (10-7 K-1), a partir do cálculo da regra das misturas. O material foi sintetizado por evaportação total.e seu coeficiente de expansão térmica intrínseco determinado in situ por difração de Raios-X foi de 1,6x10-7 K-1 na faixa de temperatura de 100 a 500 graus Celsius, enquanto o coeficiente de expansão térmica maciço, medido por dilatometria, foi de 6,68 x 10-7 K-1, na faixa de temperatura de 100 a 800 graus Celsius. Esse material apresenta uma transição de fase de monoclínica para ortorrômbica na temperatura de 82 graus Celsius o que limita seu uso como material termomiótico em temperaturas abaixo de 100 graus Celsius. / [en] Thermomiotic ceramics have been arousing interest due to their property of presenting a low, near or zero thermal expansion under hearing. This property comes from a transverse vibration of the anion, which results in an approximation of atoms in certain crystallographic axes. The A2M3O12 family (A = a trivalent cation and M = Mo6 positive or W6 positive) presents a phase transition from monoclinic to orthorhombic, with only the orthorhombic phase exhibiting thermomiotic behavior. This family is widely researched since it has the advantage of allowing a wide chemical flexibility without changing the crystalline structure and consequently allowing adjustments in the coefficient of thermal expansion according to the application, which the material is intended. Thermal expansion close to zero can lead to a promising high thermal shock resistance. This work aimed to study the thermal and mechanical properties of Al2W3O12 that has low thermal expansion with the goal of determining its thermal shock resistance by the Hasselman figure of merit. For this, all its thermal properties (thermal expansion and conductivity) and mechanical (Young modulus and mechanical strength) were obtained experimentally and presented a promising value of 120K (comparable to sapphire) for thermal shock resistance by the figure of merit of Hasselman under severe heating. A second research was developed with the goal of refining the microstructure and increasing the relative density of the Al2W3O12 bulk ceramics and thus increasing its mechanical properties. A synthesis by co-precipitation, folled by an isostatic pressing and a three steps sintering were carried out, obtaining an increase of 91 percent to 96 percent in the relative density, with increase of 19 percent in modulus of elasticity and 35 percent in Vickers hardness when compared to conventional sintering. The thermal expansion of a new material (In0,5(ZrMg)0,75Mo3O12) with promising thermal expansion close to zero (10-7 K1), calculated by mixing rule was studied in the third chapter of this thesis. The material was synthesized by total evaporation. Its intrinsic thermal expansion coefficient was determined in situ by X-ray diffraction and presented a value of 1.6x10-7 K-1 in the temperature range of 100 to 500 Celsius degrees, while the coefficient of expansion of the bulk obtained by dilatometry, was 6.68 x 10-7 K-1, in the temperature range of 100 to 800 Celsius degrees. This material presents a phase transition from monoclinic to orthorhombic at 82 Celsius degrees, which limits its use as thermomiothic material at temperatures above 100 Celsius degrees.

Historically ceramic crystal laser material has had disadvantages compared to single crystal laser material. However, progress has been made in the last decade and a half to overcome the disadvantages associated with ceramic crystal. Today, because of the promise of ceramic crystal as a high power laser material, investigation into its properties, both physical and optical, is warranted and important. Thermal expansion was measured in this thesis for Nd:YAG (yttrium aluminum garnet) ceramic crystal using an interferometric method. The interferometer employed a spatially filtered HeNe at 633 nm wavelength. Thermal expansion coefficients measured for the ceramic crystal samples were near the reported values for single crystal Nd:YAG. With a similar experimental setup as that for the thermal expansion measurements, dn/dT for ceramic crystal Nd:YAG was measured and found to be slightly higher than the reported value for single crystal. Depolarization loss due to thermal gradient induced stresses can limit laser performance. As a result this phenomenon was modeled for ceramic crystal materials and compared to single crystals for slab and rod shaped gain media. This was accomplished using COMSOL Multiphysics, and MATLAB. Results indicate a dependence of the depolarization loss on the grain size where the loss decreases with decreased grain size even to the point where lower loss may be expected in ceramic crystals than in single crystal samples when the grain sizes in the ceramic crystal are sufficiently small. Deformation-induced thermal lensing was modeled for a single crystal slab and its relevance to ceramic crystal is discussed. Data indicates the most notable cause of deformation-induced thermal lensing is a consequence of the deformation of the top and bottom surfaces. Also, the strength of the lensing along the thickness is greater than the width and greater than that due to other causes of lensing along the thickness of the slab. Emission spectra, absorption spectra, and fluorescence lifetime were measured for Nd:YAG ceramic crystal and Yb:Lu2O3 ceramic crystal. No apparent inhomogeneous broadening appears to exist in the Nd:YAG ceramic at low concentrations. Concentration and temperature dependence effects on emission spectra were measured and are presented. Laser action in a thin disk of Yb:Y2O3 ceramic crystal was achieved. Pumping was accomplished with a fiber coupled diode laser stack at 938 nm. A slope efficiency of 34% was achieved with maximum output energy of 28.8 mJ/pulse.

We present a phase-field crystal model for solidification that accounts for thermal transport and a temperature-dependent lattice parameter. Elasticity effects are characterized through the continuous elastic field computed from the microscopic density field. We showcase the model capabilities via selected numerical investigations which focus on the prototypical growth of two-dimensional crystals from the melt, resulting in faceted shapes and dendrites. This work sets the grounds for a comprehensive mesoscale model of solidification including thermal expansion.